Solvents: Liquids that dissolve other substances (solutes), generally solids, without any change in chemical composition, as, water containing sugar. (Grant & Hackh's Chemical Dictionary, 5th ed)Hexanes: Six-carbon saturated hydrocarbon group of the methane series. Include isomers and derivatives. Various polyneuropathies are caused by hexane poisoning.Acetonitriles: Compounds in which a methyl group is attached to the cyano moiety.Organic Chemicals: A broad class of substances containing carbon and its derivatives. Many of these chemicals will frequently contain hydrogen with or without oxygen, nitrogen, sulfur, phosphorus, and other elements. They exist in either carbon chain or carbon ring form.PaintDimethylformamideChromatography, High Pressure Liquid: Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed.Toluene: A widely used industrial solvent.Methanol: A colorless, flammable liquid used in the manufacture of FORMALDEHYDE and ACETIC ACID, in chemical synthesis, antifreeze, and as a solvent. Ingestion of methanol is toxic and may cause blindness.Acetone: A colorless liquid used as a solvent and an antiseptic. It is one of the ketone bodies produced during ketoacidosis.Chromatography, Gas: Fractionation of a vaporized sample as a consequence of partition between a mobile gaseous phase and a stationary phase held in a column. Two types are gas-solid chromatography, where the fixed phase is a solid, and gas-liquid, in which the stationary phase is a nonvolatile liquid supported on an inert solid matrix.Chromatography, Affinity: A chromatographic technique that utilizes the ability of biological molecules to bind to certain ligands specifically and reversibly. It is used in protein biochemistry. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Chloroform: A commonly used laboratory solvent. It was previously used as an anesthetic, but was banned from use in the U.S. due to its suspected carcinogenicity.Xylenes: A family of isomeric, colorless aromatic hydrocarbon liquids, that contain the general formula C6H4(CH3)2. They are produced by the destructive distillation of coal or by the catalytic reforming of petroleum naphthenic fractions. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)Water: A clear, odorless, tasteless liquid that is essential for most animal and plant life and is an excellent solvent for many substances. The chemical formula is hydrogen oxide (H2O). (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Chromatography: Techniques used to separate mixtures of substances based on differences in the relative affinities of the substances for mobile and stationary phases. A mobile phase (fluid or gas) passes through a column containing a stationary phase of porous solid or liquid coated on a solid support. Usage is both analytical for small amounts and preparative for bulk amounts.Octanes: Eight-carbon saturated hydrocarbon group of the methane series. Include isomers and derivatives.Chromatography, Gel: Chromatography on non-ionic gels without regard to the mechanism of solute discrimination.Occupational Exposure: The exposure to potentially harmful chemical, physical, or biological agents that occurs as a result of one's occupation.Dimethyl Sulfoxide: A highly polar organic liquid, that is used widely as a chemical solvent. Because of its ability to penetrate biological membranes, it is used as a vehicle for topical application of pharmaceuticals. It is also used to protect tissue during CRYOPRESERVATION. Dimethyl sulfoxide shows a range of pharmacological activity including analgesia and anti-inflammation.Alcohols: Alkyl compounds containing a hydroxyl group. They are classified according to relation of the carbon atom: primary alcohols, R-CH2OH; secondary alcohols, R2-CHOH; tertiary alcohols, R3-COH. (From Grant & Hackh's Chemical Dictionary, 5th ed)Chromatography, Ion Exchange: Separation technique in which the stationary phase consists of ion exchange resins. The resins contain loosely held small ions that easily exchange places with other small ions of like charge present in solutions washed over the resins.Chromatography, Thin Layer: Chromatography on thin layers of adsorbents rather than in columns. The adsorbent can be alumina, silica gel, silicates, charcoals, or cellulose. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)2-Propanol: An isomer of 1-PROPANOL. It is a colorless liquid having disinfectant properties. It is used in the manufacture of acetone and its derivatives and as a solvent. Topically, it is used as an antiseptic.Trichloroethanes: Chlorinated ethanes which are used extensively as industrial solvents. They have been utilized in numerous home-use products including spot remover preparations and inhalant decongestant sprays. These compounds cause central nervous system and cardiovascular depression and are hepatotoxic. Include 1,1,1- and 1,1,2-isomers.Ionic Liquids: Salts that melt below 100 C. Their low VOLATILIZATION can be an advantage over volatile organic solvents.Chromatography, Liquid: Chromatographic techniques in which the mobile phase is a liquid.Enzymes, Immobilized: Enzymes which are immobilized on or in a variety of water-soluble or water-insoluble matrices with little or no loss of their catalytic activity. Since they can be reused continuously, immobilized enzymes have found wide application in the industrial, medical and research fields.Chemistry, Organic: The study of the structure, preparation, properties, and reactions of carbon compounds. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Tetrachloroethylene: A chlorinated hydrocarbon used as an industrial solvent and cooling liquid in electrical transformers. It is a potential carcinogen.Kinetics: The rate dynamics in chemical or physical systems.PrintingSolubility: The ability of a substance to be dissolved, i.e. to form a solution with another substance. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Hydrogen-Ion Concentration: The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH = log 1/2[1/(H+)], where (H+) is the hydrogen ion concentration in gram equivalents per liter of solution. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Benzene: Toxic, volatile, flammable liquid hydrocarbon byproduct of coal distillation. It is used as an industrial solvent in paints, varnishes, lacquer thinners, gasoline, etc. Benzene causes central nervous system damage acutely and bone marrow damage chronically and is carcinogenic. It was formerly used as parasiticide.Occupational Diseases: Diseases caused by factors involved in one's employment.Formamides: A group of amides with the general formula of R-CONH2.Trichloroethylene: A highly volatile inhalation anesthetic used mainly in short surgical procedures where light anesthesia with good analgesia is required. It is also used as an industrial solvent. Prolonged exposure to high concentrations of the vapor can lead to cardiotoxicity and neurological impairment.1-Propanol: A colorless liquid made by oxidation of aliphatic hydrocarbons that is used as a solvent and chemical intermediate.Temperature: The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.Enzyme Stability: The extent to which an enzyme retains its structural conformation or its activity when subjected to storage, isolation, and purification or various other physical or chemical manipulations, including proteolytic enzymes and heat.Methylene Chloride: A chlorinated hydrocarbon that has been used as an inhalation anesthetic and acts as a narcotic in high concentrations. Its primary use is as a solvent in manufacturing and food technology.Lipase: An enzyme of the hydrolase class that catalyzes the reaction of triacylglycerol and water to yield diacylglycerol and a fatty acid anion. It is produced by glands on the tongue and by the pancreas and initiates the digestion of dietary fats. (From Dorland, 27th ed) EC 3.1.1.3.HydrocarbonsStyrenes: Derivatives and polymers of styrene. They are used in the manufacturing of synthetic rubber, plastics, and resins. Some of the polymers form the skeletal structures for ion exchange resin beads.Ethylene Glycols: An ethylene compound with two hydroxy groups (-OH) located on adjacent carbons. They are viscous and colorless liquids. Some are used as anesthetics or hypnotics. However, the class is best known for their use as a coolant or antifreeze.Organic Chemistry Phenomena: The conformation, properties, reaction processes, and the properties of the reactions of carbon compounds.Cyclohexanes: Six-carbon alicyclic hydrocarbons.Benzene DerivativesMolecular Weight: The sum of the weight of all the atoms in a molecule.Solutions: The homogeneous mixtures formed by the mixing of a solid, liquid, or gaseous substance (solute) with a liquid (the solvent), from which the dissolved substances can be recovered by physical processes. (From Grant & Hackh's Chemical Dictionary, 5th ed)Magnetic Resonance Spectroscopy: Spectroscopic method of measuring the magnetic moment of elementary particles such as atomic nuclei, protons or electrons. It is employed in clinical applications such as NMR Tomography (MAGNETIC RESONANCE IMAGING).Catalysis: The facilitation of a chemical reaction by material (catalyst) that is not consumed by the reaction.Spectrophotometry, Ultraviolet: Determination of the spectra of ultraviolet absorption by specific molecules in gases or liquids, for example Cl2, SO2, NO2, CS2, ozone, mercury vapor, and various unsaturated compounds. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Protein Conformation: The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Alkanes: The generic name for the group of aliphatic hydrocarbons Cn-H2n+2. They are denoted by the suffix -ane. (Grant & Hackh's Chemical Dictionary, 5th ed)Chemistry, Physical: The study of CHEMICAL PHENOMENA and processes in terms of the underlying PHYSICAL PHENOMENA and processes.Air Pollutants, Occupational: Air pollutants found in the work area. They are usually produced by the specific nature of the occupation.Ethylene Dichlorides: Toxic, chlorinated, saturated hydrocarbons. Include both the 1,1- and 1,2-dichloro isomers. The latter is considerably more toxic. It has a sweet taste, ethereal odor and has been used as a fumigant and intoxicant among sniffers. Has many household and industrial uses.Mass Spectrometry: An analytical method used in determining the identity of a chemical based on its mass using mass analyzers/mass spectrometers.Volatilization: A phase transition from liquid state to gas state, which is affected by Raoult's law. It can be accomplished by fractional distillation.Surface-Active Agents: Agents that modify interfacial tension of water; usually substances that have one lipophilic and one hydrophilic group in the molecule; includes soaps, detergents, emulsifiers, dispersing and wetting agents, and several groups of antiseptics.Molecular Structure: The location of the atoms, groups or ions relative to one another in a molecule, as well as the number, type and location of covalent bonds.Amino Acid Sequence: The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.Gas Chromatography-Mass Spectrometry: A microanalytical technique combining mass spectrometry and gas chromatography for the qualitative as well as quantitative determinations of compounds.Physicochemical Phenomena: The physical phenomena describing the structure and properties of atoms and molecules, and their reaction and interaction processes.Styrene: A colorless, toxic liquid with a strong aromatic odor. It is used to make rubbers, polymers and copolymers, and polystyrene plastics.Carbon Disulfide: A colorless, flammable, poisonous liquid, CS2. It is used as a solvent, and is a counterirritant and has local anesthetic properties but is not used as such. It is highly toxic with pronounced CNS, hematologic, and dermatologic effects.Models, Molecular: Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.ButanonesElectrophoresis, Polyacrylamide Gel: Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.Neurasthenia: A mental disorder characterized by chronic fatigue and concomitant physiologic symptoms.Pseudomonas putida: A species of gram-negative, aerobic bacteria isolated from soil and water as well as clinical specimens. Occasionally it is an opportunistic pathogen.Thermodynamics: A rigorously mathematical analysis of energy relationships (heat, work, temperature, and equilibrium). It describes systems whose states are determined by thermal parameters, such as temperature, in addition to mechanical and electromagnetic parameters. (From Hawley's Condensed Chemical Dictionary, 12th ed)Chromatography, Supercritical Fluid: A CHROMATOGRAPHY method using supercritical fluid, usually carbon dioxide under very high pressure (around 73 atmospheres or 1070 psi at room temperature) as the mobile phase. Other solvents are sometimes added as modifiers. This is used both for analytical (SFC) and extraction (SFE) purposes.Substrate Specificity: A characteristic feature of enzyme activity in relation to the kind of substrate on which the enzyme or catalytic molecule reacts.Hydrolysis: The process of cleaving a chemical compound by the addition of a molecule of water.Dioxanes: 1,4-Diethylene dioxides. Industrial solvents. According to the Fourth Annual Report on Carcinogens (NTP 85-002, 1985), dioxane itself may "reasonably be anticipated to be a carcinogen." (Merck Index, 11th ed)Ethanol: A clear, colorless liquid rapidly absorbed from the gastrointestinal tract and distributed throughout the body. It has bactericidal activity and is used often as a topical disinfectant. It is widely used as a solvent and preservative in pharmaceutical preparations as well as serving as the primary ingredient in ALCOHOLIC BEVERAGES.Octanols: Isomeric forms and derivatives of octanol (C8H17OH).Escherichia coli: A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.Drug Stability: The chemical and physical integrity of a pharmaceutical product.Micelles: Particles consisting of aggregates of molecules held loosely together by secondary bonds. The surface of micelles are usually comprised of amphiphatic compounds that are oriented in a way that minimizes the energy of interaction between the micelle and its environment. Liquids that contain large numbers of suspended micelles are referred to as EMULSIONS.EstersAcetates: Derivatives of ACETIC ACID. Included under this heading are a broad variety of acid forms, salts, esters, and amides that contain the carboxymethane structure.Amino Acids: Organic compounds that generally contain an amino (-NH2) and a carboxyl (-COOH) group. Twenty alpha-amino acids are the subunits which are polymerized to form proteins.Chemistry, Agricultural: The science of the chemical composition and reactions of chemicals involved in the production, protection and use of crops and livestock. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Subtilisins: A family of SERINE ENDOPEPTIDASES isolated from Bacillus subtilis. EC 3.4.21.-Circular Dichroism: A change from planar to elliptic polarization when an initially plane-polarized light wave traverses an optically active medium. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Hydrocarbons, Chlorinated: Hydrocarbon compounds with one or more of the hydrogens replaced by CHLORINE.KetonesDetergents: Purifying or cleansing agents, usually salts of long-chain aliphatic bases or acids, that exert cleansing (oil-dissolving) and antimicrobial effects through a surface action that depends on possessing both hydrophilic and hydrophobic properties.Citraconic Anhydrides: Methylmaleic anhydrides.Automobiles: A usually four-wheeled automotive vehicle designed for passenger transportation and commonly propelled by an internal-combustion engine using a volatile fuel. (Webster, 1973)Chlorophenols: Phenols substituted with one or more chlorine atoms in any position.Models, Chemical: Theoretical representations that simulate the behavior or activity of chemical processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.Freeze Drying: Method of tissue preparation in which the tissue specimen is frozen and then dehydrated at low temperature in a high vacuum. This method is also used for dehydrating pharmaceutical and food products.AcetalsChemistry: A basic science concerned with the composition, structure, and properties of matter; and the reactions that occur between substances and the associated energy exchange.Chemical Fractionation: Separation of a mixture in successive stages, each stage removing from the mixture some proportion of one of the substances, for example by differential solubility in water-solvent mixtures. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Hydrocarbons, Aromatic: Organic compounds containing carbon and hydrogen in the form of an unsaturated, usually hexagonal ring structure. The compounds can be single ring, or double, triple, or multiple fused rings.Cattle: Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.Ether: A mobile, very volatile, highly flammable liquid used as an inhalation anesthetic and as a solvent for waxes, fats, oils, perfumes, alkaloids, and gums. It is mildly irritating to skin and mucous membranes.1-Butanol: A four carbon linear hydrocarbon that has a hydroxy group at position 1.Hydrogen Bonding: A low-energy attractive force between hydrogen and another element. It plays a major role in determining the properties of water, proteins, and other compounds.Rhizomucor: A genus of zygomycetous fungi of the family Mucoraceae, order MUCORALES.Chemical Phenomena: The composition, conformation, and properties of atoms and molecules, and their reaction and interaction processes.Protein Denaturation: Disruption of the non-covalent bonds and/or disulfide bonds responsible for maintaining the three-dimensional shape and activity of the native protein.ChymotrypsinogenEnzymes: Biological molecules that possess catalytic activity. They may occur naturally or be synthetically created. Enzymes are usually proteins, however CATALYTIC RNA and CATALYTIC DNA molecules have also been identified.Glycols: A generic grouping for dihydric alcohols with the hydroxy groups (-OH) located on different carbon atoms. They are viscous liquids with high boiling points for their molecular weights.Chromatography, DEAE-Cellulose: A type of ion exchange chromatography using diethylaminoethyl cellulose (DEAE-CELLULOSE) as a positively charged resin. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Solid Phase Microextraction: A solventless sample preparation method, invented in 1989, that uses a fused silica fiber which is coated with a stationary phase. It is used for sample cleanup before using other analytical methods.Stereoisomerism: The phenomenon whereby compounds whose molecules have the same number and kind of atoms and the same atomic arrangement, but differ in their spatial relationships. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)Spectrometry, Mass, Electrospray Ionization: A mass spectrometry technique used for analysis of nonvolatile compounds such as proteins and macromolecules. The technique involves preparing electrically charged droplets from analyte molecules dissolved in solvent. The electrically charged droplets enter a vacuum chamber where the solvent is evaporated. Evaporation of solvent reduces the droplet size, thereby increasing the coulombic repulsion within the droplet. As the charged droplets get smaller, the excess charge within them causes them to disintegrate and release analyte molecules. The volatilized analyte molecules are then analyzed by mass spectrometry.Occupational Medicine: Medical specialty concerned with the promotion and maintenance of the physical and mental health of employees in occupational settings.Chemistry, Pharmaceutical: Chemistry dealing with the composition and preparation of agents having PHARMACOLOGIC ACTIONS or diagnostic use.Industry: Any enterprise centered on the processing, assembly, production, or marketing of a line of products, services, commodities, or merchandise, in a particular field often named after its principal product. Examples include the automobile, fishing, music, publishing, insurance, and textile industries.Hydrophobic and Hydrophilic Interactions: The thermodynamic interaction between a substance and WATER.Crystallization: The formation of crystalline substances from solutions or melts. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Dioctyl Sulfosuccinic Acid: All-purpose surfactant, wetting agent, and solubilizer used in the drug, cosmetics, and food industries. It has also been used in laxatives and as cerumenolytics. It is usually administered as either the calcium, potassium, or sodium salt.Maleic Anhydrides: Used in copolymerization reactions, in the Diels-Alder(diene)synthesis, in the preparation of resins, pharmaceuticals and agricultural chemicals. It is a powerful irritant and causes burns.Butanols: Isomeric forms and derivatives of butanol (C4H9OH).Hot Temperature: Presence of warmth or heat or a temperature notably higher than an accustomed norm.Gases: The vapor state of matter; nonelastic fluids in which the molecules are in free movement and their mean positions far apart. Gases tend to expand indefinitely, to diffuse and mix readily with other gases, to have definite relations of volume, temperature, and pressure, and to condense or liquefy at low temperatures or under sufficient pressure. (Grant & Hackh's Chemical Dictionary, 5th ed)Polysorbates: Sorbitan mono-9-octadecanoate poly(oxy-1,2-ethanediyl) derivatives; complex mixtures of polyoxyethylene ethers used as emulsifiers or dispersing agents in pharmaceuticals.Furans: Compounds with a 5-membered ring of four carbons and an oxygen. They are aromatic heterocycles. The reduced form is tetrahydrofuran.Bacterial Proteins: Proteins found in any species of bacterium.Hippurates: Salts and esters of hippuric acid.Spectrometry, Fluorescence: Measurement of the intensity and quality of fluorescence.Respiratory Protective Devices: Respirators to protect individuals from breathing air contaminated with harmful dusts, fogs, fumes, mists, gases, smokes, sprays, or vapors.Plant Extracts: Concentrated pharmaceutical preparations of plants obtained by removing active constituents with a suitable solvent, which is evaporated away, and adjusting the residue to a prescribed standard.Liquid-Liquid Extraction: The removal of a soluble component from a liquid mixture by contact with a second liquid, immiscible with the carrier liquid, in which the component is preferentially soluble. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Chymotrypsin: A serine endopeptidase secreted by the pancreas as its zymogen, CHYMOTRYPSINOGEN and carried in the pancreatic juice to the duodenum where it is activated by TRYPSIN. It selectively cleaves aromatic amino acids on the carboxyl side.1-Octanol: A colorless, slightly viscous liquid used as a defoaming or wetting agent. It is also used as a solvent for protective coatings, waxes, and oils, and as a raw material for plasticizers. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)Ethylene Glycol: A colorless, odorless, viscous dihydroxy alcohol. It has a sweet taste, but is poisonous if ingested. Ethylene glycol is the most important glycol commercially available and is manufactured on a large scale in the United States. It is used as an antifreeze and coolant, in hydraulic fluids, and in the manufacture of low-freezing dynamites and resins.Polymers: Compounds formed by the joining of smaller, usually repeating, units linked by covalent bonds. These compounds often form large macromolecules (e.g., BIOPOLYMERS; PLASTICS).Halobacteriales: An order of extremely halophilic archaea, in the kingdom EURYARCHAEOTA. They occur ubiquitously in nature where the salt concentration is high, and are chemoorganotrophic, using amino acids or carbohydrates as a carbon source.Proteins: Linear POLYPEPTIDES that are synthesized on RIBOSOMES and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of AMINO ACIDS determines the shape the polypeptide will take, during PROTEIN FOLDING, and the function of the protein.Indicators and Reagents: Substances used for the detection, identification, analysis, etc. of chemical, biological, or pathologic processes or conditions. Indicators are substances that change in physical appearance, e.g., color, at or approaching the endpoint of a chemical titration, e.g., on the passage between acidity and alkalinity. Reagents are substances used for the detection or determination of another substance by chemical or microscopical means, especially analysis. Types of reagents are precipitants, solvents, oxidizers, reducers, fluxes, and colorimetric reagents. (From Grant & Hackh's Chemical Dictionary, 5th ed, p301, p499)Binding Sites: The parts of a macromolecule that directly participate in its specific combination with another molecule.Polyethylene Glycols: Polymers of ETHYLENE OXIDE and water, and their ethers. They vary in consistency from liquid to solid depending on the molecular weight indicated by a number following the name. They are used as SURFACTANTS, dispersing agents, solvents, ointment and suppository bases, vehicles, and tablet excipients. Some specific groups are NONOXYNOLS, OCTOXYNOLS, and POLOXAMERS.Spectroscopy, Fourier Transform Infrared: A spectroscopic technique in which a range of wavelengths is presented simultaneously with an interferometer and the spectrum is mathematically derived from the pattern thus obtained.Noise, Occupational: Noise present in occupational, industrial, and factory situations.X-Ray Diffraction: The scattering of x-rays by matter, especially crystals, with accompanying variation in intensity due to interference effects. Analysis of the crystal structure of materials is performed by passing x-rays through them and registering the diffraction image of the rays (CRYSTALLOGRAPHY, X-RAY). (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Molecular Conformation: The characteristic three-dimensional shape of a molecule.Technology, Pharmaceutical: The application of scientific knowledge or technology to pharmacy and the pharmaceutical industry. It includes methods, techniques, and instrumentation in the manufacture, preparation, compounding, dispensing, packaging, and storing of drugs and other preparations used in diagnostic and determinative procedures, and in the treatment of patients.Chemistry Techniques, Analytical: Methodologies used for the isolation, identification, detection, and quantitation of chemical substances.Green Chemistry Technology: Pollution prevention through the design of effective chemical products that have low or no toxicity and use of chemical processes that reduce or eliminate the use and generation of hazardous substances.Countercurrent Distribution: A method of separation of two or more substances by repeated distribution between two immiscible liquid phases that move past each other in opposite directions. It is a form of liquid-liquid chromatography. (Stedman, 25th ed)Chromatography, Agarose: A method of gel filtration chromatography using agarose, the non-ionic component of agar, for the separation of compounds with molecular weights up to several million.Spectrophotometry, Infrared: Spectrophotometry in the infrared region, usually for the purpose of chemical analysis through measurement of absorption spectra associated with rotational and vibrational energy levels of molecules. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Crystallography, X-Ray: The study of crystal structure using X-RAY DIFFRACTION techniques. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Methods: A series of steps taken in order to conduct research.Biotechnology: Body of knowledge related to the use of organisms, cells or cell-derived constituents for the purpose of developing products which are technically, scientifically and clinically useful. Alteration of biologic function at the molecular level (i.e., GENETIC ENGINEERING) is a central focus; laboratory methods used include TRANSFECTION and CLONING technologies, sequence and structure analysis algorithms, computer databases, and gene and protein structure function analysis and prediction.Peptides: Members of the class of compounds composed of AMINO ACIDS joined together by peptide bonds between adjacent amino acids into linear, branched or cyclical structures. OLIGOPEPTIDES are composed of approximately 2-12 amino acids. Polypeptides are composed of approximately 13 or more amino acids. PROTEINS are linear polypeptides that are normally synthesized on RIBOSOMES.Rhodococcus: A bacterial genus of the order ACTINOMYCETALES.Tanning: A process of preserving animal hides by chemical treatment (using vegetable tannins, metallic sulfates, and sulfurized phenol compounds, or syntans) to make them immune to bacterial attack, and subsequent treatments with fats and greases to make them pliable. (McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)Hempa: A chemosterilant agent that is anticipated to be a carcinogen.Spectrophotometry: The art or process of comparing photometrically the relative intensities of the light in different parts of the spectrum.Protein Binding: The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.Pesticide Residues: Pesticides or their breakdown products remaining in the environment following their normal use or accidental contamination.Protein Structure, Secondary: The level of protein structure in which regular hydrogen-bond interactions within contiguous stretches of polypeptide chain give rise to alpha helices, beta strands (which align to form beta sheets) or other types of coils. This is the first folding level of protein conformation.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Oxidation-Reduction: A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).Buffers: A chemical system that functions to control the levels of specific ions in solution. When the level of hydrogen ion in solution is controlled the system is called a pH buffer.Liquid Phase Microextraction: Miniaturized methods of liquid-liquid extraction.Environmental Monitoring: The monitoring of the level of toxins, chemical pollutants, microbial contaminants, or other harmful substances in the environment (soil, air, and water), workplace, or in the bodies of people and animals present in that environment.Particle Size: Relating to the size of solids.Deuterium: Deuterium. The stable isotope of hydrogen. It has one neutron and one proton in the nucleus.Medical Laboratory Personnel: Health care professionals, technicians, and assistants staffing LABORATORIES in research or health care facilities.Electrochemistry: The study of chemical changes resulting from electrical action and electrical activity resulting from chemical changes.Calorimetry, Differential Scanning: Differential thermal analysis in which the sample compartment of the apparatus is a differential calorimeter, allowing an exact measure of the heat of transition independent of the specific heat, thermal conductivity, and other variables of the sample.Amines: A group of compounds derived from ammonia by substituting organic radicals for the hydrogens. (From Grant & Hackh's Chemical Dictionary, 5th ed)Isomerism: The phenomenon whereby certain chemical compounds have structures that are different although the compounds possess the same elemental composition. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)Structure-Activity Relationship: The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups.Carbohydrates: The largest class of organic compounds, including STARCH; GLYCOGEN; CELLULOSE; POLYSACCHARIDES; and simple MONOSACCHARIDES. Carbohydrates are composed of carbon, hydrogen, and oxygen in a ratio of Cn(H2O)n.Phospholipids: Lipids containing one or more phosphate groups, particularly those derived from either glycerol (phosphoglycerides see GLYCEROPHOSPHOLIPIDS) or sphingosine (SPHINGOLIPIDS). They are polar lipids that are of great importance for the structure and function of cell membranes and are the most abundant of membrane lipids, although not stored in large amounts in the system.Chromatography, Reverse-Phase: A chromatography technique in which the stationary phase is composed of a non-polar substance with a polar mobile phase, in contrast to normal-phase chromatography in which the stationary phase is a polar substance with a non-polar mobile phase.Tandem Mass Spectrometry: A mass spectrometry technique using two (MS/MS) or more mass analyzers. With two in tandem, the precursor ions are mass-selected by a first mass analyzer, and focused into a collision region where they are then fragmented into product ions which are then characterized by a second mass analyzer. A variety of techniques are used to separate the compounds, ionize them, and introduce them to the first mass analyzer. For example, for in GC-MS/MS, GAS CHROMATOGRAPHY-MASS SPECTROMETRY is involved in separating relatively small compounds by GAS CHROMATOGRAPHY prior to injecting them into an ionization chamber for the mass selection.Biocatalysis: The facilitation of biochemical reactions with the aid of naturally occurring catalysts such as ENZYMES.Salts: Substances produced from the reaction between acids and bases; compounds consisting of a metal (positive) and nonmetal (negative) radical. (Grant & Hackh's Chemical Dictionary, 5th ed)EthaneGramicidin: A group of peptide antibiotics from BACILLUS brevis. Gramicidin C or S is a cyclic, ten-amino acid polypeptide and gramicidins A, B, D are linear. Gramicidin is one of the two principal components of TYROTHRICIN.Colloids: Two-phase systems in which one is uniformly dispersed in another as particles small enough so they cannot be filtered or will not settle out. The dispersing or continuous phase or medium envelops the particles of the discontinuous phase. All three states of matter can form colloids among each other.Esterification: The process of converting an acid into an alkyl or aryl derivative. Most frequently the process consists of the reaction of an acid with an alcohol in the presence of a trace of mineral acid as catalyst or the reaction of an acyl chloride with an alcohol. Esterification can also be accomplished by enzymatic processes.Isosorbide: 1,4:3,6-Dianhydro D-glucitol. Chemically inert osmotic diuretic used mainly to treat hydrocephalus; also used in glaucoma.Volatile Organic Compounds: Organic compounds that have a relatively high VAPOR PRESSURE at room temperature.Mouth Abnormalities: Congenital absence of or defects in structures of the mouth.Urea: A compound formed in the liver from ammonia produced by the deamination of amino acids. It is the principal end product of protein catabolism and constitutes about one half of the total urinary solids.Fatty Acids: Organic, monobasic acids derived from hydrocarbons by the equivalent of oxidation of a methyl group to an alcohol, aldehyde, and then acid. Fatty acids are saturated and unsaturated (FATTY ACIDS, UNSATURATED). (Grant & Hackh's Chemical Dictionary, 5th ed)Spectrum Analysis: The measurement of the amplitude of the components of a complex waveform throughout the frequency range of the waveform. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Chemical Precipitation: The formation of a solid in a solution as a result of a chemical reaction or the aggregation of soluble substances into complexes large enough to fall out of solution.Calibration: Determination, by measurement or comparison with a standard, of the correct value of each scale reading on a meter or other measuring instrument; or determination of the settings of a control device that correspond to particular values of voltage, current, frequency or other output.Chloroplast Thioredoxins: A subtype of thioredoxins found primarily in CHLOROPLASTS.Ventilation: Supplying a building or house, their rooms and corridors, with fresh air. The controlling of the environment thus may be in public or domestic sites and in medical or non-medical locales. (From Dorland, 28th ed)Glycosides: Any compound that contains a constituent sugar, in which the hydroxyl group attached to the first carbon is substituted by an alcoholic, phenolic, or other group. They are named specifically for the sugar contained, such as glucoside (glucose), pentoside (pentose), fructoside (fructose), etc. Upon hydrolysis, a sugar and nonsugar component (aglycone) are formed. (From Dorland, 28th ed; From Miall's Dictionary of Chemistry, 5th ed)Reproducibility of Results: The statistical reproducibility of measurements (often in a clinical context), including the testing of instrumentation or techniques to obtain reproducible results. The concept includes reproducibility of physiological measurements, which may be used to develop rules to assess probability or prognosis, or response to a stimulus; reproducibility of occurrence of a condition; and reproducibility of experimental results.Environmental Exposure: The exposure to potentially harmful chemical, physical, or biological agents in the environment or to environmental factors that may include ionizing radiation, pathogenic organisms, or toxic chemicals.Phenol: An antiseptic and disinfectant aromatic alcohol.
... analysis should be tweaked in the area of stationary phases to elute such analytes that may be sensitive to organic solvents. ... the PIPA acts as a typical nonpolar stationary phase that would be used in reverse-phased chromatography. There are also ... Hydrophobic interaction chromatography requires high concentration salt elutions and eluent cleaning to remove the salt. To ... Reverse-phased size-exclusion chromatography (SEC) revealed pore size and pore size distribution of the particles and its ...
... and the higher the concentration of organic solvent that will be required to elute the molecule. Many of the mathematical and ... Reversed-phase chromatography (also called RPC, reverse-phase chromatography, or hydrophobic chromatography) includes any ... hence the term reversed-phase chromatography. Reversed-phase chromatography employs a polar (aqueous) mobile phase. As a result ... "reversed-phase chromatography". Akul Mehta (December 27, 2012). "Principle of Reversed-Phase Chromatography HPLC/UPLC (with ...
On reverse-phase materials, a wash with a high percentage of organic solvent may suffice. Large pH shifts are also often ... As displacement chromatography offers the advantage of concentration of trace components, two dimensional chromatography ... as well as reversed-phase chromatography. Displacement chromatography is well suited for obtaining mg quantities of purified ... Retention in elution chromatography is usually controlled by adjusting the composition of the mobile phase (in terms of solvent ...
The maximum concentration of organic depends on the organic solvent itself, and on the micelle. This information is generally ... Micellar liquid chromatography (MLC) is a form of reversed phase liquid chromatography that uses an aqueous micellar solutions ... Reverse phase high-performance liquid chromatography (RP-HPLC) involves a non-polar stationary phase, often a hydrocarbon chain ... usually with a small amount of organic modifier added to complete the mobile phase. A typical reverse phase alkyl-bonded ...
HILIC can offer a ten fold increase in sensitivity over reversed-phase chromatography because the organic solvent is much more ... their concentration must be higher to achieve the same degree of retention for an analyte relative to an aprotic solvent - ... phases amide bonded phases cationic bonded phases zwitterionic bonded phases A typical mobile phase for HILIC chromatography ... See also Aqueous Normal Phase Chromatography It is commonly believed that in HILIC, the mobile phase forms a water-rich layer ...
In reversed-phase chromatography, solvent A is often water or an aqueous buffer, while B is an organic solvent miscible with ... This also improves the peak shape for tailed peaks, as the increasing concentration of the organic eluent pushes the tailing ... is a chromatographic technique which encompasses the mobile phase region between reversed-phase chromatography (RP) and organic ... showing normal phase elution using reversed-phase solvents.[citation needed] A separation in which the mobile phase composition ...
Most commonly, the crude product is desalted using ethanol precipitation, size exclusion chromatography, or reverse-phase HPLC ... Volume 5: Deprotect to completion in organic solvents. Glen Report 22 (2) Boal, J. H.; Wilk, A.; Harindranath, N.; Max, E. E.; ... In contrast, the concentration of the activator is primarily determined by its solubility in acetonitrile and is irrespective ... In contrast to organic solid-phase synthesis and peptide synthesis, the synthesis of oligonucleotides proceeds best on non- ...
THF is used as a component in mobile phases for reversed-phase liquid chromatography. It has a greater elution strength than ... "Drying of Organic Solvents: Quantitative Evaluation of the Efficiency of Several Desiccants". Journal of Organic Chemistry. 75 ... Immediately Dangerous to Life and Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH ... It is an aprotic solvent with a dielectric constant of 7.6. It is a moderately polar solvent and can dissolve a wide range of ...
Thirdly, proteins may be separated by polarity/hydrophobicity via high performance liquid chromatography or reversed-phase ... The proteins are eluted by a gradient of increasing amounts of an organic solvent, such as acetonitrile. The proteins elute ... One can express the active concentration of the protein as the percent of the total protein. SPR can be a powerful method for ... High performance liquid chromatography or high pressure liquid chromatography is a form of chromatography applying high ...
... as the stationary organic phase, and nitric acid as the mobile aqueous phase. The actinide elution sequence is reversed from ... Separation of the 3+ actinides can also be achieved by solvent extraction chromatography, using bis-(2-ethylhexyl) phosphoric ... This method was tried in two tests and instantly provided hundreds kilograms of material, but with actinide concentration 3 ... Two other phases, monoclinic and hexagonal, are known for this oxide. The formation of a certain Es2O3 phase depends on the ...
For reactions in aqueous solution, they must first be dissolved in an organic solvent, then diluted into the aqueous reaction ... Upon the standard deprotection, the conjugates obtained can be purified using reverse-phase or anion-exchange HPLC ... The biotin tag can be used in affinity chromatography together with a column that has avidin (or streptavidin or Neutravidin) ... which are compatible with most proteins at low concentrations. Because of the hydrophobicity of NHS-esters, NHS biotinylation ...
Industrial and analytical ion-exchange chromatography is another area to be mentioned. Ion-exchange chromatography is a ... Liquid-phase (aqueous) ion-exchange desalination has been demonstrated. In this technique anions and cations in salt water are ... Organic acids, often molecules containing −COO− (carboxylic acid) functional groups. Biomolecules that can be ionized: amino ... That happened only when water leaving the exchanger contains more than the desired maximal concentration of the ions being ...
Also possible are ion exchange chromatography, reversed-phase chromatography (RP), affinity chromatography or expanded bed ... The mobile phase or eluent is either a pure solvent or a mixture of different solvents. It is chosen so that the retention ... A solution of the organic material is pipetted on top of the stationary phase. This layer is usually topped with a small layer ... Because the column chromatography has a constant flow of eluted solution passing through the detector at varying concentrations ...
There is a notable rate enhancement when certain Diels-Alder reactions are carried out in polar organic solvents such as ... Regardless of which situation pertains, the HOMO and LUMO of the components are in phase and a bonding interaction results as ... Diels-Alder reactions can be reversible under certain conditions; the reverse reaction is known as the retro-Diels-Alder ... Several explanations for this effect have been proposed, such as an increase in effective concentration due to hydrophobic ...
... a clean eluent for reverse phase high performance chromatography". Analytical Communications. Royal Society of Chemistry. 33 (9 ... Water becomes less polar and behaves more like an organic solvent such as methanol or ethanol. Solubility of organic materials ... However, when the oxygen levels are lower, organic compounds can be quite stable in superheated water. As the concentration of ... Reverse phased HPLC often uses methanol / water mixtures as the mobile phase. Since the polarity of water spans the same range ...
Brodsky J, Ballschmiter K (1988). "Reversed phase liquid chromatography of PCBs as a basis for calculation of water solubility ... represents the concentration of solute A being tested, and "org" and "aq" refer to the organic and aqueous phases, respectively ... is defined as a particular ratio of the concentrations of a solute between the two solvents (a biphase of liquid phases), ... both phases usually are solvents. Most commonly, one of the solvents is water while the second is hydrophobic such as 1-octanol ...
The free base is then dissolved in an organic solvent, sulfuric acid added, and amphetamine precipitates out as the sulfate ... The concentrations of the main neurotransmitters involved in reward circuitry and executive functioning, dopamine and ... Gas chromatography-mass spectrometry (GC-MS) of amphetamine and methamphetamine with the derivatizing agent (S)-(−)- ... Subsequently, the cytosolic dopamine molecules are released from the presynaptic neuron into the synaptic cleft via reverse ...
... can also be isolated from whole blood samples by solid phase extraction (SPE) and detected using liquid chromatography ... or other organic solvents. The poppy straw methods predominate in Continental Europe and the British Commonwealth, with the ... The latter completely reverses morphine's effects, but may result in immediate onset of withdrawal in opiate-addicted subjects ... Urinary concentrations of endogenous codeine and morphine have been found to significantly increase in individuals taking L- ...
... by reverse-phase high-performance liquid chromatography estimation. Ashton CH (February 2001). "Pharmacology and effects of ... As with many aromatic terpenoids, THC has a very low solubility in water, but good solubility in most organic solvents, ... High concentrations are reached in neocortical, limbic, sensory and motor areas. Huestis MA (August 2007). "Human cannabinoid ... Röhrich J, Schimmel I, Zörntlein S, Becker J, Drobnik S, Kaufmann T, Kuntz V, Urban R (2010). "Concentrations of Δ9- ...
Pressure driven operations microfiltration ultrafiltration nanofiltration reverse osmosis Concentration driven operations ... In gas phase filtration different deposition mechanisms are operative, so that particles having sizes below the pore size of ... Rm can be interpreted as a membrane resistance to the solvent (water) permeation. This resistance is a membrane intrinsic ... Dense membranes are utilized for gas separations (removal of CO2 from natural gas, separating N2 from air, organic vapor ...
"Reversed-phase high-performance liquid chromatography of virus proteins and other large hydrophobic proteins in formic acid ... It is miscible with water and most polar organic solvents, and is somewhat soluble in hydrocarbons. In hydrocarbons and in the ... Pb(HCOO)2 + H2S → 2HCOOH + PbS Formic acid is named after ants which have high concentrations of the compound in their venom. ... Formic acid is often used as a component of mobile phase in reversed-phase high-performance liquid chromotagraphy (RP-HPLC) ...
For a cleaner product, the reaction is conducted in the gas phase or in an organic solvent. Ethylene fluorohydrin is obtained ... which is a solvent used in many products. Gas chromatography is the principal method for analysis and detection of ethylene ... At concentrations in the air about 200 parts per million, ethylene oxide irritates mucous membranes of the nose and throat; ... that is to reverse the ethylene oxide synthesis reaction. Thiocyanate ions or thiourea transform ethylene oxide into thiirane ( ...
The larger members are also poorly soluble in organic solvents as well as lipids. They are usually colorless. Although PAHs ... Detection of PAHs in materials is often done using gas chromatography-mass spectrometry or liquid chromatography with ... regulate concentrations of PAHs in air, water, and soil. The European Commission has restricted concentrations of 8 ... this pattern is reversed as the lower molecular weight PAH are attenuated by biotic decay and photodegradation. Evaluation of ...
It was later shown via vapor phase chromatography that the amount of the endo- epimer of product produced was less than 0.02%, ... In organic chemistry, the term 2-norbornyl cation (equivalent with 2-bicyclo-[2.2.1]heptyl cation) describes one of the three ... The major reason for this failure is reported to be extremely rapid forward and reverse reaction rates, which indicate a very ... In addition, Raman spectra of the 2-norbornyl cation in some acidic solvents show an absorption band at 3110 cm-1 indicative of ...
Lipids are usually defined as hydrophobic or amphipathic biological molecules but will dissolve in organic solvents such as ... Many viruses have an RNA genome, such as HIV, which uses reverse transcription to create a DNA template from its viral RNA ... This system of enzymes acts in three stages to firstly oxidize the xenobiotic (phase I) and then conjugate water-soluble groups ... Modern biochemical research has been greatly aided by the development of new techniques such as chromatography, X-ray ...
A solvent is a substance, that becomes a solution by dissolving a solid, liquid, or gaseous solute. A solvent is usually a liquid, but can also be a solid or gas. The most common solvent in everyday life is water.. Most other commonly-used solvents are organic (carbon-containing) chemicals. These are called organic solvents. Solvents usually have a low boiling point and evaporate easily or can be removed by distillation, thereby leaving the dissolved substance behind. Solvents should therefore not react chemically with the dissolved compounds - they have to be inert. Solvents can also be used to extract soluble compounds from a mixture, the most common example is the brewing ...
A solvation shell is the solvent interface of any chemical compound or biomolecule that constitutes the solute. When the solvent is water it is often referred to as a hydration shell or hydration sphere.. A classic example is when water molecules arrange around a metal ion. For example, if the latter were a cation, the electronegative oxygen atom of the water molecule would be attracted electrostatically to the positive charge on the metal ion. The result is a solvation shell of water molecules that surround the ion. This shell can be several molecules thick, dependent upon the charge of the ion, its distribution and spatial dimensions.. A number of molecules of solvent is involved in the solvation shell around anions and cations from a dissolved salt in a solvent. Metal ions in aqueous solutions form metal aquo complexes. This number can be determined by various methods ...
The Kauri-butanol value ("Kb value") is an international, standardized measure of solvent power for a hydrocarbon solvent, and is governed by an ASTM standardized test, ASTM D1133.[1] The result of this test is a scaleless index, usually referred to as the "Kb value". A higher Kb value means the solvent is more aggressive or active in the ability to dissolve certain materials. Mild solvents have low scores in the tens and twenties; powerful solvents like chlorinated solvents and "High Sol 10" or "High Sol 15" (naphthenic aromatic solvents) have ratings that are in the low hundreds.. In terms of the test itself, the kauri-butanol value (Kb) of a chemical shows the maximum amount of the hydrocarbon that can be added to a solution of kauri resin (a thick, gum-like material) in ...
... (1-methyl-4-[(oxocyclohexadienylidene)ethylidene]-1,4-dihydropyridine, MOED) is an organic dye belonging to the class of merocyanines. MOED is notable for its solvatochromic properties, meaning it changes color depending on the solvent in which it is dissolved. As shown in the structural formula, MOED can exist in two resonance forms: A neutral molecule and a zwitterion. Research indicates that the zwitterion form is most representative when the compound exists in polar solvents such as water, and the neutral form when it exists in nonpolar solvents such as chloroform. When MOED is dissolved in various liquids, its colour will vary, depending on the solvent and its polarity. In general, the more polar the solvent, the shorter the wavelengths of the light absorbed will be. When light of a certain colour ...
Organic solvents are psychoactive when sufficient amounts are inhaled. Such solvents are common inhalants for adolescents[4] due, in part, to the fact that they are inexpensive in comparison to other recreational drugs. Use of correction fluid as an inhalant can cause the heart to beat rapidly and irregularly, which can cause death. An unpleasant smell is added to some brands in order to deter abusers.[5] Companies have worked closely with authorities in order to ensure that all the warnings are duly mentioned on packaging (card and product labels) to inform parents and younger users of the risks associated with inhaling or drinking the fluid. India has imposed a ban on the retail sale of bottled nail polish remover and bottled correction fluid, but permits its sale in devices that provide a small amount of the chemical in a container that dispenses it in a controlled way. The manufacturer is required to ...
... (also known as Nile blue oxazone) is a lipophilic stain. Nile red stains intracellular lipid droplets yellow. In most polar solvents, Nile red will not fluoresce; however, when in a lipid-rich environment can be intensely fluorescent, with varying colours from deep red (for polar membrane lipid) to strong yellow-gold emission (for neutral lipid in intracellular storages). The dye is highly solvatochromic and its emission and excitation wavelength both shift depending on solvent polarity [1] and in polar media will hardly fluoresce at all.[2] Nile red has applications in cell biology, where it can be used as a membrane dye which can be readily visualized using an epifluorescence microscope with excitation and emission wavelengths usually shared with red fluorescent protein. Nile red has also been used as part of a sensitive detection process for microplastics in bottled water.[3][4] ...
Solvation significantly affects the basicity of amines. N-H groups strongly interact with water, especially in ammonium ions. Consequently, the basicity of ammonia is enhanced by 1011 by solvation. The intrinsic basicity of amines, i.e. the situation where solvation is unimportant, has been evaluated in the gas phase. In the gas phase, amines exhibit the basicities predicted from the electron-releasing effects of the organic substituents. Thus tertiary amines are more basic than secondary amines, which are more basic than primary amines, and finally ammonia is least basic. The order of pKb's (basicities in water) does not follow this order. Similarly aniline is more basic than ammonia in the gas phase, but ten thousand times less so in aqueous solution.[11]. In aprotic polar solvents such as DMSO, DMF, and acetonitrile the energy of solvation is not as high as in protic polar ...
This is a key difference between the SN1 and SN2 mechanisms. In the SN1 reaction, the nucleophile attacks after the rate-limiting step is over. But in a SN2 reaction, the nucleophile forces off the leaving group in the limiting step. In other words, the rate of SN1 reactions depend only on the concentration of the substrate while the SN2 reaction rate depends on the concentration of both the substrate and nucleophile. In cases where both mechanisms are possible (for example at a secondary carbon center), the mechanism depends on solvent, temperature, concentration of the nucleophile or on the leaving group. SN2 reactions are generally favored in primary alkyl halides or secondary alkyl halides with an aprotic solvent. They occur at a negligible rate in tertiary alkyl halides due to steric hindrance. SN2 and SN1 are two extremes of a sliding scale of reactions. It is possible to find many ...
... is an organic compound with the molecular formula (CH2)5NH. This heterocyclic amine consists of a six-membered ring containing five methylene bridges (-CH2-) and one amine bridge (-NH-). It is a colorless liquid with an odor described as objectionable, and typical of amines. the name comes from the genus name Piper, which is the Latin word for pepper. Although piperidine is a common organic compound, it is best known as a representative structure element within many pharmaceuticals and alkaloids. Piperidine was first reported in 1850 by the Scottish chemist Thomas Anderson and again, independently, in 1852 by the French chemist Auguste Cahours, who named it. Both men obtained piperidine by reacting piperine with nitric acid. Industrially, piperidine is produced by the hydrogenation of pyridine, usually over a molybdenum disulfide catalyst: C5H5N + 3 H2 → C5H10NH Pyridine can also be reduced to piperidine via a modified Birch reduction ...
... (MMPP) is a water-soluble peroxy acid used as an oxidant in organic synthesis. Its main areas of use are the conversion of ketones to esters (Baeyer-Villiger oxidation), epoxidation of alkenes (Prilezhaev reaction), oxidation of sulfides to sulfoxides and sulfones, oxidation of amines to produce amine oxides, and in the oxidative cleavage of hydrazones. Due to its insolubility in nonpolar solvents MMPP has seen less use than the more widely used meta-chloroperoxybenzoic acid (mCPBA). Although work up procedures are more simply handled in polar solvents, usage of MMPP to oxidize nonpolar substrates in biphasic media combined with a phase transfer catalyst have been inefficient. Despite this MMPP has certain advantages over mCPBA including a lower cost of production and increased stability. MMPP is also used as the active ingredient in certain surface disinfectants such as Dismozon Pur. ...
The rate of reaction for many reactions involving unimolecular heterolysis depends heavily on rate of ionization of the covalent bond. The limiting reaction step is generally the formation of ion pairs. One group in the Ukraine did an in-depth study on the role of nucleophilic solvation and its effect on the mechanism of bond heterolysis. They found that the rate of heterolysis depends strongly on the nature of the solvent. A change of reaction medium from hexane to water increases the rate of t-BuCl heterolysis by 14 orders of magnitude.[5] This is caused by very strong solvation of the transition state. The main factors that affect heterolysis rates are mainly the solvent's polarity and electrophilic as well as its ionizing power. The polarizability, nucleophilicity and cohesion of the solvent had a much weaker effect on heterolysis.[5] However, there is some debate on the effects of the nucleophilicity of ...
Mare Piirsalu on töölise tütar.[1] Lõpetas 1969 Paide 1. Keskkooli, 1974 TÜ keemia osakonna, M.Sc. (1997, TÜ), väitekiri "Alküülbensoaatide ja asendatud fenüülbensoaatide leeliselise hüdrolüüsi kineetika uurimine", Ph.D. (TÜ, 2003), väitekiri "Substituent, temperature and solvent effects on the alkaline hydrolysis of substituted phenyl and alkyl esters of benzoic acid". Oli 1974-76 Tallinna Polütehnilise Instituudi (TPI) sanitaartehnilise probleemlabori vaneminsener, 1976-90 TÜ orgaanilise keemia kateedri nooremteadur, 1990-92 keemilise kineetika ja katalüüsi labori nooremteadur, 1992- keemiline füüsika instituudi teadur.[1] ...
A solvent (frae the Laitin solvō, "I loosen, untie, I solve") is a substance that dissolves a solute (a chemically different liquid, solid or gas), resultin in a solution. ...
Results for solvent separation equipment from ​​RediSep, ​​CombiFlash, ACQUITY and other leading brands. Compare and contact a ... Preparative Chromatography UV Flash - Solutions. High performance flash chromatography separation. As an organic chemist your ... One can say that HILIC is a normal-phase (NPLC) type of separation but uses reversed-phase (RPLC) type eluents. In HILIC one ... buffer and a high concentration of water-miscible organic solvent - Improved ... ...
Results for solvent separation equipment from Airdot, AMBERLITE, Analtech and other leading brands. Compare and contact a ... ES Industries manufactures Polar Bonded materials for Normal Phase HPLC that are compatible with most organic solvents. These ... Prepsolv - Solvents optimized for preparative Chromatography. Prepsolv® solvents are tailored to the requirements of ... One can say that HILIC is a normal-phase (NPLC) type of separation but uses reversed-phase (RPLC) type eluents. In HILIC one ...
... of the electrospray voltage decreased as the concentration of organic solvent in the eluent increased during reversed-phase LC ... Changes in liquid composition during gradient elution liquid chromatography (LC) coupled to mass spectrometry (MS) analyses ...
... analysis should be tweaked in the area of stationary phases to elute such analytes that may be sensitive to organic solvents. ... the PIPA acts as a typical nonpolar stationary phase that would be used in reverse-phased chromatography. There are also ... Hydrophobic interaction chromatography requires high concentration salt elutions and eluent cleaning to remove the salt. To ... Reverse-phased size-exclusion chromatography (SEC) revealed pore size and pore size distribution of the particles and its ...
Samples are loaded at high organic solvent concentration and eluted by increasing the polarity of the mobile phase (e.g. an ... 1 The abbreviations used are: SCX, strong cation exchange; HILIC, hydrophilic interaction chromatography; RP, reverse phase; 2D ... Peptide separation in normal-phase liquid chromatography: study of selectivity and mobile phase effects on various columns. J. ... Yoshida, T. (1998 ) Calculation of peptide retention coefficients in normal-phase liquid chromatography. J. Chromatogr. A 808, ...
Reversed-phase chromatography of proteins using ion-pairing reagents such as TFA or FA can be used to separate protein mixtures ... Gradients of increasing organic solvent concentration are frequently used to affect separations in the presence of ion-pairing ... Protein Reversed-Phase Columns. Reversed-Phase Chromatography. Reversed-phase chromatography of proteins, performed on columns ... BioSuite pPhenyl Reversed-Phase Chromatography (RPC) HPLC Columns. BioSuite RPC Column offerings include a phenyl (pPhenyl) ...
... and the higher the concentration of organic solvent that will be required to elute the molecule. Many of the mathematical and ... Reversed-phase chromatography (also called RPC, reverse-phase chromatography, or hydrophobic chromatography) includes any ... hence the term reversed-phase chromatography. Reversed-phase chromatography employs a polar (aqueous) mobile phase. As a result ... "reversed-phase chromatography". Akul Mehta (December 27, 2012). "Principle of Reversed-Phase Chromatography HPLC/UPLC (with ...
... is achieved only upon further separation on SDS PAG electrophoresis or C4-reverse phase high pressure liquid chromatography ( ... The organic solvents employed in eluting tumor necrosis factor from the C4 column reduced tumor necrosis factor activity about ... Indole acetic acid was added to give a final concentration of 20 μg/ml and the culture grown to A550 =1. 10 ml of cells were ... Reverse-phase HPLC. Tumor necrosis factor also was purified by reverse-phase HPLC using C4 Synchropak columns on Waters ...
The other methods include UV spectrometry and reversed-phase liquid chromatography, the latter with a detection limit in blood ... The sodium salts are soluble in water but insoluble in organic solvents. Further physical and chemical properties of warfarin ... The sodium salt is available at 0.5% concentrate for use at a final concentration of 0.05% in liquid base. Warfarin is also ... When a single oral dose of 1.5 mg warfarin/kg was given to male and female volunteers, maximum concentration in plasma was ...
The U.S. EPA method 549.2 utilizes reversed-phase chromatography with ion pairing for the separation of diquat and paraquat ... For HILIC, a water sample would first require dilution with the organic solvent. ... The possibility of removing laborious and time-consuming solid phase extraction and sample concentration is highly desirable. ... require the use of ion pairing additives when analyzing quaternary amines by reversed-phase chromatography. ...
The components were isolated by chromatography on C18 reverse phase silica gel followed by DE52 anion exchange separation, and ... Chromatography on ODS-AQ Gel (Reverse Phase C18 Silica). This chromatography was made possible by the development of C18 silica ... packing that can operate in an aqueous environment without organic solvent; ODS-AQ gel. ... To prepare standards GSH was dissolved in 8% TCA at approximately the same concentration as the measurable thiol in the ASF and ...
The resulting extract was divided into five fractions: two for analysis by two separate reverse phase (RP)/UPLC-MS/MS methods ... Each reconstitution solvent contained a series of standards at fixed concentrations to ensure injection and chromatographic ... Samples were placed briefly on a TurboVap (Zymark) to remove the organic solvent. The sample extracts were stored overnight ... Samples were run in a Waters ACQUITY ultra-performance liquid chromatography (UPLC) and a Thermo Scientific Q-Exactive high ...
Reversed-phase SPE is considered the least selective retention mechanism when compared to normalphase or ion-exchange SPE. ... Reversed-Phase SPE Methodology in Solid Phase Extraction. ... sorbent functional groups with an organic solvent or solvent ... GC analysis often requires further SPE eluate concentration and/or possible matrix exchange with a more volatile solvent. ... Analytical Chromatography Home * Analytical / Chromatography Products * Air Monitoring * Analytical Reagents & Solvents * ...
Activities were analyzed by reverse-phase high-performance liquid chromatography (HPLC) with equipment consisting of a tertiary ... supplementing the reaction mixture with the corresponding concentration of organic solvent (12% acetonitrile, 6% DMSO, or 3% ... vi) Activity in organic solvents.The relative activities in organic solvents were assessed with the ABTS assay described above ... was defined as the ratio of the activity in the presence of organic solvent to that in the absence of organic solvent, ...
... to allow the direct injection of organic solvents onto a reversed phase system. As part of the study the mode of 2D operation ... "Micro Flow Liquid Chromatography MS/MS: The Present and Future in Bioanalytical Laboratories", Chad Christianson, Casey Johnson ... chemists are charged with the task of developing high sensitivity assays for drug candidates with low circulating concentration ... Methods - The mAb was analyzed using normal flow liquid chromatography (LC)-MS method. The intact mAb protein was eluted from a ...
reciprocal of the organic solvent concentration in an aqueous binary mobile... ... of the solute on hydrophobic interaction with the stationary ligand in reversed-phase high-performance liquid chromatography. ... reciprocal of the organic solvent concentration in an aqueous binary mobile phase) and on the 1-octanol/water partition ... the effect on the partition coefficient depends on the difference in the abilities of the organic solvent and water to interact ...
The effects of changing the organic-aqueous ratio, the pH of the aqueous phase, the flow rate of the mobile phase and the ... concentration of 0.075 mg/ml in the same solvent mixture, which corresponded to the theoretical 100% concentration level of the ... effective and state-of-the-art reversed-phase chromatographic method for routine analysis. Our literature search revealed that ... The aim of this work was to develop a rapid, effective high-performance liquid chromatography method to assay aminophenazone in ...
Organic Solvent Modifier and Temperature controllers in first state Exclusion Chromatography on Reversed-Phase Columns, Journal ... Viovy, Advanced concentrations for buy metabolic effects of phone. Heller, C, Principles of DNA hydrogen with molecular ... buy metabolic of siRNA Stereoisomers customizing Reversed-Phase Ion-Pairing Chromatography, Journal of Chromatography A, 2017, ... Selected Organic Solvents as Electroosmotic Velocity Markers in Micellar Electrokinetic Capillary Chromatography. compound of ...
Thus, the present cyclic oligopeptide is stable under strict conditions, such as those for reverse phase chromatography, and it ... The terms "pharmaceutically-acceptable organic solvent" refer to a solvent which is capable of having an oligopeptide of the ... Thereafter, a test oligopeptide solution (solvent: PBS) was added to one well to a final concentration of 20 μM, and only a ... Thus, the cyclic oligopeptide of the present invention can be purified by reverse phase chromatography, thereby increasing ...
... and neutral fractions suggested the presence of uleine that was isolated from the alkaloid fraction by column chromatography ... 2695, USA), C-18 reverse phase column (5 μm, 125 × 45 mm, LiChrocart 125-4, Merck, Germany), at 40 °C, flow rate of 1 mL/min, ... HCl 1 N (500 mL) and was extracted with dichloromethane (5 × 200 mL). The organic solvent was removed in a rotary evaporator ... ammonium hydroxide, followed by extraction with dichloromethane (5 × 200 mL). Solvent concentration in a rotary evaporator ...
The analysis of micropollutants was done using a binary gradient of DI water (A) and organic solvent (B) at 0.2 mL/min, as the ... chemicals in the liquid and solid phases of activated sludge by solid phase extraction and gas chromatography-mass spectrometry ... Chemical separation was achieved using a 4 μm C12 polar reversed-phase column with a length of 150 mm and inner diameter of 2.0 ... Concentrations of organic micropollutants at sampling points A, B, C and D (* indicates that the mean value (n = 3) is lower ...
... stationary phase to cleanup your sample for chromatographic analysis. ... Learn how to select the optimal solid phase extraction (SPE) ... Aqueous or organic samples (low salt concentration). * ... SPE phases in depth - functionality and typical applications Polymerics Reversed Phase Silica Phases Normal Phase Silica Phases ... Chromatography Sample Preparation › * Sample Preparation Consumables › * Solid Phase Extraction (SPE) Consumables › * SPE Phase ...
What is Organic solvent? Meaning of Organic solvent as a finance term. What does Organic solvent mean in finance? ... Definition of Organic solvent in the Financial Dictionary - by Free online English dictionary and encyclopedia. ... Behaviour of proteins on reversed-phase supports during high-performance liquid chromatography and prediction of protein ... Treatment with organic solvents for the delignification of rice husk was optimized by varying the concentration of solvents, ...
The final concentration of organic solvent was ⋜0.5% by volume. Modifications of the published procedure (11) included (i) use ... on reverse-phase columns (Whatman Partisil 10 ODS-2; 250 × 4 mm) on a Waters HPLC system equipped with a photodiode array ... All samples were extracted with triple solvent and the component glucosinolates were resolved by paired-ion chromatography (18 ... Although triple solvent is a more efficient solvent, it was not used to make these preparations because solvent residues could ...
Impact of Injection Solvent Choice on Peak Shape and Resolution in Reversed-phase Flash Chromatography. Reversed-phase ... Commonly used reversed-phase solvents typically include water with an organic solvent such as methanol or acetonitrile - each ... to purify you want your crude sample fully solubilized in the weakest possible solvent at the highest possible concentration. ... Greener reversed-phase Flash Chromatography Using Acetone Instead of Acetonitrile. As reversed-phase flash chromatography gains ...
  • Tryptic peptides are separated on TSKgel Amide-80 columns using a shallow inverse organic gradient. (mcponline.org)
  • Although bioactive peptides can be produced chemically by a variety of synthesis strategies, recombinant technology offers the potential for inexpensive, large-scale production of peptides without the use of organic solvents, highly reactive reagents or potentially toxic chemicals. (patentsencyclopedia.com)
  • These columns are quite useful for 2-D LC MS/MS proteomics applications or for neuropeptides, growth factors, CNBr peptide fragments, and synthetic peptides as a complement to RPC, or to remove organic reagents from peptide samples which would cause smearing on a RPC column. (nestgrp.com)
  • Especially for peptidomics, 2-DE is difficult to apply, due to the low concentration of the peptide molecules, their small sizes (up to 10 kDa), their partial hydrophobic character, and their ionic characteristics, as many peptides are strongly cationic. (scielo.br)
  • This includes chromatographic aspects as the selection and effects of mobile and stationary phase, flow rate and temperature, as well as mass spectrometric characteristics such as ionization and detection modes, collision-induced dissociation of peptides and factors influencing the mass spectrometric response. (chemweb.com)
  • Reversed phase chromatography also separates proteins and peptides on the basis of hydrophobicity. (cytivalifesciences.com)
  • First a top-down approach was used on intact and reduced MAbs by liquid chromatography coupled to an electrospray ionization-time of flight mass spectrometer (LC-ESI-TOF), which provided fast and accurate profiles of MAbs glycosylation patterns for routine controls. (chemweb.com)
  • The possibility of removing laborious and time-consuming solid phase extraction and sample concentration is highly desirable. (waters.com)
  • The use of solid-phase sorbents in techniques like solid-phase extraction (SPE), solid-phase microextraction (SPME), stir-bar sorptive extraction (SBSE), and others is becoming well-established for analytical extraction and sample cleanup, though development of new, often selective, phases continues. (chromatographyonline.com)
  • The research that appeared to spark an onslaught of modified applications was a gel permeation chromatography technique of fixing poly(isopropyl acrylate) (PIPA) strands to glass beads and separating a mixture of dextrans, which was developed by Gewehr et al. (wikipedia.org)
  • Also called Gel Permeation Chromatography. (slideserve.com)
  • Finally, a change of solvent or phase (A3) is sometimes needed due to incompatabilities between the sample and the analytical method. (umass.edu)
  • For analytical plates, because thin layer chromatography is extremely sensitive, it is really important to apply a small quantity using a glass capillary ( or a micro pipette ) to get optimal resolution. (silicycle.com)
  • For analytical chromatography, co-spotting is frequently used for similar polarity products. (silicycle.com)
  • The method used showed linearity in the concentration ranges of 0.25 to 16.0 µg mL−1 for enrofloxacin (r = 0.9997) and 0.125 to 8.0 µg mL−1 for piroxicam (r = 0.9999) as well as precision (relative standard deviation lower than 2%), accuracy (mean recovery 100 ± 2%), and robustness, according to ICH (International Conference on Harmonization) and AOAC (Association of Official Analytical Chemists) guidelines. (bvsalud.org)
  • Its innovative algorithms significantly reduce the amount of solvent required to complete the puriifcation and is also fully compatible with ACI systems. (biotage.com)
  • One advantage of the latter is the reduced amount of solvent that must be disposed of. (umass.edu)
  • The most suitable solvent system is the one that moves all components off the baseline with Rf values between 0.15 and 0.85 ( ideally, close to 0.2 - 0.4 ). (silicycle.com)
  • Place approximately 0.5 cm of the suitable solvent system inside the chamber. (silicycle.com)
  • These systems showed a very high preference for K + over Na + ion, which was suitable for fluorescence imaging of the potassium concentration gradient in a living cell. (go.jp)