An Improved High Performance Liquid Chromatographic Method for Tryptophan Analysis in Rat Brain Administrated by Seaweed Abstract.
Indirect evidence has implicated a role for central angiotensin II in blood pressure control. To answer directly the question of whether angiotensin II exists in the brain, independent of blood-borne angiotensin, and to quantify the amounts in different parts of the central nervous system, a sensitive radioimmunoassay was used to measure extracts of male adult rat brain hypothalamus and cortex after purification with high pressure liquid chromatography with a high recovery. The fractions coeluted with authentic angiotensin. Rats were nephrectomized bilaterally, and 24 hours later the brains were extracted in acetic acid and boiled. SepPak C-18 purification preceded reverse phase high pressure liquid chromatography. High pressure liquid chromatography revealed two peaks, one which comigrated precisely with [Ile5] angiotensin II, and another smaller peak which overlapped with [Ile5] angiotensin III. The highest levels were found in the hypothalamus (125 pg/g tissue), pituitary (190 pg/g tissue), ...
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A new high-performance liquid chromatographic method was developed for quantification of midazolam in plasma samples from intensive care unit patients on long-term intravenous infusion of this benzodiazepine. Plasma samples (0.5 ml) were mixed with 1 microgram flurazepam (internal standard), alkalinized with 2.5 N NaOH, and extracted with toluene. The organic phase was evaporated to dryness, and the residue was dissolved in the mobile phase (acetonitrile/0.05 M phosphate buffer pH 4.5) and injected into the analytical column (C18 Nova-Pak 3.9 x 150 mm, 4 microns, maintained at room temperature; mobile phase flow rate: 1.2 ml/minute). The eluate was monitored at 207 nm, which reduced the risk of interferences from concurrent medications. Retention times of flurazepam, 1-hydroxymidazolam (an active metabolite) and midazolam were approximately 4.5, 6.1 and 13.5 minutes, respectively. The assay was linear over the range 100 to 3000 ng/ml. The coefficients of variation of the within-day and ...
The general aim of this thesis was to evaluate a newly designed and constructed miniaturized rotating disk apparatus for in vitro dissolution rate measurements of different drug substances from all of the classes in the Biopharmaceutical Classification System (BCS). The new equipment is based on a low volume flow-through cell of Plexiglas, a gold plated magnetic bar and a special designed press. The disk of drug substance (approx. 5 mg) is placed eccentrically in the bar. Rotation speeds were set with a graded magnetic stirrer. An external HPLC pump delivered a continuous flow of aqueous medium to the flow-through cell during dissolution testing.. A reversed phase high-performance liquid chromatography system using diode array detection (RP-HPLC-DAD) was coupled online to the new equipment. The injections from the miniaturized rotating disk outlet into the quantifying HPLC system were controlled by a six-position switching valve. The injection volumes from the valve and the autosampler, used for ...
Determination of free urinary cortisol is a test of choice in the diagnosis of Cushings syndrome. In this study, cortisol was quantified using reversed-phase high-performance liquid chromatography (RP-HPLC) in urine samples previously extracted with ether and using triamcinolone acetonide as internal standard (IS). A BDS-Hypersil-C18® column, water-acetonitrile (72:28; v/v), with a flow rate of 1.0 mL/min and detection at 243 nm were used. This method showed to be both effective and efficient, with sensitivity and linearity ranging from 2.50 to 150 μg/L, and can be used in substitution to the radioimmunoassay technique within this concentration range ...
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We describe a simple, sensitive, and specific high-performance liquid-chromatographic method with ultraviolet detection (256 nm) for the simultaneous analysis of nicotine and cotinine in urine of passive smokers. The analytes are extracted and purified from the complex and impure matrix in two stages; first, by liquid-liquid extraction and followed by solid-phase extraction (C2 column). We used a "DB" C8 5-microns-particle column (25 x 0.46 cm) and a mobile phase of phosphate-citrate buffer and acetonitrile (91:9 by vol) containing 5 mL of triethylamine and 600 mg of heptanesulfonate per liter, adjusted to pH 4.4, to separate the compounds. Two internal standards (2-phenylimidazole and N-ethylnorcotinine) were used. The detection limit of the HPLC assay was less than 1 microgram/L for both analytes. The average interassay CV for nicotine was 7.6%, for cotinine 6.5%, in the concentration range 0-60 micrograms/L. The mean analytical recovery of nicotine with respect to the internal standard ...
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This article details the elements used in the method verification for the simultaneous high performance liquid chromatography (HPLC) assay of Pentoxifylline, Mupirocin, Itraconazole, and Fluticasone Propionate in Humco™ Lavare Wound base. The method was proven to be linear over 50%-150% of the nominal concentration of the standards. The method was proven to be accurate over 50%-150%, with 98%-102% recovery of the actives from spiked placeboes over that range. The method was shown to be specific to the analytes listed and precise, yielding acceptable results for system reproducibility and method repeatability. The method, as written, is considered to have been verified.
Background: Losartan potassium is a non-peptide AT1 receptor drug used in the treatment of hypertension. Methods: A simple, rapid, sensitive, and validated isocratic reverse-phase ultra-performance liquid chromatographic (RP-UPLC) method was developed and validated for the determination of losartan potassium (LOS) in bulk drug and tablets. The assay was developed using Waters Acquity BEH C18 (100 mm × 2.1 mm), 1.7-μm column with a mobile phase consisting of a mixture of phosphate buffer (pH 3.2) and acetonitrile (50:50 v/v). Results: An assay with a total run time of only 5 min was developed. The method monitored at 245 nm exhibited linearity over a concentration range of 2.0 to 15.0 μg mL−1 LOS. The limits of detection and quantification (signal-to-noise ratio (S/N) = 10) were found be 0.018 and 0.054 μg mL−1 , respectively. The intraday and interday RSDs were less than 1.0%. The method was validated by the determination of LOS levels in tablets where the percentage on the label claim ...
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Background: Elevated circulating levels of "BNP" as detected on commercial antibody-based assays in heart failure (HF) patients may reflect a mixture of degraded BNP fragments, rather than intact BNP1-32.. Methods: Blood samples from 20 HF patients were collected, immediately centrifuged with plasma promptly aliquoted and frozen at -80°C. In a single thaw, 50uL of 10N HCL was added to 200 uL of plasma, incubated for 10 minutes then centrifuged. 100 uL of supernatant was injected into liquid chromatography mass spectrometry system. On-line extraction and high performance liquid chromatography methods were optimized using Onyx C18 guard and analytical column. Purified synthetic BNP1-32 was then incubated in patient serum and BNP fragments identified. Lastly, a proprietary protocol to inhibit BNP degradation was developed.. Results: The estimated limit of detection of the mass spectrometry method was 0.78 ng/mL and the lower limit of quantitation was 1.5 ng/mL with a good linear relationship ...
Biodistribution and metabolism of oligonucleotides were determined using a 3H-labeled 20-nucleotide phosphodiester and its phosphorothioate analog. The oligonucleotides were radiolabeled by 3H-methylation of an internal deoxyctidine with HhaI methylase and S- [3H]adenosylmethionine. Biodistribution studies were conducted after intravenous injection of 6 mg/kg (5 muCi) oligonucleotide. Metabolism of the oligonucleotides was determined by paired-ion high performance liquid chromatography. After phosphodiester injections, radiolabel rapidly cleared the blood. Relative initial concentrations were as follows: kidney , blood , heart , liver , lung , spleen. Radiolabel in spleen peaked at 1 hr and remained elevated for 24 hr. At 2 hr the concentration in all organs, except spleen, was equal to that in blood. High performance liquid chromatographic analysis of the kidney, liver, and spleen extracts and urine indicated extremely rapid metabolism to monomer. Results of studies after the injection of ...
TSKgel ODS-100V and TSKgel ODS-100Z columns incorporate the best-in-class surface properties to limit secondary interactions of basic, acidic and chelating compounds. Take advantage of the benefits of high column efficiency and symmetrical peak shapes to reduce your analysis and method development time! The ultra high purity Type B base silica contains negligible amounts of metal ion impurities. Combined with monomeric bonding chemistry, this silica makes the best general purpose Reversed Phase columns suitable for the most demanding separations in quality control as well as in research and development. TSKgel ODS-100V columns have a lower carbon content than ODS-100Z columns, making the bonded phase surface 100% water wettable and the preferred choice to retain polar metabolites.
Academic Journals Database is a universal index of periodical literature covering basic research from all fields of knowledge, and is particularly strong in medical research, humanities and social sciences. Full-text from most of the articles is available. Academic Journals Database contains complete bibliographic citations, precise indexing, and informative abstracts for papers from a wide range of periodicals.
... : LiChrospher® is a reliable and versatile traditionally produced spherical silica carrier with a particle size of 5µm or 10 µm, providing well balanced pressure / separation performance ratio. A broad range of modifications on LiChrospher® are very widely used by HPLC-users all over the world for a broad range of applications. LiChrospher® sorbents are available as reversed phase derivatives (RP-8, RP-18 endcapped, RP-18, RP-18 endcapped and RP-select B), medium polar (NH2, CN, DIOL) and polar derivatives (Si 60). Furthermore LiChrospher® PAH is highly efficient and selective for the separation of PAH; LiChrospher® WP is very well suited for the separation of peptides and low molecular weight proteins. LiChrospher® sorbents are available as Hibar® RT columns or as LiChroCART® cartridges in different lengths ans internal diameters. To operate with LiChroCART® cartridges, the cartridge holder manu-CART® has to be used.
MODEL RELEASED. (High pressure liquid chromatography) Biochemist analyses a new compound synthesized by microcide chemists for its interaction with biological macromolecules using HPLC. - Stock Image C009/4186
denaturing high performance liquid chromatography释义,背景概述,例举denaturing high performance liquid chromatography相关的SCI文献,让我们更理解denaturing high performance liquid chromatography的应用.
Fish oil made from menhaden (Brevoortia tyrannus) can be used as a dietary supplement for the presence of high levels of the long-chained omega-3 fatty acids, viz. epentaenoic and docosahexanoic. In this work, for the first time, two different multidimensional approaches were developed and compared, in terms of peak capacity, for triacylglycerol characterization. In particular, silver ion chromatography with a silver-ion column and non-aqueous reverse-phase liquid chromatography with a C18 column were tested in both comprehensive (stop-flow) and off-line modes. The use of mass spectra attained by atmospheric pressure chemical ionization for both LC approaches, and the fatty acids methyl esters profile of menhaden oil obtained by gas chromatography analysis, greatly supported the elucidation of the triacylglycerol content in menhaden oil. The off-line approach afforded a better separation and, thus, higher peak capacity to allow identifying and semiquantifying more than 250 triacylglycerols. Such a huge
Definition : High-pressure packed-column liquid chromatography systems in which the packing of the column is made of microparticulate silica gel. The functional groups of the stationary phase may be polar relative to those of the mobile phase (i.e., normal bonded-phase chromatography) or, more usually, nonpolar (i.e., reverse bonded-phase chromatography).. Entry Terms : "Reverse-Phase Liquid Chromatography Systems" , "Normal-Phase Liquid Chromatography Systems" , "Bonded-Phase Liquid Chromatography Systems". UMDC code : 18278 ...
A unique polypeptide, called enhancing factor (EF), which enhances the binding of labeled epidermal growth factor (EGF) to cells, has been isolated. It has been purified to homogeneity from the acid-soluble proteins of mouse intestines. Earlier, EF was partially purified by two cycles of gel-permeation chromatography on Bio-Gel columns. We now report the final purification of EF on high-performance liquid chromatography (HPLC), using a reverse-phase column (μBondapak C18). The purity of the protein was confirmed when a single peak was obtained in HPLC. Also, a single protein band was obtained in SDS-PAGE. Purified EF has the same properties in vitro as those reported earlier for partially purified EF. ...
A simple and reliable reversed-phase high-performance liquid chromatographic (HPLC) method for the routine determination of vitamins A and E and β-carotene in plasma (or serum) with wavelength-programmed ultraviolet-visible absorbance detection is described. A 200-μl aliquot of serum or plasma sample, after deproteinization with ethanol, and containing tocopherol acetate as internal standard, was extracted with butanol-ethyl acetate. Sodium sulphate was added for dehydration. Analytes of extracted samples were found to be stable for at least four days. A 10-μl aliquot of this organic extract was used for HPLC analysis. The mobile phase was methanol-butanol-water (89.5:5:5.5, v/v) and the flow-rate was set at 1.5 ml/min. The analytes of interest were well separated from other plasma constituents within 22 min at 45°C. The lowest detection limits of vitamins A and E and β-carotene were 0.02, 0.5 and 0.1 μg/ml, respectively. The recovery and reproducibility of the present method were around ...
The presence of 6-methyladenine and 5-methylcytosine at Dam (GATC) and Dcm (CCA/TGG) sites in DNA of mycobacterial species was investigated using isoschizomer restriction enzymes. In all species examined, Dam and Dcm recognition sequences were not methylated indicating the absence of these methyltransferases. On the other hand, high performance liquid chromatographic analysis of genomic DNA from Mycobacterium smegmatis and Mycobacterium tuberculosis showed significant levels of 6-methyladenine and 5-methylcytosine suggesting the presence of DNA methyltransferases other than Dam and Dcm. Occurrence of methylation was also established by a sensitive genetic assay. ...
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The present study describes a novel sensitive live-cell assay for studying ECE activity. ET-1 is formed from its precursor preproET-1 via the cleavage of the intermediate bigET-1 by ECE-1. However, the subcellular site at which this step occurs is not clear: It could occur intravesicularly along the secretory pathway or bigET-1 may be released and processed extracellularly. To address this point, we have developed an integrated autocrine system.. Until now, ECE activity has been evaluated in solubilized membrane fractions by high-performance liquid chromatography assays,32 immunoassays,12 fluorogenic determinations,33 receptor assays,34 and fluorescence polarization assays.35 Most of these assays require an incubation in vitro with high concentrations of substrate, and all of them need an independent second step to measure the product, ET-1.. In the present study, a recombinant CHO reporter cell line permanently expressing the human ETA receptor and a reporter gene sensitive to its activation ...
A normal-phase Bondapak high performance liquid chromatographic (HPLC) system was compared to two different reversed-phase Bondapak C//1//8 systems for separating and quantifying aldehydes and ketones. In the normal-phase system, isocratic elution with 2-propanol (IPA) and hexane produced the best results. One reversed-phase system consisted of two C//1//8 columns in series. The other reversed-phase system consisted of a single radial compression cartridge (RCC). Both reversed-phase systems employed solvent programming with acetonitrile/water as the mobile phase. Ultraviolet (UV) detection at 340 nm was used in all of the systems.
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[Incidence of sample storage temperature on HbA 1c determination by high performance liquid chromatography method].: We have evaluated the conservation prior to
LiChrospher is a reliable and versatile traditionally produced spherical silica support. LiChrospher silica is available with a variety of modifications. LiChrospher Si material with no modification is most suitable for normal phase HPLC. LiChrospher Si 60 and Si 100 are versatile HPLC sorbents based on spherical silica particles possessing polar properties. Superspher for highly efficient HPLC of complex mixtures where high peak capacity is required. It improves the separation efficiency of HPLC analysis. This high performance spherical silica carrier with a mean particle size of 4 µm yields the best pressure/separation performance ratio on even the latest generation of HPLC systems and according to theoretical calculation and practical experience.The guaranteed number of theoretical plates for Superspher is , 100.000 N/m. Therefore, they are always first choice if complex mixtures demand high peak ...
The peroxidase was purified by anion exchange high performance liquid chromatography using 50 mM KH-2PO4, pH 7.0, and a linear gradient (0-500 KCl) on a DEAE Poros (4.6 mm/100 mm) column. Figure 1 shows a representative chromatogram for unpurified soybean seed coat SBP extract. The protein was obtained by collecting fractions corresponding to the peak marked "*" in Figure 1. Fractions were pooled using ultrafiltration with a YM10 (Amicon). The salt was removed by washing five times with distilled water from an initial volume of 50 ml to a final volume of 10 ml. 100 l of this final solution were re-injected into the HPLC. The result is shown in Figure 2.. Next, a loading study was performed to determine how much SBP could be purified in one run. Figure 3 shows the results for 20 l, 50 l and 100 l injections. It shows that every time an increasing of SBP was injected, the peak shape was not affected. Therefore, up to an injection volume of 100 l could be purified in one run.. Finally, the purified ...
MATERIALS AND METHODS:. Chemicals and Reagents: Both Daunorubicin and Cytarabine (API) were obtained as a gift sample from Spectrum Pharma Pvt. Ltd., Hyderabad, India. The marketed formulation in the brand name Vyoxeos (Dauno-29 mg & Cyta-65 mg) procured from the local pharmacy. All the chemicals and reagents used in this work were HPLC grade water, acetonitrile, phosphate buffer, methanol, potassium dihydrogen orthophosphate buffer, orthophosphoric acid was obtained from Rankem.. Instrumentation: A HPLC system with waters 2695 separation module provided with a photodiode array detector, autosampler injection with Empower-2 software. Electronic balance, ultrasonicator, hot air oven were used.. Chromatographic Conditions: The chromatographic separations achieved on a kromosil C18 column (250 × 4.6 mm, 5 µm particle size) as a stationary phase. The mobile phase was composed of 55:45 v/v of 0.1% orthophosphoric acid (OPA) and acetonitrile at a flow rate of 0.8ml/min and injection volume is 10 ...
Semi-preparative high performance liquid chromatography facilities have been developed, capable of separating up to 100mg of material per injection. Stirred slurry column packing techniques were studied in detail. The effects of packing pressure, slurrying solvent, slurry concentration and the duration of the packing process were examined. The optimised packing technique was successfully used to pack columns of 12.5 to 50cm length and 4.9 to 10.9mm internal diameter. Analytical columns (4.9mm I.D.) were packed to evaluate twenty-two commercially available packing materials on a cost-performance basis. Semi-preparative columns (8.1 or 10.9mm I.D.) were packed with materials which gave either high efficiency or showed high performance to cost benefit. The performance of these columns compares favourably with the best results reported in the literature. The sample injection technique was studied using dye mixtures. Experimental results showed that the valve injection technique implemented the full ...
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Browse our extensive catalog of new & used Gas Liquid Chromatograph Equipment for sale or auction. Find any required new, refurbished or used Gas Liquid Chromatograph Equipment or device.
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ly, the high-performance liquid chromatography analysis was performed using Agilent 1100 series system. The column temperature was maintained at 40C. The flow
Present and see the latest results on column technologies, cutting-edge applications & instrumentation, coupling with mass spectrometry and new trends, including microfluidics and nanotechnologies at HPLC 2017 Prague. Click to read more...
A maltogenic amylase (MAG1) from alkaliphilic Bacillus lehensis G1 was cloned, expressed in Escherichia coli, purified and characterised for its hydrolysis and transglycosylation properties. The enzyme exhibited high stability at pH values from 7.0 to 10.0. The hydrolysis of β-cyclodextrin (β-CD) produced malto-oligosaccharides of various lengths. In addition to hydrolysis, MAG1 also demonstrated transglycosylation activity for the synthesis of longer malto-oligosaccharides. The thermodynamic equilibrium of the multiple reactions was shifted towards synthesis when the reaction conditions were optimised and the water activity was suppressed, which resulted in a yield of 38% transglycosylation products consisting of malto-oligosaccharides of various lengths. Thin layer chromatography and high-performance liquid chromatography analyses revealed the presence of malto-oligosaccharides with a higher degree of polymerisation than maltoheptaose, which has never been reported for other maltogenic amylases. The
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Immediately find HPLC and UHPLC columns for reversed phase, chiral, normal phase, GFC, GPC, ion exchange, HILIC, and SFC using our HPLC product search.
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Ceratonia siliqua is a typical plant of the Mediterranean area, which is mainly used as animal and human food and in folk medicine for treating some diseases such as antidiarrheal and diuretic. The present study was planned to evaluate the potential of antimicrobial and antioxidant activities of C. siliqua leaves extract and the identification of bioactive compounds by high performance liquid chromatography/mass spectrometry (HPLC/MS) in the active extract. The antioxidant activities of the different organic extracts of C. siliqua were assayed by 2,2-diphenyl-l-picrylhydrazyl (DPPH) and β-carotene tests. Among the tested extracts, results showed that the ethyl acetate extract displayed the greatest DPPH scavenging ability with an IC50 of 1.8 µg/ml and a strong β-carotene bleaching inhibition after 120 min of incubation with an IC50 of 24.01 µg/ml. The investigation of the phenolic and flavonids content showed that the ethyl acetate extract of C. siliqua revealed the highest
Chemicals for high-performance liquid chromatography analyses. (±)-Benzo[a]pyrene-trans-7,8-dihydrodiol (B[a]P-7,8-DHD), (±)-benzo[a]pyrene-trans-9,10-dihydrodiol (B[a]P-9,10-DHD), and (±)-3-hydroxy-benzo[a]pyrene (B[a]P-3OH) were purchased from the National Cancer Institute, Chemical carcinogen Repository (Midwest Research Institute, Kansas City, MO). Methanol was from Lab-Scan (Stillorgan, Ireland). B[a]P was purchased from Sigma (St. Louis, MO).. Genotyping of the CYP1B1 missense mutations. The genomic DNA used was from 116 healthy unrelated Spaniards who participated in a previous study concerning genetic polymorphism in the CYP2A6 gene ( 34). The ethics committee at Karolinska Institutet approved the use of these samples for the current investigation.. Genotyping for CYP1B1, missense mutations in exon 2 (142C , G, 355G , T) and in exon 3 (4326C , G, 4390A , G, 4360C , G), was done using a two-step allele-specific PCR method. For primer sequence and PCR conditions, see ref. 19. In brief, ...
Animals. Female A/J mice were obtained from The Jackson Laboratory (Bar Harbor, ME) at 5 weeks of age and housed according to the guidelines of the Animal Care and Use Committee of the NIH. Mice were fed AIN-93G/M chow from Dyets (Bethlehem, PA) and autoclaved water ad libitum and were weighed weekly. NIH animal facilities are accredited by the Association for Assessment of Laboratory Animal Care. All experiments were carried out under an NIH-approved animal study protocol.. Carcinogen and drug treatment. For the study assessing the effect of rapamycin on established tumors, 25 mice per group were given a single dose of NNK (Toronto Research Chemicals, North York, ON) at 6 weeks of age. For the prevention of tumor development study, NNK was obtained from EaglePicher Pharmaceuticals (Lenexa, KS), and 15 mice per group were treated with three doses of NNK over 3 weeks beginning at 6 weeks of age. The purity of both NNK samples was verified by high-performance liquid chromatography analysis. NNK ...
In HPLC columns, reverse-phase and normal-phase chromatography separation methods are based on polarity. Reverse phase columns separate analytes based on
Diluted worts are injected into a high-performance liquid chromatography system. A cation exchange column with water as mobile phase is used to separate the sugars, which are then measured by a refractive index detector. Sugars having a degree of polymerization of 1-3 are quantitatively determined by comparison with aqueous standards containing fructose, glucose, maltose, and maltotriose.. ...
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Serum concentrations of vitamins A (retinol) and E (α and γ-tocopherol), two retinyl esters, and six carotenoids (α-carotene, trans-β-carotene, cis β-carotene, β-cryptoxanthin, combined lutein/zeaxanthin, and trans-lycopene) are measured using high performance liquid chromatography with photodiode array detection. A small volume (100 μL) of serum is mixed with an ethanol solution containing two internal standards- retinyl butyrate and nonapreno-β-carotene (C45). The micronutrients are extracted from the aqueous phase into hexane and dried under vacuum. The extract is redissolved in ethanol and acetonitrile and is filtered to remove any insoluble material. An aliquot of the filtrate is injected onto a C18 reversed phase column and isocratically eluted with a mobile phase consisting of equal parts of ethanol and acetonitrile. Absorbance of these substances in solution is linearly proportional to concentration, thus spectrophotometric methods are used for quantitative analysis. Three ...
Determination of sulfonamides by liquid chromatography, ultraviolet diode array detection and ion-spray tandem mass spectrometry with application to cultured salmon flesh
Determination of sulfonamides by liquid chromatography, ultraviolet diode array detection and ion-spray tandem mass spectrometry with application to cultured salmon flesh
Figure 2 Separation of a 1 µL sample injection using UHPLC. A flow rate of 0.8 mL/min, nearly half that of the HPLC separation, was used for elution of the sample using an X-PressPak C18S column with 2 µm particles (2.1 mm i.d. X 50 mm L). This resulted in an analysis time of 1.3 min, approximately 7 times faster than the HPLC separation. The gradient elution program of 1.5 min is 10 times shorter than that for HPLC.. Table II Comparison between UHPLC and conventional HPLC.. Table 2. Comparison between UHPLC and conventional HPLC ...
Several lines of evidence suggest that d-serine, an endogenous agonist of the glycine site on the NMDA receptors, might play a role in the pathophysiology of schizophrenia. The purpose of this study was to determine whether levels of d- and l-serine or d-serine ratio (d-serine/total serine) in cerebrospinal fluid (CSF) were altered in first episode and drug-naive schizophrenic patients. The CSF levels of d- and l-serine in 25 male first episode and drug-naive schizophrenic patients and 17 age-matched male healthy subjects were measured using a column-switching high performance liquid chromatography system. The percentage of d-serine in the total serine of patients was significantly (z = - 2.01, p = 0.044) lower than that of controls. This study suggests that synthetic or metabolic pathways of d-serine may be abnormal in the brain of drug-naive schizophrenic patients, supporting the NMDA receptor dysfunction hypothesis of schizophrenia. © 2005 Elsevier Inc. All rights reserved.. ...
AIMS--To compare high performance liquid chromatography (HPLC) with conventional methods for the estimation of blood haemoglobin A2 (HbA2) and haemoglobin F (HbF) concentrations in routine thalassemia screening. METHODS--An HPLC system (the VARIANT Hemoglobin Testing System) was tested for precision and reproducibility in the measurement of HbA2 and HbF, and reference ranges were obtained for a local healthy adult population. HPLC was compared with column anion exchange chromatography for HbA2 measurement, and radial immunodiffusion, or alkaline denaturation for HbF measurement. The reliability of HbA2 measurement by HPLC for the detection of beta thalassaemia and HbE was assessed in 200 consecutive samples for routine thalassaemia screening. RESULTS--HPLC was rapid, technically easy, and gave good precision and reproducibility. In all comparisons linear regression analysis showed good correlation between HbA2 or HbF concentrations determined by HPLC and by the respective conventional methods. ...
Abstract:. Peptides and proteins are large biomolecules composed of long chains of L -amino acids and plays key functions in the living organisms. A variety of techniques are used to characterize these biomolecules and, among the techniques used, high performance liquid chromatography (HPLC) has been extensively employed both for the preparative as well as the analytical characterization of peptides and proteins. Various HPLC techniques developed for the separation of proteins rely on the differences in the adsorption characteristics, surface charge, ligand specificity, and molecular size of protein molecules. Advancements made in these HPLC techniques have contributed immensely to the development of peptides and proteins based pharmaceuticals. Present article summarizes the principle, methods, and applications of the most common HPLC techniques used in the field of peptides and proteins.. ...
... About Gel Permeation Chromatography GPC is an analytical method used for the separation - Market research report and industry analysis - 11819766
Fast protein liquid chromatography (FPLC) is a liquid chromatography technique for separation of protein molecules under pressure. It differs from high performance liquid chromatography in that the pressures are generally lower, around 435 to 580 psi, compared to 3000-to 5000 psi for an HPLC system.
Background: Chaiqin Qingning Capsule (CQQNC) was a prescription of Traditional Chinese Medicine with the effects of clearing away heat and removing toxin, harmonizing the exterior and interior, it was widely used in Asian, for example, China and Japan, different batches of the raws materials and different processing time may be the vital factor which raised a challenge to control the quality of the CQQNC. Experimental Methods: In this experiment, a high-performance liquid chromatography-mass spectrometry/MS (HPLC-MS/MS) method was developed to simultaneously determine ten bioactive components for the quality control of CQQNC ...
A high sensitivity reversed-phase HPLC method is presented for the simultaneous determination of marker compounds of paracellular transport (atenolol), transcellular transport (propranolol) and P-gp functionality (talinolol) in the Caco-2 system. The Caco-2 system is presently commonly accepted as an in vitro cell culture model of the intestinal mucosa. A programmed wavelength fluorescence detection method was used to optimise the response of the marker compounds. This marker compound mixture and the corresponding HPLC assay can be used for in house validation of the Caco-2 system or to evaluate simultaneously the effect of test compounds or absorption enhancing strategies on monolayer integrity and P-gp functionality. The method can easily be adapted to determine the concentration of atenolol, propranolol and talinolol in blood, thus allowing to use the same compounds in the in situ rat perfusion system with blood sampling from the mesenteric vein ...
Mutalik, S., Hewavitharana, A., Shaw, P. N., Anissimov, Y. G., Roberts, M. S. and Parekh, H. S. (2009) Development and validation of a reversed-phase high-performance liquid chromatographic method for quantification of peptide dendrimers in human skin permeation experiments. Journal of Chromatography. B, Analytical Technologies in the Biomedical and Life Sciences, 877 29: 3556-3562. doi:10.1016/j.jchromb.2009.08.039 ...
Food Additives and Contaminants: Part A. 2013;30(1):11-45. Esters of 2 - and 3-monochloropropane-1,2-diol (MCPD) and glycidol esters are important contaminants of processed edible oils used as foods or food ingredients. This review describes the occurrence and analysis of MCPD esters and glycidol esters in vegetable oils and some other foods. The focus is on the analytical methods based on both direct and indirect methods. Methods of analysis applied to oils and lipid extracts of foods have been based on transesterification to free MCPD and determination by gas chromatography-mass spectrometry (indirect methods) and by high-performance liquid chromatography-mass spectrometry (direct methods). The evolution and performance of the different methods is described and their advantages and disadvantages are discussed. The application of direct and indirect methods to the analysis of foods and to research studies is described. The metabolism and fate of MCPD esters and glycidol esters in biological ...
Fittings and tubing comprise a vital, but often ignored portion of the HPLC system. At first glance, the inexperienced eye sees little or no difference between fittings styles and brands. Although these components are not particularly complicated, a solid understanding of their application and use is essential to avoid certain HPLC problems.. ...
A targeted reversed-phase gradient UPLC-MS/MS assay has been developed for the quantification /monitoring of 66 amino acids and amino-containing compounds in human plasma and serum using precolumn derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AccQTag Ultra). Derivatization of the target amines required minimal sample preparation and resulted in analytes with excellent chromatographic and mass spectrometric detection properties. The resulting method, which requires only 10 μL of sample, provides the reproducible and robust separation of 66 analytes in 7.5 min, including baseline resolution of isomers such as leucine and isoleucine. The assay has been validated for the quantification of 33 amino compounds (predominantly amino acids) over a concentration range from 2 to 20 and 800 μM. Intra- and interday accuracy of between 0.05 and 15.6 and 0.78-13.7% and precision between 0.91 and 16.9% and 2.12-15.9% were obtained. A further 33 biogenic amines can be monitored in samples ...
Amino acids are very polar compounds which are used as a building blocks in pharmaceutical industry. They are widely used as supplements and food additives. Depending on the pH of the mobile phase they can exist in acidic, basic or zwitter-ionic form. At pH below 3, amino acids are basic in nature and have the highest hydrophobicity. Within pH of 3 to 7 amino acids are in zwitter-ionic form where they are the most hydrophilic. There is no mechanism of retention on reversed-phase column and amino acids are not retained. Bufferless ion-separation (BLIS) was introduced by SIELC as a way to retain and analyze amino acids in reversed-phase cation-exchange mode. This mode allows to analyze amino acids as zwitter-ions without any ions/buffers in the mobile phase. The method was adopted for analysis of amino acids on core-shell mixed-mode columns. A similar approach on a reversed-phase core-shell column results in distorted peaks and no separation or significant retention to achieve baseline separation. ...
Analytical calibre of high performance liquid chromatography and ion exchange chromatography resin methods in estimation of glycated hemoglobin: a comparitive study, Rukmini MS, As
A straightforward and available reversed-phase high performance liquid chromatography (HPLC) method with UV detection has been developed and validated for mycophenolic acid (MPA) A-770041 assay in human plasma. with enough accuracy and precision. The method showed significant linear response-concentration relationship throughout the MPA concentration range of 0.2-10 μg/ml. A typical linear regression equation of the method was: y = 8.5523 A-770041 x + 0.094 with x and y representing MPA concentration (in μg/ml) and peak height respectively and the regression coefficient (r) of 0.9816. The average within-run and between-run variations of 7.81 and 4.78 percent. The average drug recovery from plasma was 95.24 percent throughout the linear concentration range. The limits of detection (LOD) and quantitation (LOQ) of the method were 0.05 and 0.2 μg/ml respectively. The practical applicability of the method was proven throughout a bioequivalence study. The results showed the acceptable degree of ...
High-Performance Liquid Chromatography (HPLC), a chromatographic technique is used to identify, quantify and separate each component from a sample of complex chemical mixtures. Presently, HPLC is a versatile technique, available for analyzing all types of biological compounds that can be isolated or synthesized. This method involves the passage of liquid sample over solid adsorbent material packed in a column with solvent. HPLC technique has been used in various fields such as legal, medical, manufacturing processes and in research. This technique relies on pumps and other accessories to pass the sample through the column filled with sorbent (active ingredient of the column). HPLC is highly efficient and different from the conventional liquid chromatographic methods in terms of high operational pressures used in HPLC to run the mobile phase through the column. In addition, the resolution power of HPLC used during separation is higher when compared to conventional liquid chromatographic ...
The normal phase of iron is as a lustrous, gray, solid metal. Its melting point is 2800 degrees Fahrenheit, and its density is 7874 kg m-3. Like many metals, it is able to be hammered into thin...
Nova-Pak HR Silica columns are silica-based, semi-preparative and preparative columns that are based on 6 µm particle technology. Compared to a 5 µm column, Nova-Pak HR columns offer higher resolution, more efficient separations, and faster chromatography.
Non-covalent immobilized artificial membrane reverse-phase high performance liquid chromatography was previously evaluated as a means whereby elution times for antimicrobial peptides from columns mimicking the lipid bilayers of different membrane systems might be used as a fast-screening method to compare relative binding effectiveness. Such a system would aid in the development of antimicrobial peptides that bind preferentially to model pathogenic systems and leave the hosts membranes reasonably unaffected. A non-covalent approach allows for flexibility in membrane composition but was found to be inadequate for analysis of most peptides due to significant lipid loss at high acetonitrile concentrations. A covalent approach where phosphatidylcholine was amide-linked to the silica surface was examined to evaluate its use as a fast-screening method and compare its data to that collected from the non-covalent columns. Initial work with a 1-cm column proved ineffective due to problems with balancing ...
BioSuite™ Peptide Analysis columns consist of two premier reversed-phase column chemistries specifically optimized for peptide mapping from simple to complicated digests. BioSuite PA Columns are available in various configurations for LC or LC/MS applications, including 250 mm lengths for ultra high resolution. These BioSuite™ PA-A and PA-B columns provide excellent batch-to-batch reproducibility for consistent results and are uniquely QC tested specifically for peptide mapping. BioSuite™ C18 3µm PA-A is a100Å, difunctional bonded, low ligand density, silica-based reverse-phase column and BioSuite™ C18 3.5µm PA-B is a 300Å, high ligand density, monofunctional, silica-based reverse-phase column.
HPLC Column Configurator helps you save up money & time. Find and compare HPLC columns specifications, manufacturers, prices, application methods, etc.
Thermo Fisher Scientific Inc., the world leader in serving science, today announced that it will feature its Thermo Scientific Dionex UltiMate 3000 Biocompatible Rapid Separation (BioRS) liquid chromatography system during Pittcon 2013. This system is designed to combine the performance advantages of ultrahigh-performance liquid chromatography (UHPLC) with the corrosion resistant flow path demanded by the analysis of proteins, peptides, nucleic acids and biotherapeutics. Thermo Fisher wi
A sensitive, simple and rapid method without sample pretreatment is presented for the simultaneous determination of flunitrazepam and its main metabolites (norflunitrazepam, 7-amino- and 7-acetamidoflunitrazepam) in urine. The single-step procedure i
Catecholamines and their metabolites have been separated isocratically by reverse-phase chromatography with aqueous (no organic solvent admixed) eluents. Unlike ion-exchange or ion-pair chromatography, mixtures of both acidic and basic substances can be separated in a single chromatographic run, because the retention is governed by hydrophobic interactions between the nonpolar moiety of the solute molecules and the octadecyl-silica stationary phase. The relative retention values strongly depend on the pH of the eluent, which governs the degree of dissociation of ionogenic solutes. The reproducibility of the results and the stability and efficiency of the chromatographic systems make this approach particularly attractive for use in clinical analysis.. ...
Chlrorophylls and their Degradation Products using High Performance Liquid Chromatography (HPLC), with Data from Suspended and Sinking Particulate Matter in Prydz Bay, Antarctica - chlorophyll;chlorophyllide;phaeophorbide;sediment trap;HPLC;Prydz Bay;flux;
Higher value products demand for chromatographic techniques. The techniques are used for. concentration, de salting and purification of protein preparation. When choosing a chromatographic. technique, a number of factors need to be put into consideration. These factors may include iso-. electric point, biological affinity, hydro-phobicity and molecular weight in proteins. Each of the above. properties can be exploited by different specific chromatographic methods. The following are the. chromatographic parameters that need to be considered; recovery, capacity and resolving power.. The following are different types of chromatography used in downstream processing.  Adsorption chromatography.  Affinity chromatography.  Gel filtration chromatography.  Ion exchange chromatography.  High performance liquid chromatography.  Distillation.  Ion exchange chromatography. In adsorption chromatography, separation is done according to affinity of protein or any other. material. Affinity ...
LC1620A HPLC (high performace Liquid Chromatography) instrument system with HPLC column, US $ 2,000 - 10,000 / Set, Zhejiang, China (Mainland), westtune, LC1620A.Source from Hangzhou West Tune Trading Co., Limited on Alibaba.com.
Sujatha, * and Rai, Lavanya and Kumar, Prathap and Krishnand, BR and Mahato, KK and George, Sajan D and Kartha, VB and Santhosh, C (2007) Protein profile study of Pap smear and cervix biopsy tissues using High Performance Liquid Chromatography (HPLC) - Laser Induced Fluorescence (LIF). In: First Asian Spectroscopy conference & Asian Biospectroscopy Conference (ASC-07),,, 29th January - 2nd February 2007, 221-222., Bangalore,. (Submitted) ...
High performance liquid chromatography (HPLC) spectra of surfactin (dashed line) and surfactin-(Glu-γ, Asp-β)-hexyl ester (solid line) under the same conditio
BACKGROUND: Biochemical measurement of fat-soluble vitamins would allow direct assessment in epidemiological studies of their association with disease. However, the perceived instability of these compounds and typically high cost of collection and analysis may make their measurement impractical, particularly in large-scale studies. Using a high performance liquid chromatography assay developed in-house, we have investigated the separate effects of temperature and light on the stability of vitamins in whole blood over several days. METHODS: Multiple blood samples from 10 volunteers were stored at 20 degrees C or 4 degrees C and in dark or light conditions. Immediately after collection and 1, 2, 3, 4, and 7 days later, samples stored under each condition were centrifuged, and the plasma was aliquoted and stored at -80 degrees C. Subsequently, all aliquots from each individual were analysed in one analytical run. RESULTS: In whole blood stored under any of the four conditions for up to 7 days,
Abstract In this bachelor thesis, ADP and ATP samples were analysed and detected with HPLC- MS/MS method. Approximate limit of detection (LOD) for these particular substances were found and their values were compared with the LOD values published in the literature obtained via the same methods and under very similar experimental conditions. Our limits of detection for nucleotides were comparable with the limits described in the literature. Mass spectrometry analysis was performed in the positive and the negative mode of multiple reaction monitoring analysis and electrospray was used for the analyte ionization. The optimal conditions for high performance liquid chromatography of ATP and ADP analysis were acquired on a ZIC - HILIC column with the mobile phase of 75:25 (v/v) acetonitrile / 10 mM ammonium acetate. Ammonium acetate buffer was adjusted to pH of 7.15 and the separation was done under the isocratic elution. ...
Photolysis of r-1,c-2,t-3,t-4-tetraphenylcyclobutane: quantum yield determinations via high performance liquid chromatography | R.B. Frings; W. Schnabel | download | BookSC. Download books for free. Find books
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This study was aimed to investigate the anticancer activities and the mechanism of the anticancer activities of a novel anticancer agent - 2-acetylamino-3-[4-(2-acetylamino-2-carboxyethylsulfanylthiocarbonylamino)phenylthiocarbamoylsulfanyl]propionic acid (2-AAPA). 2-AAPA was found to inhibit various human cancer cell lines with a narrow range of IC50 values (28-75 μM). These cell lines include lung (NCI-H226), prostate (PC-3), breast (MCF-7), skin (A431), melanoma (UACC-62 and SK-MEL-2), and renal (UO-31) cancers, as well as human ovarian cancers (OVCAR-3 and NCI/ADR-RES) which are resistant toward doxorubicin. Flow cytometric studies revealed that 2-AAPA induced cell cycle arrest at G2/M phase and produced significant cell apoptosis in UACC-62 cells. Through immunofluorescence studies, 2-AAPA was found to depolymerize microtubules and cause cell morphological change. An HPLC (high performance liquid chromatography) assay demonstrated that proteins were glutathionylated in both OVCAR-3 and ...
In Agilent Technologies Deutschland GmbH v Waters Corp and another (spotted by LexisNexis subscription-only All England Direct service) [2004] EWHC 2992 (Ch) Mr Justice Pumfrey, sitting in the Patents Court, dismissed what looked like a pretty far-out patent infringement claim. Agilent owned a patent for to pumping apparatus for the delivery of liquid at high pressure which could be used in high pressure liquid chromatography columns. Following unreported proceedings in which the Court of Appeal ([2002] All ER (D) 152 (May)) held the patent valid and infringed, Agilent sued again, alleging that another Waters pump system infringed. This machine operated in manual mode,the operator selecting pump volume from four pre-selectable volumes and separately specifying the flow rate of solvent delivered by the machine. This machine informed the operator if it could not deliver the specified flow rate at the volume specified but did not automatically change the range. Waters maintained that automatic ...
Pravadali, Sercan, Bassanese, Danielle N., Conlan, Xavier A., Francis, Paul S., Smith, Zoe M., Terry, Jessica M. and Shalliker, R. Andrew 2013, Comprehensive sample analysis using high performance liquid chromatography with multi-detection, Analytica chimica acta, vol. 803, pp. 188-193, doi: 10.1016/j.aca.2013.08.013. ...
Omnifit™ Glass Columns for Low/Medium Pressure Liquid Chromatography Two adjustable endpieces; Length: 400mm; Bore: 6.6mm Omnifit™ Glass Columns for...
[96 Pages Report] Check for Discount on United States High-performance Liquid Chromatography (HPLC) Market Report 2017 report by QYResearch Group. In this report, the United States High-performance Liquid Chromatography (...
Lab Manager features articles relating to management, technology, and equipment common to laboratories in industry, medicine, universities, and
|p|Silia|em||span style=color: #46423c;|Chrom|/span||/em||sup|®|/sup| XDB1 NH2 is a very versatile stationary phase which can be used in normal phase, reverse phase or ion exchange conditions as a weak anionic exchanger (WAX).|/p|
Specialised Conductives Pty. Ltd. was established in 1987 to sell nickel particulates for EMI paint coatings to shield electronics. In the 1990s, it acquired a number of agency product lines from USA, UK and elsewhere. Now, Specialised Conductives provides a range of materials for EMI shielding and ESD applications, ferrites and Zippertubing jackets for cables and stainless steel fibres for conductive plastics . The company also supplies specialty high pressure liquid chromatography columns for medical research. On July 1st, 2010, the part of the company importing high performance metal flakes for coatings and metal finishing and stainless steel fibres for conductive plastics was sold to Australian Metal Powders Supplies ...
Interlink Scientific Services Limited : SIELC Technologies HPLC Columns - Chromatography Systems Chromatography Supplies Reconditioned Instruments Lab Equipment Dissolution Spectroscopy CDS - Integrators Engineering interlink scientific services, iss, hplc
Free Online Library: Rapid quantification of resveratrol in mouse plasma by ultra high pressure liquid chromatography (UPLC) coupled to tandem mass spectrometry.(FULL-LENGTH ARTICLES, Report) by Puerto Rico Health Sciences Journal; Health, general Fluorides High performance liquid chromatography Mass spectrometry Resveratrol
By employing science and nature in a smart, innovative way, were able to take your dream and design a superior product that performs. Analytical testing in our in-house lab during all stages of production verifies an ingredients fingerprint - this is achieved through a highly accurate infrared spectrometer, plus high-pressure liquid chromatography analysis. Using the intelligence found in premium organic botanicals, our skilled team of chemists and product developers monitor every step of the process. We guarantee that our formulas comply with all recognized standards, as well as our clients requirements ...
Roswit W.T., McCourt D.W., Partridge N.C., Jeffrey J.J.. Two protein inhibitors of metalloproteinases (TIMP) were isolated from medium conditioned by the clonal rat osteosarcoma line UMR 106-01. Initial purification of both a 30-kDa inhibitor and a 20-kDa inhibitor was accomplished using heparin-Sepharose chromatography with dextran sulfate elution followed by DEAE-Sepharose and CM-Sepharose chromatography. Purification of the 20-kDa inhibitor to homogeneity was completed with reverse-phase high-performance liquid chromatography. The 20-kDa inhibitor was identified as rat TIMP-2. The 30-kDa inhibitor, although not purified to homogeneity, was identified as rat TIMP-1. Amino terminal amino acid sequence analysis of the 30-kDa inhibitor demonstrated 86% identity to human TIMP-1 for the first 22 amino acids while the sequence of the 20-kDa inhibitor was identical to that of human TIMP-2 for the first 22 residues. Treatment with peptide:N-glycosidase F indicated that the 30-kDa rat inhibitor is ...
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