Isomers phases phase separation. Medical search. Frequent questions

Chiral separation and determination of enantiomeric purity of the pharmaceutical formulation of cefadroxil using coated and immobilized amylose-derived and cellulose-derived chiral stationary phases. (jddtonline.info)
5. Aboul-Enein HY, Ali I. Polysaccharide-based chiral stationary phases, Chapter 2 in chiral separation by liquid chromatography and related technologies. (jddtonline.info)
9. Khan M, Viswanathan B, Rao DS, Reddy R. Chiral separation of frovatriptan isomers by HPLC using amylose based chiral stationary phase. (jddtonline.info)
Polysaccharide phases deliver familiar chiral separation behaviorAll available Chiral ART Polysaccharide Phases - immobilized types - are available in 3μm in addition to 5, 10, and 20μm particle sizes. (ymcamerica.com)

When developing an HPLC method, the first step is always to consult the literature to ascertain whether the separation has been previously performed and if so, under what conditions - this will save time doing unnecessary experimental work. (pharmtech.com)
for example, if the sample includes polar analytes then reverse phase HPLC would offer both adequate retention and resolution, whereas normal phase HPLC would be much less feasible. (pharmtech.com)
For low/medium polarity analytes, normal phase HPLC is a potential candidate, particularly if the separation of isomers is required. (pharmtech.com)
Reverse phase gradient HPLC is commonly used in peptide and small protein analysis using an acetonitrile-water mobile phase containing 1% trifluoroethanoic acid. (pharmtech.com)
Four pairs of isomers (1a/1b, 2a/2b, 3a/3b, and 4a/4b) were resolved by using chiral-phase HPLC separation. (bvsalud.org)
7. Aboul-Enein HY, Ali I. Studies on the effect of alcohols on the chiral discrimination mechanisms of amylose stationary phase on the enantioseparation of nebivolol by HPLC. (jddtonline.info)
That means it may be possible to separate isomers and other compounds by SFC that are difficult to separate by HPLC. (shopshimadzu.com)
Different separation methods are generally used for fatty acids, which are typically analyzed by GC, and glycerides, which are typically analyzed by HPLC. (shopshimadzu.com)
Learn to capitalize on the advantages of both core-shell and thermally modified fully porous stationary phase media to expand the options for HPLC and UHPLC method development. (phenomenex.blog)
Kinetex Core-Shell particles are available in 1.3, 1.7, 2.6, 3.5, and 5 μm sizes suitable for UHPLC to preparative HPLC, and utilize a variety of bonded phases for standard reversedphase. (phenomenex.blog)

8. Ishii K, Minato K, Nishimura N, Miyamoto T, Sato T. Direct chromatographic resolution of four optical isomers of diltiazem hydrochloride on a Chiralcel OF column. (jddtonline.info)

The separation selectivity of acetonitrile and methanol differ, but since selectivity depends on the properties of the dissolved compound, it is not the case that selectivity is always higher for one or the other. (shimadzu.com)
Mobile phase composition, for example, is the most powerful way of optimizing selectivity whereas temperature has a minor effect and would only achieve small selectivity changes. (pharmtech.com)
The selectivity of 11 isomeric analogue sets (out of 12) increased by 2 to 25% over the 5% diphenyl/95% dimethylpolysiloxane phase showing an ionic liquid column is more favorable for separating fentanyl analogues. (ojp.gov)
A proposed mechanism for this unique ability combines the shape selectivity of polymeric phases, previously recognized for planar polycyclic aromatic hydro¬ carbons, and the different 'molecular footprints' of the isomers. (canada.ca)
In this article we will discuss the introduction of new certified reference materials and their analysis by GC using an ionic liquid column as an alternative with unique selectivity and stability as compared to traditional wax/PEG phases. (sigmaaldrich.com)
For example, one of the most orthogonal combinations that can be used in 2D-LC is the combination of RPLC and HILIC because these two separation mechanisms present completely different selectivity for the retention of the analytes. (springer.com)
A hydrocarbon test mix confirms proper phase retention and selectivity. (restek.com)
To calculate k (retention or capacity factor), which is a measure of phase retention, 1,3-butadiene is used, while selectivity is measured using retention indices for propadiene and methyl acetylene. (restek.com)
It offers high selectivity, allowing a wide range of CFC isomers to be resolved at above ambient temperatures. (restek.com)

In addition to hydrophobic interactions, π-π interactions of the phenyl stationary phase contribute to separation. (shimadzu.com)
The stationary phase should be C 18 bonded. (pharmtech.com)
We routinely analyze fatty acid composition by gas chromatography equipped either with a fused silica capillary column or with a stationary phase of intermediate or high polarity. (ugent.be)
Enantiomeric separation of docetaxel starting material by chiral LC using amylose-based stationary phase. (jddtonline.info)
This report examines the morphology and performance of two types of stationary phase media( Luna® Omega Thermally Modified Fully Porous Particles and Kinetex® Core-Shell Particles from Phenomenex) and their application in method development work. (phenomenex.blog)
Most chromatographers are familiar with conventional fully porous stationary phase material. (phenomenex.blog)
As a sample travels through the column in the mobile phase, it diffuses in and out of the pores, interacts with the stationary phase, and becomes separated. (phenomenex.blog)
The reactivity of the aluminum oxide stationary phase is minimized by deactivation with inorganic salts, such as KCl or Na 2 SO 4 , to improve column response for polar unsaturates, like dienes, and the column's sensitivity (or response) ensures linear and quantitative chromatographic analysis for these compounds. (restek.com)

Cyano-bonded phases are easier to work with than plain silica for normal phase separations. (pharmtech.com)
Three octadecyl-silica stationary phases were incapable of ade¬quately separating the fullerenes according to the number of carbons. (canada.ca)

Therefore, an online two-dimensional reversed phase liquid chromatography x hydrophilic interaction liquid chromatography (RPLCxHILIC) system coupled with mass spectrometry was applied for further detailed investigation of the chemical constituents in Buddleja dividii . (springer.com)
Both sample preparations were coupled with reversed phase liquid chromatography and isotope dilution tandem mass spectrometry (LC-MS/MS) for analyte detection. (cdc.gov)

Fig. 7 shows an example of separation by methanol or acetonitrile of compounds in which one hydrogen atom of a benzene ring is substituted with a carboxyl group or a hydroxyl group. (shimadzu.com)
24 compounds were separated 36% faster with an elution window increase of 33% on the ionic liquid phase compared to the 5% diphenyl/95% dimethylpolysiloxane phase. (ojp.gov)
Shim-pack UC series was designed with a variety of stationary phases, making it suitable for analysis of various compounds. (shimadzu.com)
Isomers and structurally similar compounds that are difficult to separate can be analyzed by Nexera UC and Shim-pack UC series. (shimadzu.com)
They are suitable for separations of a wide range of chiral compounds, cis-trans isomers, and geometric isomers. (ymcamerica.com)
UC-Diol and UC-Diol II normal phase columns can even be used for lipids and other compounds with low polarity. (shopshimadzu.com)

Reverse phase is the choice for the majority of samples, but if acidic or basic analytes are present then reverse phase ion suppression (for weak acids or bases) or reverse phase ion pairing (for strong acids or bases) should be used. (pharmtech.com)

Fatty acid composition of lipid fractions are determined with a prior separation in lipid classes (cholesteryl-esters, triacylglycerols, non-esterified fatty acids and phospholipids). (ugent.be)
In accordance with the research, particular attention is devoted to the analysis of poly-unsaturated fatty acids, branched-chain fatty acids and 18:1 isomers. (ugent.be)

When conducting analysis with the Nexera UC supercritical fluid chromatography system, because diffusion of the sample band in the mobile phase is high compared with liquid chromatography, separation behavior changes significantly depending on the types of columns used. (shimadzu.com)
Coated Phase - with familiar separation behavior. (ymcamerica.com)
Immobilized Phase - exhibits similar separation behavior, while broadening separation flexibility by enabling the use of a wider range of solvents. (ymcamerica.com)

Various particle sizes and column dimensions offer outstanding cost effectiveness from analytical separation to preparative separation. (ymcamerica.com)

Shim-pack UC series offers various stationary phases suitable for the mobile phase of high diffusion and low-viscosity liquid carbon dioxide. (shimadzu.com)

Since the continuous emergence of novel fentanyl analogues has created a need for improved methods able to distinguish between fentanyl analogues and their isomers, in this study, the utility of commercially available ionic liquid columns is demonstrated for GC-FID and GC-MS separation and unambiguous identification of fentanyl, 22 fentanyl analogues, and U-47700. (ojp.gov)
The separation of fullerenes and their derivatives on four commercially available reversed-phase columns was investigated using liquid chroma¬tography/mass spectrometry with atmospheric pressure chemical ionization. (canada.ca)

High capacity and loadability give you exceptionally symmetrical peaks, making these columns ideal for volatile hydrocarbon separations at percent levels, as well as impurity analyses at ppm concentrations. (restek.com)

In the separation of positional isomers, phenyl columns may be the most appropriate amongst columns for reverse-phase chromatography. (shimadzu.com)
YMC Chiral ART phases are available in packed columns for analytical scale separations. (ymcamerica.com)
Given that normal phase separation is the main separation mode used for SFC, normal phase UC-Diol and UC-Diol II columns are commonly used. (shopshimadzu.com)
However, given that normal phase columns separate by class, UC-HyP columns may be better suited for separation by molecular type. (shopshimadzu.com)
Columns with specific or multiple interaction modes may help improve separation. (shopshimadzu.com)
Restek Rt-Alumina BOND columns are highly selective for C1-C5 hydrocarbons and separate all saturated and unsaturated hydrocarbon isomers above ambient temperatures. (restek.com)

Analysis of Amino Acids in Mixed-Mode Chomatography: How to Tune Up Your Separation? (helixchrom.com)
Their structures, including the absolute configurations of the resolved isomers, were elucidated by analysis of spectroscopic data (1D and 2D NMR, IR, and HRESIMS), single-crystal X-ray diffraction, and electronic circular dichroism (ECD) calculations. (bvsalud.org)
Analysis time can be reduced at a high flow rate without impairing the separation performance. (shimadzu.com)
In this two-dimensional liquid chromatography (2D-LC) method, a new at-column dilution (ACD) modulator was introduced in the 2D-LC system to solve the incompatibility problem of the mobile phase between two dimensions, which resulted in a 2D-LC analysis with high orthogonality. (springer.com)

Methanol and acetonitrile are organic acids commonly used as the mobile phase in reverse-phase chromatography. (shimadzu.com)
When switching the mobile phase from acetonitrile to methanol, the pressure resistance of the equipment and column should be rechecked. (shimadzu.com)
It can be seen that when acetonitrile and methanol are mixed with water in the same ratio, an acetonitrile mobile phase displays greater elution strength. (shimadzu.com)
If we have previously been using acetonitrile as the mobile phase with a ratio to water of 50/50 (v/v), when changing to methanol the equivalent ratio of methanol/water would be 60/40 (v/v). (shimadzu.com)
For a phenyl column, using methanol as the mobile phase allows π-π interactions, which improves the separation. (shimadzu.com)
If adequate separation cannot be obtained with an acetonitrile-based mobile phase, switching to a methanol-based mobile phase to change the elution order is one useful possibility for method development. (shimadzu.com)
The main reason is that the weak solvent in the 1 D consists of a strong eluent solvent for the 2 D, which can lead to a problem of mobile phase mismatch and poor or no separation in the 2 D. (springer.com)

YMC Chiral ART Polysaccharide Phases exhibit high stereoselectivity. (ymcamerica.com)

groups bonded to the fullerene surface appear to disrupt adsorptive interactions between the fullerene molecular footprints and the stationary phases. (canada.ca)

With this new modulator, much better peak separation and better peak shape were achieved compared to two-dimensional liquid chromatography system using a traditional standard (TS) modulator. (springer.com)

Shim-pack UC series was designed with eight types of stationary phases and sizes to meet diverse research and development needs. (shimadzu.com)
Two types of automated solid phase extraction (SPE) were assessed for the determination of human exposure to fentanyls in urine. (cdc.gov)

Some of them may not be related to your immediate task, but may still be helpful in learning new separation techniques and methods. (helixchrom.com)

In online comprehensive 2D-LC (LCxLC), where the sample is completely and continuously transferred from the first dimension ( 1 D) to the second dimension ( 2 D), the combination of orthogonal dimensions is usually hard to achieve because incompatible mobile phases are often used in both dimensions. (springer.com)

This new analytical method has been developed by the IFRA Analytical Working Group to identify and to quantify the 57 fragrance substances and their relevant isomers at a concentration higher than 0.002% (20 mg/kg) in ready to inject fragrance materials and oils using Gas Chromatography with FID (GC-FID) or with Mass Spectrometry (GC-MS) detection. (sigmaaldrich.com)

The resolution of individual fullerene isomers, on the other hand, was best accomplished with a poly¬ meric octadecylsilica bonded phase. (canada.ca)

HILIC Mixed-Mode Separations: What is involved? (helixchrom.com)

The pelagic phase marks a free-living period and includes trochophores, swimming larvae, and swimming veliger larvae. (hindawi.com)

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Phenomena and Processes54

Disciplines and Occupations12

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HPLC10

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