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Chromatographic Efficiencies (chromatographic + efficiency)
Selected AbstractsUltra-performance liquid chromatography coupled to linear ion trap mass spectrometry for the identification of drug metabolites in biological samplesRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 8 2006G. J. Dear The coupling of ultra-performance liquid chromatography, operating at elevated pressures, to a linear ion trap mass spectrometer provides a high-performance system suitable for drug metabolite characterisation. This system demonstrates improved chromatographic efficiency and sensitivity and at the same time provides diagnostic MSn data often critical for metabolite structural assignment. The linear ion trap was capable of dealing with the high chromatographic efficiencies and hence narrow peak widths associated with 1.7,µm particle-packed column separations. Polarity switching and data-dependent MSn data were generated with ease, and applied to the identification of metabolites found in human plasma. Copyright © 2006 John Wiley & Sons, Ltd. [source] Fast chiral separation of drugs using columns packed with sub-2 ,m particles and ultra-high pressureCHIRALITY, Issue 3 2010Davy Guillarme Abstract The use of columns packed with sub-2 ,m particles in liquid chromatography with very high pressure conditions (known as UHPLC) was investigated for the fast enantioseparation of drugs. Two different procedures were evaluated and compared using amphetamine derivatives and ,-blockers as model compounds. In one case, cyclodextrins (CD) were directly added to the mobile phase and chiral separations were carried out in less than 5 min. However, this strategy suffered from several drawbacks linked to column lifetime and low chromatographic efficiencies. In the other case, the analysis of enantiomers was carried out after a derivatization procedure using two different reagents, 2,3,4-tri-O-acetyl-,- D -arabinopyranosyl isothiocyanate (AITC) and N -,-(2,4-dinitro-5-fluorophenyl)- L -alaninamide (Marfey's reagent). Separation of several amphetamine derivatives contained within the same sample was achieved in 2,5 min with high efficiency and selectivity. The proposed approach was also successfully applied to the enantiomeric purity determination of (+)-(S)-amphetamine and (+)-(S)-methamphetamine. Similar results were obtained with ,-blockers, and the separation of 10 enantiomers was carried out in less than 3 min, whereas the individual separation of several ,-blocker enantiomers was performed in 1 min or less. Chirality, 2010. © 2009 Wiley-Liss, Inc. [source] The application of small porous particles, high temperatures, and high pressures to generate very high resolution LC and LC/MS separationsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 8 2007Robert Plumb Abstract The effect of combining sub-2 ,m porous particles with elevated operating temperatures on chromatographic performance has been investigated in terms of chromatographic efficiency, productivity, peak elution order, and observed operating pressure. The use of elevated temperature in LC does not increase the obtainable performance but allows the same performance to be obtained in less time. Increasing the column temperature did allow the use of longer columns, generating column efficiencies in excess of 100 000 plates and gradient peak capacities approaching 1000. Raising the temperature increased the optimal mobile phase linear velocity, negating somewhat the pressure benefits observed by reducing the solvent viscosity. When operating at higher temperature the analyte retention is not only reduced, but the order of elution will also often change. High temperature separations allowed exotic organic modifiers such as isopropanol to be exploited for alternative selectivity and faster analysis. Finally, care must be taken when using high temperature separations to ensure that the narrow peak widths produced do not compromise the quality of data obtained from detectors such as high resolution mass spectrometers. [source] Ultra-performance liquid chromatography coupled to linear ion trap mass spectrometry for the identification of drug metabolites in biological samplesRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 8 2006G. J. Dear The coupling of ultra-performance liquid chromatography, operating at elevated pressures, to a linear ion trap mass spectrometer provides a high-performance system suitable for drug metabolite characterisation. This system demonstrates improved chromatographic efficiency and sensitivity and at the same time provides diagnostic MSn data often critical for metabolite structural assignment. The linear ion trap was capable of dealing with the high chromatographic efficiencies and hence narrow peak widths associated with 1.7,µm particle-packed column separations. Polarity switching and data-dependent MSn data were generated with ease, and applied to the identification of metabolites found in human plasma. Copyright © 2006 John Wiley & Sons, Ltd. [source] | ||||||||||