We describe the use of electron-capture gas chromatography or reversed-phase "high-performance" liquid chromatography for concurrent analysis for diazepam and nordiazepam in serum. In the gas-chromatographic analysis our use of a new chemically deactivated stationary liquid phase, SP 2250-DB (Supelco, Inc.), resulted in improved chromatographic sensitivity and peak symmetry for the two benzodia...

A high performance liquid chromatography method was studied for determination of 18 ?-glycyrrhetinic acid in Glycyrrhiza glabra L. (licorice) extract. The operating condition were C-18 reversed phase column (VP-ODS, (250×4.6 mm, 5 mm)) at room temperature, acetonitril/phosphoric acid (3/1) as mobile phase, at flow rate of 0.6ml/min (0-8min), 0.4ml/min (8-20min) and UV detection at 230 nm. The...

A high performance liquid chromatography method was studied for determination of 18 ?-glycyrrhetinic acid in Glycyrrhiza glabra L. (licorice) extract. The operating condition were C-18 reversed phase column (VP-ODS, (250×4.6 mm, 5 mm)) at room temperature, acetonitril/phosphoric acid (3/1) as mobile phase, at flow rate of 0.6ml/min (0-8min), 0.4ml/min (8-20min) and UV detection at 230 nm. The...

of isotopically labelled vitamin D metabolites by HPLC. Journal of Chromatography 303: 229}233. Kaspersen FM, van Acquoy J, van de Laar GLM, Wagenaars GN and Funke CW (1984) Deuterium isotope effects in mianserin. Recueil Travaux Chimique de Pay-Bas 103: 32}36. Klein PD (1966) Occurence and signiRcance of isotope fractionation during analytical separation of large molecules. Advances in Chromat...

When several plant hormones with similar structures are present in a sample, conventional analytical methods are not sufficiently selective to effectively differentiate them. However, the excellent selectivity of micellar liquid chromatography allows similarly structured compounds to be easily differentiated. We used reversed cholic acid micelles dissolved in tetrahydrofuran as the mobile phase...

A major disadvantage of gradient elution in terms of speed results from the need to adequately re-equilibrate the column. This work distinguishes two states of re-equilibration: (1) run-to-run repeatability and (2) full equilibration. We find that excellent repeatability (+/-0.002 min in retention time) is achieved with at most 2 column volumes of re-equilibration whereas full equilibration can...

The zein proteins of eight opaque maize mutants were examined by reversed-phase high-performance liquid chromatography (RP-HPLC) and the microstructure of their endosperms by scanning electron microscopy (SEM). The opaque (0) mutants included 01, 05, 09) 010) 011) hI, Oh43JlI and V\ 64AJll. In these opaque mutant maize kernels, the proportion (%) of ex-zein, the major component of the alcohol-e...

er than the normal amount. Especially, it is interesting that nicotinic acid reduces serum cholesterol and triglycerides.i) To study the unknown mechanism, the establishment of a practical method to measure nicotinic acid and its direct metabolite, nicotinuric acid, is important. In l978, Hengen et al.2] measured nicotinic acid and nicotinuric acid in plasma and urine with reversed-phase high-p...

The proposed isocratic liquid-chromatographic method for uric acid has good performance characteristics. Results by this procedure and by an enzymic method for uric acid correlated well (r = 0.986). Our method is inexpensive, rapid, and considerably simpler than other techniques for determining uric acid in urine.