The lactulose/mannitol dual sugar absorption test is a non-invasive test of intestinal permeability. Its widespread use has been limited by the difficulties of analysis for carbohydrates in urine at low concentrations. We describe a "high-pressure" liquid-chromatographic method for determining lactulose and mannitol in urine, in which anion-exchange chromatography and pulsed amperometric detect...

1.1 This gas chromatographic method is designed to determine the concentrations in soil and water of petroleum hydrocarbons from nhexane (C6) to n-pentatriacontane (C 35); an approximate boiling point range from 70C to 500C. This includes the gasoline, diesel range, and some portions of heavier fuels and lubricating oils. This method also describes the separation of the petroleum hydrocarbons i...

A highly sensitive gas chromatographic assay is described for the simultaneous determination of gallopamil, a calcium channel blocking agent, and its major metabolite, norgallopamil. A multi-step extraction procedure is employed followed by on-column capillary gas chromatographic analysis using nitrogen-selective detection. Acetylation of norgallopamil is performed to enable accurate quantifica...

During the last decade, high pH anion exchange chromatography with pulsed amperometric detection (HPAED/PAC) has gained increasing acceptance as the method of choice for analysis of neutral sugars commonly occurring in woods, pulps, and other lignocellulosics. This paper describes modified chromatographic conditions and discusses other critical factors that improve the precision and efficiency ...

We describe a gas-liquid chromatographic method for determining mephenytoin and its active metabolite, desmethylmephenytoin, in human serum. 5-Methyl-5-phenylhydantoin is used as the internal standard. The method involves extraction of the drugs by adsorption onto charcoal and off-column derivatization to their pentyl derivatives. Peak height and concentration are linearly related and the day-t...

The volatile fatty acid profiles were determined by a simple gas chromatographic method in 375 microbiologically positive and negative blood cultures. Aerobic bacteria yielded profiles with low content of acids, some of which were chromatographically negative. Anaerobic bacteria produced more acids and more distinctive profiles. The method makes it possible to confirm the microbiological findin...

We describe an isothermal gas-liquid chromatographic procedure developed for measuring thiamylal and thiopental in plasma. The unchanged drug is extracted into ethyl acetate from acidified plasma, together with an internal standard. The solvent is removed, the residue methylated, aliquots, diluted with benzene, are injected into a 183-cm gas-liquid chromatographic column containing 3% OV-17. Se...

A method is described for measuring doxepin-related material excreted in urine. Unchanged doxepin and certain doxepin metabolites are oxidized to doxepin ketone with KMnO4. The doxepin ketone is extracted with n-hexane and quantitated by ultraviolet spectrophotometry at the absorption maximum, 266 nm. This method is fast, reproducible, and measures a greater percentage of doxepin-related materi...

We describe a method for the 7-min determination of theophylline in less than 100 muL of serum. The procedure requires no centrifugation or solvent evaporation after extraction. Butylation is done on the gas-chromatographic column by injecting the serum extract followed by a butylating mixture which contains 1-iodobutane as the alkylating agent. The method is precise, accurate, and free of inte...

phase together with a counterion. Schurig V (1984) Gas chromatographic separation of enantiomers on optically active stationary phases. Angewarde Chemie International Edition English 23: 747}765. Schurig V (1994) Enantiomer separation by gas chromatography on chiral stationary phases. Journal of Chromatography 666: 111}129. Schurig V and Nowotny H-P (1990) Gas chromatographic separation of enan...