Determination of theophylline in serum by reversed-phase liquid chromatography.

An improved micromethod for theophylline determination by reversed-phase liquid chromatography.

We describe an improved micro-scale method for determining serum theophylline by reversed-phase liquid chromatography. Samples are deproteinized with two volumes of methanol containing beta-hydroxyethyltheophylline as an internal standard. The supernate is chromatographed with a methanol/sodium acetate buffer (15/85 by vol) mobile phase, and the amount of theophylline is calculated from the rat...

Determination of monosaccharides in cider by reversed-phase liquid chromatography

A reversed-phase high-performance liquid chromatographic (HPLC) method is described for the simultaneous determination of aldoses and uronic acids in cider, previously derivatized with p-aminobenzoic ethyl ester (ABEE). Narrow-bore C8 columns are recommended as this alternative provides good separation efficiency, along with greater economy and sensitivity. Detection limits for aldoses (glucose...

HIGH-PERFORMANCE LIQUID CHROMATOGRAPHIC DETERMINATION OF THEOPHYLLINE IN HUMAN SERUM

A simple, rapid and sensitive HPLC method for the determination of theophylline (T) in human serum has been developed. An isocratic system consisting of a /-l Bondapak C18 column, mobile phase of methanol, phosphate buffer (22:78, pH=4.5), and a flow rate of 1.4 mL/min was used. The eluent was detected by UV at 275 nm at room temperature. 8-Chlorotheophylline (8-CT) was used as an internal ...

Micro-scale method for theophylline in body fluids by reversed-phase, high-pressure liquid chromatography.

We describe a micro-scale method for determining serum theophylline. The chromatography system includes a muBondapack C18 column and acetonitrile, 70 ml/liter of sodium acetate buffer (10 mmol/liter, ph 4.0) as the mobile phase. Test serum or plasma, 30 mul, is mixed with an equal quantity of a solution containing the internal standard, beta-hydroxyethyltheophylline in acetonitrile/sodium aceta...

Separation and quantitation of theophylline and paraxanthine by reversed-phase liquid chromatography.