Determination of theophylline and paraxanthine in urine samples by liquid chromatography using the H-point standard additions method

✍ Scribed by Pilar Campíns-Falcó; Francisco Bosch-Reig; Rosa Herráez-Hernández; Adela Sevillano-Cabeza

• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 631 KB
• Volume: 268
• Category: Article
• ISSN: 0003-2670
• DOI: 10.1016/0003-2670(92)85250-a

✦ Synopsis

The simultaneous determmatlon of theophylhne and paraxanthme m urine samples by the H-pomt standard additions method (HPSAM) IS described Samples are extracted with Cl, solid-phase extraction cartndges and chromatographed using a Hypersd Cl,-ODS column and a mobile phase conslstmg of acetomtnle-phosphate buffer m the gradient elutlon mode Under these conditions theophylhne and paraxanthme are eluted with short retention times Although then chromatographlc peaks are overlapped and their spectra are very similar, the H-point standard addltlons method provides excellent results m the determmatlon of both xanthmes at therapeutic levels Keywords Liquid chromatography, H-point standard addltlon method, Paraxanthme, Theophylhne, Xanthmes Numerous hqmd chromatographlc (LC) methods for the determmatlon of theophylhne m blological fluids have been proposed Although theophylhne 1s easily detected when it IS present at therapeutic concentrations (l-20 pg ml-'), it has been reported that many exogenous and endogenous compounds Interfere [l] The mablhty to separate theophyllme from some of its metabohtes m a reasonable tune has been a typlcal problem m most of the LC procedures [2-71 The presence of the pharmacologically active dietary methylxanthmes caffeine, theobromme and paraxanthme (1,7-dlmethylxanthme) may mfluence patient compliance and may also complicate the evaluation and interpretation of theophyllme therapeutic drug momtormg The separation of theophylhne from paraxanthme, the mam metab-