Capillary gas chromatographic-mass spectrometric determination of stable isotopically labelled and unlabelled theophylline in serum and urine and of 1,3-dimethyluric acid in urine.
A capillary gas chromatographic-mass spectrometric method for the determination of [13C,15N2]theophylline and unlabelled theophylline (TP) and of 1,3-dimethyluric acid (1,3-DMU), a major metabolite of TP, is described. TP and the metabolite were extracted separately from serum or urine, purified by high-performance liquid chromatography and converted into alkyl derivatives (monoethyl-TP and dibutyl-1,3-DMU). The internal standards used for the respective determinations were [2H6]TP and [2H6]1,3-DMU. Detection was performed by monitoring the molecular ions of the alkyl derivatives. The method needed no complex corrections for contributions and provides good accuracy and precision.
Kasuya
Y
Y
Tokyo College of Pharmacy, Japan.
Furuta
T
T
Shimota
H
H
D000478:Alkylation; D002247:Carbon Isotopes; D002851:Chromatography, High Pressure Liquid; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006801:Humans; D009587:Nitrogen Isotopes; D012015:Reference Standards; D013806:Theophylline / Q000032:analysis*; D014527:Uric Acid / Q000031:analogs & derivatives* / Q000652:urine
D002247:Carbon Isotopes; D009587:Nitrogen Isotopes; D014527:Uric Acid; D013806:Theophylline; C031274:1,3-dimethyluric acid