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Abstract |
The Measurement of Theophylline in Human Serum or Plasma Using Gas Chromatography and Isotope Dilution-Mass Spectrometry (GC-IDMS) Taking other Substituted Xanthines into Consideration |
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A method is described which uses a combination of gas chromatography and isotope dilution-mass spectrometry (GC-IDMS) to determine the concentration of theophyltine (1,3-dimethyl xanthine) in human plasma or serum samples. The effects of similar substituted xanthines - namely theobromine (3,7-dimethyl xanthine), paraxanthine (1,7-dimethyl xanthine) 1,3-dimethyl-7-(2-hydroxyethyl) xanthine (internal standard HPLC) and caffeine (I,3,7- trimethyl xanthine) were tested to confirm the specificity of the method. The derivatisation of all xanthines was performed with N-methyl-N-trimethylsilyl trifluroacetamide (MSTFA). The internal standard used was 2-13C,1,3-15N2theophylline. The extraction and derivatisation procedures were examined in detail and optimised stepwise during the development of the method. High-performance liquid chromatography (HPLC) was used for comparison. (Clin. Lab. 2002;48:535-540) |
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