Analyt: Theophylline
Matrix: Serum
Measuring Method: GC-ID/MS
Standard: Cerilliant IMPC-051-01 Primary Standard Theophylline
Internal Standard: ¹³C,¹⁵N₂-Theophyllin
Sample Processing: Samples are spiked gravimetrically with internal standard, equilibrated, then precipitated with TCA, centrifuged and the supernatant is extracted into chloroform/2-propanol, centrifuged and the lower phase evaporated to dryness. Derivatisation is performed with MSTFA.
Measurement: Measurement at m/z 237 and m/z 240 or at m/z 252 and m/z 255