Dusci L J, Hackett L P, McDonald I A
J Chromatogr. 1975 Jan 29;104(1):147-50. doi: 10.1016/s0021-9673(01)85498-4.
A gas-liquid chromatographic method for the estimation of theophylline in human plasma is described. The method is based on the methylation of theophylline on-column and allows the determination of concentration of the drug down to the level of 1.0 mu-g/ml in plasma.