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A rapid gas chromatographic method for the determination of underivatized theophylline in whole blood is described. Theophylline is extracted from acidified blood and chromatographed directly using cyheptamide as an internal standard. Concentrations of the drug down to 2 mug/ml in blood could be determined with recoveries ranging from 90 to 110%.

A combined thin-layer and gas-liquid chromatographic (TLC-GLC) procedure for determination of tricyclic antidepressant drugs in urine is described. GLC on 1.5% OV-17 was utilized to analyzed basic urine extracts directly for the tricyclics and to confirm the identity of spots extracted from thin-layer chromatograms, and TLC was used to confirm the results of these GLC screens. Lower limits of sensitivity for the thin-layer spot extraction procedure were found to range from 2 mug/ml for amitriptyline and imipramine to 10 mug/ml for desipramine and nortriptyline. Turn-around-times for the GLC tricyclic screens were usually less than 1 h. The finding that nortriptyline and desipramine were chemically altered under various extraction conditions was used as a means of confirming the identity of these drugs, and the identity of these chemically altered derivatives was discussed with reference to their low resolution mass spectra.