Methamphetamine (I) [537-46-2] and pentobarbital (II) [57-33-0] were selectively extracted from blood samples with a H2SO4 solution and ethyl ether, resp. II was then separated by a gas-chromatog. method similar to that of Kazyak and Knoblock (1963), using a glass column packed with acid washed Chromosorb W, silylated with dimethylchlorosilane, and having a 5% SE-30 liquid load. A flame-ionization detector was used for determining II. Recovery of II was .sim.93.4%. I was converted to methamphetamine trichloroacetamide [33522-93-9] and then chromatographed on Gas Chrom Q having a 3% load of OV-1. The electron-capture detector used had responses to the I derivative which were linear over a 0-1 ng range. Recovery of I was .sim.68.4%. When urine samples were analyzed, I recovery was .sim.94.0%.