Paired-ion reversed-phase high-pressure liquid chromatographic assay of pentobarbital-pyrilamine suppositories.

The assay of suppositories containing pentobarbital and/or pyrilamine in a water-soluble polyethylene glycol base by high-pressure liquid chromatography is described. No extraction is required. The suppository is dissolved in the mobile phase. This solution is diluted with an internal standard stock solution containing phenobarbital. Chromatographic conditions include a C18 bonded microporous silica column and a mobile phase of 65% 4 x 10(-3) M n-butyl sodium sulfonate in 1% acetic acid and 35% acetonitrile. The procedure using commercial products gave results comparable to those obtained by GLC.