Extraction of acidic drugs from water and plasma: study of recovery with five different solvents.

The recovery of 28 acidic drugs from water and plasma was investigated spectrophotometrically using five different solvents for extraction: hexane, diethyl ether, toluene, n-butyl chloride, and chloroform. Nine barbiturates, three sulfonamides, four diuretics, and twelve other acidic drugs were studied. As classes, the barbiturates, the sulfonamides, and the diuretics were optimally extracted with diethyl ether from both water and plasma, while considerable variation in recovery was noted among solvents for the other drugs. In general, recoveries from water were higher than those from plasma with most solvents, except for the sulfonamides for which recoveries were often better from plasma. Extraction recoveries for the individual drugs are tabulated and compared.