Screening of basic drugs in biological samples using dual column capillary chromatography and nitrogen-phosphorus detectors.

A method is presented for the extraction and screening of basic and neutral drugs, including amphetamines. Two milliliters of blood are buffered to pH 9.0 and extracted with n-chlorobutane. Underivatized extracts are analyzed simultaneously on two complementary capillary columns placed together in one injection port using split injection. A relative retention time list comprised of 110 common drugs of abuse and metabolites has been compiled for both capillary columns. The internal standard used is SKF-525A. The success of the method depends upon four areas: inertness of the system, nitrogen detector optimization, extraction technique, and lack of contamination. The percent recovery has been calculated for twelve commonly encountered drugs. The within-run and day-to-day recoveries and retention time reproducibility have been investigated for the internal standard SKF-525A. The authors have found the combination of fused silica capillary columns and nitrogen-phosphorus detectors makes for a stable screening system for basic and neutral drugs in biological samples.