Screening for neutral and basic drugs in blood by dual fused-silica column chromatography with nitrogen-phosphorus detection.

We describe a capillary gas-chromatographic method for detection and quantification of basic and neutral drugs in the plasma of patients thought to be poisoned after dangerous overdose. Without further derivatization, the drugs are extracted from 1 mL of plasma, at basic pH, into diethyl ether. The extracts are injected onto two fused-silica capillary columns of different polarity (Ultra 1 and CP Sil 19 CB) coupled to nitrogen-phosphorus detectors. Under these conditions, drug-free plasmas give blank chromatograms, with a peak only for the internal standard (RN 927, an antihistamine not being marketed). Plasma samples from patients who have taken drugs show additional peaks, the relative retention times (RRTs) of which are used to identify the drugs. Here we list the RRTs of about 200 drugs on the two columns. Analyses are routinely performed with an automatic injector; overall analysis time is about 1 h per sample. During the last six years, more than 1000 plasma samples per year have been analyzed. We find this method a powerful tool for toxicological analysis, especially in cases of multi-drug intoxications.