Automated quantitative screening for acidic and neutral drugs in whole blood by dual-column capillary gas chromatography.

A method consisting of single-step extraction, dual-channel capillary gas chromatography, nitrogen-selective detection, and automated data processing is evaluated for the quantitative screening of acidic and neutral drugs in postmortem blood. The drugs are identified by their cubic spline retention indices using multidetector retention index standards. The data processing is performed with Micman software, which offers several advantages in the maintenance of identification reliability. The precision of the retention indices during a three-month period with a routine loading of 14 samples per day is presented for eight different drugs at therapeutic and toxic concentrations: The CV ranges from 0.11% to 1.12% for NB-54 and from 0.05% to 0.21% for NB-1701. The within-day CV is less than 0.05% in each case. The status of these results and the means of achieving further precision are discussed. The long-term precision of quantification, normally under 10%, is considered adequate for most forensic toxicological purposes.