The sensitivity obtained even with the free compounds (except morphine) make gas chromatography a good technique for trace analysis of drugs in biological samples.

For many of the drugs studied the detector response curves are not linear with sample concentration but the calibration curves are reproducible if care is exercised. This makes quantitative analysis feasible down to 50-100 nanogram levels with proper technique.

Long column life is needed for routine analyses. Those columns employed in this work were used continuously for over seven months with no appreciable deterioration.