Emergency toxicology testing (detection, confirmation, and quantification) of basic drugs in serum by liquid chromatography with photodiode array detection.

We investigated the applicability of liquid chromatography with photodiode array detection as a serum drug screening technique in an emergency toxicology setting. Basic compounds are extracted from alkalinized serum with hexane and chromatographed on a cyanopropyl reversed-phase column. The photodiode array detector records the ultraviolet spectrum of each eluting peak for identification and quantification. More than 30 drugs/metabolites including antidepressants, antihistamines, phenothiazines, and analgesics are detected at their therapeutic concentrations or less. Quantitative run-to-run precision (CV) for antidepressant drugs at low therapeutic concentrations is less than 6%. We evaluated the potential for interference of greater than 140 compounds of clinical interest. In a split-sample study, 151 of 154 positive drug findings by the method were confirmed by alternative techniques (gas chromatography/mass spectrometry and liquid chromatography with either normal-phase or reversed-phase columns). In the three unconfirmed findings, this method detected drugs at concentrations below the limit of identification of the comparison method. Also, 275 samples judged negative by this procedure were negative by a different liquid-chromatographic method.