Automated liquid chromatographic analysis of drugs in urine by on-line sample cleanup and isocratic multi-column separation.

A multi-column system has been developed for automated analysis of basic drugs in urine. Two polymeric pre-columns, containing PRP-1 and Aminex A-28, were used to isolate the drugs. A short reversed-phase column, coupled to a 150 x 4.6 mm I.D. silica column, produced the analytical separation. Sample preparation consisted of dilution and centrifugation. The entire procedure required less than 30 min. Careful optimization of mobile phase conditions led to retention of benzoylecgonine and barbiturates. For most drugs, levels of 0.3 mg/l were sufficient to produce peaks that could be matched against stored spectra with a computerized library search program.