On-line dialysis-SPE-CE of acidic drugs in biological samples

A fully automated method is presented for the determination of acidic drugs in urine and serum using on-line dialysis-solid-phase extraction (SPE)-cap illary electrophoresis (CE) with UV detection. With non-steroidal anti-infl ammatory drugs (NSAIDs) as test compounds, detection limits in the biologic al samples were 0.05-1.0 mu g ml(-1). Calibration plots were linear over tw o orders of magnitude and the within-day and between-day repeatability were better than 10%. The CE capillary and SPE column were used for over 500 an alyses; the dialysis membrane was replaced after 250 analyses. A general pr otocol for dialysis-SPE-CE which can be used for amphoteric and acidic drug s was devised. The present results show that this protocol has general vali dity and can be recommended for future work on other classes of drugs.