Determination of Non-Narcotic Analgetics by HPLC with Preconcentration on Triton X-100 Induced Phases

The induced micellar-extraction preconcentration of mefenamic acid, naproxen, and indomethacin on Triton X-100 phases in the presence of salicylic and benzoic acids is studied. The optimal conditions for the preconcentration of analgetics are found: the pH of the solutions and the concentration of analytes. The maximum extraction of analgetics is observed at pH < pK(a) of the analyte and modifier. An increase in the recovery of analgetics with a decrease in their concentration in the initial solution is shown. A procedure for the determination of non-narcotic analgetics by HPLC with preliminary micellar-extraction concentration on Triton X-100 induced phases is developed. The procedure was used to analyze an urine sample with additives.