Cloud point extraction combined with HPLC-MS for the determination of nimesulide in biological samples

A high performance liquid chromatography (HPLC) method with mass spectrometry (MS) detection coupled previously cloud point preconcentration was developed for the determination of nimesulide in synthetic urine. Non-ionic surfactants Triton X-100 and Triton X-114 were used for cloud point extraction (CPE) of nimesulide. Various influencing parameters on the CPE process, such as pH, the concentration of non-ionic surfactant, equilibration temperature, incubation time and centrifugation parameters were studied and optimized. The developed method was validated; the linear range was in the range 67-5000ngmL(-1), the detection (3 sigma) and quantification (10 sigma) limits were 20ngmL(-1) and 67ngmL(-1), respectively. The intra-day and inter-day precisions were less than 14%, the average recovery factors were in the range 95-117%. The suggested CPE-HPLC-MS method was simple and sensitive and could be an effective tool for the determination of nimesulide in biological samples.