VALIDATED LC-MS/MS METHOD FOR THE DETERMINATION OF THE NONSTEROIDAL ANTI-INFLAMMATORY DRUG (NSAID) DICLOFENAC FROM HUMAN PLASMA

The purpose of this study was the development and validation of an LC-MS/MS method, for the determination of diclofenac from human plasma. The sample workup involved a simple protein precipitation procedure. A core/shell type analytical column (50x2,1 mm, 2.6 angstrom) was used with C18 stationary phase. The mobile phase consisting of 52.5% acetonitrile and 47.5% water provided good peak shape, accuracy and precision (stable ionization). The mass spectrometer was operated in negative electrospray ionization mode for analyte and internal standard. The following parameters were evaluated for validation purpose: Selectivity, sensitivity, matrix effect, anticoagulant effect, linearity, precision and accuracy, recovery, short and long term analyte/IS stability in solvent/matrix and carryover. The validated calibration range was 3.9-1194 ng/ml. The correlation coefficient R-2 was at least 0.999 in all validation batches. The validated method has been successfully used for the evaluation of bioequivalence of a generic diclofenac potassium formulation of 12.5 mg strength.