A simple, fast, selective, and precise solid-liquid chromatography-MS/MS method has been established and validated for concurrent quantification of Aceclofenac and Thiocolchicoside in human plasma and it was enriched with the help of Protein Precipitation technique.   Hibar^® C18 (5µm, 50 x 4.6 mm i.d.) column used as adsorbent and the following eluant is used to separate the aceclofenac and thiocolchicoside by using Cyanomethane and 10mM Ammonium acetate buffer (pH 4.0) with  80:20 v/v ratio and the elution rate was fixed 0.5ml/min and the detection was performed by Triple quadrupole LC-MS/MS using electron spray ionization as positive and negative mode. The calibration curve was consistently accurate for the Aceclofenac and Thiocolchicoside between the range of 785 to 15700ng/ml and 6 to 120ng/ml using Etodolac as the internal standard. Aceclofenac detected (LOD) and quantified (LOQ) 1.5ng/ml and 4.5ng/ml and similarly, thiocolchicoside was detected 1ng/ml and quantified 3ng/ml. The precision, accuracy and the correlation coefficient (R²) of Aceclofenac and Diclofenac are within the limits as per USFDA guidelines, so this can be used for the quantification of Aceclofenac and Thiocolchicoside in Human plasma for the study of biomedical and biopharmaceutical sciences.

Keywords: LC-MS/MS, Bio-analytical, Aceclofenac, Thiocolchicoside, Human Plasma.