Two accurate, precise, and sensitive methods were developed for the simultaneous determination of ternary mixtures containing paracetamol (PAR), thiocolchicoside (THIO) and aceclofenac (ACE) in bulk powder and combined dosage form without prior separation. The first method is RP-HPLC which depended on isocratic elution using an agilent C18 column and mobile phase consisting of ammonium acetate buffer (pH 7) â methanol â acetonitrile--triethylamine (50:30:20:0.1, v/v) pumped at flow rate of 1 ml/min with UV detection at 258 nm. The second method is based on TLC separation of the three drugs followed by densitometric measurements of their spots at 248, 380 and 275 nm for PAR, THIO and ACE, respectively. The separation was carried out on silica gel 60 F254 using ethyl acetate-toluene-methanol âglacial acetic acid (2:2:1:20.25 v/v/v/v) as a developing system. The suggested methods were tested using laboratory-prepared mixtures and were successfully applied for the analysis of pharmaceutical preparations. The methods retained their accuracy and precision when the standard addition technique was applied. HPLC method was applied over the concentration range (1-120 ?g/ml) for Paracetamol, (0.8-60 ?g/ml) for Thiocolchicoside and (10-80 ?g/ml) for Aceclofenac while densitometric method was linear over the concentration range (200-10000ng/spot) Paracetamol, (10-1000ng/spot) for Thiocolchicoside and (100-10000ng/spot) for Aceclofenac, respectively. The developed RP-HPLC and TLC densitometric methods are rapid, sensitive and accurate and can be applied in quality control laboratories for routine determination of Paracetamol, Thiocolchicoside and Aceclofenac simultaneously in their ternary mixture without prior separation.
