A turbidimetric determination of paracetamol in pharmaceutical formulations

Sensitive, selective, accurate and precise turbidimetric procedure has been developed for the determination of paracetamol in pure and in dosage forms. The procedure is based on the reduction of silver-gelatin or auric-gelatin complexes in alkaline medium at room temperature after 15 min. The yellow or golden yellow coloured product showed an absorption maximum at 414 and 539 nm with molar absorptivity of 6.3 x 10(3) and 2.73 x 10(3) L mol(-1) cm(-1) and Sandell sensitivity of 0.024 and 0.055 mug cm(-2) using Ag+ and Au3+-gelatin complexes, respectively. The determination 1-23 and 1-35 mug mL(-1) of paracetamol using Ag+ and Au3+-gelatin complexes is possible at lambda(max) of each reduction product (Ag-n- or Au-n-gelatin) in the presence of additives and excipients usually present in dosage forms. The relative standard deviation +/- 0.95 and 0.83\% on using Ag+ and Au3+-gelatin complex, respectively. To examine the applicability of the turbidimetric method, the proposed method is successfully applied to determine paracetamol in pharmaceutical formulations.