A simple, rapid and sensitive method is described for the determination of tramadol hydrochloride (TMH) in pure form or in tablets. The method is based on the reduction of FolinCiocalteu (F-C) reagent by TMH in alkaline me-dium, leading to the formation of a blue coloured chromogen, which absorbs maximally at 760 nm. Under the op-timized experimental conditions, the colour is stable for over 12 h and Beer's law is obeyed in the concentration range of 2.5-50 pLg/mL. The regression coefficient (r) is calculated to be 0.9998 with molar absorptivity value of 6.3 × 103 L/mol/cm and Sandell sensitivity of 0.0478 fig/cm per 0.001 absorbance unit. The limits of detection (LOD) and quantification (LOQ) are also reported. Within-day variation determined on three different concentrations showed accuracies ranging from 0.70 to 1.53% and the RSD was determined to be < 2%. Day to day variation presented ac-curacies ranging from 1.12 to 1.53% with an RSD < 2%. The proposed method was successfully applied to the de-termination of TMH in tablets with good recoveries.
Keywords: Tramadol, Determination, F-C reagent, Spectrophotometry, Pharmaceuticals