Spectrophotometric Method for Determination of Chloramphenicol in Pharmaceutical Preparations using 1,2-Naphthoquinone-4- Sulphonate as a Chromogenic Reagent

A simple, sensitive and rapid spectrophotometric method for the determination of chloramphenicol in pure as well as in dosage form is described. The method is based on the condensation reaction of reduced chloramphenicol with sodium 1,2-naphthaquinone-4-sulfonate (NQS) in an alkaline medium to form an orange-red colored Schiff's base of maximum absorption peak (λmax) at 480 nm. Under the optimized reaction conditions, Beer’s law correlating the absorbance with chloramphenicol concentration was obeyed in the range of 0.814 μg ml. The molar absorptivity was 1.02×10 L molcm. The limits of detection and quantitation were 0.124 and 0.473 μg ml, respectively. The accuracy and precision of the method were satisfactory; the average recovery was 99.54 % and values of relative standard deviations better than 3.5 %. The stoichiometry of the reaction was studied, and the reaction mechanism was postulated. The proposed method was successfully applied to the determination of chloramphenicol in its pharmaceutical capsule, syrup and ointment with good accuracy and precisions. The results obtained by the proposed method are compared with those obtained by the official method.