Spectrophotometric determination of chloramphenicol and its esters in complex drug mixtures.

When aromatic nitro compounds are reduced with zinc and calcium chloride and reacted with trisodium pentacyanoaminoferrate they give a purple product having an absorbance maximum between 480 and 540 nm. Applying this reaction, a quantitative method has been developed for the determination of chloramphenicol and its esters. Various reaction conditions have been standardized. Beer's law is obeyed in the concentration range of 4 to 32 micrograms/mL reaction mixture. Average recoveries and standard deviations were 99.78 +/- 0.627 and 99.90 +/- 0.660; 101.06 +/- 0.702; and 99.90 +/- 0.880% for chloramphenicol, chloramphenicol sodium succinate, and chloramphenicol palmitate, respectively. The method has also been applied to determine chloramphenicol and its esters as well as chloramphenical in the presence of combination drugs in dosage forms. The presence of benzocaine, lignocaine, sulfadiazine, nitrofurantoin, ascorbic acid, hydrocortisone, prednisolone, streptomycin, and tetracycline does not interfere with the proposed spectrophotometric procedure. The method does not require prior separation of chloramphenicol from combination drugs.