New spectrophotometric methods for the quantitative determination of chloramphenicol in pharmaceuticals

Three new methods are proposed for the simple and sensitive spectrophotometric determination of chloramphenicol in pure form and in related pharmaceutical preparations. Two methods are based on the diazotization of reduced chloramphenicol, followed by coupling either with iminodibenzyl to give a violet colored product (λmax = 590 nm) or with 3-aminophenol to produce an orange-red colored product (λmax = 470 nm). The third method makes use of sodium molybdate and pyrocatechol as coupling agents to give a pale red colored product (λmax = 490 nm). The proposed procedures are highly reproducible and the maximum relative standard deviation is 0.3 % for five determinations. The new methods have been applied to the determination of chloramphenicol in capsules and injection solutions, and the results compare favorably with the official method. Common auxiliary substances used as components of pharmaceutical preparations do not interfere with the proposed methods. Plausible reaction mechanisms are proposed. © 2006 Springer Science+Business Media, Inc.