Colorimetric determination of Chloramphenicol and metronidazole in pharmaceutical formulations after schiff-base formation with vanillin and anisaldehyde

Abstract

The nitro groups in chloramphenicol and metronidazole drugs were reduced to their amino functions using zinc dust in concentrated hydrochloric acid. Vanillin and anisaldehyde were used to form Schiff-base adducts with chloramphenicol and metronidazole respectively. The chloramphenicol couple gave an absorption maximum (lm) at 385 nm while that of metronidazole absorbed (lm) at 400 nm. Both colours were stable over a period of 9h. Both derivatives obey Beer/Lambert law within the range of 1 mg/ml and 10 mg/ml that was investigated. The molar absorptivities were 2491 and 3151 l mol-1 cm-1 for chloramphenicol and metronidazole adducts respectively. Sandell's sensitivity values were 8.5 ng/ml for chloramphenicol and 22.5 ng/ml for metronidazole suggesting that the vanillin couple was more sensitive than the anisaldehyde adduct. The adduct formation was highly selective so quantitative recoveries indicated high precision although statistical comparison employing Student's t-test did not suggest any significant (p > 0.05) difference between the proposed and the Pharmacopoeia method. This proposed method is more sensitive, accurate and simple to carry out.


Keywords: Chloramphenicol and Metronidazole assay; Schiff-base adduct


[Global Jnl Pure & Appl. Sci. Vol.9(3) 2003: 359-364]