Spectrophotometric determination of metronidazole by prior reduction and subsequent diazotisation and coupling with N-(1-naphthyl)‎ ethylenediamine-application to pharmaceutical preparations

الملخص EN

A simple, rapid and sensitive spectrophotometric method for the determination of microgram amounts of metronidazole (MZ) has been proposed.

The method is based on the reduction of metronidazole with iron metal and hydrochloric acid followed by diazotisation and coupling with N-(1-naphthyl) ethylenediamine in acidic medium to give a pinkish-red colored azo dye which has maximum absorption at 503 nm.

Beer's law is obeyed in the concentration range of 20-500 μg of metronidazole in a final volume of 25 ml, i.e., 0.8-20 ppm, with a molar absorptivity of 4.673×103 l.mol-1.

Cm-1 and Sandell's sensitivity index of 0.0366 μg.cm-2 a relative error of –1.73 to + 1.58 % and relative standard deviation of ± 0.47to ±1.32 %, depending on the concentration level.

The method has been applied successfully to the determination of metronidazole in pharmaceutical preparations.