Quantitative analysis of metronidazole in intravenous admixture with ciprofloxacin by first derivative spectrophotometry.

Metronidazole in parenteral admixture with ciprofloxacin was analysed by first-derivative spectrophotometry using the zero-crossing technique of measurement. The procedure did not require prior separation steps. The method was found to be linear (r(2)>0.999) in the range of 2.5-10 microg ml(-1) for metronidazole in absence or presence (at constant concentration) of ciprofloxacin. The first-derivative method was applied for the analysis of intravenous admixture of metronidazole and ciprofloxacin and proved to be rapid, accurate and reproducible.