Flow injection spectrophotometric determination of 4-aminophenazone based on diazotisation and coupling reactions

Abstract

The flow injection spectrophotometric determination of 4-aminophenazone (4-aminoantipyrine), based on the diazotisation of p-nitroaniline with nitrite and coupling with 4-aminophenazone, is developed. The coupling reaction takes place in a 250-cm reaction coil, and the resulting azo-compound is quantified by spectrophotometry at 380 nm. A linear calibration graph is obtained for increasing concentrations up to 50 µg ml^–1. The experimental limit of detection (three times the noise signal) is 0.05 µg ml^–1(200 µl), and the relative standard deviation is 0.61 and 0.27% for 4 and 50 µg ml^–1(ten injections), respectively. The sampling rate is 50 h^–1 and the over-all dispersion of the system is 1.96.