Air-segmented continuous-flow visible spectrophotometric determination of cephalosporins in drug formulations by alkaline degradation to hydrogen sulphide and formation of methylene blue and determination of sulphide-producing impurities including cephalosporins in penicillin samples

Abstract

A manual visible spectrophotometric method for the determination of cephalosporins by alkaline degradation to sulphide and formation of methylene blue has been adapted for use with an air-segmented AutoAnalyzer I system. The system has been tested for the determination of twelve cephalosporins; rectilinear calibration graphs were obtained with good precision in the general range 8–80 µg ml^–1 of cephalosporin.

The automated procedure was tested as a method of determining trace amounts of cephalosporins and other sulphide-producing impurities in penicillin G and V samples. The detection limit was calculated to be 1–2 µg g^–1 of cephalosporin in penicillin samples.