Abstract
Simple and selective spectrophotometric methods for the determination of norfloxacin, ciprofloxacin, cinoxacin and nalidixic acid are described. The methods are based on the measurement of the intensity of the orange-red colour produced by the drugs with ferric chloride in dimethylsulphoxide-methanol medium. The methods are highly accurate and have been successfully applied for analysis of bulk drugs and pharmaceutical preparations. The results are in good agreement with the official methods.