Quantitative determination of chlorthalidone by fluorescence labelling using 5-dimethylaminonaphthalene-1-sulphonyl chloride

A sensitive method is presented for the fluorimetric determination of chlorthalidone based on the dansylation process of the secondary amino group present in chlorthalidone. The fluorescence developed can be measured directly without previous extraction or chromatographic separation of the labelled fluorescent compound. The limit of determination is 10 to 100 ng/ml and the relative standard deviation is less than 2\%. The proposed method was applied for the determination of this drug in the pure form and in pharmaceutical preparations.