Spectrophotometric and spectrofluorimetric determination of cycloserine with p-benzoquinone

Abstract

Spectrophotometric and spectrofluorimetric methods are described for the determination of cycloserine. Both methods are based on the reaction of cycloserine in aqueous solution of pH 8.2 with p-benzoquinone. A fluorescent compound with an absorption maximum (and also an excitation maximum) at 381 nm is obtained. The complex has an apparent molar absorptivity of 4.76 × 10³ l mol^–1 cm^–1 and Beer's law is obeyed over the range 4–20 µg ml^–1. The emission maximum of the complex is at 502 nm. The fluorescence intensity is linearly related to concentration over the range 0.04–0.2 µg ml^–1. When applied to capsules labelled to contain 250 mg, the proposed methods gave mean recoveries of 100.97 ± 1.14 and 99.8 ± 1.13%, respectively.