Spectrophotometric determination of cycloserine with 9-methoxyacridine

Spectrophotometric assay for cycloserine based on the interaction of the drug with 9-methoxyacridine as a chromogenic agent is described. The highly colored substituted acridine product was identified as 9-(d-4-imino-3-isoxazolidinone)acridine. Color development was affected by time and temperature of heating and by the quantity of 9-methoxyacridine reagent utilized. The absorbance at 438 nm is linearly proportional to concentrations of cycloserine with a detection limit of 0.3 microgram/mL. The optimum range for the assay of cycloserine was from 5.0 X 10(-6) to 3.0 X 10(-4) M (correlation coefficient = 0.9999, n = 6). When applied to cycloserine capsules labeled to contain 250 mg, the proposed method gave mean recoveries of 101.84 +/- 0.48%. The procedure is sufficiently sensitive, precise, and accurate for the determination of cycloserine in its dosage form.