Semiautomated method for analysis of enteric-coated and plain coated diethylstilbestrol tablets

A semiautomated fluorometric method for the analysis of enteric-coated and plain coated diethylstilbestrol tablets is presented. To eliminate interferences from tablet excipients, diethylstilbestrol is extracted into an organic solvent and then into a basic aqueous solution. After UV irradiation, a product of diethylstilbestsrol is formed from which a fluorophore is produced chemically. The fluorescence is measured at an excitation wavelength of 335 nm and an emission wavelength of 410 nm. The coefficient of variation measured for the semiautomated procedure was 0.59%. Assay results agreed well with the USP procedure for tablets containing greater than 1 mg of diethylstilbestrol. Tablet dyes and excipients interfered in the USP procedure, which yielded low results for tablets containing less than 1 mg of diethylstilbestrol. Standard recovery data and assays of tablet composites showed that dyes and other excipients do not interfere with semiautomated procedure.