Fluorophotometric Determination of Diethylstilbestrol

In 0.4 mmol·L-1 B-R buffer medium of pH 4.1, butyl-rhodamine B (BRMB) was rapidly oxidized by hydroxyl free radical produced by the reaction between Fe(Ⅱ) and H2O2, leading to significant decrease of fluorescence intensity of BRMB. When diethylstilbestrol (DES) was present in the above reaction system, due to the elimination action of DES toward OH free radical, the magnitude of decrease of fluorescence intensity was decreased, and values of fluorescence difference (ΔF=F-F0) were found to keep linear relationship with mass concentration of DES in the range of 0.1-50 μg·L-1. Based on these facts, a method of fluorophotometric determination of DES was proposed. Optimum conditions for this reaction were found as follows: ① mass concn. of BRMB: 2.0 mg·L-1; ② concn. of FeSO4: 0.05 mmol·L-1; ③ concn. of H2O2: (φ) 0.000 3% and ④ time of reaction: 6 min. Detection limit (3s/k) of the method was found to be 0.045 μg·L-1. Test for recovery was made by standard addition method, giving results in the range of 91.0%-106%, with values of RSD′s (n=5) less than 5%.