Voltammetric Behavior of Mifepristone (RU‐486) Using Square‐Wave and Adsortive Stripping‐Wave Techniques. Determination in Urine Samples

The behavior of Mifepristone (RU-486) was studied by square-wave technique, leading to two methods for its determination in aqueous samples and urine samples at pH 2. The application of the square-wave (SW) without the adsorptive accumulation and stripping voltammetric (AdSV) show the maximum response at −0.896 V using an accumulation potential of −0.5 V. The effect of experimental parameters that affect this determination are discussed. For the stripping technique, Mifepristone proved to be more sensitive, yielding signals four times larger than those obtained by applying a square-wave scan without the previous accumulation. The calibration plot to determine Mifepristone was linear in the range 2.4×10−8 and 5.4×10−7 M by stripping mode with an accumulation time tacc of 30 s. The relative standard deviation obtained for concentration levels of Mifepristone as low as 2.0×10−7 M with square-wave was 1.17% (n=10) and with stripping square-wave 2.02% (n=10) in the same day. The two proposed methods (SW and SWAdSV) were applied to the determination of Mifepristone in urine.