Anodic Stripping Voltammetric Determination of Aurothiomalate in Urine Using a Screen‐Printed Carbon Electrode

This work describes an electroanalytical method for determining gold(I) thiomalate, aurothiomalate, widely used for treatment of reumatoid arthiritis, using a screen‐printed carbon electrode (SPCE). Aurothiomalate (AuTM) was determined indirectly at the same electrode by accumulating it first at −1.5 V vs. printed carbon. At this potential in the adsorbed state, the AuTM is reduced to Au(0), which is then oxidized at two steps at −0.22 V and +0.54 V on SPCE. Using optimized conditions of 60 s deposition time, −1.5 V (vs. printed carbon) accumulation potential, 100 mV s −1 scan rate, linear calibration graphs can be obtained by monitoring the peak at +0.54 V for AuTM in HCl 0.1 mol L −1 from 1.43×10 −6 to 1.55×10 −4  mol L −1 . A limit of detection obtained was 6.50×10 −7  mol L −1 , and the relative standard deviation from five measurements of 3.0×10 −5  mol L −1 AuTM is 4.5%. The method was successfully applied for AuTM determination in human urine sample.