A simple spectrophotometric method for determination of gold (III) in aqueous samples

A simple method for rapid determination of trace Au in natural water was presented by using UV–vis spectrophotometry after reaction of gold (III) with 3,3′, 5,5′-tetramethylbenzidine hydrochloride (TMBH) in acidic solution. Under the optimum conditions, in a concentration range of 100–2000 μg L−1 of Au (III) a good linear calibration graph was obtained (r = 0.9969, n = 7). The percent relative standard deviation (RSD) for determination of 1000 μg L−1 Au was 10% (n = 3) and limit of detection based on a signal-to-noise ratio (S/N) of 3 (3Sbl) was 50 μg L−1. The proposed method has been successfully applied to the determination of gold spiked and real aqueous samples.