Determination of Trace Amounts of Gold in Environmental Samples by Adsorptive Stripping Voltammetry of Its Complex with Rhodamine Using Osc-Pls

The multivariate calibration method was applied for the determination of trace amounts of gold based on a hanging mercury drop electrode (HMDE) in the presence of rhodanine, followed by reduction of adsorbed gold by voltammetric scan using differential pulse modulation The optimum experimental conditions are: rhodanine concentration of 0.20 ?g mL-1, pH 5.0, accumulation potential of -600 mV versus Ag/AgCl, accumulation time of 100 sec, scan rate of 30 mV s-1 and pulse height of 100 mV. The calibration matrix for partial least squares (PLS) regression was designed with 9 samples. Orthogonal signal correction (OSC) is a preprocessing technique used for removing the information unrelated to the target variables based on constrained principal component analysis. OSC is a suitable preprocessing method for PLS calibration without loss of prediction capacity using electrochemical method. The RMSEP for gold determination with PLS and OSC-PLS were 8.51 and 1.94, respectively. This procedure allows the determination of gold in synthetic and real samples with good reliability of the determination.