Voltammetric determination of boron by using Alizarin Red S

A novel voltammetric method for boron determination in ppb level is described. Boron complexes with Alizarin Red S (ARS) and the complex, as well as the free ligand, both adsorbs on a hanging mercury drop electrode. The method is based on the monitoring the anodic peak of the complex at −0.47 V in ammonium acetate–phosphate buffer (pH 7). The maximum peak current was obtained by scanning the potential from −700 mV versus Ag/AgCl to more positive potentials without accumulation in the presence of 1 × 10−6 mol L−1 of ARS. The instrumental parameters were mainly differential pulse mode with a pulse duration of 0.02 s and a scan rate of 5 mV s−1. The limit of detection based on signal to ratio of 3 was calculated as 15 μg L−1. The calibration plot for boron was linear in the range of 0–500 μg L−1. The interference of various ions was examined and serious interference was observed from antimony(III). The relative standard deviation was found to be 5.1% for the 100 μg L−1 boron level (n = 10). The method was applied to the determination of boron in water and seawater samples with high boron content. The results obtained from the developed method were compared with Azomethine-H-method and no statistically significant difference was found.