Spectrophotometric determination of arsenic via arsine generation and in-situ colour bleaching of methylene blue (MB) in micellar medium.

A new spectrophotometric method has been developed to determine arsenic in parts-per-million (ppm) level. It is based on the colour bleaching of methylene blue (MB) in anionic micellar medium. Arsine gas was formed by borohydride reduction of arsenite/arsenate. Arsine generation and colour bleaching (quantification of arsenic) could be done in one-pot. The presence of silver or gold nanoparticles makes the determination faster. Different calibration graphs at the three different ranges of arsenic concentration such as 0-8.63, 0-1.11 and 0-0.11 ppm were constructed and limit of detection (LODs) were found to be 1.3, 0.53 and 0.03 ppm, respectively. The method is simple, rapid, reproducible (relative standard deviations lies within +/-5%) and eco-friendly. It is free from phosphate and silicate interferences and applicable for real sample analysis.