A novel highly sensitive catalytic determination of selenium using a digital camera

Abstract

Simple, lower-cost, selective and highly sensitive methods for the assessment of Selenium (IV) as a critical environmental pollutant are highly desirable, especially under resource limited settings. Therefore, herein we describe the coupling of digital imaging with catalytic analysis for the extremely sensitive determination of Se(IV) using its catalytic effect on the micellar sensitized Methylene blue (MB)hydrosulfide reduction reaction. The initial rate kinetic measurement was applied by following the decolorization of MB within 60 sec of mixing the reactants using a digital camera or spectrophotometrically at 665 nm. The optimum reaction conditions were: 9.0 mol L -1 MB, 10.0 mmol L -1 Na 2 S, 6.3 mmol L -1 Na 2 SO 3 , 8.0 mmol L -1 CTAB, 90.0 mmol L -1 borax, 0.15 v/v% HCHO, 30.0 mmol L -1 of EDTA, 3.0 v/v% triethanolamine, at pH = 9.30±0.10 and 30C. The calibration graphs fitted second order polynomial equations for up to 19.0 and 20.0 ng mL -1 Se(IV) with a detection limit (3S b ) of 0.2 and 0.5 ng mL -1 Se(IV), for the spectrophotometric and digital imaging monitoring respectively. The amended methods were successfully applied to various natural waters and bird feed samples. The analytical data were statistically in excellent agreement with those obtained following the official AOAC 996.16 method.