A Simple, Stable, and Highly Sensitive Spectrophotometric Method for the Determination of Arsenic(III) from Different Biological Media in the Presence of Nanosilica-Cysteine Composite

This paper describes a selective and fairly stable colorimetric approach to determine trace amounts of arsenic conjugated with nanosilica-cysteine composite in various aqueous and biological samples in milligram per liter (mg/L) using Leucocrystal Violet (LCV) as a chromogenic reagent. Attenuated total reflectance-Fourier-transform infrared (ATR-FTIR) spectroscopy analysis was applied to characterize the composite. Novelty of this method is dealing with the presence of nanosilica which is reflected in the difficulty of obtaining a clear solution. The maximum absorbance is measured and Beer's law shows linearity over the concentration range of (0.75 to 5.00 mg/L) of As(III) at 590 nm. The molar absorptivity, Sandell’s sensitivity, and detection limit of the method were found to be 6.00 × 105 L/mol.cm, 8.55 × 10-2 μg/cm2, and 0.043 mg/L, respectively. The optimum reaction conditions and other analytical parameters were evaluated. Arsenic was successfully detected in a variety of aqueous and biological samples using the proposed method.