Highly selective and sensitive colorimetric detection of arsenic(III) in aqueous solution using green synthesized unmodified gold nanoparticles

A simple, efficient, economically viable, and fast analytical method to perform arsenic (As3+) determination using silk sericin capped gold nanoparticles (SS-AuNPs) and UV-Visible spectroscopy as a detection technique is reported. In this work, biomediated AuNPs were synthesized using an eco-friendly biomaterial Bombyx mori SS. Formation of the AuNPs was verified by surface plasmon spectrum using UV-Visible spectroscopy. The crystalline structure of the AuNPs was characterized by X-ray diffraction technique. Morphologically spherical in shape with good dispersion and average diameter of 12.5 nm was revealed by transmission electron microscope (TEM). The size and shape of the AuNPs are greatly associated with their optical properties. When the As(3+)ions are added to SS-AuNPs the color change occurs due to the aggregation of AuNPs allowing the detection of As(3+)at parts per billion (ppb). Results showed an excellent correlation (R-2=0.985) exists between the decrease in the absorbance signal and the As3+ concentrations over the range from 1 ppb to 10 ppb. The limit of detection (LOD) of As3+ ions is found to be 2.94 ppb (3 sigma) and is many folds lower than the world health organization (WHO) recommended limit of 10 ppb. The described study could be a very useful method for the detection of As3+ ions in water and offers a basis for developing an optical sensing system for different applications.