Peroxidase mimic feroxyhyte (FeOOH) nanoparticles enabled highly specific colorimetric detection of arsenate in water and fish.

Arsenic poses a serious health risk to humans. Hence, a simple and robust analytical approach for monitoring arsenic levels in water and food matrixes is required. We present a simple and rapid approach for quantifying arsenate in water and fish using feroxyhyte (FeOOH) nanoparticles as a sensor probe. The FeOOH nanoparticles showed peroxidase mimetic activity oxidizing 3,5,3'5'-tetramethylbenzidine (TMB) to a blue product (oxTMB, λ 650 nm) in the presence of HO. However, arsenate's presence inhibits the peroxidase activity of FeOOH nanoparticles through binding on the catalytic active sites. Based on this principle, the presently developed method obtained a good linear response (R, 0.99) over the range of 0.005 to 5.000 mg L arsenate with 0.006 mg L as the detection limit which is less than the prescribed limit (0.010 mg L) by WHO for drinking water. The average recoveries at different fortification levels ranged from 89.51 to 115.61 % in water and 101.11 to 106.99 % in fish muscle. The present analytical technique showed good selectivity due to pronounced peroxidase inhibition alibility (60.53-103.78 %) by arsenate than other non-target ions like PO, NO, CrO, etc. The FeOOH nanoparticles showed a promising application prospect for colorimetric detection of arsenate with a wide detection range in water and fish samples.