There is a lack of field compatible analytical method for the speciation of As(III) to characterize groundwater pollution at anthropogenic sites. To address this issue, an inhibition-based acetylcholine esterase (AchE) sensor was developed to determine As(III) in groundwater. 4-Acetoxyphenol was employed to develop an amperometric assay for AchE activity. This assay was used to guide the fabrication of an AchE sensor with screen-printed carbon electrode. An As(III) determination protocol was developed based on the pseudo-irreversible inhibition mechanism. The analysis has a dynamic range of 2-500 μM (150 - 37,500 μg L-1) for As(III). The sensor exhibited the same dynamic range and sensitivity in a synthetic groundwater matrix. The electrode was stable for at least 150 days at 22 ± 2 °C.
Keywords: acetylcholinesterase sensor; arsenic speciation; groundwater; screen printed electrode.