Rapid and visual detection of dichloroacetonitrile in water

Dichloroacetonitrile (DCAN) is a common biotoxic disinfection by-product (DBP) of chlorine. The current methods used for detecting DCAN are tedious and heavily instrument-dependent, and are not suitable for on-site detection. In the present study, we developed a colorimetric assay for rapid detection of DCAN. DCAN in water acted as a complexing agent that formed a complex with cuprous species. The cuprous species was then extracted by chloroform and visualized using dithizone. The visual detection limit for DCAN was 20 ng mL^-1, while fluorescence quantification could detect DCAN at a concentration as low as 8.75 ng mL^-1. Moreover, haloacetonitriles (HANs) derived from chlorine disinfection and structurally similar to DCAN, including TCAN, BCAN, and DBAN, could also be detected using this method. Other DBPs at concentrations as high as 200 ng mL^-1 did not affect the detection process. The low cost and instrument-independence characteristic of the present method enables its routine determination of the concentration of DCAN in water.