Evaluation of an arsenic test kit for rapid well screening in Bangladesh

Abstract

Exposure to arsenic in groundwater via drinking remains unabated for millions of villagers in Bangladesh. Since a blanket testing campaign using test kits almost a decade ago, millions of new wells have been installed but not tested; thus affordable testing is needed. The performance of the Arsenic Econo-Quick (EQ) kit was evaluated by blindly testing 123 wells in Bangladesh and comparing with laboratory measurements; 65 wells were tested twice. A subset of the same 123 wells was also tested using the Hach EZ kit in the field and the Digital Arsenator in the laboratory in Bangladesh. The EQ kit correctly determined the status of 110 (89%) and 113 (92%) out of 123 wells relative to the WHO guideline (10 μg/L) and the Bangladesh standard (50 μg/L), respectively. Relative to the WHO guideline, all misclassifications were underestimates for wells containing between >10 and 27 μg/L As. Relative to the Bangladesh As standard, over- and underestimates were evenly distributed. Given its short reaction time of 10 min relative to the Hach EZ and its lower cost compared to the Arsenator, the EQ kit appears to have several advantages for well testing in Bangladesh and elsewhere.

Figure 1

Comparison of ICP-MS and Field Kit Arsenic Results Relative to 50 μg/L and 10 μg/L.

Figure 2

Comparison of As concentrations in water samples measured by inductively-coupled plasma mass spectrometry (ICP-MS) compared with the outcome of field and laboratory testing with three different kits. One tubewell with an ITS EQ reading of 1000 μg/L and an actual concentration of 395 μg/L is excluded from (a) for clarity. The data in (d) are an expanded version of the same data shown in (c). Horizontal bars indicate the estimated 2-sigma errors for HR ICP-MS measurements (22). Vertical error bars in (a) and (b) indicate the full range of As concentrations ranges for the ITS EQ and the EZ kit listed in the text, respectively. Vertical errors bars in (c) and (d) correspond to an estimated error of ±10% of the reported Arsenator readings. The one-to-one relationship indicating a perfect match is shown as a dotted line.