Smartphone-enabled field monitoring tool for rapid hexavalent chromium detection in water

Chromium contamination of soil and water is a serious environmental and public health concern as the hexavalent form of chromium [Cr(VI)] is readily soluble in water and is a confirmed carcinogen. There is an imminent need for a robust, low-cost, and simple analytical technique to facilitate in situ monitoring of Cr(VI) in water. Current quantitative methods of Cr(VI) detection are largely laboratory-based, time-consuming, expensive, and require training for implementation. In this contribution, a portable, easy-to-use, and compact measuring tool is presented that provides Cr(VI) concentration within 10 min of water sampling over a linear range of 0–3 mg L −1 . This tool utilizes a relatively inexpensive camera-enabled smartphone with a custom-made test chamber attachment to seamlessly perform Cr(VI) measurements on water samples in the field. For analysis, an android-based software application was developed that directs the user to perform a simple series of steps following the diphenylcarbazide-based colorimetric method prescribed by the American Public Health Association. The tool was validated against a standard UV-visible spectrophotometer for a variety of synthetic and naturally contaminated water samples, with correlation factors greater than 0.993 ( p