Smart-phone based colorimetric detection of toxic Cr(VI) in water samples combined with in-situ solvent formation microextraction technique

Even so far, accurate, fast and low cost monitoring of water quality for toxic inorganic speciessuch as Pb, Hg, Cd, As, Cr(VI) and others is a challenging task, especially when regulators arenot equipped to monitor at the desired spatial and temporal scales. Laboratory-based centralizedtesting, besides being technically challenging, requires periodic water sampling at potentiallycontaminated sites, careful preservation of samples, and transportation before analysis in alaboratory. This process especially for Cr(VI) is expensive, time-consuming, and prone tohandling errors due to possible inter-conversion between Cr(III) and Cr(VI) [۱], if adequate careduring transportation and storage is not taken. There is an urgent need to have reliable and easyto-use monitoring techniques that can enable water quality measurements at site. Thisdecentralized testing can potentially be achieved through portable devices, such as smartphonesor in situ sensors [۲]. These devices require minimal handling and facilitate easy processing andtransmission of the recorded data for onward integration on a digital map [۳]. So, a transportable,instrument-free, simple, rapid, reliable and on-site quantitative determination method fordetermining trace amount of toxic Cr(VI) in water samples was described. The sensing of Cr(VI)was carried out using in situ solvent formation method to concentration of Cr(VI) ions on a probeand then detection by calorimetric method. The probe composed of ethylenediamineteraaceticacid (EDTA) anchored on gold nanoparticle. Changes in color from pale red to the gray wasdone after sensing of Cr(VI) with high sensitivity and selectivity. Finally, using a smartphonecolor scan application software, Cr(VI) concentration could be readily quantified on the spot.This sensing has low detection limit (about ۰.۹۵ μg L-۱) and wide linear dynamic range (between۱.۰ to ۵۰ μg L-۱) with satisfactory accuracy (~۱.۹%). Conclusively, by use of smartphonetechnologies, this nanomaterials-based probe showed the potential in the field of environmentmonitoring for on-site quantitative determination of Cr(VI) in aqueous water samples.

کلیدواژه ها:

Cr(VI) colorimetric detection ، smart phone technology ، in-situ solvent formation microextraction technique ، EDTA