Simple and Equipment-Free Paper-Based Device for Determination of Mercury in Contaminated Soil |
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| Authors: | Hikmanita Lisan Nashukha Jirayu Sitanurak Hermin Sulistyarti Duangjai Nacapricha Kanchana Uraisin |
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| Institution: | 1.Flow Innovation-Research for Science and Technology Laboratories (Firstlabs), Mahidol University, Rama 6 Road, Bangkok 10400, Thailand; (H.L.N.); (J.S.); (D.N.);2.Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand;3.Department of Chemistry, Faculty of Science, Brawijaya University, Jl. Veteran Malang 65145, Indonesia; |
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| Abstract: | This work presents a simple and innovative protocol employing a microfluidic paper-based analytical device (µPAD) for equipment-free determination of mercury. In this method, mercury (II) forms an ionic-association complex of tetraiodomercurate (II) ion (HgI42−(aq)) using a known excess amount of iodide. The residual iodide flows by capillary action into a second region of the paper where it is converted to iodine by pre-deposited iodate to liberate I2(g) under acidic condition. Iodine vapor diffuses across the spacer region of the µPAD to form a purple colored of tri-iodide starch complex in a detection zone located in a separate layer of the µPAD. The digital image of the complex is analyzed using ImageJ software. The method has a linear calibration range of 50–350 mg L−1 Hg with the detection limit of 20 mg L−1. The method was successfully applied to the determination of mercury in contaminated soil and water samples which the results agreed well with the ICP-MS method. Three soil samples were highly contaminated with mercury above the acceptable WHO limits (0.05 mg kg−1). To the best of our knowledge, this is the first colorimetric µPAD method that is applicable for soil samples including mercury contaminated soils from gold mining areas. |
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| Keywords: | tetraiodomercurate mercury paper-based iodometry soil water |
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