Remote Investigation of Total Chromium Determination in Environmental Samples of the Kombolcha Industrial Zone, Ethiopia, Using Microfluidic Paper-based Analytical Devices

Abstract

Microfluidic paper-based analytical devices (μ-PADs) fabricated in Japan were employed for the determination of total chromium (Cr) in water, soil, and lettuce irrigated with wastewater in Ethiopia. The μ-PADs, which were printed by wax printing in Japan, were transported to Ethiopia followed by preparation for the determination of total Cr by adding appropriate reagents to the pretreatment and detection zones. Soil and lettuce samples were determined by the μ-PADs and a UV-Vis spectrophotometer in Ethiopia. The paired t-test showed that the mean total Cr concentrations determined in the soil and lettuce samples were not significantly different between μ-PADs and UV-Vis spectrophotometric analysis at the 5% level of significance. This implies that the μ-PADs has good accuracy and reliability and could be employed to monitor Cr in environmental samples. We found that the total Cr concentrations in all soil and lettuce samples were above the permissible limit. Moreover, the evaluation of Cr contamination level using the geo-accumulation index indicated that the soils are contaminated with Cr moderately to heavily. Thus, the present work successfully demonstrated the potential remote investigation of pollution in a less-equipped laboratory by transporting the μ-PADs fabricated in another laboratory.

Speciation of chromium in water samples using microfluidic paper-based analytical devices with online oxidation of trivalent chromium

“…In early studies, Rattanarat et al and Cate et al used an online oxidation reaction with Ce(IV) to present colorimetric measurements of total Cr [30,31]. We also demonstrated a remote investigation of total Cr in environmental samples from Ethiopia using μ-PADs [32].…”

“…Microfluidic paper-based analytical devices (μ-PADs) have tremendous potential to address the demands for simplicity, expeditiousness, portability, and easy operation that will permit use in remote areas and developing countries [26]. Several research groups have reported the colorimetric detection of Cr(VI) using μ-PADs based on the specific reaction with 1,5-diphenylcarbazide (DPC) [27][28][29][30][31][32][33][34]. In early studies, Rattanarat et al and Cate et al used an online oxidation reaction with Ce(IV) to present colorimetric measurements of total Cr [30,31].…”

Microfluidic paper-based analytical devices coupled with coprecipitation enrichment show improved trace analysis of copper ions in water samples

“…The stability of the μ-PADs was examined for 1, 10, 20, and 30 consecutive days to validate the expected utility of μ-PADs for remote investigation in developing countries, as we reported previously. 16 The prepared μ-PADs were stored in the dark at room temperature and in a refrigerator at 4 o C. The μ-PADs stored in the dark at room temperature showed responses consistent with that of freshly prepared μ-PADs for as long as 10 days, after which the intensity was progressively decreased in the subsequent 20 and 30 days (Fig. S6, Supporting Information).…”

“…Microfluidic paper-based analytical devices (μ-PADs) have the potential to address the demands of developing countries. 15,16 The colorimetric μ-PADs developed thus far for Cu assay, however, have shown difficulty in detecting the regulatory limits set by the WHO and the EPA because of insufficient levels of sensitivity. 17 Therefore, Cu assay using μ-PADs requires coupling with an enrichment procedure to enhance the analytical sensitivity.…”

Spectrometric Analyses of Microplastics

“…Analytical scientists have continuously developed or applied novel microfluidic systems, paper-based analytical devises, and image processing tools. [35][36][37] The development of novel analytical methods and application to MPs analysis will be effective in gaining a deeper understanding of the impacts of MPs.…”