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

Abstract

Speciation of chromium (Cr) was demonstrated using microfluidic paper-based analytical devices (μ-PADs) that permit the colorimetric determination of hexavalent chromium (Cr(VI)) and trivalent chromium (Cr(III)) via online oxidation. The μ-PADs consist of left and right channels that allow the simultaneous measurements of Cr(VI) and total Cr based on the colorimetric reaction of Cr(VI) with 1,5-diphenylcarbazide (DPC). For the determination of Cr(VI), a sample solution was directly reacted with DPC in the left channels whereas total Cr was determined in the right channels, which permitted online oxidation in the pretreatment zone containing cerium (IV) (Ce(IV)) followed by a colorimetric reaction with DPC. We found that the online oxidation of Cr(III) proceeded 100% whereas Ce(IV) inhibited the reaction of Cr(VI) with DPC. Therefore, speciation can be achieved by measuring the Cr(VI) and total Cr in the left and right channels followed by the subtraction of Cr(VI) from total Cr. The limits of detection and quantification were 0.008 and 0.020 µg mg L -1 for Cr(VI) and 0.07 and 0.1 mg L -1 for Cr(III) or total Cr, respectively. The linear dynamic ranges were 0.02-100 mg L -1 and 0.1-60 mg L -1 for Cr(VI) and Cr(III), respectively. The RSDs were less than 7.5%. The results obtained using μ-PADs were in good agreement with those obtained via ICP-OES with recoveries of 92-108% for Cr(III) and 108-110% for Cr (VI) using μ-PADs, and 106-110% for total Cr using ICP-OES. Thus, the μ-PADs could potentially be utilized for the speciation of chromium in developing countries where environmental pollution and the availability of sophisticated instruments are significant problems.

Microfluidic Devices for Heavy Metal Ions Detection: A Review

“…These kinds of metal ions are probably released in the environment through waste water due to industrial activities but also from other human activities (i.e., agriculture activities). Drinking water is also polluted by Cr (III) and Cr (VI) as a result of the utilization of corrosion inhibitors in water pipes and containers or by the pollution of underground water [ 124 , 125 , 126 ]. Thus, the detection of chromium in water samples is necessary and, in this direction microfluidic devices with optical and electrochemical methods are widely used [ 125 , 127 , 128 , 129 , 130 , 131 , 132 ].…”

“…Diphenylcarbazide (DPC) is again used for the colorimetric detection of Cr (VI), while for the quantitative analysis a commercial desktop scanner with ImageJ software is used. Abdellah Muhammed et al [ 126 ] have developed a simple, portable, and low-cost μPAD, in which Cr (VI) and Cr (III) can be detected. The device uses the left channels for the detection of Cr (VI) using 1,5-diphenylcarbazide and the right channels for the total Cr detection.…”

Transition of chemical engineering from macro to micro/nano scales

“…Solvent extraction microfluidic equipment has been developed for a wide range of applications, including metal ion separation and DNA purification [39][40][41][42][43][44][45][46][47]. Sarkar, et al investigated liquid-liquid biphasic flow patterns in microchannels [48].…”

Cationic Waste Cotton Fabric for the Adsorptive Colorimetric Detection of Chromium Ion Traces

“…Multiple Cr­(VI)-reactive color-developing agents have been combined with solid supports for the fabrication of sensors. This includes 1,5-diphenylcarbazide (DPC), carbon dots, metal nanoparticles, 3,3′,5,5′-tetramethylbenzidine, and composites such as MCC/TEPAA. ,− Among these, DPC exhibits excellent properties for Cr­(VI) detection including high sensitivity and selectivity, low cost, and fast response time . The principle of action of DPC is that it will be oxidized by Cr­(VI), resulting in the formation of 1,5-diphenylcarbazone (DPCO) and Cr­(III).…”