Occupational exposure to Cr is concerning because of its myriad of health effects. Assessing chromium exposure is also cost and resource intensive because the analysis typically uses sophisticated instrumental techniques like Inductively-Coupled Plasma-Mass Spectrometry (ICP-MS). Here, we report a novel, simple, inexpensive microfluidic paper-based analytical device (µPAD) for measuring total Cr in airborne particulate matter. In the µPAD, tetravalent cerium (Ce(IV)) was used in a pretreatment zone to oxidize all soluble Cr to Cr(VI). After elution to the detection zone, Cr(VI) reacts with 1,5-diphenylcarbazide (1,5- DPC) forming 1,5-diphenylcarbazone (DPCO) and Cr(III). The resulting Cr(III) forms a distinct purple colored complex with the DPCO. As proof-of-principle, particulate matter (PM) collected on a sample filter was analyzed with the µPAD to quantify the mass of total Cr. A log-linear working range (0.23–3.75 µg; r2=0.998) between Cr and color intensity was obtained with a detection limit of 0.12 µg. For validation, a certified reference containing multiple competing metals was analyzed. Quantitative agreement was obtained between known Cr levels in the sample and the Cr measured using the µPAD.
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机译：由于铬对健康有无数的影响，因此职业暴露于铬令人担忧。评估铬暴露量也是成本和资源密集型的，因为该分析通常使用复杂的仪器技术，例如电感耦合等离子体质谱法（ICP-MS）。在这里，我们报告了一种新颖，简单，廉价的基于微流体纸的分析设备（µPAD），用于测量空气中颗粒物中的总Cr。在µPAD中，在预处理区使用四价铈（Ce（IV））将所有可溶性Cr氧化为Cr（VI）。洗脱到检测区后，Cr（VI）与1,5-二苯卡巴肼（1,5-DPC）反应形成1,5-二苯卡巴zone（DPCO）和Cr（III）。生成的Cr（III）与DPCO形成鲜明的紫色络合物。作为原理证明，使用µPAD分析样品过滤器上收集的颗粒物（PM），以量化总Cr的质量。铬和颜色强度之间的对数线性工作范围为（0.23–3.75 µg； r 2 = 0.998），检出限为0.12 µg。为了进行验证，分析了包含多种竞争金属的认证参考。样品中已知的Cr水平与使用µPAD测量的Cr之间获得了定量一致性。
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