title: A microfluidic paper-based analytical device for rapid quantification of particulate chromium.
abstract: 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; r(2)=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.
authors.affiliation: Electrochemistry and Optical Spectroscopy Research Unit (EOSRU), Department of Chemistry, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330, Thailand.
authors.forename: Poomrat
authors.initials: P
authors.lastname: Rattanarat
authors.forename: Wijitar
authors.initials: W
authors.lastname: Dungchai
authors.forename: David M
authors.initials: DM
authors.lastname: Cate
authors.forename: Weena
authors.initials: W
authors.lastname: Siangproh
authors.forename: John
authors.initials: J
authors.lastname: Volckens
authors.forename: Orawon
authors.initials: O
authors.lastname: Chailapakul
authors.forename: Charles S
authors.initials: CS
authors.lastname: Henry
mesh_terms: D002563:Cerium / Q000737:chemistry; D002857:Chromium / Q000032:analysis*; D003124:Colorimetry / Q000295:instrumentation*; D004160:Diphenylcarbazide / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D008872:Microwaves; D017942:Nitric Acid / Q000737:chemistry; D010084:Oxidation-Reduction; D010209:Paper; D052638:Particulate Matter / Q000737:chemistry*; D011095:Polyethylenes / Q000737:chemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry
chemical_list: D052638:Particulate Matter; D011095:Polyethylenes; D000644:Quaternary Ammonium Compounds; D002857:Chromium; D004160:Diphenylcarbazide; C041004:poly-N,N-dimethyl-N,N-diallylammonium chloride; D002563:Cerium; D017942:Nitric Acid
keywords: Chromium; Microfluidics; Paper-based analytical device; Particulate matter