AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Inexpensive Microfluidic Devices for Multiplexed Metal Measurement in Particulate Matter
David Cate, Poomrat Rattanarat, Killean OConaill, John Volckens, CHARLES HENRY, Colorado State University
Abstract Number: 581 Working Group: Portable and Inexpensive Sensor Technology for Air Quality Monitoring
Abstract Metal exposure remains an important topic in human health. While there are many sources of metals, metals in particulate matter (PM) are particularly concerning because PM is ubiquitous and individual exposure can vary substantially across a regional population. Furthermore, PM exposure can be high in some jobs such as welding. At present, most methods collect PM on filters using long sampling times (24 hours) and high flow rates. Quantification is subsequently done using Atomic Absorption Spectroscopy or Inductively Coupled Plasma coupled with either Mass Spectrometry (ICP-MS) or Optical Emission Spectroscopy (ICP-OES). While these techniques are exquisitely sensitive and selective, they are also expensive and required highly trained laboratory staff for operation. As a result, analyzing a single filter can cost hundreds of dollars. Our group has developed an alternative approach using microfluidic devices made from filter paper (microfluidic paper-based analytical devices or mPADs) that can quantify low levels of metals in minutes. The results can be read using either the naked eye or simple, low-cost instrumentation. As a result, the assays cost pennies and can be used by virtually anyone. To demonstrate multiplexed metals analysis, we developed chemistry to measure Fe, Ni, Cu, Cr, Pb, and Cd in welding fume samples. Fe, Ni, Cu, and Cr are detected using colorimetric reactions while Pb and Cd are detected simultaneously on the same mPAD using electrochemistry. PM samples were digested on filter using 5 μL of acid and then transferred to the mPAD by elution with buffer. Detection limits of 0.1μg were achieved for colorimetric assays while electrochemical assays provided detection limits of 100 pg (1 ppb solution levels). We subsequently applied the mPADs to measure metal concentrations in welding fume PM plumes where samples were collected with personal samplers. Results from the mPAD were validated against ICP-OES.