John Volckens, Ph.D.; Charles Henry, Ph.D.
Colorado State University
NIEHS Grant R21ES024719
NIEHS grantees developed a simple technique that uses microfluidic paper-based devices to quantify concentrations of nickel, copper, and iron in airborne particulate matter. With commercial techniques costing more than $100 per sample and requiring trained specialists for operation, low-cost approaches that are applicable at the point-of-need would greatly improve exposure assessment for particulate metals.
The researchers used paper substrates to create devices that quantify an analyte in only a drop of sample. Unlike other colorimetric approaches, the devices don’t require an external optical device for analysis. Instead, they rely on distance-based detection, which can be visually read much like the temperature on a thermometer.
The researchers demonstrate that the paper analytical devices can achieve detection limits as low as 0.1 micrograms for individual measurements of nickel and copper, and 0.05 micrograms for iron. When analyzing all three metals simultaneously, the devices showed a detection limit of 1 microgram for nickel and iron, and 5 micrograms for copper. They further tested the method by measuring the three metals in samples of certified welding fume, finding the levels measured with the paper devices matched known values determined with gravimetric analysis.
Citation: Cate DM, Noblitt SD, Volckens J, Henry CS. 2015. Multiplexed paper analytical device for quantification of metals using distance-based detection. Lab Chip 15(13):2808-2818.