This analytical platform enables simultaneous determination of trace analytes in water.

Multiplexed colorimetric solid-phase extraction (MC-SPE) is an extension of colorimetric solid-phase extraction (CSPE) — an analytical platform that combines colorimetric reagents, solid phase extraction, and diffuse reflectance spectroscopy to quantify trace analytes in water. In C-SPE, analytes are extracted and complexed on the surface of an extraction membrane impregnated with a colorimetric reagent. The analytes are then quantified directly on the membrane surface using a hand-held diffuse reflectance spectrophotometer. Im por - tant ly, the use of solid-phase extraction membranes as the matrix for impregnation of the colorimetric reagents creates a concentration factor that enables the detection of low concentrations of analytes in small sample volumes.

In extending C-SPE to a multiplexed format, a filter holder that incorporates discrete analysis channels and a jig that facilitates the concurrent operation of multiple sample syringes have been designed, enabling the simultaneous determination of multiple analytes. Separate, single analyte membranes, placed in a readout cartridge create unique, analyte-specific addresses at the exit of each channel. Following sample exposure, the diffuse reflectance spectrum of each address is collected serially and the Kubelka-Munk function is used to quantify each water quality parameter via calibration curves. In a demonstration, MC-SPE was used to measure the pH of a sample and quantitate Ag(I) and Ni(II).

This work was done by Daniel B. Gazda, James S. Fritz, and Marc D. Porter of Iowa State University for Johnson Space Center. For further information, contact the JSC Innovation Partnerships Office at (281) 483- 3809.

In accordance with Public Law 96-517, the contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be addressed to:

Iowa State University Research

Foundation, Inc.

310 Lab of Mechanics

Ames, IA 50011-2131

Phone No.: (515) 294-4740

Fax No.: (515) 294-0778

Refer to MSC-23850-1, volume and number of this NASA Tech Briefs issue, and the page number.

The U.S. Government does not endorse any commercial product, process, or activity identified on this web site.