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Publisher Summary This chapter describes dry chemistry sensing of analytes using integral threshold detection. An enzyme-based, dry chemistry system that measures analyte concentration definitively by giving a colored response above a preset concentration threshold is under development. As part of this proprietary research and development program, some fundamental aspects of the threshold response have been investigated. The dry chemistry system presently under investigation is based on the measurement of hydrogen peroxide. In a study described in the chapter, hydrogen peroxide was detected using a number of horseradish peroxide (HRP)-catalyzed colorimetric reactions. Using this procedure, a range of different quenchers and color reagents were tested for their suitability in displaying an overall threshold response. It was found that compounds containing a free sulphydryl group such as cysteine, mercaptoethane, sulphonate, and glutathione were effective quenchers at appropriate pH. The threshold principle illustrated in these simple experiments is being applied to the measurement of various analytes, including ethanol and glucose, in a simple dry chemistry format. |
