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QUARTZ CRYSTAL MICROBALANCE BIOSENSOR FOR MEASUREMENT OF 2,4-D IN WATER
Citation:
Rogers, K., E. Poziomek, AND M. Yu. QUARTZ CRYSTAL MICROBALANCE BIOSENSOR FOR MEASUREMENT OF 2,4-D IN WATER. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/A-95/057.
Description:
Due to proportional relationship between vibrational frequency and surface mass, the quartz crystal microbalance (QCM) has been used to detect the accumulation of small quantities of chemical and biological compounds on electrode-covered quartz crystals. lassically, these devices have been used to detect gases and vapor which adhere to chemically selective coatings. ecently, however, increasing attention has been focused on the use of QCMs in aqueous environments. erein reported is the development of an antibody-based QCM biosensor for measurement of (2-4-dichlorophenoxy)acetic acid (2,4-D) in aqueous systems. he dynamic range of measurement of 2,4-D is 0.1 to 10 ppm. iotinylated-2,4-D coating antigen is immobilized in the gold electrode by means of a spontaneously formed streptavidin monolayer. ,4-D (analyte) then competes with the surface-bound antigen for binding to anti-2,4-D IgG labeled with alkaline phosphatase. he amount of labeled antibody that binds to the crystal is inversely proportional to the analyte (2,4-D) concentration. he mass of the labeled antibody which binds to the crystal is then amplified by the enzyme-catalyzed dimerization of 5-bromo-4-chloroindolyphosphate (BCIP) which precipitates on the crystal surface. onsequently, the observed rate of frequency change is inversely proportional to the concentration of 2,4-D.