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DETECTION OF HEAVY METALS BY IMMUNOASSAY: OPTIMIZATION AND VALIDATION OF A RAPID, PORTABLE ASSAY FOR IONIC CADMIUM (R824029)
Citation:
Khosraviani, M., A. R. Pavlov, G. C. Flowers, AND D. A. Blake. DETECTION OF HEAVY METALS BY IMMUNOASSAY: OPTIMIZATION AND VALIDATION OF A RAPID, PORTABLE ASSAY FOR IONIC CADMIUM (R824029). ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 32:137-142, (1998).
Description:
An immunoassay is described that measured Cd(II) in aqueous samples at
concentrations from approximately 7 to 500 ppb. The assay utilized a monoclonal
antibody that bound tightly to a cadmium-ethylenediaminetetraacetic acid (EDTA)
complex but not to metal-free EDTA. A inhibition immunoassay format was employed
for this analysis; ionic cadmium was diluted into an excess of EDTA before being
incubated with the antibody in the presence of an immobilized Cd(II)-EDTA
conjugate. Ca(II), Na(I), and K(I), cations commonly encountered in ambient
water samples, did not interfere with the cadmium immunoassay at concentrations
approaching their solubility limit. The assay reliably measured Cd(II) in the
presence of a 1 mM excess of Fe(III), Mg(II), and Pb(II). Zn(II) and Ni(II) had
minimal effect on the assay at levels below 100 src="/ncer/pubs/images/mgr.gif">M, and the immunoassay was relatively
insensitive to interferences by In(III) and Mn(II) at concentrations up to 10 
M. Hg(II) had the ability to cause a
false positive in the assay, but only at concentrations higher than 1 src="/ncer/pubs/images/mgr.gif">M. The assay compared favorably with atomic
absorption spectroscopy in its ability to measure cadmium in spiked water
samples taken from a Louisiana bayou.