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ANNOUNCEMENT AND CALL FOR PAPERS
INTERNATIONAL SYMPOSIUM METALS SPECIATION, SEPARATION A N D RECOVERY
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July 27-31, 1986 Chicago, Illinois
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Sponsors
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Symposium Chairman J a m e s W. Patterson, Ph.D. IIT
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2.0 3.0 4.0 Estriol (/xg/nriL.)
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Figure 7. Plot of differential pulse polarogram peak currents of 5.5 ml_ of phos phate buffer solution containing dinitroestriol (5.6 μΓηοΙ/L) plus 150 μΙ_ of estrogen-specific antibody vs. estriol added to the solution (21)
was detected by differential pulse polarography (26). Homogeneous immunoassays of this type are apparently based in part on the difference in diffusion coefficient between the free labeled antigen and the labeled antigen bound to the much larger antibody (27). Consequently, this is a general approach that should be applicable when the antigen is suf ficiently smaller than the antibody to give a large difference in diffusion co efficient. Immunoassays for human serum al bumin (HSA) have been based on HSA labeled with P b 2 + (28), Co 2+ (29), and Zn 2+ (30). The metal ion bound to the HSA can be detected with differential pulse polarography by reduction at a mercury electrode. The peak current for the labeled HSA decreases on binding with Ab, which is the basis for the immunoassay. An electrochemical luminescencebased immunoassay has been present ed with HSA labeled with the aromat ic hydrocarbon amino-pyrene (31). The pyrene-labeled HSA luminesces during reduction at a platinum elec trode, and on binding to Ab the inten sity of luminescence is decreased. A detection limit of ΙΟ - 6 Μ for HSA was obtained. Labels with greater lumines cence efficiency should provide lower detection limits. This latter assay relies more on steric hindrance of access of the electroactive groups to the electrode sur face than on changes in diffusion coef ficient on binding to Ab. Thus, its
Topics include: • Metals Chemistry - Soluble and Solid Phases Analytical Methodologies, Metals Speciation, Equilibrium Chemistry, and Reaction Kinetics • Metals Separation Research Precipitation, Ion Exchange, Adsorption Process, Electrochemical Processes, and Other Processes • Metals Recovery Process Applications Process Research, Case Studies, and Economic Evaluations Symposium speakers and participants will be selected according to research interests and activities. Authors are invited to offer papers within the range of symposium topics. For further information and applications: Secretariat Office - International Symposium CAPS, Ltd. 50 Green Bay Road, Lake Bluff, IL 60044, (312) 234-2353 CIRCLE 109 ON READER SERVICE CARD
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ANALYTICAL CHEMISTRY, VOL. 57, NO. 12, OCTOBER 1985 · 1329 A
