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Preliminary Investigations on the application of a divinylbenzene (DVB), cross-linked poly( acrylamidoxime) resin for the concentration of trace metals from aqueous solutions is reported. The pH dependence of metal-resin chelation has been determined for Na, Mg, K, Ca, Ti(IV), V(V), Cr(III), Cr(VI), Mn(II), Fe( 11), Fe(III), Co(II), Ni( II), Cu(II), Zn(II), Ag( I ) ,Cd(II), Hg(II), and Pb(I1). The resin exhibits no affinity for the alkali or alkaline earth metals tested over the pH range 2-8, and the resin selectivity has been determined at pH 5 for several of the metals. The order of decreasing Selectivity Is Cu(II), Ni(II), Co(II), Zn(II), Mn(I1).

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4pparently compounds that react readily with hydrogen chloride prevent the normal color reaction.-4bsorption spectra of the reactions of activated GDH with vitamin A when solvent to reagent ratios of 1:0, 1:5, l : , l , 5:1, and 9 : 1 were employed are presented. The extinction coefficients a t 555 mp were essentially the same in the cases of the 1 : 3, 1 : 7, 1 : 5, and 1 : 3 ratios. As the ratios were increased above 1 : 3, the absorption a t 555 mp decreased while the absorption at 337, 353, 372,395, and 422 mp increased and reached maximum values when a 9 : 1 ratio was used. These maxima in and near the ultraviolet resemble to some extent the type absorption spectrum of anhvdro vitamin .4.