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An enzyme electrode for amygdalin is constructed by immobilizing ß-glucosidase in a polymer gel layer coupled to a cyanide-sensing membrane electrode. The characteristics of a novel inverted electrode configuration are shown to be superior to earlier designs and to permit analyses of samples as small as 0.2 ml. Optimum operating conditions for the enzyme electrode system are described.

The response characteristics ot the calcium selective membrane electrode were Investigated In calcium test solutions containing linear alkylbenzene sulfonate (LAS) or dilsobutylphenoxyethoxyethyl(dlmethyl)benzylammonlum chloride (Hyamlne). Both surfactants were found to Interfere at the membrane electrode, albeit by different mechanisms. LAS Interferes via competing reactions at the organophilic membrane between LAS and Ca2+ on the one hand, and Ca2+ and the Ion-exchanger site on the other. Hyamlne Interferes through the displacement of Ca2+ In the Ion-exchanger site. The Interference effect of LAS can be overcome by loading the membrane phase with an equilibrium amount of LAS. This procedure desensitizes the sensing element from surfactant effects and permits the use of the calcium electrode for Ca2+-surfactant Interaction studies. Hyamlne Interference patterns cannot be overcome. Selectivity studies showed the calcium electrode to be ~103 times more selective to Hyamlne than to calcium. This, however, permits the use of the electrode for LAS-Hyamlne titration analysis and also for the direct potentiometric measurement of Hyamlne and analogous species.

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