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Nickel electrodes chemically modified with an interfacial layer of nickel ferrocyanide are shown to be of analytical utility for simultaneously sensing sodium and potassium ions in aqueous solutions, human whole blood serum, and human whole blood. By controlling the charge-transfer characteristics of this versatile interface, interfering blood proteins and potential interferences associated with other alkali cations can be avoided. A solid-state model which explains the excellent simultaneous selectivity and sensitivity of the nickel ferricyanide interface is proposed.

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The anodization derivatization of nickel ferrocyanide on a nickel electrode is shown to be sensitive (with respect to surface coverage) to the electrode potential and the electrode crystal face. The epitaxial alignment of the Ni(100) face and the nickel ferrocyanide lattice promotes surface derivatization, while the mismatch of the surface layer and the Ni(lll) face inhibits formation of a surface overlayer. Electrode potential is found to play a dual role. First, the Ni2+ concentration in the interfacial region depends on this parameter; thus both reaction rate and electrode coverage are affected. Second, at higher electrode potentials (>1.0 V vs. SCE), reconstruction of the nickel surface to a surface which promotes epitaxial growth is observed.In the area of electrochemistry, crystal face effects typically are small compared to other phenomena associated with the electrode-electrolyte interface. A major exception to this statement involves submonolayer processes associated with electrodeposition and specific ion adsorption.1 We report here a strong macroscopic crystal face effect associated with the multiple-layer chemical derivatization of the nickel electrode.Recently we reported that polycrystalline nickel electrodes could be chemically derivatized with a nickel ferrocyanide matrix by anodizing the nickel electrode in the presence of aqueous ferricyanide.2 34Electrochemical3-5 and spectroscopic6 investigations of these systems suggested that the surface material consisted of a cubic lattice containing cyanides which bridged iron and nickel centers to generate octahedral sites for both metals in analogy to Prussian Blue. Data available indicated the surface to be

The pyrolytic conversion of an organosilsesquioxane (Owens-Illinois resin GR650) to SiO2 is characterized by ir spectroscopy, thermogravimetry and evolved gas analysis (line-of-sight mass spectroscopy). Scanning calorimetry, ramping at 10°C/min, on the as-received (room temperature annealed) resin indicates a glass transition temperature of 67°C which decreases to 58°C for an unrelaxed sample. The ir spectra have bands which can be assigned to Si-CH3 and Si-O-Si modes. For 30 minute isothermal anneals at temperatures above 420°C there is a continuous decrease in the bands associated with the Si-CH3 groups such that after 30 minutes at 650°C the ir spectrum has evolved to that for SiO2. Evolved gas analysis indicates that there are four major components evolving. Over the temperature range (ramping at 10°C/min) ∼180 to ∼500°C we observe C2H5OH and H2O, both of which are condensation reaction products from the curing reaction. Methane is a major evolving species over the temperature range ∼500 to ∼800°C and the thermal spectrum is double peaked which we attribute to CH3+ bound to the inside and outside of the polymer cage structures. The final major component detected was H2, over the temperature range ∼600 to ∼1100°C, which was attributed to pyrolysis of the organic components, both trapped and evolving. The features of the weight loss curve can be accounted for by the measured evolving species spectra.