A chemical catalytic method for determination of silver in human saliva.
Abstract A catalytic method for the determination of silver in saliva is suggested. Silver was determined by a very simple technique in concentrations in saliva higher than 1 μg/100 ml with a coefficient of variation of 5.7 per cent. The method was used to investigate the correlation between some pathogalvanic phenomena connected with the presence of amalgam restorations in the oral cavity and the concentration of silver in saliva. The application of the method showed no correlation between the number of restorations and the silver concentration in saliva. The joint effects of restorations, their corrosion potential and the concentration of silver in saliva were correlated with the occurrence of unpleasant sensations in the mouth.
Simple and sensitive catalytic method for determination of copper in blood serum
SummaryA new catalytic method is proposed for determination of copper in blood serum, based on the oxidation of sulphanilic acid with H2O2, catalysed by copper(II). Because of its high sensitivity the method requires a serum sample of only 0.10 ml. Using the fixed-time method reduces the procedure to that of an ordinary photometric determination. The method shows reasonable precision and accuracy and is suitable for routine serial analyses in clinical practice.ZusammenfassungEine neue katalytische Methode wurde für die Bestimmung des Kupfers in Blutserum vorgeschlagen. Sie beruht auf der durch Cu(II) katalysierten Oxydation der Sulfanilsäure mit H2O2. Infolge ihrer großen Sensitivität genügt für diese Methode eine Serumprobe von nur 0,10 ml. Infolge Ablesung nach Ablauf einer bestimmten Zeit verlangt das Verfahren nicht mehr Zeit als eine gewöhnliche photometrische Methode. Es zeigt gute Genauigkeit und eignet sich für Serienanalysen in der klinischen Praxis.
Measuring Sheet Resistances of Dielectrics Using Co‐Planar Hydrogel Electrochemical Cells with Practical Applications to Characterize the Protective Quality of Paints on Sculptures
Electrical properties of thin dielectric films at the solid-liquid phase boundary are an important performance characteristic of many devices, coatings and sensors. In this paper, co-polymeric hydrogels of polyacrylic acid co-sulfonic acid, swollen with a salt solution to act as the solid electrolyte, were used to assess interfaces using electrochemical impedance spectroscopy (EIS) in a co-planar geometry. Silane-modified glasses were characterized by the co-planar hydrogel EIS cell and found to be distinguishable based on their surface monolayer chemistry. EIS measurements were also made on primed and painted metal substrates, using both test panels and an outdoor sculpture, Tony Smith's Stinger. The panels were then exposed to accelerated and outdoor weathering and showed degradation on the surface paint layers, which was observable electrochemically using EIS and confirmed visually by SEM. Electrochemical spectral features were compared between data from a standard paint-test cell versus this co-planar hydrogel cell; both cell types were able to measure coating capacitance, providing useful information about the condition of the bulk coating. Yet, sheet resistance (Rs) was a spectral feature seen only by the co-planar hydrogel cell. Thus, it can be concluded that the use of such co-planar hydrogel cells can provide an earlier warning sign to coating degradation and such cells provide a new type of spectral information that is not assessable by the standard geometry.