RESUMO
There are many variations of differential phase contrast imaging methods. Although these imaging methods are different in configuration, they are alike in imaging by extracting differential phase information through the evaluation of the refraction angles. In this paper, we investigate common characteristics shared by various different differential phase contrast imaging methods.
RESUMO
A versatile method for the determination of Ag is described. It is based on controlled-potential electrolysis with a tantalum cathode in the presence of lactic acid at pH 2-6. An SCE of double-junction type with sodium formate bridge electrolyte is used as the reference electrode. The role of washing after electrolysis is studied and a novel technique suggested. The standard deviation of the determination is 0.13 mg. A preliminary separation is needed only if W is present. The proposed method has been satisfactorily applied to the analysis of a large number of silver alloys with different compositions.
RESUMO
A method is proposed for the determination of copper in white-metal bearing alloys by direct controlled-potential electrolysis with a tantalum cathode at -0.32 V vs. SCE in a sulphate/bisulphate buffered electrolyte (pH 2) with fluoroboric acid and sodium tartrate as masking agents. Only Bi(III) interferes. Any co-deposited Bi can be corrected for by its spectrophotometric determination with Semi-Xylenol Orange after preconcentration with La(III) as carrier, from an ammoniacal solution containing the redissolved deposit. Any residual Cu(II) in the electrolyte is determined by spectrophotometry with 2,9-dimethyl-1, 10-phenanthroline. The standard deviation of this method has been found to be 0.03 mg (n = 12) and its relative standard deviation from 0.03 to 0.17%. It has been successfully used for referee analysis and certification of standard reference materials.
