ASTM C760-90 (2020) pdf free.Standard Test Methods for Chemical and Spectrochemical Analysis of Nuclear-GradeSilver-Indium-Cadmium Alloys.
1 This test method is applicable to the determination ofthe trace impurities listed in 19.1 in silver-indium-cadmiumalloys.
2 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards，Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.
3.1 The sample is cleaned, and a weighed quantity isdissolved in nitric acid. An equivalent weight of graphite isadded to the solution and it is evaporated to dryness at 85 ±5°C.The residue is moistened with a few drops of water andmixed until a slurry is obtained. A dilute hydrochloric acidsolution is added and mixed well.The slurry is evaporated todryness at 85 ± 5C in subdued light.
3.2 The dried sample mixture is blended with a bariumfluoride-graphite carrier， weighed into graphite anode caps, andexcited in a d-c arc. The spectrum is recorded photographically,and the spectral lines of interest are compared visually withstandards exposed on the same plate.
A spectrograph with sufficient resolving power and linear dispersion to separate the analytical linesfrom other lines in the spectrum of the sample in the spectralregion from 220 to 400 nm is recommended.Instruments witha reciprocal linear dispersion of 0.3 nm/mm or less aresatisfactory.
4 Visually compare the density of the sample impurityspectral line with the corresponding line in the standardspectrum. Estimate the impurity concentration using the lineslisted in the following table.
5.1 Precision—-When the sample plates are visually com-pared to the standard plates， experienced analysts can expectanalytical results to vary within a factor of two; that is,50 % to200 % of the actual impurity element concentration.
5.2 Bias—Since there is no accepted reference material fordetermining bias in this test method, no statement on bias isbeing made.
A weighed sample is dissolved in nitric acid and dilutedto a known volume，and aliquots are removed for analysis.Silver is determined first by titrating with standardized sodiumchloride solution to the potentiometric endpoint indicated by achloride-selective ion electrode.Following the silver titration,the solution is boiled to coagulate the silver chloride.The pHis adjusted to 2.5 and the indium content is titrated with EDTA,using PAN ( 1-(2-pyridylazo)-2-naphthol) indicator. The pH isthen raised to 6.0 and the cadmium is titrated with EDTA usingthe same indicator. The entire process requires approximately20 min per aliquot,exclusive of sample weighing and dissolution.ASTM C760 pdf download.