Determination of Tin by Controlled Potential Coulometry.

Separation and Determination of Lead, Cadmium, and Tin by Controlled Potential Coulometry.

“…Four values were obtained ranging from 0.96 to 0.98% tin with an average of 0.97%. These values are in closer agreement with the certificate value (0.97%) than when the tin was precipitated as metastannic acid, dissolved in 3M NaBr + 0.2.1Í HBr, and determined by potentiostatic coulometry (11). Probably some lead was interfering with the latter method.…”

“…Then tin(II) should reduce to the amalgam at -0.70 volt, and the reverse oxidation should proceed at -0.30 volt. That tin can be quantitatively reduced and oxidized at these potentials with 100% current efficiency using an acidic bromide medium has been established (11).…”

“…of arsenic in crude oils is needed in petroleum technology because of the possible effect of arsenic on expensive platinum reforming catalysts. The decrease in hydrogenation activity of platinum metal in aqueous systems in the presence of arsenic (IS, 17), and the deposition of arsenic on the platinum catalyst during the reforming process (18) may indicate that in certain forms arsenic has a specific poisoning effect in hydrocarbon media similar to that observed in aqueous systems but opinion on this point is divided (5,9,10,11). The amount of arsenic recovered from the used catalyst indicates that the concentration of arsenic in platformer feedstocks is generally less than 10 p.p.b.…”

“…Sir: The reduction of tin(II) at controlled potential to the amalgam from an acidic bromide solution followed by coulometric anodic stripping can be used for the determination of tin (11).…”

“…Procedure. Reductions and oxidations were essentially conducted as previously described (11), and for reasons mentioned in the same article, all current integrations were done during the oxidation part of the electrolysis cycle. All control potentials are given with respect to the Ag, AgCl/sat.…”