GB/T 15072.8-2008 "Test method of precious metal alloys - Determination of copper content for gold, palladium and silver alloys - Complexometric return titration using thiourea releasing EDTA"

This standard specifies the method for determining the copper content in gold, palladium and silver alloys, which is applicable to various precious metal alloys containing copper (such as AuAgCu, PdAgCu, etc.), and the determination range is 4% to 35%. In the method, the silver alloy sample is dissolved with nitric acid, and the excessive EDTA solution is added to complex copper, nickel, vanadium and aluminum palladium; the silver-copper alloy is dissolved with nitric acid, and the gold alloy and palladium-silver-copper-gold-platinum-zinc alloy are dissolved with muriatic acid mixed with nitric acid. The gold alloy containing gold is reduced with sulfuric acid, and the palladium alloy is separated with dimethyl ethylene dioxime solution. Copper in EDTA was complexed with Miscellaneous metal, hexamethylenetetramine was used as buffer and xylenol orange was used as indicator. The copper content was determined by back titration with lead standard solution at pH 5.8.

This summary is not the original standard text and is for reference only. For accurate information, please obtain it through official channels.