Potentiometric Titration of Gold, Platinum, and Some Other Precious Metals

Conference · Sat Mar 09 23:00:00 EST 1991

OSTI ID:5996572

Selig, Walter S. ^[1]

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1. Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)

Gold, platinum, and several other platinum metals can be determined by titration with cetylpyridinium chloride (CPC). CPC forms a precipitate with AuCl₄^₋ and PtCl₆^2₋. Differentiation of AuCl_4₋ and PtCl₆^2₋ with this titrant is not possible; however, their sum can be determined. Titration with tetraphenylarsonium chloride at pH 1 is selective for tetrachloroaurate, which thus can be determined in the presence of hexachloroplatinate. Hexachloroosmate(IV), tetrachloroplatinite(II), tetrachloropalladate(II), hexachloropalladate(IV), and hexachloroiridate(IV) can also be determined potentiometrically vs. CPC. The indicating electrode is prepared by coating a spectroscopic graphite rod with a solution of poly(vinyl chloride) (PVC) and dioctylphthalate (DOP) in tetrahydrofuran (THF). Gold in gold cyanide plating baths and in potassium aurocyanide can be determined by potentiometric titration vs standard silver nitrate, using a silver ion-selective indicating electrode. The monovalent gold need not be converted to the trivalent state with aqua regia, resulting in a considerable saving of time and effort. Free cyanide and aurocyanide can be titrated sequentially by this method. Chloride does not interfere and can, in fact, also be sequentially determined.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5996572
• Report Number(s): UCRL-JC--106511; CONF-9103135--1; ON: DE91008989
• Country of Publication: United States
• Language: English

Related Subjects

Cetylpyridinium Chloride
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400102* -- Chemical & Spectral Procedures
AMINES
AMMONIUM COMPOUNDS
ARSENIC CHLORIDES
ARSENIC COMPOUNDS
AZINES
CHLORIDES
CHLORINE COMPOUNDS
CYANIDES
ELECTRODES
ELEMENTS
GOLD
Gold
HALIDES
HALOGEN COMPOUNDS
HETEROCYCLIC COMPOUNDS
ION-SELECTIVE ELECTRODES
IRIDIUM CHLORIDES
IRIDIUM COMPOUNDS
METALS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PALLADIUM CHLORIDES
PALLADIUM COMPOUNDS
PH VALUE
PLATINUM
PLATINUM CHLORIDES
PLATINUM COMPOUNDS
PLATINUM METALS
POTENTIOMETRY
PYRIDINES
PYRIDINIUM COMPOUNDS
Platinum
Potentiometry
Precious Metal Analysis
QUATERNARY COMPOUNDS
REFRACTORY METAL COMPOUNDS
SILVER
Silver
TITRATION
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
Tetraphenylarsonium Chloride
Titration