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

Conference · Sun Mar 10 00:00:00 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
• Resource Relation: Conference: International Precious Metals Institute Sampling and Analysis Seminar, New Orleans, LA (United States), 10-12 Mar 1991
• Country of Publication: United States
• Language: English

Related Subjects

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