Direct Spectrophotometric Determination of Gold in Alloys as Chloroaurate

Abstract

A method is presented for a simple and direct determination of gold in alloys, utilizing a preliminary separation of gold from an alloy, and its subsequent conversion to chloroauric acid. The optical density of the chloroaurate ion is measured at two selected wavelengths, calculating the gold content of alloys by using the absorbance difference technique as developed by Glasner and Avinur. A suitable technique enables wide‐range determination in various samples of gold alloys ranging from 0.001% to over 90% gold content. Platinum does not interfere when present in small amounts in the alloy.

Mass Thickness Analysis of Gold Thin Films Using Room Temperature Gas-Phase Chlorination

“…15,18,20 Calibration curves show that Beer's law holds for both absorption peaks in the concentration range 1-100 µg Au/mL (shown in Figure 3 for concentrations <10 µg Au/mL). The experimentally determined molar extinction coefficient for AuCl 4ion at 314 nm ε 314 ) 5 280 M -1 cm -1 is close to the known literature values of 5 560, 18 5 760, 20 and 5 480, 15 taking into account differences in the solution composition used by different authors. For the absorption peak at 227 nm, the measured AuCl 4molar absorption coefficient value of ε 227 ) 36 430 M -1 cm -1 is comparable to that of the most sensitive absorption peak of AuBr 4at 254 nm, with ε 254 ) 42 560 M -1 cm -1 .…”

“…The absorption spectrum of AuCl 4 − solution shows two peaks at 227 and 314 nm (Figure ); however, in previous studies only measurements of the absorption at 314 nm were used for analysis. ,, Calibration curves show that Beer’s law holds for both absorption peaks in the concentration range 1−100 μg Au/mL (shown in Figure for concentrations <10 μg Au/mL). The experimentally determined molar extinction coefficient for AuCl 4 − ion at 314 nm ε 314 = 5 280 M −1 cm −1 is close to the known literature values of 5 560, 5 760, and 5 480, taking into account differences in the solution composition used by different authors. For the absorption peak at 227 nm, the measured AuCl 4 − molar absorption coefficient value of ε 227 = 36 430 M −1 cm −1 is comparable to that of the most sensitive absorption peak of AuBr 4 − at 254 nm, with ε 254 = 42 560 M −1 cm −1 .…”

“…Rutherford back scattering (RBS) − and X-ray photoelectron spectroscopy (XPS), , neutron activation analysis, , and radiotracer methods have been used for determination of the mass thickness of Au thin films. Chemical methods for Au analysis in solutions include atomic absorption spectroscopy, , inductively coupled plasma mass spectrometry, , X-ray fluorescence, spectrophotometry, − and electrochemical stripping analysis. − Among the variety of analytical methods, spectrophotometric determination of the concentration of chloroaurate ion (AuCl 4 − ) in solution seems attractive due to the simplicity of the procedure and the required equipment. The objective of the present study was to develop a simple analytical procedure for the determination of the mass thickness of nanostructured Au films which can be used routinely in a materials research laboratory.…”