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AN-V-199

2024-06

Voltammetric determination of gold(I) in gold plating baths

Gold plating bath analysis with the Multi-Mode Electrode pro

Summary

In the metal plating industry, particularly during gold electroplating, the meticulous control and determination of gold(I) concentration in the gold plating bath is critical. This not only ensures a high quality and consistent thin layer of gold, but also plays a significant role in optimizing the efficiency and cost of gold plating.

The conversion of Au(I) to pure gold metal is relatively simple and efficient, using one unit of electricity per mole of gold deposited. However, when Au(III) forms and accumulates in the gold bath, it significantly lowers the current efficiency because the reduction of Au(III) to gold metal requires three units per mole. A lower fraction of Au(I) leads to inefficient use of electricity and gold, making the process more costly and less sustainable.

Voltammetric analysis using the Multi-Mode Electrode pro emerges as a highly effective tool, offering a direct and straightforward method for the determination of gold(I) in both cyanide and sulfite gold plating baths without the need for time-consuming sample preparation.

Configuration

884 Professional VA manual for Multi-Mode Electrode (MME)

884 Professional VA manual for Multi-Mode Electrode (MME)

2.884.0110

884 Professional VA manual for Multi-Mode Electrode (MME) is the entry-level instrument for high-end trace analysis with voltammetry and polarography with the Multi-Mode Electrode pro or the scTRACE Gold or the Bismuth drop electrode. The proven Metrohm electrode methods in combination with a high-performance potentiostat/galvanostat and the extremely flexible viva software open up new perspectives for the determination of heavy metals. The potentiostat with a certified calibrator readjusts itself automatically before each measurement, thus guaranteeing maximum precision.Determinations with rotating disc electrodes can also be performed with the instrument, e.g. determinations of organic additives in electroplating baths with "Cyclic Voltammetric Stripping" (CVS), "Cyclic Pulse Voltammetric Stripping" (CPVS), and chronopotentiometry (CP). The replaceable measuring head enables rapid changes between the various applications with different electrodes.The viva software is required for control, data collection, and evaluation.The 884 Professional VA manual for MME is supplied with extensive accessories and a measuring head for the Multi-Mode Electrode pro. Electrode set and viva license need to be ordered separately.  

Multi-Mode Electrode pro

Multi-Mode Electrode pro

6.1246.120

Mercury electrode for voltammetry. Can be operated as DME, SMDE or HMDE.

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Sample

Gold cyanide bath
Gold sulfite bath

Experimental

884 Professional VA manual for MME
Figure 1. 884 Professional VA manual for MME

Add the electrolyte solution and the gold plating bath sample into the measuring vessel and degas the mixture for five minutes. The determination is carried out using the parameters listed in Table 1. Quantification is done with the 884 Professional VA manual for MME (Figure 1) using two Au(I) standard solutions.

Table 1. Parameters
Parameter Setting
Mode DME
Start potential -0.9 V
End potential -1.75 V
Sweep rate 15 mV/s
Peak potential Au(I) -1.45 V

Electrodes

  • Multi-Mode Electrode pro

Results

Determination of Au(I) in a gold sulfite plating bath, β(Au(I)) = 12.1 g/L
Figure 2. Determination of Au(I) in a gold sulfite plating bath, β(Au(I)) = 12.1 g/L

Figure 2 presents results of Au(I) determination in a gold sulfite plating bath.

Table 2. Result
Sample Au(I) in g/L
Gold cyanide plating bath 1.6
Gold sulfite plating bath 12.1
Contact

Metrohm SA

1 Bridle Close
2052 Woodmead

Contact

Internal references: AW CH4-0498-052010, AW CH4-0412-082004

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