Analysis of Impurities in Silver by Spark Ablation Sampling, Combined with ICP-OES

Abstract

A method for the determination of elemental impurities in solid silver samples was developed using a spark ablation accessory in combination with ICP-OES. Detection limits at the sub-ppm level were achieved along with good accuracy and precision.

Refinery plants receiving silver from suppliers must analyze the supplied raw material for its elemental content. Silver may be analyzed after dissolution in nitric acid or aqua regia, but significant solubility issues exist for various elements.

The Separate Sampling and Excitation Accessory (SSEA) is a spark ablation accessory which, coupled with ICP-OES, offers an instrumental solution to these issues. The Kolyma State Refinery, in the Magadan region of Russia recently added SSEA-ICP-OES to their capabilities for the analysis of silver. This note describes the basis of their methodology.

Experimental Conditions

A Thermo Scientific iCAP 6500 Duo spectrometer was used. This offers enhanced sensitivity in axial view mode and has the ability to couple with, and fully support, the SSEA spark accessory. Table 1 gives the parameters used in the method.

Table 1: Instrumental parameters

Silver certified reference materials (Russian State reference samples of silver) were used for calibration. The silver wavelengths 232.468 nm and 233.137 nm were used as internal standard lines to maximize the precision of the method and to minimize differential transport efficiency effects.

Results

Reference samples were analyzed against the calibration with multiple replicates to demonstrate the accuracy and precision of the method. Table 2 gives a summary of the results of the analysis of two materials along with detection limits.

Table 2: Found and certified values and detection limits (all units in % w/w)

Conclusions

Thermo Scientific iCAP 6500 Duo in combination with the SSEA enables high sensitivity, multi-element analysis of impurities in silver samples at ppm and sub-ppm levels as well as the ability to determine silver itself. The SSEA accessory provides a solid phase sampling technique that side-steps the problems that can be encountered with acid digestion approaches.

To download the full application note, please visit www.thermo.com/icap and browse to the ICP literature library.

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