Development of Certified Reference Materials of Trace Elements in Gold Solution (GBW02797–GBW02800)

Abstract

Based on ISO 17034 and ISO Guide 35, a new series of matrix reference materials for 23 trace elements in 2 mg/mL gold solutions with five concentration levels (0, 1, 5, 10 and 20) ng/mL were developed, respectively. High-purity gold CRM GBW02793 with purity of 99.9995 % used as raw material was dissolved and then doped with multi-element solutions to prepare the candidate RMs. For ICP-MS measurements, matrix-matched and internal standard calibrations were studied and evaluated. The limits of detection (LoDs) ranged from 0.002 to 0.35 ng/mL. The satisfactory spike recoveries from 96 % to 108 % were obtained, demonstrating the measurement trueness. The ICP-MS method was also applied in the homogeneity and stability study. The statistical analysis suggested that the elements were well distributed by measuring 11 units with duplicate analysis for each. Besides, no significant trends were observed in the long-term stability test at room temperature for 12 months or in the short-term stability test at 60 ℃ and − 20 ℃ for 7 days. Through collaborative characterization by eight expert laboratories, the RM at each concentration level was certified for the mass fractions of 23 elements, respectively. All applied measurement methods in the characterization were further validated by using CRM ERM-EB507. The measurement results from all laboratories showed great consistency, and the overall mean values which were consistent with the target values were used as the certified values. Additionally, uncertainties arising from inhomogeneity (u_bb), instability (u_s) and value assignment (u_char) were comprehensively combined. The developed RMs would ensure reliable and traceable analytical results of trace elements in fine gold and gold jewelry.