CRM Gold (Au) - Aqueous calibration solution ASTASOL® AN7004C

Importance of the topic

Certified reference materials (CRMs) are essential for guaranteeing accuracy, comparability and traceability in quantitative analytical chemistry. Reliable calibration standards underpin method validation, quality assurance and compliance with international regulations across research, industrial and regulatory laboratories.

Objectives and overview of the certificate

This certificate documents the preparation and certification of ASTASOL® AN7004C, an aqueous calibration solution containing gold at a nominal concentration of 10.00 ± 0.05 mg/L in a 5% HCl matrix. The primary aims are to deliver an SI-traceable standard, define its metrological characteristics and ensure homogeneity and stability over its shelf life.

Methodology and instrumentation

The CRM was prepared by gravimetric dissolution of high-purity gold (99.999%) into sub-boil distilled hydrochloric acid and ultrapure water (resistivity ≥ 18 MΩ·cm). Key methodological steps include:

• Gravimetric formulation ensuring direct traceability to the kilogram.
• Verification of concentration and uncertainty against an independent gold solution (SRM NIST 3121).
• Quantification of trace impurities by AAS, ICP-OES and ICP-MS to inform users of potential matrix effects.

Used instrumentation

• Atomic Absorption Spectrometry (AAS)
• Atomic Emission Spectrometry (AES)
• Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES)
• Inductively Coupled Plasma Mass Spectrometry (ICP-MS)

Main results and discussion

The certified gold concentration is 10.00 mg/L at 20 °C with an expanded uncertainty (k = 2) of 0.05 mg/L. The solution density at 20 °C was determined as 1.0084 ± 0.0005 g/cm³. Trace element screening showed impurity levels below detection limits for most analytes, confirming the high purity of the matrix and minimizing calibration biases.

Benefits and practical application

• Provides a robust, SI-traceable gold standard for calibration of spectrometric and electroanalytical methods.
• Supports method validation, routine quality control and accreditation requirements in laboratories.
• Ensures documented homogeneity and stability under specified storage conditions.

Future trends and possibilities of use

Ongoing developments in CRM technology will focus on multi-element matrices, lower uncertainties and enhanced digital traceability. Emerging analytical platforms such as laser-based spectroscopy and hyphenated techniques will benefit from expanded CRM portfolios with tailored matrices.

Conclusion

ASTASOL® AN7004C is a high-quality, gravimetrically prepared gold calibration solution with SI traceability and well-characterized metrological properties. Its low impurity profile and proven stability make it a reliable tool for rigorous analytical workflows.

Reference

• ISO Guide 31:2015 – Reference Materials – Contents of Certificates and Labels
• ISO 17034:2017 – General Requirements for the Competence of Reference Material Producers
• NIST SRM 3121 – Gold Standard Reference Material