CRM Sulfates (SO42-) - Aqueous calibration solution ASTASOL® AN90781H

Significance of the topic

This certified reference material provides a highly accurate sulfate standard solution essential for ensuring the quality and comparability of analytical results across laboratories. Reliable calibration of instruments analyzing aqueous samples is critical in environmental monitoring, industrial QAQC and research applications.

Objectives and Study Overview

The certificate defines the production, characterization and intended use of ASTASOL AN90781H, an aqueous calibration solution with a nominal sulfate concentration of 1000 mg per liter. The document aligns with ISO Guide 31 and ISO 17034 requirements for reference materials.

Methodology and Instrumentation

• Gravimetric preparation of solution from high-purity ammonium sulfate (purity 99.9999 percent) and ultrapure water, ensuring direct SI traceability to the kilogram.
• Verification of sulfate concentration by gravimetric determination of barium sulfate precipitation and crosschecking against NIST SRM 3181.
• Ion chromatography for determination of trace anionic impurities (Br minus, Cl minus, F minus, I minus, nitrite, nitrate, phosphate).

Main Results and Discussion

• Certified sulfate concentration: 1000 mg per liter with expanded uncertainty 2 mg per liter (k equals 2) at 20 °C.
• Solution density: 0.9990 g per cubic centimeter with expanded uncertainty 0.0005 g per cubic centimeter at 20 °C, used to derive concentration in mg per kg.
• Trace impurities all below detection limits of 0.02 mg per liter; sulfate impurity designation indicated analyte.
• Demonstrated homogeneity and stability over a five-year shelf life when stored sealed at 5–30 °C. After first opening, material remains valid for twelve months.

Benefits and Practical Applications

This CRM supports calibration and method validation for a range of techniques including atomic absorption and emission spectrometry, ICP-OES, ICP-MS, molecular absorption spectrometry and selected electrochemical methods. Its certified accuracy enhances data comparability in environmental, industrial and research laboratories.

Future Trends and Potential Applications

• Development of multi-element and multi-analyte aqueous CRMs to streamline calibration workflows.
• Integration of digital data carriers or QR codes linking to certificates and stability data in real time.
• Miniaturized, on-site calibration kits enabling field-based quality control.
• Advanced packaging materials to extend post-opening stability beyond 12 months.

Conclusion

ASTASOL AN90781H offers a rigorously characterized sulfate standard solution with traceability to the SI unit, low uncertainty and validated stability. It represents a reliable tool for accurate calibration and quality assurance in aqueous analysis across diverse spectrometric and electroanalytical methods.

Reference

1. ISO Guide 31 Reference Materials – Contents of Certificates and Labels.
2. ISO 17034 General Requirements for the Competence of Reference Material Producers.
3. NIST SRM 3181 Sulfate Standard Solution.