CRM Sulfates (SO4 2-) - Aqueous calibration solution ASTASOL® AN8078H

Significance of the topic

Certified reference materials for calibration solutions play a critical role in guaranteeing the accuracy and traceability of quantitative analyses in environmental monitoring, pharmaceutical quality control, and industrial processes. A reliable sulfate calibration solution supports method validation and comparability across laboratories.

Objectives and Overview

This document summarizes the certification of an aqueous sulfate calibration solution (ASTASOL® AN8078H) produced by Analytika, spol. s r.o. The primary aim is to provide a high-purity reference material for accurate determination of SO₄²⁻ in aqueous matrices using various analytical techniques.

Methodology

The solution was prepared gravimetrically from ultra-pure ammonium sulfate ((NH₄)₂SO₄, 99.9999 %) and demineralized water (resistivity ≥ 18 MΩ·cm) filtered at 0.22 µm. Traceability to the SI unit kilogram is established through documentary proof of mass and purity. Homogeneity tests and stability studies ensure consistent performance throughout the five-year shelf life.

Instrumentation Used

• Ion chromatography for impurity screening (Br⁻, Cl⁻, F⁻, I⁻, NO₂⁻, NO₃⁻, PO₄³⁻)
• Gravimetric precipitation (BaSO₄) for sulfate quantification
• Comparative measurements against NIST SRM 3181

Main Results and Discussion

The certified sulfate concentration is 100.0 mg/L with an expanded uncertainty of ±0.2 mg/L (k = 2) at 20 °C. Mass fraction in mg/kg is also provided, derived from the measured density (0.9997 g/cm³ ± 0.0005 g/cm³). Impurity levels were below detection limits (<0.02 mg/L), ensuring negligible interference. Batch homogeneity and long-term stability studies confirm the material’s reliability under recommended storage conditions (5–30 °C).

Benefits and Practical Applications

• Calibration and validation of spectrometric and electroanalytical methods (AAS, AES, ICP-OES, ICP-MS, UV-Vis, voltammetry)
• Quality control in environmental, industrial, and research laboratories
• Direct SI traceability for regulatory compliance

Future Trends and Potential Applications

Emerging analytical techniques such as microfluidic platforms and portable spectrometers will benefit from certified solutions. Integration of digital certificates and blockchain-based traceability could further enhance data integrity. Expansion into multi-component calibration standards may support simultaneous analysis of related anions.

Conclusion

ASTASOL® AN8078H provides a robust and traceable reference for sulfate determination in aqueous systems. Its high purity, well-documented uncertainty, and verified stability make it a cornerstone for accurate method development and routine analysis.

References

The certification follows ISO Guide 31 and references NIST SRM 3181 for verification of sulfate content.