CRM Ca, K, Mg, Na - Aqueous calibration solution ASTASOL® AN9091MN

Significance of the Topic

The development and certification of precise aqueous calibration standards are crucial for ensuring accuracy and traceability in a wide range of analytical techniques. Certified reference materials (CRMs) support quality assurance in laboratories, enable method validation, and underpin reliable results in environmental monitoring, pharmaceutical analysis, food testing, and industrial quality control.

Study Objectives and Overview

This document presents the certification of ASTASOL® AN9091MN, an aqueous calibration solution containing four major cations (Ca, K, Mg, Na) at 1000 mg/L. The primary goals are to:

• Establish certified concentrations and associated uncertainties at 20°C.
• Demonstrate traceability to SI units through gravimetric preparation and verification by primary and instrumental methods.
• Provide guidance on handling, storage, and shelf life to maintain CRM integrity.

Methodology and Instrumentation

The CRM production employed gravimetric weighing of high-purity primary compounds (CaCO3, KNO3, Mg metal, NaNO3) in a 2% HNO3 matrix prepared from sub–boiling-distilled acid and ultrapure water. Traceability to the kilogram was ensured by direct mass measurements. Certified values and uncertainties were verified using:

• Gravimetric and titrimetric methods (complexometric EDTA titration for Ca and Mg).
• Atomic spectrometry techniques: AAS, AES, ICP-OES, ICP-MS.

Used Instrumentation

• Complexometric titration system with EDTA.
• Atomic absorption spectrometer (AAS).
• Atomic emission spectrometer (AES).
• Inductively coupled plasma optical emission spectrometer (ICP-OES).
• Inductively coupled plasma mass spectrometer (ICP-MS).

Main Results and Discussion

The CRM exhibits the following certified concentrations at 20°C, with expanded uncertainties (k = 2):

• Calcium, Potassium, Magnesium, Sodium: 1000 mg/L ± 2 mg/L.
• Equivalent mass fraction: 979 mg/kg ± 3 mg/kg (derived from solution density).

The solution density was determined as 1.0213 g/cm3 ± 0.0005 g/cm3. Trace impurity analysis by AAS, ICP-OES, and ICP-MS confirmed that common cations and trace metals are below detection or present at negligible levels, ensuring minimal matrix interference.

Benefits and Practical Applications

ASTASOL® AN9091MN serves as a primary calibration standard for the validation and calibration of analytical methods including AAS, AES, ICP-OES, ICP-MS, molecular absorption spectroscopy, and electroanalytical techniques. Its high purity, documented uncertainty, and SI traceability support robust quality control and method accreditation in research and industrial laboratories.

Future Trends and Applications

Ongoing developments in CRM production may include multi-element matrices tailored to emerging analytical challenges, enhanced stability protocols, and digital certification records. Integration with automated preparation systems and on-line calibration feeds will further streamline laboratory workflows and improve data integrity.

Conclusion

ASTASOL® AN9091MN provides a reliable, SI-traceable calibration solution for major cations in aqueous media. Its rigorous certification process and stability data ensure long-term performance, facilitating accurate and reproducible measurements across diverse analytical platforms.

Reference

• NIST SRM 928, Standard Reference Material for complexometric titration validation.
• NIST SRM 3109a, Traceable calcium standard solution.
• NIST SRM 3131a, Traceable magnesium standard solution.
• NIST SRM 3152a, Traceable sodium standard solution.