CRM - Calibration buffer solution for pH measurement pHanal™ CRMpH4001

Importance of the Topic

This certificate describes a high‐precision certified reference material (CRM) for pH measurement. Consistent and traceable pH calibration is essential in laboratories across research, quality control, environmental monitoring and industrial processes. A well‐characterized CRM ensures comparability of pH results worldwide and underpins reliable decision making.

Objectives and Overview

The document certifies pHanal™ CRMpH4001, a potassium hydrogen phthalate‐based buffer solution formulated according to IUPAC and NIST recommendations. It provides certified pH values with associated uncertainty, instructions for use and traceability information aligned with ISO Guide 31 and ISO 17034 standards.

Methodology and Instrumentation

The CRM was prepared gravimetrically under controlled conditions using ultrapure demineralized water (resistivity ≥18 MΩ·cm) and analytically pure reagents. Traceability to SRM NIST 185i was maintained via an unbroken chain of calibrations. Homogeneity and stability studies, following ISO 17034 guidelines, confirmed uniformity across the batch and shelf‐life stability under prescribed storage conditions (5–30 °C).

Main Results and Discussion

The certified pH at 20 °C is 4.001 ± 0.010 (k=2). Temperature‐dependent indicative values range from 3.997 at 10 °C to 4.018 at 35 °C. Uncertainty assessment incorporates contributions from calibration, temperature control, homogeneity and stability. The narrow uncertainty supports high‐accuracy pH measurements in diverse applications.

Benefits and Practical Applications

• Calibration of routine and high‐accuracy pH meters.
• Validation of analytical methods requiring precise pH control.
• Quality assurance in pharmaceutical, environmental and chemical industries.
• Interlaboratory comparisons and proficiency testing.

Future Trends and Potential Applications

• Development of multi‐point pH CRM kits covering a wider pH range.
• Integration of digital data logging and QR codes for real‐time traceability.
• Automated calibration systems using CRM syringes or cartridges.
• Further reduction of uncertainty through advanced characterization techniques.

Conclusion

pHanal™ CRMpH4001 offers a robust and traceable solution for precise pH calibration, backed by ISO‐compliant certification, homogeneity and stability data. Its defined uncertainty and temperature‐dependent values make it a valuable tool for ensuring accuracy and comparability in pH measurement.

References

• ISO Guide 31: Reference materials – Contents of certificates and labels.
• ISO 17034:2017: General requirements for the competence of reference material producers.
• ISO/IEC 17025:2018: General requirements for the competence of testing and calibration laboratories.
• NIST SRM 185i: Primary pH standard reference material.