IEC TR 62434:2006 PDF

Overview

IEC TR 62434:2006 - "pH measurements in difficult media – Definitions, standards and procedures" is a Technical Report from the IEC that defines terminology, measurement methodology, and performance requirements for pH determination in non‑aqueous and aqueous–organic solvent mixtures. It applies to analyzers, sensor units and electronic units (notably glass electrodes) used in challenging solvent media, and describes manufacturer statement requirements, performance tests and verification methods.

Key topics

• Scope and applicability: pH in non‑aqueous solvents and aqueous‑organic mixtures; measurement systems using glass electrodes and appropriate salt bridges.
• Definitions & symbols: Conventional pH definition pH = −log a (activity), plus explanation of molal and concentration bases and conversion considerations for solvent density.
• Operational measurement: The operational pH cell concept and the calibration/measurement scheme. Core operational equation:
  • pHsample = pHstandard − (Esample − Estandard)/k where k = 2.3026·R·T/F (Nernstian coefficient). Annex A lists k values from 0 °C to 100 °C.
• Calibration and practical slope: Aging glass electrodes may show a reduced practical slope k'