ASTM D1293-18 PDF

Full title and description

ASTM D1293-18 — Standard Test Methods for pH of Water. This standard specifies electrometric procedures using a glass electrode and pH meter for determination of the hydrogen‑ion activity (pH) of water. It contains two methods: Method A for precise laboratory measurement and Method B for routine or continuous measurement, and includes guidance on calibration, buffer solutions, temperature compensation, and limitations for low‑conductivity waters.

Abstract

ASTM D1293-18 defines accepted laboratory and field procedures for measuring pH in water samples by electrometric (glass electrode) techniques. The document covers two measurement approaches (precision laboratory and routine/continuous), requirements for instrument standardization with reference buffer solutions, temperature compensation, and notes limitations (for example, reduced suitability for very low conductivity waters). The standard is intended to promote repeatable, comparable pH measurements across laboratories and monitoring programs.

General information

• Status: Active (current revision published and in use).
• Publication date: January 15, 2018 (designated D1293-18).
• Publisher: ASTM International (formerly American Society for Testing and Materials).
• ICS / categories: 13.060.50 — Examination of water for chemical substances / Water quality analysis.
• Edition / version: D1293-18.
• Number of pages: 10 pages.

Scope

These test methods cover electrometric determination of pH in water using a glass electrode and pH meter. Two test methods are provided: Test Method A (precise laboratory measurement) which uses rigorous calibration with multiple standard reference buffers for high‑accuracy applications; and Test Method B (routine or continuous measurement) which provides a simplified calibration regimen suited to routine monitoring and on‑line measurement. The scope notes that the methods are not considered adequate for waters with very low conductivity (approximately less than 5 μS/cm) and references other methods for such cases.

Key topics and requirements

• Principles of electrometric pH measurement using a glass electrode and reference electrode.
• Two measurement procedures: Method A (precision) and Method B (routine/continuous).
• Instrument standardization and calibration using NIST‑traceable buffer solutions (multiple buffers for Method A; two buffers for Method B).
• Temperature compensation and reporting of measurement temperature.
• Guidance on electrode condition, sample handling, and electrode maintenance to ensure accuracy.
• Limitations: reduced applicability for very low conductivity waters (≈ < 5 μS/cm) and interference considerations.
• Recommendations to verify method suitability for unusual matrices and to follow laboratory quality controls.

Typical use and users

ASTM D1293-18 is used by environmental laboratories, municipal and industrial water quality analysts, water treatment facilities, research laboratories, regulatory agencies, and field monitoring programs. Users apply Method A when high precision and traceable calibration are required (e.g., reference labs, research, regulatory reporting) and Method B for routine monitoring, process control, and continuous on‑line pH monitoring.

Related standards

Relevant and commonly referenced documents include ISO 10523 (Water quality — Determination of pH), ASTM standards related to on‑line pH measurement and low‑conductivity waters (for example ASTM D6569, D5128, D5464 where applicable), Standard Methods for the Examination of Water and Wastewater procedures for pH, and manufacturer guidance for pH electrodes and meters. Users often consult calibration reference material specifications (NIST SRMs) and local/regulatory analytical method guidance when implementing D1293.

Keywords

pH; hydrogen ion concentration; glass electrode; pH meter; electrometric measurement; buffer solutions; calibration; water quality; temperature compensation; low conductivity; monitoring; ASTM D1293-18.

FAQ

Q: What is this standard?

A: ASTM D1293-18 is the ASTM International standard that provides test methods for measuring the pH of water by electrometric techniques using a glass electrode and pH meter.

Q: What does it cover?

A: It covers two procedures: Method A for precise laboratory measurement (rigorous calibration with multiple buffers) and Method B for routine or continuous measurement (simpler calibration suitable for monitoring). It also addresses calibration, temperature compensation, electrode care, limitations (noted for very low conductivity waters), and quality control considerations.

Q: Who typically uses it?

A: Environmental and analytical laboratories, municipal and industrial water utilities, researchers, regulatory bodies, and operators of continuous water monitoring systems use the standard to ensure consistent, traceable pH measurements.

Q: Is it current or superseded?

A: The version D1293-18 was published on January 15, 2018 and is the recognized revision identified as D1293-18. It is treated as the active ASTM revision unless a later ASTM revision has been issued by ASTM International after that date; users should check ASTM International or an institutional standards subscription for any revisions published after February 20, 2026 to confirm currency.

Q: Is it part of a series?

A: D1293 is part of ASTM's water and environmental technology standards (Annual Book of ASTM Standards, Volume 11.01). It is related to other ASTM water analysis methods and to international standards (for example ISO 10523) that cover pH determination and complementary water quality procedures.

Q: What are the key keywords?

A: Key keywords are pH, hydrogen ion concentration, glass electrode, pH meter, buffer calibration, electrometric measurement, water quality, temperature compensation, and low conductivity.