ISO 11265-2025 PDF

Full title and description

Environmental solid matrices — Determination of the specific electrical conductivity. This International Standard specifies an instrumental, routine method for determining the specific electrical conductivity of an aqueous extract prepared from environmental solid matrices such as soil, sludge, biowaste and waste; the result provides an indication of the concentration of water‑soluble electrolytes in the tested sample.

Abstract

This document gives a simple, repeatable instrumental procedure to measure the specific electrical conductivity in an aqueous extract of air‑dried samples (soil, sludge, biowaste and waste). The measurement is intended as an indicator of water‑soluble electrolytes and is suitable for routine laboratory use. The standard is applicable to all types of air‑dried samples of the listed matrices.

General information

• Status: Published (International Standard).
• Publication date: 28 August 2025 (Edition 2, 2025).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 13.080.20 — Physical properties of soils / environmental solid matrices.
• Edition / version: Edition 2 (2025).
• Number of pages: 7 (typical ISO published PDF length for this edition).

Key bibliographic facts above are taken from the ISO record and recognized national catalogues that list the 2025 edition. The 2025 edition replaces the previous 1994 edition (and its corrigendum).

Scope

The standard specifies the instrumental method for routine determination of specific electrical conductivity in an aqueous extract prepared from environmental solid matrices (soil, sludge, biowaste and waste). It is intended to provide an indication of the content of water‑soluble electrolytes and applies to air‑dried samples of the named matrices. The procedure is intended for routine laboratory application rather than for in‑situ measurements.

Key topics and requirements

• Definition of the target property: specific electrical conductivity of an aqueous extract as an indicator of water‑soluble electrolytes.
• Applicable matrices: soil, sludge, biowaste and waste (air‑dried samples).
• General sample preparation requirements (air‑drying and homogenization appropriate for physico‑chemical analysis; normative references handle detailed pretreatment).
• Instrumental measurement: use of calibrated conductivity meters and defined measurement conditions to ensure repeatability (device calibration, temperature control/compensation and reporting conventions).
• Requirements for reporting results and expressing conductivity (units, rounding, any reference temperature or temperature compensation to be indicated).
• Notes on applicability and limitations: method gives an indication of soluble electrolytes and is not a full compositional analysis; results depend on extractant ratio and sample pretreatment (follow sample‑prep standards where required).

Typical use and users

Laboratories performing environmental and soil testing, environmental consultants, waste and biowaste processors, agricultural laboratories, research institutions and regulatory agencies use this method to screen samples for soluble salt/electrolyte content, to support soil quality assessment, waste characterisation and process control. The method is commonly used as a routine indicator test within broader physico‑chemical testing programs.

Related standards

Standards commonly used alongside ISO 11265 include ISO sample‑preparation and sampling standards (for example ISO 11464 — pretreatment of samples for physico‑chemical analysis) and relevant soil sampling standards (ISO 10381 series / ISO 18400 family) that set out sampling and pretreatment practices to ensure representative and compatible laboratory results. Users should consult those documents for detailed sampling and pretreatment procedures referenced by ISO 11265.

Keywords

environmental solid matrices, soil, sludge, biowaste, waste, specific electrical conductivity, aqueous extract, conductivity measurement, electrolytes, soil quality, sample pretreatment.

FAQ

Q: What is this standard?

A: ISO 11265:2025 is an International Standard that specifies a routine instrumental method for determining the specific electrical conductivity of an aqueous extract prepared from environmental solid matrices (soil, sludge, biowaste and waste). It is Edition 2, published in 2025.

Q: What does it cover?

A: It covers the preparation (within the limits of air‑dried samples), extracting and instrumental measurement steps needed to obtain a repeatable value of specific electrical conductivity as an indicator of water‑soluble electrolytes in those matrices. It is intended for routine laboratory screening and reporting.

Q: Who typically uses it?

A: Environmental testing laboratories, soil scientists, waste and biowaste managers, agricultural testing labs, regulatory bodies and researchers — anyone needing a standardized routine measurement of soluble electrolyte content in environmental solid samples.

Q: Is it current or superseded?

A: ISO 11265:2025 (Edition 2) is the current published edition (published 28 August 2025) and supersedes ISO 11265:1994 (and its corrigendum). Users using older national adoptions should update to the 2025 edition where required.

Q: Is it part of a series?

A: While ISO 11265 is a stand‑alone method for conductivity measurement, it is typically used alongside other soil quality and sampling standards (for example ISO 11464 for sample pretreatment and the ISO 10381 / ISO 18400 family for sampling guidance) to ensure representative sampling and proper sample preparation.

Q: What are the key keywords?

A: Specific electrical conductivity; aqueous extract; soil; sludge; biowaste; waste; environmental solid matrices; electrolytes; conductivity meter; sample pretreatment.