ASTM E3264-21 PDF

Full title and description

Standard Guide for Homogeneity of Samples and Reference Materials Used for Inter- and Intra-Laboratory Studies (ASTM E3264-21). This guide provides techniques, statistical procedures, and practical guidance to evaluate and assure the homogeneity of individual samples and bulk reference materials used in interlaboratory comparisons, proficiency testing, and intra‑laboratory studies.

Abstract

ASTM E3264-21 describes five techniques for assessing sample homogeneity across a range of circumstances and rigor. Techniques 1–3 describe procedures and statistical evaluations when replicate testing is possible, Technique 4 addresses assessment when replicates are not available, and Technique 5 provides recommended practices for producing homogeneous samples when testing is not feasible. The guide includes example spreadsheets and recommendations (for example, a minimum study design of ten samples with two replicates for many cases) and notes limitations for certified reference materials and calibration materials.

General information

• Status: Active (ASTM tracking shows last update Mar 24, 2023).
• Publication date: April 1, 2021 (designated E3264-21).
• Publisher: ASTM International.
• ICS / categories: 19.020 — Test conditions and procedures in general.
• Edition / version: E3264-21 (2021).
• Number of pages: 32 pages.

Scope

The guide is applicable to samples and reference materials used in proficiency testing programs, interlaboratory studies to determine precision estimates for test methods, and intra‑laboratory quality‑control studies. It presents five non‑exhaustive techniques for assessing homogeneity, offers statistical evaluation procedures and example calculation spreadsheets, and provides guidance for producing homogeneous samples when direct homogeneity testing cannot be performed. It is not intended as a complete protocol for evaluation of certified reference materials (CRMs) or calibration materials, which require additional traceability and uncertainty considerations.

Key topics and requirements

• Presentation of five distinct techniques for assessing homogeneity covering scenarios with and without replicate testing, and for producing homogeneous samples when testing is impractical.
• Recommendation of a practical minimum design (commonly ten samples with two replicate tests per sample) for many homogeneity assessments.
• Statistical procedures and decision rules (including use of Cochran’s test and other common laboratory-statistics methods) with worked examples and spreadsheets in the appendices.
• Guidance on distinguishing within‑sample and between‑sample homogeneity and on how to account for inhomogeneity in study evaluations.
• Notes on limitations—explicitly states the guide is not sufficient alone for CRM evaluation or calibration material certification (additional traceability and uncertainty analysis required).
• Cross-reference to established statistical guidance used in proficiency testing (for example, ISO 13528 methods are referenced as related methodology).

Typical use and users

Used by interlaboratory study designers, proficiency testing providers, laboratory quality managers, reference‑material producers (for non‑CRM homogeneity checks), test method developers, and statisticians supporting laboratory studies. Typical applications include assessing sample sets before round‑robin testing, designing homogeneity studies, and documenting sample suitability for precision or proficiency programs.

Related standards

Commonly used alongside international and accreditation documents such as ISO 13528 (statistical methods for proficiency testing by interlaboratory comparisons), ISO/IEC 17043 (conformity assessment — proficiency testing), ISO 17034 (general requirements for the competence of reference material producers), and guidance documents for reference material characterization (historically ISO Guide 35 / successor guidance). Users often combine ASTM E3264-21 statistical approaches with these standards when planning PT schemes or reference‑material programs.

Keywords

homogeneity, sample homogeneity, reference materials, proficiency testing, interlaboratory study, intra‑laboratory study, precision, Cochran’s test, statistical evaluation, reference material production, ASTM E3264-21

FAQ

Q: What is this standard?

A: ASTM E3264-21 is a standard guide that provides techniques and statistical procedures for assessing and assuring homogeneity of samples and reference materials used in inter‑ and intra‑laboratory studies.

Q: What does it cover?

A: It covers five techniques for homogeneity assessment (three for replicate testing, one for no‑replicate situations, and one for producing homogeneous samples), example spreadsheets for calculations, decision rules, and guidance on how homogeneity affects interpretation of study results. It explicitly excludes the full set of requirements needed for certified reference materials and calibration materials.

Q: Who typically uses it?

A: Proficiency testing providers, laboratories running interlaboratory comparisons, quality managers, reference‑material producers (for non‑CRM homogeneity checks), statisticians, and test method developers use this guide.

Q: Is it current or superseded?

A: The edition E3264-21 was published April 1, 2021 and is listed as Active; ASTM’s tracking indicates a last update on March 24, 2023. Users should verify the ASTM catalog for any amendments or later revisions if confirmation is needed beyond February 21, 2026.

Q: Is it part of a series?

A: It is developed by ASTM’s E11 committee (quality and statistics) and complements other standards and guides used in proficiency testing and reference material production; it is not one of a numbered "series" but is commonly used in conjunction with ISO and other ASTM guidance documents addressing proficiency testing and reference materials.

Q: What are the key keywords?

A: Homogeneity, sample homogeneity, reference materials, proficiency testing, interlaboratory study, intra‑laboratory study, precision, Cochran’s test, statistical evaluation.