Introduction to 4E/RM/069rev 5 and 4E/RM/072

Appendices

Annex 1

Third party quality assessment of reference materials and their production—a position paper prepared by EA, EURACHEM, EUROMET and EUROLAB working group on reference materials (4E/RM/069rev5)

Introduction

Reference materials (RM)¹ are widely used for the calibration of equipment and the validation of measurement procedures, e.g. in chemical analysis or materials testing. They may be characterised for "identity" (e.g. chemical structure, fibre type, microbiological species etc.) and for "property values" (e.g. hardness etc.). The measurand needs to be clearly defined and the property values need to be, where possible, traceable to the SI units of measurement, or to other internationally agreed references such as the values carried by certified reference material².

The key characteristics of RMs, and therefore the characteristics whose quality needs to be assured, include the following: definition of the measurand, traceability of the assigned property values, measurement uncertainty, stability and homogeneity.

Users of reference materials require reliable information concerning the RM property values, preferably in the form of a certificate. The user and accreditation bodies will also require that the RM has been produced by a competent body³. Where appropriate, the technical competence of the producer⁴ will have been assessed and recognised by a competent third party.

Aim

The aim of this paper is to help create user confidence in RMs. It recommends the use of third party technical assessment, based on use of existing standards and infrastructure. The recommendations are applicable to all types and applications of RMs.

Important steps in the production of RMs

All or some of the following activities can be crucial in RM production and their quality assessment can be crucial to the quality of the final RM:

• Assessment of needs and specification of requirements

• Financial planning and cost benefit analysis

• Subcontracting and selection of collaborators

• Sourcing of materials including synthesis

• Processing of materials including purification, grinding, particle size separation, etc.

• Packaging, storage and design of dispatch processes

• Homogeneity and stability testing

• Development, validation or measurement methods, including consideration of the traceability and measurement uncertainty of measurement results

• Measurement of property values, including evaluation of measurement uncertainty

• Certification and sign off of the RM

• Establishment of shelf life

• Promotion, marketing and sales of RM

• Post certification stability monitoring

• Post certification corrective action

• Other after sales services

• QC and QA of quality systems and technical aspects of the work

Models of third party quality assessment

The internationally recognized technical standards and guides available for the quality assessment of RMs and their production are ISO Guide 34, ILAC G12, (ISO/IEC 17025 with reservation).

Compliance with internationally recognized definitions and practice for the assessment of competence is required. In this connection the following definitions and meanings are used:

• Accreditation is a procedure by which an authoritative body gives formal recognition that a body or a person is competent to carry out specific tasks. It is used for:

  • Laboratories who offer tests and calibrations (ISO/IEC 17025),

  • Organisations that provide RMs or proficiency testing

  • Certification bodies who certify products produced by other organisations (ISO/IEC Guide 65),

  • Certification bodies who certify quality management systems in other organisations (ISO/IEC Guide 62),

  • Inspection bodies who offer inspections (ISO/IEC 17020) etc.

• Certification is a procedure by which a third party gives written assurance that a product, process or service conforms to specified requirements. It may in certain circumstances also require the assessment of technical competence. Certification in the above sense is a "third party activity" defined in ISO/IEC Guide 2. The assignment of property values to RMs is usually not a certification activity in the above sense, because it is a first party declaration

The advantages and disadvantages of the key approaches to third party quality assessment of RMs and their production are detailed in Annex A. The conclusions and recommendations resulting from extensive discussion within the EA, EURACHEM, EUROLAB and EUROMET Working Group on RMs, including input from ILAC, are as follows.

Conclusions and recommendations

RMs are important measurement standards used for both measurement system calibration and for method validation. Their quality critically affects the quality of measurements. As a consequence all RMs should be produced by competent organisations working in compliance with ISO Guide 34, and the analyses, measurements and tests necessary for the characterisations, stability or homogeneity tests should be performed by competent laboratories working in compliance with ISO/IEC 17025. Therefore, a thorough technical assessment is considered to be an essential component to create user confidence.

The recommended approach to the quality assessment of RMs is accreditation of RM producers⁴ to ISO/IEC 17025 in combination with ISO Guide 34. This approach combines the benefits to be gained from using the internationally recognized expertise and infrastructure supporting ISO/IEC 17025, with the comprehensive description of the technical requirements detailed in ISO Guide 34 and it is in line with ILAC G12. When using this approach, the following issues also need to be considered:

• The scope of accreditation should refer to both ISO/IEC 17025 and ISO Guide 34.

• In some cases, e.g. intrinsically stable and homogeneous material, where the quality of an RM is primarily determined by the measurement of the property values, the use of ISO/IEC 17025 alone can be adequate.

• The traceability and measurement uncertainty requirements of ISO/IEC 17025 need to be given appropriate attention.

• In the longer term, ISO/IEC17025 needs to be revised, to explicitly recognize conformity assessment of RMs, as a laboratory task. ISO Guide 34 also needs to be revised to remove issues already covered in ISO/IEC 17025 and to focus on issues specific to RM production.

It is, however, recognized that ISO Guide 34 alone is fully adequate for the quality assessment of RM producers⁴ (and makes normative references to ISO/IEC 17025) and is currently in use for that purpose. However, accreditation according to this guide is not currently covered by any of the existing MLAs.

In addition, the RM¹ itself can be assessed as a product by an accredited (to ISO/IEC Guide 65) product certification body. This assessment has to include ISO Guide 34. Product certification of RMs can be recommended when the RM producer is not a laboratory, and therefore laboratory accreditation is not possible.

Customer confidence can best be achieved by keeping the number of types and approaches of quality assessment used for RMs to a minimum and by ensuring that any systems used place emphasis on technical competence. For these reasons, certification to ISO/IEC 9001(2000) is not suitable for the quality assessment of RMs.

The establishment of customer confidence will depend critically on the following:

• Establishing the equivalence of the quality assessment systems used in different parts of the world

• Providing transparent evidence concerning the competence of the third party quality assessment bodies undertaking the work

ILAC is invited to consider including the quality assessment of RM producers within its MRA and provide oversight of the process.

Bibliography

• EEE/RM/062rev2 The selection and use of reference materials—a basic guide for laboratories and accreditation bodies, 2002

• ISO Guide 31 Contents of certificates of reference materials (ISO Guide 31:2000)

• ISO Guide 35 Certification of reference materials—general and statistical principles (ISO Guide 35:1989)

• ISO Guide 34 General requirements for the competence of reference material producers (ISO Guide 34:2000)

• ILAC Guidelines for the competence of reference material producers, ILAC G12, 2000

• ISO/IEC 17025 General requirements for the competence of testing and calibration laboratories (ISO/IEC 17025:1999)

• ISO/IEC Guide 65 General requirements for bodies operating product certification systems (ISO/IEC Guide 65:1996)

• ISO/IEC Guide 62 General requirements for bodies operating assessment and certification/registration of quality systems (ISO/IEC Guide 62:1996)

• ISO/IEC Guide 2 Standardization and related activities—general vocabulary (ISO/IEC Guide 2:1996)

• ISO/IEC 17020 General criteria for the operation of various types of bodies performing inspection (ISO/IEC 17020:1998)

• ISO 9001 Quality management systems—requirements (ISO 9001:2000)

Annex 2

The advantages and disadvantages of various third party quality assessment systems — additional paper to "Third party quality assessment of reference materials and their production — a position paper prepared by EA, EURACHEM, EUROMET and EUROLAB working group on reference materials (4E/RM/072)"

Accreditation of RM producers¹ to ISO/IEC 17025 in combination with the ISO Guide 34

Advantages

• The combination covers all requirements

• The combination would reap the advantages of the expertise and infrastructure supporting ISO/IEC 17025, including the existence of a MLA

Disadvantages

• ISO Guide 34 is designed as a stand-alone document. Overlapping requirements would ideally require a new interpretative document to explain the combined use of the two documents.

• RM producers who are not laboratories cannot be accredited according to ISO/IEC 17025.

Accreditation of RM producers⁵ to ISO Guide 34 (and ILAC G12)

The requirements of these guides are very similar. Use of ISO Guide 34 is recommended in preference to ILAC G12, with modification or a supplement to address the additional issues covered in ILAC G12. (ILAC recommends use of ILAC G12 as a guide to ISO Guide 34). The following apply to both documents:

Advantages

• Both guides have been especially developed for the quality assessment of RM producers

• They cover all of the issues relevant to the quality assessment of RM producers

• They are already in use for the accreditation of RM producers

• ISO-Guide 34 does not require that the RM producer is a laboratory

Disadvantages

• There is currently no MLA covering ISO Guide 34 accreditation and it would be necessary to establish such an arrangement (or extend the ISO/IEC 17025 arrangement)

• There is no standard or guide describing the requirements for accreditation for accreditation bodies accrediting RM producers

• Some laboratories require accreditation for testing, calibration and RM production and thus would require accreditation to both ISO/IEC 17025 and ISO Guide 34

Accreditation of RM producers¹ to ISO/IEC 17025 alone

Advantages

• It is a well-recognized and accepted system of accreditation for testing and calibration laboratories and is covered by a MLA

• It could provide a basis for accreditation of testing, calibration and RM production¹ in a single scheme

• It is already in use for the accreditation of RM producers

Disadvantages

• It does not cover some important elements required for the quality assessment of RM production

• RM producers who are not laboratories cannot be accredited according to ISO/IEC 17025

Product certification of RM in combination with ISO Guide 34

Product certification bodies, accredited to ISO/IEC Guide 65, can also certify reference materials as products, if they are specialised in this technical field.

Product certification can include production surveillance (see ISO/IEC Guide 65) and therefore consider ISO Guide 34.

Advantages

• If the RM producer is not a laboratory and cannot be accredited according to ISO/IEC 17025, then the quality of the product (RM) can be assessed

• Accreditation of product certification bodies is covered by a MLA (but this does not specifically address RM work)

• It is already in use for product certification of RMs

Disadvantages

• When product certification is used, the work must be shown by a competent third party to comply with the appropriate requirements of ISO Guide 34 (and other relevant standards and guides)

Certification of RM producers¹ to ISO 9001 (2000) in combination with ISO guide 34

This option offers no advantages beyond use of ISO Guide 34 alone. There are no reference points between standard ISO 9001 (2000) and ISO Guide 34.