How to Select the Right Reference or Certified Reference Materials

By Andrade Shannon, Manager – MarCom, Cole-Parmer India

Covering important aspects from quality grades and certificates of analysis to metrological traceability and what they mean for your ISO 17025 certified labs.

In recent times, we have seen a very stringent stance on regulatory guidelines to ensure continued improvements in the safety and quality of finished products across industries – more so for the food and pharma sector. Traceability is now a major agenda for laboratories to prove that the CRMs used for analytical purposes are homogenous, stable and metrologically distinguishable.

What are certified reference materials (CRMs)?

As per ISO 17034, certified reference materials are defined as “sufficiently homogenous and stable with respect to one or more specified properties (qualitative or quantitative) which have been established to be fit for its intended use in a measurement process.” A CRM is distinguished and identified by a certificate that demonstrates not only the metrological traceability but also the uncertainty value of each property.

Traceability is very important

Superior CRM manufacturers comply to ISO 17034:2016 for General Requirements for the Competence of Material Producers. Section A.3.1 of ISO 17025:2017 (Latest version) demonstrates the focus on metrological traceability. The section states that “Laboratories are responsible for establishing metrological traceability in accordance with this document. Regulatory bodies focus on not only the final products but also the intermediates involved in it. For E.g. Absence of Osmium or Nitrosamines in any CRM. This needs to be proved by a valid certificate.

Challenges for an ISO 17025 certified lab (while complying to ISO 17034)

Chemists have to make a number of hard decisions in order to comply with the regulations. One of the most important decisions is procuring the right options from the market.

Know the difference between reference material’s (RMs) and certified reference material’s (CRMs)

Not all standards available in the market are classified as CRMs. The comparison between RMs and CRMs are quite notable:

Particulars Reference Material
Certified Reference Material (CRMs)
True value traceability to primary standard or SI Units May or may not be Traceable Always traceable
Certificate of Analysis (CoA) Not required Is a must for every CRM
Recorded uncertainty associated to true value (characterization, homogenity and stability factors) Uncertainty cannot be associated Can be associated accurately
Metrological traceability No Yes
Acceptance by regulatory bodies Not accepted by all regulatory bodies
Widely accepted by all regulatory bodies


Accuracy and precision Does not guarantee Assures best accuracy and precision
(within stated validity)
Best fit for – Type of A\analysis Can be used for qualitative analysis Best for all qualitative & quantitative analysis

Action: Be smart & pick the right standards to fully comply with your ISO 17025 certified lab

Check of all accreditations

The Certificate of Analysis (CoA) is the most critical component for all CRM offerings. ISO has established a set of guidelines designed to define common business practices, increase responsibility, and ensure clarity and full disclosure in the industry. Each ISO standard has its own set of internationally recognized criteria against which companies are formally measured. There are three ISO quality management systems that are very important with reference materials are ISO 9001, ISO/IEC 17025 and ISO 17034.

Action: Make a key point to observe all these accreditations well mentioned on CoA.

Right state (powdered/liquid) of CRMs to best fit in accordance to ISO 17034

Chemists are always in doubt when they are offered with two CRM options (Liquid OR Powdered) for Organic standards. There are observations made by many publications and end users that the experience with liquid CRMs have almost always better than powdered ones.

It is important to take note that powdered CRMs are not ISO 17034 accredited due to which a high number of rejections are seen (for powdered CRMs) in an ISO 17025 certified lab.powder liquid CRM ISO 17034

The powdered CRM if not stored properly is susceptible to moisture, making it unacceptable for the next use. Also, regulatory bodies are bound to raise queries on quality due to the possibility of errors from a number of uncertainties including:

  • Laboratory Components: Syringes, pipettes, glassware, storage containers, scales
  • Standard preparation techniques: Serial dilutions, weighing out and preparation
  • Laboratory environment: Lab surfaces: residue and dust, ventilation and fume hoods, waste containers
  • Laboratory Personnel: Cosmetics, glove contamination, lab hygiene practices, human error

Action: Make a key point to observe all these accreditations well mentioned on CoA.

Concluding note

Laboratories have many choices for reference and calibration standards but the selection of the correct reference material can be difficult in some cases. Some laboratories feel that they can produce their own in-house standards but often do not fully understand the quality, value and requirements of properly certified standards or reference materials. In-house production of standards or the dilution of a solid reference material does not guarantee the quality of a reference material. A certified reference material is required for any laboratory operating within the ISO 17025 guidelines. The ISO accreditation of a CRM guarantees accuracy, identity and quality the material without additional contamination or error. A certified reference material provides not only the instruction to maintain homogeneity and stability, but also provides traceability required under ISO guidelines.

To understand more about the dynamics involved in selecting the right CRMs, for your ISO 17025 Certified lab laboratories please connect with me via email at [email protected]

For those outside of India, contact your local representative.


Cole-Parmer Blog

2 Comments on "How to Select the Right Reference or Certified Reference Materials"

  1. Reference materials is generally used by scientists for research purpose. This article will help a lot to choose the right one. Thanks for sharing.

  2. Nice article!!!
    Thank you for sharing this article which is really interesting to know about the selection of reference material for ISO 17025.

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