The LCGC Blog: NIST Reference Materials

Have you ever wondered how we really know that product labels or our blood test results are accurate? We live in a world based on analytical measurements, but those results are only as good as the standards we use to compare them. Enter the National Institute of Standards and Technology (NIST), whose mission is to promote U.S. innovation and industrial competitiveness by advancing measurement science, standards, and technology in ways that enhance economic security and improve quality of life.

One way NIST fulfills this mission is by delivering reference materials. NIST produces a library of over 900 physical objects—from packets of infant/adult nutritional formula to metabolites in frozen human plasma—that act as the rulers for science and industry. Technical publication NIST SP 260-136 outlines NIST's categorization of these materials.¹ While it sounds like dry bureaucracy, it is actually a fascinating look at the role NIST plays in providing certainty in an uncertain world.

The Hierarchy of NIST Reference Materials

Not all reference materials are created equal!

1. Standard Reference Materials (SRMs)

SRMs are the heavy hitters: a type of certified reference material (CRM) available from NIST, they carry NIST-assigned values with well-understood uncertainty statements, representing the institute's best assertion of truth. When a laboratory needs to calibrate a medical device or prove to a regulator that its multivitamins bottle has accurate product labels, it uses an SRM. NIST has the highest possible confidence in its certified values that are metrologically traceable to the International System of Units (SI). The provision of that traceability is arguably the most important function of NIST as the United States national metrology institute.

2. Reference Materials (RMs)

Sometimes, materials are useful but don't quite meet all the requirements for an SRM. NIST RMs are essential tools that provide fit-for-purpose values and uncertainties for established measurands. This means that while the homogeneity and stability of the material have been established, the absolute accuracy of the values has not been established with the confidence required for certification. They are perfect for demonstrating that Lab A and Lab B in different states are getting the same results, even if we aren't certain of the absolute "true" value.

3. Research-Grade Test Materials (RGTMs)

When a new measurement need emerges—such as a new regulation setting a threshold for Δ⁹-THC in Cannabis plant samples —NIST doesn't always have an SRM or RM available. They can start with RGTMs. These are materials NIST is studying to determine whether they can one day become an RM or an SRM, as with RM 8210 Hemp Plant (Figure 1). RGTMs are commonly used in NIST Quality Assurance Programs, collaborative exercises that help laboratories improve measurement accuracy. NIST provides blind samples to participants, analyzes their results, provides NIST results when possible, and helps laboratories identify potential inaccuracies through sample preparation procedures, analytical measurements, and calibration.

What Makes a Value Certified?

NIST doesn't just put a sticker on a packet and call it a day. For a value to be certified, NIST must have the upmost confidence in this value as it must pass a gauntlet of scientific rigor:

1. Defining the What: NIST must know exactly what they are measuring (the target analyte or measurand) in a material.
2. Homogeneity: Every packaged unit of material must be identical. If this is not true, the standard is not fit for purpose.
3. Stability: It can’t change during storage. If the material degrades at a certain point, it is no longer suitable.
4. Accuracy: NIST must understand all sources of bias and provide a window of confidence with its uncertainty.
5. Traceability: The value must be linked back to a reliable and accepted reference, like the mole, the SI unit for amount of substance.
6. Documentation: It must come with a "birth certificate" (a Certificate of Analysis) that summarizes the values, uncertainties, expiration dates, and traceability. In addition, NIST releases a special publication (SP-260) detailing how the material was prepared and exactly how the value was reached.

If NIST can't adequately establish the first three (What, Homogeneity, Stability), they won't provide a value.

Why This Matters to You

Reliable measurements are the backbone of modern science, medicine, and industry. You might never buy SRM 2921a: Human Cardiac Troponin Complex, but your life one day may depend on it. It is used as a medical diagnostic tool to ensure that lab tests for heart attacks are accurate and consistent worldwide. Similarly, when a doctor tests your cholesterol, the lab instrument's measurement results are traceable to the SI through a NIST standard such as SRM 911c (Figure 2).

Conclusion: The Language of Science

Measurement science is a conversation, but without NIST, it would be a house of cards. By categorizing materials into SRMs, RMs, and RGTMs, NIST provides the grammar and vocabulary for that conversation.

Whether it is a certified value (a value of “highest confidence”) or a non-certified value (a "best estimate"), NIST is transparent about what it knows and—more importantly—what it doesn't know about its standards.

Next time you see a measurement value—be it the nutritional label of a product or a glucose test result—remember that somewhere in Maryland, South Carolina, or Colorado, there is a NIST standard holding that number accountable.

Reference

1. NIST SP 260-136; https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.260-136-2021.pdf (accessed 2026-10-05).