When do Certified Reference Materials Really Expire?
Certified reference materials (CRMs) are vital in a range of industries as they ensure measurements are accurate and reliable. They are commonly used in environmental and pharmaceutical industries, as well as mining and scientific research. One aspect that is often questioned is the expiration date of a CRM - which is a crucial consideration, as it signifies the duration during which the material is expected to maintain its certified properties under recommended storage conditions. This blog post will discuss CRM expiration dates, the factors involved, and when cRMs actually expire.
Explanation of Certified Reference Materials (CRMs)
CRMs are high-quality materials with known properties that serve as benchmarks for calibrating and validating measuring systems. These materials are meticulously characterized by various manufacturers and should achieve traceability to the International System of Units (SI). This is usually accomplished for trace metal standards by tracing certified values to the National Institute of Standards and Technology (NIST) in the United States. CRMs are homogeneous and stable substances, allowing scientists and analysts to compare their measurement results against a certified and traceable reference.1
Importance of CRMs in Various Industries
CRMs are invaluable assets in a wide array of industries. They provide a standardized foundation for quality control, method validation, and instrument calibration. Pharmaceutical companies need cRMs to authenticate drug potency and purity, and environmental laboratories use them to monitor pollutants accurately. In research and development, CRMs are essential for developing and validating new analytical methods. The ISO/IEC 17025 standard and ISO Guides2 further emphasize the necessity of using CRMs for calibration and validation procedures.
CRM Expiration Dates
The expiration date of a certified reference material is crucial to ensure its accuracy and reliability. A standard's expiration date depends on three crucial factors while using a standard, which are:
- Chemical stability
- Physical stability
- Human error
Inorganic Ventures has eliminated the first factor and greatly reduced the second, leaving the "human factor" as the primary concern. Physical stability, also known as transpiration, is a present factor in every standard because all containers transpire, thus being physically unstable. As the standard is used, the transpiration rate is increased. If unopened, a bottled standard (125mL) has a shelf-life of up to twenty-one months; however, the more it is used, the less time it can remain on the shelf.
Mistakes happen, so human error plays a large factor in a standard’s shelf life. Contamination of standards can occur from pipet tips, volumetric glassware, switched bottle caps, loosely screwed caps, dust and vapors, and other potential sources of error.
Most federal and state regulatory agencies recommend expiration dates not exceeding one year, while some are stricter and require expiration dates of half that time. Using a standard for longer than a year increases the risk of contamination or alteration of the chemical components. It is important to note that the expiration date is defined as the amount of time that a standard should remain in use after opening.
Maintaining and Monitoring the Quality of Opened CRMs
To preserve the quality and validity of opened CRMs, laboratories should use strict storage practices. The key actions include sealing containers tightly to minimize exposure to air, moisture, and contaminants and storing CRMs at the required temperature, away from light or heat sources. These are all crucial for preserving their stability.
Inorganic Ventures and Inflexible Expiration Dates
At Inorganic Ventures, we do our utmost to ensure our client's needs are met. However, expiration dates are one area we are not flexible on. Due to transpiration, standards should not be used for more than one year, and our extensive studies and scientific data support this.
To learn more about certified reference materials and their expiration dates, contact inorganic ventures today, and let’s have a chat.
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