Which format should I choose for a reference material?

By Keith Williams, Ph.D. - Business Manager, Analytical Standards Europe, Cayman Chemical

The choice of a solid versus solution reference material is driven by technical requirements, your quality system, perceived economics, and personal preferences. There is no single right form of a reference material that will meet everyone’s needs.

Some analytical techniques need a reasonable quantity of a solid product to enable an effective analysis to be carried out. For example, only a few grains of solid material are required for ATR-FTIR analysis. There is no benefit to having the material in a pre-made solution. Our analytical standards or reference material products best fit this need.

If you are after convenience and efficiency, you can choose one of our ready-made solutions. These are particularly advantageous if you are planning to use the product to spike into matrix or inject into a chromatographic system. The concentration provided on the Certificate of Analysis (CofA) of our Certified Reference Materials (CRMs) accurately and precisely reflects the true value of the concentration, along with its associated uncertainty. The solution CRMs also take into account purity and any salt form (if present). The solution can then be simply dispensed into new containers and diluted appropriately. This mechanism of preparing a working standard takes far less time than weighing out a solid material, releasing your valuable time for other activities.

To save even more time in preparing working standards, you could consider using one of our pre-made mixtures. Crack the ampoule, dilute as needed, and inject it into your instruments, potentially saving hours of your time. And if you happen to need something not listed in the catalogue, we may be able to make a custom mixture for you.

What Grades of Reference Materials Should I Purchase?

Here at Cayman we produce three types of reference materials; each one has been developed to serve a specific purpose.

Analytical Standards

Usually, when a reference material is produced, it is initially released as an analytical standard. Typically, it is a solid material but occasionally can be a solution. This is the quickest route for us to get the reference material available for you to use. We synthesise and qualify the product using a range of analytical techniques to verify identify, purity, and other relevant characteristics. As with all our products, analytical standards are accompanied by a CofA. These products can be used for identification, method validation, and quantification. The suitability of our analytical standards for your application will depend on your quality system and the various international guidelines/recommendations that your laboratory follows. Our analytical standards may require some in-house verification prior to use in order to satisfy the needs of your specific quality system.

Reference Materials

Our qualified Reference Materials (RMs) have been manufactured and tested under ISO/IEC 17025 and ISO Guide 34/ISO 17034. After sourcing and synthesis, they are tested using validated analytical methods on appropriately qualified instrumentation to ensure traceability of measurements. All traceable RMs may be distinguished by their CofAs and can be downloaded using the batch number located on the product label. ISO/IEC 17025 recognises the intrinsic quality of such products produced under ISO 17034, and they can be used without any further verification for identification, method validation, and quantification.

Certified Reference Materials

Our solution-based Certified Reference Materials (CRMs) have undergone all the analyses required for reference materials (ISO/IEC 17025 and ISO 17034), and also provide a metrologically traceable certified concentration. The expanded uncertainty for the product incorporates the above-mentioned data sets, long-term stability, and homogeneity. As solutions, they are very convenient and ready to use once they reach room temperature. In some jurisdictions, they are at concentrations that are not subject to regulatory control, considerably simplifying the procurement processes. As with our RM grade, ISO/IEC 17025 recognises the intrinsic quality of our CRMs produced under ISO 17034, and they can be used without any further verification for identification, method validation, and quantification. On occasion we will combine several components together to offer a quantitative CRM mixture, such as our phytocannabinoid mixtures.

Why Do You Offer Three Levels?

It takes a significant effort to produce just one of our analytical standards, and even more time and commitment to produce RMs and CRMs. As said above, the quickest way we can make material available to our customers is by releasing it first as an analytical standard. If we extended the analysis of a product to qualify it as a RM or CRM, it would delay its release, impacting your work through the lack of an appropriate reference material. With new NPS showing up in casework at a steady pace, it is imperative that reference standards are made available quickly.

If there is ongoing demand for a specific analytical standard, we further qualify the material to convert it into an RM, CRM, or both. But with many NPS, there is little need for this as they only appear on the various markets for a relatively short period of time before being replaced by another NPS.