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By Shannon Andrade, Manager of Mar-Com, India The CoA is the marker of high-quality Certified Reference Materials Many manufacturers supply Certified Reference Materials (CRMs) across the globe. The certification of these regulated standards are the utmost importance for an audit. And, since you will be using them to either check the quality and metrological traceability of products, validate analytical measurement methods, or for calibrating lab equipment and instruments, you want something that is reliable. With so many CRMs on the market, is there really a way for you to select the right product based on quality and integrity? The short answer to this is YES! Not all manufacturers that produce standards have a CoA program because it is a costly undertaking. So, first and foremost, you should find a manufacturer that can provide you with reliable CRMs. This is verified by their Certificate of Analysis (CoA). This is a detailed document, issued by the manufacturer’s quality assurance team, that confirms the standard meets its specification. The specification factors included in the CoA are quality, purity, strength, and validation. The CoA also includes any analytical techniques or application where the CRM can be used. If you an accredited lab and are looking to obtain accurate, precise, and reproducible results for your application, the CoA becomes a very important piece of documentation required for your audit process. What do you need to look for in a CoA? The CoA not only qualifies the certified reference material but also validates the manufacturing process and the quality incorporated by the manufacturer. Every CoA should address: Material details Report of certifications from manufacturer Process qualification 1. Material details You need to review metrological traceability, homogeneity, concentration, stability/expiration, uncertainty, and confidence. Metrological traceability: Metrological traceability is essential to ensure that measurement results are consistent and comparable and valid. Here the results can be correlated to a reference through an unbroken chain of documented calibrations, each contributing to the measurement uncertainty. Traceability is necessary to comply with ISO 10725 requirements. Homogeneity: The homogeneity of the CRM needs to be confirmed by procedures consistent with ISO 17025, ISO 17034, ASTM D6362 Appendix X2 whereby random, replicate samples of the final, packaged material are analysed to prove homogeneity. Any sample that is sampled out of any sample size needs to be placed within the uncertainty range. Concentration: The concentration of the CRM should originate from the gravimetric material weighing (using weight traceable to SI units) and material purity factor (assay of the neat material). Stability or Expiration: The materials need to be put through accelerated studies and later backed by stability test at regular intervals. The data obtained from this process should be enough define the expiration and ensure the best stability. Uncertainty and confidence limit: CoA’s need to showcase the uncertainty measurement in accordance with the Guide to the Expression of Uncertainty in Measurement. The certificate should list the expanded concentration uncertainty at about 95% level of confidence using coverage factor of 2. The document usually covers parameters including uncertainty values of purity, material density, balance and weighing techniques in specific temperature range. 2. Report of certifications from the manufacturer Certified Reference Materials must be prepared and certified under an ISO 9001 (by DQS), ISO 17025 (accredited by A2LA) and ISO 17034 (accredited by A2LA) quality system consistent with the following guides: ISO 9001: Quality management systems – Requirement ISO 17034 (Accredited by A2LA): General requirements for the competence of reference material and producers ISO/IEC 17025: General requirements for the competence of testing and calibration laboratories ISO Guide 30: Reference materials – Selected terms and condition ISO Guide 31: Reference materials – Contents of certificates and labels ISO Guide 35: Reference materials – General and principals for certification Guide to the Expression of Uncertainty in Measurement, 2008 EURACHEM/CITAC Guide: Qualifying uncertainty in Analytical Measurement NIST Technical Note 1297 3. Process qualification Material source: Sources of all materials used in the preparation and testing by manufacturer need to be tracked and documented. All analytes and matrix need to be obtained and verified as per ISO 9001, ISO 17025, ISO 17034 guidelines. Instructions: Primary use of the CRM should be included if it is to be used in neat form or serially dilution is needed with the matrix of purity at or greater than the purity of the original matrix solution. The details on diluent for dilution, whether it can be used as a spike, extraction procedure from body, needs to be clearly declared on the CoA. Method of preparation: The CoA should state that the manufacturer complies with clean laboratory practices throughout the preparation. Qualification documentations are must in CoAs for all materials, equipment, and personnel. You must make sure that the following have been used in all preparations: highest purity acids applicable, 18 MΩ, double deionized water, acid leached triple rinsed bottles (where applicable), and Class A/calibrated volumetrics. To conclude, CoA’s that provide comprehensive details give you assurance that the manufacturers are providing you superior quality CRMs. The coverage of all these parameters should ensures a smooth, hassle-free analysis and audit. To know more details on CRM’s and our offerings, connect with us on response@antylia.in or +91 70458 36546. If outside India, contact your local representative. Related Articles How to Select the Right Reference or Certified Reference Materials

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