Analytical Standards

CRM Production on a Metrological Level

History with EMPA
Production and Certification of TraceCERT standards

 

History with EMPA
For certified calibration solutions, we maintained a long-standing partnership with Swiss Federal Institute for Materials Science and Technology (EMPA). However, EMPA terminated all their activities in chemical metrology in 2004 and no longer acted as the national metrological institute. Recognizing that EMPA’s exit created the need for a first class CRM supplier in the market, Sigma-Aldrich made a strategic decision to acquire the metrological competency from EMPA and transfer it to our Buchs, site in Switzerland.

In late 2005, we began to replicate the EMPA metrological environment in order to provide a seamless transition. We first purchased from EMPA the unique equipment custom-designed to produce inter-comparison samples of the highest metrological level (CCQM Key Comparisons). Next, we built a special, dedicated laboratory at the Buchs site where the high-precision weighing capabilities, homogenization and clean room bottling equipment were installed.

Production and certification of TraceCERT® standards
To actually produce high quality CRMs, the entire development process, beginning from the selection of an appropriate starting material to the choice of a purpose-specific packaging, must be highly sophisticated.

Production and certification of TraceCERT® standards

Figure 1: Schematic representation of the production design and certification of Sigma-Aldrich TraceCERT® products.
This approach was established for the preparation of intercomparison samples at the highest metrological stage.

 


Not only is the bottled solution compared to a reference material (NIST, BAM, etc.), the starting material is checked against a second, independent reference. A key step is that the weighing operation leads to direct traceability to the SI-unit kilogram. Gravimetric preparation using pure materials is a practical and, in many cases, the most accurate calculation of concentration units, through conversion of mass and mole fraction to mass fraction.

As a final step, we provide detailed, lot-specific information in the Certificate of Analysis supplied with every TraceCERT® product. Our well-defined approach to CRM production leads to multiple-traceability and, as a further benefit, ensures that significant biases and systematic deviations are excluded to the fullest extent possible.

 

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