manufacturer and/or end-user end-user end-user -

Fig. 1 Calibration hierarchy according to one scheme given in EN ISO 17511.

Reference Material

Homogeneity testing

Stability testing

Within-bottle test

Between-bottle test

Short-term test

Long-term test

Characterization (Ring Trial)

Property values/ uncertainties

Minimum sample intake



Property values/ uncertainties

Fig. 2 Typical certification campaign scheme.

related to stated references, usually national or international standards, through an unbroken chain of comparisons (Fig. 1) all having stated uncertainties. The certification of a CRM is an integrated process of a correct preparation, homogeneity, and stability demonstration, and accurate and traceable characterization that leads to a certified value together with its total uncertainty as shown in Fig. 2.

In fact the Guide to Expressing Uncertainty in Measurement (GUM), revision of ISO Guide-35,[2] defines that all components of uncertainty of ''the sample on the desk of the user'' should be properly accounted for. The uncertainty of a CRM is calculated as the sum of the different uncertainties coming from different measurements. The role of CRMS is to facilitate measurements that are traceable, reliable, and comparable, and in which users can have confidence. Commutable CRMs (i.e., CRMs that will perform correctly in a wide variety of assays) are necessary to cover the broad scope of methodological approaches used.

Getting Started With Dumbbells

Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

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