Metrology

Example of CRM

The two examples presented below (CMR 188 and CMR 187 show two powdered milks certified for organochlorine pesticides..

The uncertainty of the certified values indicated here is half of the 95% confidence interval.

For each of the two CRM (n°187 and n°188), list of organochlorine pesticides, and for each of them the certified values (in micro grams per kilo) and the uncertainty.

For each pesticide listed in the table, there is 95% certainty that its concentration in the CRM is included in the interval [certified value – uncertainty; certified value + uncertainty].

CRM no. 188 is more contaminated with pesticides than CRM no. 187. In practice, one of the two should be chosen that best matches the range of organochlorine pesticide concentrations in the samples to be analyzed.