Reply to “Errors in the description of USP certified reference materials”

If we add to our stated uncertainty a term that includes bottle-to-bottle variability, the maximum effect for our current four CRMs would be to increase the stated uncertainty by 1.6%. [...]our reported uncertainty is not simply the standard deviation of the mean of the 3 laboratory means, but rather it includes a complete assessment of all components of uncertainty, both random and systematic. Furthermore, we do not concern ourselves only with the mechanical application of and compliance with the words of the ISO Guides, but rather we adhere to the spirit and intent of the ISO–REMCO series of ISO Guides, specifically that the provider of the certified reference material must have full understanding and awareness of all the known and suspected sources of bias and uncertainty that may affect the trueness of an assigned value as stated in the Certificate of Analysis.