Certificates of Analysis no longer show the tested value, they show the nominal ordered value. 

The new "Relative Tolerance" combines both Blend Tolerance and Analytical Accuracy. This change aims to harmonize our offerings and provide a tighter overall tolerance for our gas products. Moving forward, our CoAs will display the nominal value requested plus or minus the associated relative tolerance, which varies depending on the gas concentration.

Instead of having a separate blend and analytical tolerance, we have combined the two into one total "relative" tolerance. Depending on the target concentration, in most cases the new spec is tighter than the historical Certified Standard spec. (Ex. 50 ppm mixtures with a certified standard spec have a +/-10% blend and <= 2% analytical tolerance; our new spec has a total relative tolerance of +/-5%)