[MaxPower]

When calculating the % of an analyte in a product, say Benzoyl Peroxide in a lotion, the raw material was found to be 79% pure, and the standard used to analyze was 75% pure.  Do you take into account both purities when determining the actual % BZP?   Just the purity of the standard?  Just the purity of the raw material?  Don't include purity in the calculation?

[chenbeier]

You have to. You need a standardization.