The current requirements for check standard recovery defined in statements 11.2 and 15.2 are stated to be +/- 5% of the expected concentration for all elements. This requirement was listed in the original round robin instruction (RR D02-1282, 1991) from which the current precision is defined. Results obtained from this round robin indicate a much wider expected variability for several of the elements including Cu, Pb, P, K, Mg, Mo. This was further echoed when reviewing results obtained for only the 3 NIST reference samples that were part of the study. In many cases over half of the obtained results for individual elements found in the NIST materials would not meet the +/- 5% requirement. Recommend modifying the requirements for check standard recovery to be in alignment with defined precision stemming from the round robin or 95% - 105% recovery whichever is greater.
Keywordsadditive-elements; aluminum; barium; boron; calcium; chromium; copper; emission-spectrometry; ICP; inductively coupled plasma atomic emission spectrometry; iron; lead; lubricating oils; magnesium; manganese; molybdenum; nickel; phosphorous, potassium; silicon; silver; sodium; sulfur; tin; titanium; vanadium; wear metals; zinc;;
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