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My main comments (and the reasons for my negative vote) relate to section 6.2.5.1.4. First is the statement that spike recovery is indicative of accuracy. Spike recovery indicates that the method is capable of recovering analyte that may or may not be incorporated in the matrix in the same way as the naturally occurring analyte.

If you're evaluating reproducibility, you probably need to identify reproducibility conditions in the standard, otherwise I suspect people will be assessing their repeatability.

Re: the information in the note, a control sample should always be analyzed, regardless of whether a spike is economically feasible or not. The control material, especially if it's traceable to a natural-matrix certified reference material, will be indicative of your accuracy.

Editorial comment: In 6.2.5.1.1., correlation coefficient should be r squared.

In 6.2.5.1.2, the relative standard deviation of what? the instrument response? between runs shall not exceed 2%?

1. Don't say that spike recovery indicates accuracy.
2. Specify reproducibility conditions.
3. Recomend analysis of a certified reference material (CRM) or in-house control material (traceable to a CRM if possible) for demonstration of accuracy.

Good morning Ms. Sharpless, Thank you for your comments on the Joint Committee ballot of Standard 173 (173i29) regarding the quality assurance for quantitative test methods. Attached are your comments on this issue and the response of the issue proponent, Kerri LeVanseler of NSF International. If you have further additonal comments or wish to discuss these points further, please contact Ms. Levanseler.