AOAC SPIFAN Nutrients ERP Method Reviews (September 7, 2019)

Pros/Strengths

A chromatographic method is a modern approach to the challenges of fluoride analysis. Despite trials to identify potential interferences, the fluoride peak remains unresolved at the baseline. Using peak heights does mitigate some of the concerns on this point. The method as written requires the use of patented in-line dialysis, which renders method proprietary. However, the authors suggest the it can be removed and not undermine confidence in method performance, although this was not demonstrated for samples. If the inline dialysis is unnecessary for the method to perform as validated, we suggest this step is removed from the protocol. However, to date there is insufficient data to demonstrate the equivalence of the method with and without the dialysis unit. The use of height is an acceptable alternative to area for peaks that are not baseline resolved. Not clear what analytical range is, however standard curve exceeds the limits specified in SMPR. Values of 3.1 or 4.5 ug/100g, meets the SMPR <30 ug/100g. 1 out of 4 samples tested (117%, 120%) did not meet the SMPR for recovery requirement of 90- 110%. 1 out of 12 samples tested (9.4% RSDr) do not meet the SMPR for repeatability of< 8%. chromatogram is illustrative of challenges in obtaining baseline resolution. Is this typical, or best-case or worst-case? How does this compare to the chromatograms for SPIFAN kit samples? Examples to review would be desirable.

Cons/Weaknesses

General Comment(s)

Method Optimization

Analytical Range

LOQ

Accuracy/Recovery

Precision (RSDr)

Reproducibility (RSDR) No reproducibility data available. System Suitability Illustration of the NIST SRM sample