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

FOR EXPERT REVIEW PANEL USE ONLY NOT FOR DISTRIBUTION

Expert Review Panel for Infant Formula and Adult Nutrition Evaluation of Method Fluor-04

Title: Fluoride Determination in Milk, Soy, and Water-Based Products Using Ion Selective Electrode and Direct Measurement Technique Author: Renée Erney and (Charles) Pete Black, Abbott Nutrition Reviewer Name: Reviewer 1 Summary of Method: A six-point standard curve is prepared, over a concentration range of 0.02 – 2.0ppm, in a matrix of 1% v/v conc. HCl and 0.5M sodium citrate. The response of each standard (in mV) is recorded after allowing the electrodes to stabilize under specific time and mixing conditions. A calibration curve is prepared using log(mV) v concentration (ppm). Powder samples are prepared using the standard 25g + 200g water dilution; RTF samples are used as is. 50g of such solution is treated to match the matrix described for the standards, the HCl being added to solubilize inorganic F, and the citrate buffer to standardize pH. The response of the unknown is measured under the same conditions as the standards and is back-calculated using the calibration and dilutions to express ppm F in the original sample. Method Scope/Applicability: General comments about the method: Method Clarity: No issues with the way in which the method is written. Method Safety Concerns: No issues. Pros/Strengths: • No special equipment required beyond ISEs. • Different ISE combinations were used with consistent results. Cons/Weaknesses • See below. Supporting Data • General Comment: Information was taken from the SLV document dated 2 Aug 2019. As described below, the LoQ of the method was determined to be well below that of the SMPR; nonetheless 4 of the matrices A total of 14 fortified (i.e. non-placebo) SPIFAN matrices were analyzed.

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