AOAC SPIFAN Nutrients ERP Review (March 14, 2019)

Fluor-03 (Feb. 2019) FOR ERP USE ONLY DO NOT DISTRIBUTE

AOAC Standard Method 2014.016 Method Name: Determination of Fluoride in Infant and Adult/Pediatric Nutritional Formula by Ion Chromatography with sequentially suppressed conductivity detection Method Applicability: The Ion Chromatography method with sequential suppression, dose-in gradient and subsequent conductivity detection allows for the quantification of dissolved fluoride in infant, pediatric, and adult nutritional formulas as per AOAC SMPR 2016.016 Method authors: Theresa Steurer, Dr. Elke Suess, Dr. Christian Emmenegger, Dr. Michael Klein, Dr. Hari Narayanan This method determines the quantity of fluoride by ion chromatography with sequential suppression, dose-in gradient and subsequent conductivity detection. The concentration of fluoride is calculated by comparison with standards of known concentration. The method is validated for the quantitation of soluble fluoride in infant, pediatric, and adult nutritionals as a Single-Laboratory Validation (SLV) study. Thereby the complete analyses, i.e. preparation of samples, standards and reagents and chromatographic analyses are done by two different analysts and the analyses are performed on one instrument using two analytical columns. Repeatability is determined from replicate analyses of different sample matrices measured in a short time period. Reproducibility is determined on samples analyzed in duplicate on multiple days. Accuracy was determined from spike recovery experiments of the reference material and the samples. Limit of detection (LOD = 1.3 µg/100g) and the limit of quantification (LOQ = 1.6 µg/100g) were determined statistically from injections of UPW blanks spiked with low levels of fluoride. Reproducibility, repeatability, and recovery as well as the levels for the LOQ meet the criteria of the SMPR® 2014.016 requirements. See Tables 7 to 12 for method performance information supporting the acceptance of the method. Principle: Fluoride is extracted from the sample matrices by mixing with ultrapure water. The samples are well mixed and analyzed directly using inline dialysis with a 0.2 μm cellulose acetate membrane. The concentration of fluoride is determined from the polynomial regression (intercept = 0) of the fluoride in the standards compared to the fluoride response as peak height detected in the samples. To enable the detection of low quantities the signal to noise ratio is effectively reduced using sequential suppression. The application of a dose-in gradient enables the column clean-up from negatively charged organics. Carry-over is minimized by an automatic thorough cleaning step of the equipment including the dialysis cell.

Caution: Refer to Material Safety Data Sheets (MSDS) of chemicals prior to use and follow safe handling procedures and the suggested personal protective equipment.

1 | P a g e