AOAC SPIFAN Nutrients ERP (December 7, 2022)

For ERP/Working Group Use Only DO NOT DISTRIBUTE Fluor-04 (SLV) Resubmission FOR ERP USE ONLY DO NOT DISTRIBUTE

Table VI: Sample averages by electrode

Electrode #1 Avg. (µg/100 g)

Electrode #2 Avg (µg/100 g)

Ratio 1:2

IF. A 1869 8260 8261

16.10 14.82

16.55 14.72

1.03 0.99 0.97 0.98 0.98

3.53

3.44

10.39

10.13

IF.C

4.80

4.69

Specificity Most cations and anions do not interfere with the fluoride ion-selective electrode. Below a pH of 5.0, hydrogen can complex with fluoride to create undissociated HF and HF 2 - .Hydroxide can interfere with fluoride if its concentration is > 0.1 the level of fluoride. The addition of the citrate buffer in this method buffers the pH to approximately 5.3, avoiding the hydroxide interference and the formation of HF complexes. The pH of the samples and standards were in the range of 5.26 – 5.39 (data not shown). See Tables VII – XII for specifics for each sample and blank.

Table VII: Infant Formula A

Fluoride Rep 1 (µg/100g)

Fluoride Rep 2 (µg/100g)

AVG Fluoride (µg/100g)

Electrode #

Day

SD

RSD r (%)

1 2 1 2 1 2 1 2 1 2 1 2

16.17 16.53 16.26 16.60 16.05 16.47 16.22 16.59 16.18 16.72 16.07 16.60

16.10 16.46 16.06 16.49 15.84 16.25 15.95 16.49 16.08 16.71 16.23 16.67

16.14 16.50 16.16 16.55 15.94 16.36 16.09 16.54 16.13 16.71 16.15 16.64

0.05 0.05 0.14 0.08 0.15 0.15 0.19 0.07 0.07 0.01 0.12 0.05 0.11

0.29 0.30 0.87 0.48 0.93 0.93 1.20 0.41 0.45 0.05 0.72 0.33

1

2

3

4

5

6

Pooled SD

RSD r

0.7

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