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

b) 1 ppm intermediate fluoride standard : Pipet 10.0 mL of the 100 ppm stock fluoride solution into a 1000 mL plastic volumetric flask. Bring to volume with laboratory water. Expiration: one day. c) Working standards : Using plastic 100 mL volumetric flasks, prepare the following standards:

Calibration Curve:

For Working Standard :

Pipet:

Of the following:

2 ppm

2.0 mL

100 ppm purchased standard

1 ppm

1.0 ml

100 ppm purchased standard

High

0.5 ppm

50.0 mL

1 ppm intermediate standard

0.3 ppm

30.0 mL

1 ppm intermediate standard

0.2 ppm

20.0 mL

1 ppm intermediate standard

Both

0.1 ppm

10.0 mL

1 ppm intermediate standard

0.08 ppm

8.0 mL

1 ppm intermediate standard

0.06 ppm

6.0 mL

1 ppm intermediate standard

Low

0.04 ppm

4.0 mL

1 ppm intermediate standard

0.02 ppm

2.0 mL

1 ppm intermediate standard

Add approximately 2 mL of concentrated hydrochloric acid, followed by approximately 50 mL of a 1M sodium citrate solution, to each standard and bring to volume with laboratory water. (For 0.5 ppm standard only: add 2 mL of concentrated hydrochloric acid and bring to volume with 1M sodium citrate solution.) Mix well before analysis. Expiration: one day.

E. PROCEDURE Note: Plastic labware should be used wherever possible. HCl and sodium citrate can be added using bottle top dispensers, such as Brinkmann Dispensettes (or equivalent).

1. Sample preparation a)

Accurately weigh 25 g powder into a plastic vessel equipped with a lid. Add 200 g laboratory water. Record both weights, cap, and stir until completely dissolved. b) Record the tare weight of a plastic sample cup or beaker to 0.0001 g. c) Zero the balance and weigh the 50 ± 0.5 g reconstituted sample into the cup and record the sample weight to 0.0001 g.

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