AOAC SPIFAN Nutrients ERP (December 7, 2022)

Fluor-06 (SLV) 10-2022 FOR ERP USE ONLY DO NOT DISTRIBUTE

4.2 Apparatus HS sampling was performed with a Turbomatrix 40 (Perkin Elmer, Massachusetts, U.S.). Two different 6890N GC systems with FID detector from Agilent (California, U.S.) were used to analyze all samples. The used instrument settings for the HS autosampler and GC are given in Table 1.

Table 1. Parameters used for the HS autosampler (left) and GC (right). HS GC Parameters Settings Parameters Settings Pressure 25 psi Oven program

70 °C (2 min) – 10 °C/min – 220 °C (15 min)

Oven temperature

70 °C 100 °C

Split ratio

1:5

Transfer line temperature

FID

Temperature: 275 °C Hydrogen flow: 40 mL/min Air flow: 400 mL/min Make-up flow (N 2 ): 40 mL/min

Needle temperature

80 °C

Column Pressure

PoraPLOT Q-HT 25m x 0.32mm (10 µm film thickness)

Shaker (on/off)

On

20 psi

Incubation time Pressurization time

25 min 2 min 0.3 min 0.5 min 37 min

Injection time Withdraw time

Cycle time

Vial vent (on/off)

Off

Data analysis was performed with Empower 3 (Waters Corporation, Massachusetts, U.S.). For calculating the signal-to-noise ratio, the Empower 3 built-in tool was used for non-pharmaceutical purposes.

4.3 Reagents, materials and safety precautions The fluoride stock solution (cat. no. ICF1) of 1000 mg/L was obtained from Inorganic Ventures (Virginia, U.S.), whereas fluoride control standard (cat. no. 4400-IC10M) of 1000 mg/L was purchased from CPI International California, U.S.). The derivatizing agent TMCS (cat. no. 92360) was obtained from Sigma Aldrich (ST. Louis, U.S.). Glass 20-mL amber headspace vials (cat. no. 5190-2239) were obtained from Agilent (California, U.S.). It has to be noted that vials from other manufacturers resulted in less reliable results, maybe due to adsorption on the surface of the glass or dissoluti on traces of F⁻ from the glass surface. Aluminium crimp caps with PTFE/butyl septa were obtained from Perkin Elmer (Massachusetts, U.S.). Sulfuric acid 3.0 M was prepared by diluting 85 mL of sulfuric acid (95-98% ACS reagent) in 500 mL water. Safety precautions The method employs irritant and flammable chemicals such as TMCS and TMFS. Sulfuric acid is a toxic and corrosive chemical. Wear personal protective equipment, for example gloves, laboratory clothing and safety glasses. Refer to material safety data sheets and take appropriate safety precautions. Waste disposal should be in accordance to local requirements. 4.4 Preparation of standard and calibration solutions A standard solution of 10 mg F - /L was prepared by adding 1.0 mL (1000 mg F - /L) to a 100-mL volumetric flask and filled to the mark with water. Similarly, a 1 mg/L solution was prepared by using 100 µL stock solution.