2016 OMB Summer Meeting

AOAC OMB Meeting Book

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AOAC 2012.22 (FINAL VERSION REVIEW) - JUNE 2016 FOR ERP USE ONLY DO NOT DISTRIBUTE

(b). Ascorbic acid intermediate standard solution (50 µg/mL).- Into a 10 mL amber

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glass volumetric flask, pipet 1 mL stock solution. Make up to volume with

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TCEP solution. This solution can be used for 1 month if stored at 4 °C away

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from light.

(c). Ascorbic acid calibration standard solutions (0.5, 1.0, 2.0, 3.0, 5.0, 7.5, 10.0

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µg/mL).- Into 10 mL amber glass volumetric flasks, pipet 0.1, 0.2, 0.4, 0.6, 1.0,

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1.5 and 2.0 mL of intermediate standard solution. Make up to volume with

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mobile phase to prepare the respective concentrations given above.

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F.

Sample preparation

(a). Reconstitution of powder samples .-

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1. Weigh 25 g of powder into a brown glass 250 mL beaker, add 10 mg TCEP.

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2. Add 200 g warm water (40 °C). Mix well until complete dissolution, make sure

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there are no lumps.

(b). Extraction.-

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1. Weigh 2 g of liquid or reconstituted sample into a 10 mL amber-glass

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volumetric flask.

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2. Add 4 mL TCEP solution and 2 mL TCA 15 %.

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3. Bring up to volume with water.

4. Filter solution through folded grade 597 ½ or greater filter paper (Schleider &

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Schuell, Dassel, Germany).

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5. Transfer 1 mL of filtrate into a 10 mL amber glass volumetric flask containing

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1 mL acetate solution (pH 5.4) and bring up to volume with mobile phase.

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6. Filter about 2 mL through 0.22 µm membrane into a HPLC vial.

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G.

Analysis

(a). Chromatographic conditions.-

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