2016 OMB Summer Meeting
AOAC OMB Meeting Book
392
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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