
Contents
47.3.40
AOAC Official Method 963.20
Sulfurous Acid (Total) in Dried Fruit: Colorimetric Method
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Published:January 2023
Cite
Sulfurous Acid (Total) in Dried Fruit: Colorimetric Method', in Dr. George W Latimer, Jr. (ed.), Official Methods of Analysis of AOAC INTERNATIONAL, 22nd Edition (
Extract
First Action 1963
Final Action 1965
Reagents
...
Preparation of Standard Curve
Add 5 mL mercurate reagent to series of 100 mL volumetric flasks; then add 0, 1.0, 2.0, 3.0, etc., mL of SO2 standard solution. Dilute to volume and mix. Transfer 5.0 mL aliquots to 200 mm test tubes containing 5 mL rosaniline reagent. Add 10 mL 0.015% HCHO solution, mix, and hold 30 min at 22°C. Read A at 550 nm against 0 standard and plot standard curve.
Determination
Weigh 10 ± 0.02 g ground dried fruit and transfer to blender with 290 mL H2O. Cover and blend 2 min. Withdraw 10 g aliquot from bottom of blender with 10 mL calibrated free-running pipet, and transfer to 100 mL volumetric flask containing 4 mL 0.5 M NaOH. (Use 2 mL for apples and 1 mL for golden raisins.) Swirl and mix ca 13–30 s. Add 4 mL 0.25 M H2SO4 (2 mL for apples and 1 mL for golden raisins) and 20 mL mercurate reagent, and dilute to volume. For blank, omit 10 mL fruit extract.
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