1. 47.3.47
AOAC Official Method 892.02
Sulfurous Acid (Free)
in Meats
Titrimetric Method
Final Action
Treat 50 mL sample in 200 mL flask with ca 5 mL H2SO4 (1 + 3),
add ca 0.5 g Na2CO3 to expel air, and titrate H2SO3 with 0.02N I2,
using few mL starch indicator, (mix ca 2 g finely powdered potato
starch with cold H2O to thin paste; add ca 200 mL boiling H2O,
stirring constantly, and immediately discontinue heating; add ca 1
mL Hg, shake, and let solution stand over the Hg). Add I2 solution
as rapidly as possible and continue addition until solution stays blue
several min. 1 mL 0.02N I2 = 0.64 mg SO2.
References: J. Prakt. Chem. 46, 428(1892). Repts on Public Health
and Med. Subject No. 43 (London, Ministry of
Health, p. 12).
CAS-7446-09-5 (sulfur dioxide)
CAS-7782-99-2 (sulfurous acid)
Copyright 1998 AOAC INTERNATIONAL
