AOAC Official Method 935.43 Chloride (Total) in Cheese Volhard Method

First Action 1935
Final Action
Weigh ca 3 g prepared test portion, 955.30 (see 33.7.02), into 200 mL Erlenmeyer. Add 25 mL 0.1M AgNO3, which is more than enough to combine with all the Cl. Add 10 mL halogen-free HNO3 and 50 mL H2O, and boil. As solution boils, add ca 15 mL 5% KMnO4 solution (w/v) in 5 mL portions. (Solution becomes yellowish and clear.) Cool, filter into 200mLvolumetric flask, washing paper thoroughly with H2O at ca 20°C, and dilute to volume. Titrate excess AgNO3 in 100 mL clear solution with 0.1M KSCN, using 2 mL saturated solution of ferric alum as indicator. Determine blank on reagents used in same manner, except to add sugar to destroy excess KMnO4. Calculate Cl found to NaCl.

References: JAOAC 18, 401(1935); 20, 339(1937).