AOAC Official Method 935.10 Chloramine T Pesticide Formulations
First Action 1935
Final Action
A. Active Chlorine
Transfer 0.5 g test portion to 300–500mLErlenmeyer, dissolve in 50 mL H2O, and add excess standard As2O3 solution, 935.07A(a) (see 7.2.33), and 5 mL H2SO4 (1 + 4). Add decided excess NaHCO3 and titrate excess As2O3 with standard I2 solution, 935.07A(b) (see 7.2.33), using starch solution, 922.03A(f) (see 7.1.05), or I2 as its own indicator. From this titration, calculate active Cl in sample. 1mL0.025M As2O3 = 0.001773 g active Cl. (To convert active Cl to available Cl, multiply active Cl by 2.)
B. Total Chlorine
Dissolve 0.5 g test portion in 50 mL H2O in Erlenmeyer and add slight excess standard As2O3 solution as calculated from active Cl titration,A. Add 5 mL HNO3 (1 + 4), neutralize with CaCO3, and titrate with standard AgNO3, 941.18 (see A.1.11), using K2CrO4, 941.18B(b) (see A.1.11), as indicator. Determine blank on reagents and correct for any Cl found. From corrected titration, calculate percent total Cl in sample. 1 mL 0.1M AgNO3 = 0.003545 g Cl. If total Cl exceeds active Cl, NaCl is indicated.
