AOAC Official Method 935.14 Iodine in Mineral Mixed Feeds Elmslie–Caldwell Method
First Action 1935
Final Action
(Not applicable to iodized mineral feeds containing little or no organic matter.)
Caution: See Appendix B, safety notes on bromine.
A. Reagent
Sodium thiosulfate solution.—0.0025M. Prepare 0.05M solution as in 942.27 (see A.1.13). Dilute and standardize on day of use as follows:
Pipet into beaker 25mLof a solution containing 0.1308 g KI/L and add 200 mL water, 5 mL 20% NaHSO3 solution, and 2–3 g NaOH. Neutralize the mixture with H3PO4, add 1 mL excess, and titrate as in B. 1 mL 0.0025M Na2S2O3 solution = 0.1058 g/L.
