PHOTOELECTRIC MICRODETERMINATION OF CHLORIDE IN BIOLOGICAL FLUIDS, AND OF IODATE AND IODINE IN PROTEIN-FREE SOLUTIONS

Abstract

The writer has previously described in detail (Sendroy, 1937, a, b, c) a system of chloride analysis based on the liberation of soluble iodate from silver iodate, with subsequent estimation of iodine.The present paper outlines an adaptation of the procedure to the measurements with the Evelyn (1936) photoelectric colorimeter.Reagents-The preparation of most of the reagents has already been described (Sendroy (1937, a) pp.337, 338; (1937, b) p. 406).Reagents for Regular Technique (Procedure I)-Approximately 0.86 M, 0.34 M, and 0.085 Y phosphoric acid solutions.These solutions must be tested, and found halide-free.Caprylic alcohol.Silver iodate, powder, C.P. This material must be tested for purity as previously described (Sendroy, 1939).Tungstic acid reagent (Folin and Wu, 2929), prepared as modified by Van Slyke and Hawkins (1928); must be tested for and found free of halides.5 per cent potassium iodide solution.When tested with starch, this solution should indicate no trace of free iodine.In addition to the above, when the special technique (Procedure II) is used, the following reagents are required.2 per cent (Lintner's soluble) starch solution.This reagent must be prepared anew every 2 weeks.0.i M (= 0.6 N) standard potassium iodate solution.Exactly 21.402 gm. of analytical reagent grade KIOa are dissolved in water to make 1 liter of solution.This standard stock solution keeps indefinitely.