CHLORIDE 225 



Sendroy Method for Chloride 



SPECIAL REAGENTS 



Approxwiately 0.085 M Phosphoric Acid. Test to make sure soln. 

 is halide free. 



Caprylic Alcohol. 



Silver lodate Powder, C. P. Test for presence of potassium iodate 

 according to Sendroy (1939a): (1) Solubility measurement — 

 lodate analysis of a saturated soln. of silver iodate should give a 

 value not exceeding 0.21 mM/1. (2) Analysis of a standard 

 chloride soln. — Analyze a known 100 mM chloride soln. diluted 

 twenty times with 0.085 M phosphoric acid. 



5% Potassium Iodide. Test with starch to be sure no trace of free 

 iodine is present. 



PROCEDURE 



1. Dilute the sample chloride soln. in 0.085 M phosphoric acid, 

 or in tungstic acid soln. if protein is present, at between pH 2.0 and 

 3.0 to a final concentration of between 3 and 12 mM/\. 



2. Add solid silver iodate (10 mg./ml.) to duplicate portions in 

 15 ml. centrifuge tubes, and shake vigorously for 2 min.; then either 

 filter through halide-free paper or centrifuge for 1 min. at over 

 3000 R.P.M. The soluble iodate is now equivalent to the chloride in 

 the sample. 



3. Sendroy (1942a) recommended that the system given in 

 Table I, B, of the paper by Sendroy and Alving (1942) be followed 

 for the measurement of chloride in serum and blood. In this schedule 

 0.5-13 ml. iodate soln. containing 0.8 mM is added to 2.4 ml. 0.085 M 

 phosphoric acid and 1.2 ml. 5% potassium iodide; the vol. is made 

 up to 100 ml. with water. 



4. Promptly after the color has been developed, transfer the 

 tubes to a 25° water bath for 3-5 min. Wipe the tubes clean and 

 dry; set the Evelyn instrument with filter No. 420 to read 100 with a 

 blank soln., and then read the unknowns. The blank soln. may be 

 prepared by omitting the iodate from the reaction mixture. 



5. A calibration curve has been given by Sendroy and Alving 

 (1942), but it is usually well to obtain one's own curve with the 

 particular reagents and instrument used. The calibration may be 

 made with standard potassium iodate solns. 



