APPENDIX I 

 DETERMINATION OF NITRITES BY TROMMSDORF'S METHOD 



This method has certain advantages, although it is not strictly 

 quantitative. Some organic compounds interfere with the test. 



REAGENTS REQUIRED 



1. Starch-iodide solution. Triturate 4 g. of starch with 150 cc. of 

 water in a porcelain mortar. Cook the starch water in a steam steri- 

 lizer or on a water bath. Dissolve 20 g. of zinc chloride in 100 cc. of 

 water and add to the boiling starch paste. Remove from the steam 

 bath and allow the solution to stand until it becomes clear. Add 2 g. 

 of zinc iodide and dilute the solution to 1 liter. Filter. Keep in a 

 glass-stoppered bottle in the dark. 



ANALYTICAL PROCESS 



Take 100 cc. of the solution to be analyzed, 3 cc. of the starch-iodide 

 solution, and 1 cc. of dilute (1 : 3) sulphuric acid. After a few minutes 

 a blue color appears. Develop the color at the same time in the 

 standard nitrite solution as used for the Griess-Ilosvay method (see 

 above). 



150 



