@ Miftahul, Nessler reagent (HgI4K2) is prepared by dissolving 50 g of KI (potassium iodite) in 50 mL cold water. Add a saturated solution of mercuric chloride (about 22g in 350mL of water) until an excess is indicated by the formation of precipitation.

Tromsdoffs reagent is nothing but zinc-iodite-starch solution. It may be prepared by heating 4 parts of starch, 20 parts of zinc chloride and 100 parts of water for an hour or more at or near the boiling point, replacing from time to time the water lost by evaporation. The resulting solution is diluted to 1 litre.

@ Miftahul, Please see original description for Nessler´s reagent:

A. P. Vanselow Ind. Eng. Chem. Anal. Ed., 1940, 12 (9), pp 516–517DOI: 10.1021/ac50149a007, Preparation of Nessler's Reagent

for Trommsdorf´s reagent

https://books.google.cz/books?id=QYI4xk9kOIMC&pg=PA568&lpg=PA568&dq=Preparation+of+Trommsdorff+reagent&source=bl&ots=GsGtFnkmDa&sig=ACfU3U0xXzRczBuKphFo0f1WUP4PLXOhRA&hl=cs&sa=X&ved=2ahUKEwib0dOAxMfgAhUHmrQKHSgGCz04ChDoATAJegQIAxAB#v=onepage&q=Preparation%20of%20Trommsdorff%20reagent&f=false

Best regards

Vit

J. C. Tarafdar Vit Mateju Thank you very much.

Please use an alternative method to measure ammonia that does not involve Hg. See the methods of the APHA.

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