Nitrate test to 2.5 micrograms and a concentration of 1 in 25,000 parts. Devarda's alloy (Copper/Aluminium/Zinc) is a reducing agent. When reacted with nitrate in sodium hydroxide solution, ammonia is liberated. The ammonia formed may be detected by its characteristic odor, and by damp red litmus paper's turning blue, signalling that it is an alkali — very few gases other than ammonia evolved from wet chemistry are alkaline. Aluminium is the reducing agent in this reaction that will occur. Diphenylamine may be used as a wet chemical test for the presence of the nitrate ion. In this test, a solution of diphenylamine
Marsh test test in Strong Poison to demonstrate that the culprit was secretly in possession of arsenic. In Alan Bradley's "As Chimney Sweepers Come To Dust", 12-year old sleuth and chemistry genius Flavia de Luce uses the Marsh test to determine that arsenic was the murderer's weapon. In the first episode of the 2017 TV series "Taboo" a mirror test, referencing the Marsh test, is used to verify the protagonist's father was killed via arsenic poisoning. However, as the setting of the series is between 1814-1820, a different/earlier process should have been used. Marsh test The Marsh test is a highly sensitive