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
Alkalinity alkalinity of a typical seawater sample. Contributions are in μmolkg−soln and are obtained from "A Handbook of Methods for the analysis of carbon dioxide parameters in seawater "","(Salinity = 35 g/kg, pH = 8.1, Temperature = 25 °C). Phosphates and silicate, being nutrients, are typically negligible. At pH = 8.1 [HSO] and [HF] are also negligible. So, Addition (or removal) of CO to a solution does not change its alkalinity, since the net reaction produces the same number of equivalents of positively contributing species (H) as negative contributing species (HCO and/or CO). Adding CO to the solution lowers its pH,