GB/T 34500.5-2017 in English

1. Nessler's reagent spectrophotometry

Principle: Under alkaline conditions, the sample, the alkaline solution of mercuric iodide and potassium iodide reacts with ammonia to form a light yellow-brown complex, and the absorbance is measured at a wavelength of $420~\mathrm{nm}$.

Steps: 1. Pipette the sample and make it to volume; 2. Add potassium sodium tartrate solution and Nessler's reagent; 3. Determine the absorbance and draw a working curve.

2. Salicylic acid spectrophotometry

Principle:After distillation, ammonia is separated from coexisting ions and reacts with salicylate and hypochlorous acid in an alkaline medium to form a blue compound, which is measured at a wavelength of $700~\mathrm{nm}$.

Steps: 1. Distill and separate ammonia; 2. Add a color developer and sodium hypochlorite solution; 3. Measure the absorbance and draw a working curve.

3. Distillation-neutralization titration

Principle:In an alkaline medium, ammonia is absorbed by a boric acid solution and then titrated with a standard sulfuric acid solution.

Steps: 1. Distill and separate ammonia and collect it in a boric acid solution; 2. Add an indicator and titrate to the endpoint with a standard sulfuric acid solution.