Pollution of the surface waters is generally caused by leaving the domestic and industrial wastewater to the nature without treatment or by mixing the fertilizers used in agriculture to the water.

The nitrogenous compounds contained in the organic substances mixed with the water are also converted to ammonia and then to nitrite and nitrate. Therefore, the ammonia determination is performed before the pollution of the waters is determined. Nitrite is one of the nitrogen compounds in wastewater. Nitrite is involved in the intermediate oxidation step in the reduction of nitrate as well as in the oxidation of ammonia nitrogen to nitrate. There should be no nitrite in drinking and utility water. If nitrite is present, this indicates that feces are contaminated with water.

Different methods are used for the determination of nitrite in water. One of these is the use of a High Performance Liquid Chromatography (HPLC) instrument. This method is very sensitive and gives reliable results in the separation of non-volatile or easily degradable chemical compounds at temperature.

Nitrite content determination studies are carried out by HPLC method among chemical tests in authorized laboratories. In these analyzes, standards, analysis methods and test criteria published by domestic and foreign organizations are followed and reliable and impartial service is provided in laboratories. A few standards considered in these analyzes are:

• TS 6183 Fruit, vegetables and products - Determination of nitrite and nitrate - Molecular absorption spectrometric method
• TS EN 12014-1 Foodstuffs - Determination of nitrate and / or nitrite content - Part 1: General requirements
• TS EN 12014-2 Foodstuffs - Determination of nitrate and / or nitrite content - Part 2: Determination of nitrate content in vegetable and vegetable products by HPLC / IC method
• TS EN 12014-5 Foodstuffs - Determination of nitrate and / or nitrite content - Part 5: Enzymatic determination of nitrate content in infants and children containing vegetables