The process of nitrification in natural waters has as a mandatory stage the appearance of
nitrite content in surface waters in Moldova that ranges of 0-10 and more mg/dm3 in small rivers
water downstream of sewage discharges, insufficiently treated in biological purification plants
type. In water from the Bac river downstream of the Chisinau municipality sometimes more than
10 mg/dm3 NO2
-; in the Lunga river (village Lunga) - of 3.6 till 12.6 mg/dm3 NO2
- and nitrates
content - from 0.5 to about 20 mg/dm3 were registered [1].
Thus, the assessment of nitrate and nitrite content (NO3
- in the presence of NO2
-) in the
aquatic medium, performed by analytical services for monitoring of natural, drinking, waste
waters, food and soil is of major importance.
There are various methods for nitrate and nitrite determining, including electrochemical,
spectrophotometric, fluorometric, luminescent, electrophoretic and chromatographic methods.
For the nitrate determination there are widely used methods based on the principle of
nitrate to nitrite preventive reduction, the latter one being determined by the Griess reaction. In
all the cases nitrites influence the process.
Pre-treatment of water with sulfaminic acid (ASA) allows the removal of the nitrite and
nitrosating agents before the nitrates determination after their reduction to nitrite [2, 3].
Sulfaminic acid reacts with nitrite and forms free nitrogen, water and sulphuric acid:
NH2SO3H + HNO2 N2
+ H2SO4 + Н2О
It has been established that the nitrite removal from water with sulfaminic acid takes
place at pH 1-2.5 during about 25-30 minutes and 3 mg of sulfaminic acid remove nitrite from
10 mL solution containing 20 mg/dm3 NO2
-.
The advantage of the sulfaminic acid use consists of economy, efficiency and ease of use.
In the passport of Security according Document 1907/2006/EC, art. 31(24/09/2013, version 3) is
mentioned that sulfaminic acid has insignificant effect in the waste water canalization.
References:
[1] Mustea, M. et al. Starea resurselor de apă. În: Starea mediului în Republica Moldova în 2007-
2010 (Raport National). – Ch.: S. n., Tipografia “Nova-Imprim” SRL. – 2011. p. 75-80.
[2] Новиков, Ю. В.; Ласточкина, К. О.; Болдина, З. Н. Методы исследования качества воды
водоемов. Москва, 1990, 321 с.
[3] Mir, Shabir Ahmed. A rapid technique for determination of nitrate and nitric acid by acid
reduction and diazotization at elevated temperature. In: Anal. Chim. Acta, 2008, 620 (1-2),
183-189.