Anions in wastewaters - Determination of Anions in Natural and Treated Waters - page 558

However, the line does not go through the origin and there is a blank value that comes
from the contamination of the distilled water, probably in the atmosphere, etc. This blank
value is calculated to be about 1.3µg L −1 . The existence of this blank causes no trouble in
practice because, in the case of the analysis of nitrite in waste and untreated waters, the
concentrations of nitrite are usually larger than 10µg L −1 .
8.15.4 Ion chromatography
The application of this technique is discussed under multianion analysis in section 12.7.1.
8.15.5 Miscellaneous
8.15.5.1 Nitrite and nitrate
A method has been described for determining both of these anions in amounts down to
5µg L −1 in wastewaters [78,80,81]. In this method nitrate is reduced to nitrite in a
cadmium column. Ammonium chloride is added as a buffer to prevent further reduction
of nitrite. The nitrite reacts with sulphanilamide, forming a diazonium salt, which is
coupled with N -(1-naphthyl)ethylene diamine forming a red-purple coloured complex
which is evaluated spectrophotometrically at 650nm. Nitrite is determined separately on a
further portion of the sample which is not subjected to cadmium reduction.
8.15.5.2 Nitrogen
Haga et al. [82] and Goto et al. [83] respectively, have reported flow injection analysis
and continuous flow methods for the determination of total nitrogen in wastewaters.
8.16 Nitriloacetate
8.16.1 Liquid chromatography
Dai and Helz [64] employed liquid chromatography to determine down to 0.1mg L −1
nitrolacetate in wastewaters.
8.17 Phosphate
Recently, eutrophication in lakes and reservoirs has become an important problem.
Phosphorus is a critical nutrient aiding the eutrophication process. The principal sources
of phosphorus in environmental waters are agricultural effluents, municipal waste waters,
industrial waste waters, etc. The determination of phosphorus is important.