Anions in non saline waters - Determination of Anions in Natural and Treated Waters - page 222

2.62.12 Enzymic assay
Enzymic methods have been used for the determination of nitrate [436,474]. These
methods are based on the enzymic reduction of nitrate to nitrite or ammonia. In one
method [436] the nitrite is then estimated by the sulphanilamide- N -(1-naphthyl)
ethylenediamine dihydrochloride coupling procedure.
Kiang et al. [474] reduce nitrate with nitrate reductase and nitrite with nitrite reductase
using an air gap electrode to monitor the ammonia produced by the reduction of nitrate.
Between 5×10 −5 and 1×10 −2 mol L −1 nitrate can be determined by this procedure.
2.62.13 Ion chromatography
The application of this technique is discussed under multianion analysis in sections
12.2.1, 12.2.4, 12.2.5 and 12.2.6.
Fig. 2.30 Calibration curve for nitrate ion for the range 5-40µg mL −1 as
sodium nitrate
Source: Reproduced with permission from Alfred Huethin Verlag
GmbH [475]
2.62.14 High performance liquid chromatography
High performance liquid chromatography on a small bore column packed with
microparticulate silica based ion exchange material has been used [475] to determine