Anions in wastewaters - Determination of Anions in Natural and Treated Waters - page 553

8.13 Iodide
8.13.1 Titration method
Erdey and Kozmutza [68] used xenon difluoride as a reagent for the determination of mg
L −1 quantities of iodide and iodine in nuclear reactor cooling waters. The test solution is
made IN in sulphuric acid and excess solid xenon difluoride added to convert iodide to
periodate which is then determined by standard iodometric procedures.
8.14 Nitrate
8.14.1 Spectrophotometric method
Nitrates have been determined [69] in waste water in the presence of nitrites by a
spectrophotometric method using salicylane as the chromogenic agent. Nitrites interfere
in the determination of nitrates using the salicylane method but can be removed by amino
sulphonic acid. The spectrophotometric method with salicylane may be used for
determining nitrate levels of up to 20mg L −1 nitrate-nitrogen in the presence of equimolar
concentrations of nitrite-nitrogen.
The application of this technique is also discussed under multianion analysis in section
14.2.3.1.
8.14.2 Electrophoresis
The application of this technique is discussed under multianion analysis in section 7.28.1.
8.14.3 Ion selective electrodes
Hua [70] used an ion selective electrode to determine nitrate in wastewater; EDTA was
added to prevent electrode contamination and improve reproducibility. The detection
limit was 0.1emg L −1 and the linear range was 1-1000mg L −1 as nitrate nitrogen; the
relative standard deviation was 0.10-2.6% and recoveries were 102-108%.
8.14.4 Roman spectroscopy
Furaya et al. [71] have used resonance Raman spectroscopy to determine nitrite in waste
waters. They also proposed a method for simultaneous determination of nitrite and
nitrate. These workers [72] have also discussed a laser Raman spectroscopic method for
the determination of down to 1mg L −1 nitrate in waste waters.
Raman Spectra were recorded on a JASCO Model J-800 Laser Raman
Spectrophotometer. A Spectra-Physics Model 164 argon ion laser was used as an exciting
source. As a detector, an HTC-R-464 photomultiplier was used. The spectral data were
processed by a data processor containing a microcomputer, supplied with the