horiba TPNA-500, Инструкция по эксплуатации

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Material
224
Material
Measurement principle

Total nitrogen: Ultraviolet oxidative dissolution method
The drained total nitrogen compounds contain organic nitrogen compounds, nitrate, nitrite
salt, and ammonium salt, when largely divided.

Principle
Add potassium persulfate and sodium hydroxide to a sample and apply ultraviolet irradiation. The
nitrogen compounds in the sample are dissolved to nitrite ions (NO
3
-
). Add hydrochloric acid to the
dissolved sample to remove carbonate compounds, which interfere with measurements.
Measure the ultraviolet absorption at the absorption wavelength of 220 nm for nitrite ion and
obtain the total nitrogen.

Total nitrogen measurement flow

Features and application
The oxidation method by ultraviolet irradiation is highly efficient in oxidizing NH
4
ion, which is a
hardly oxidizable substance, even without increasing the temperature as with the autoclave
method. In addition, another advantage is that the oxygen radical generated during dissolution
of potassium persulfate creates hydroxyl radical, which has strong oxidizing power.