Water quality - Determination of total-nitrogen - Gas-phase molecular absorption spectrometry
1 Scope
This standard is applicable to the determination of total-nitrogen in surface water as well as water in reservoirs, lakes and rivers. The limit of detection is 0.050mg/L; the lower limit of determination is 0.200mg/L, and the upper limit of determination is 100mg/L.
2 Normative reference
The following normative document contains provisions which, through reference in this standard, constitutes provisions of and has the same effect as this standard.
GB 11894-89 Water quality - Determination of total nitrogen - Alkaline potassium persulfate digestion UV spectrophotometric method
If the above standard is revised, the latest version shall prevail.
3 Term and definition
For the purpose of this standard, the following definition applies.
gas-phase molecular absorption spectrometry
method, under the specified analysis conditions, to convert the components to be measured into gaseous molecules and load such molecules into the measurement system to measure their absorption of characteristic spectra
4 Principle
Ammonia, ammonium salt, nitrite and most organic nitrogen compounds in water samples are oxidized to nitrate in alkaline potassium persulfate solution at 120~124℃, and then the total-nitrogen is determined in the form of nitrate nitrogen by gas-phase molecular absorption spectrometry.
5 Reagents
Unless otherwise specified, the reagents adopted in this standard shall be analytically pure chemical agents complying with the national standard, and the water for tests shall be ammonia-free water or newly-prepared deionized water.
Foreword iii
1 Scope
2 Normative reference
3 Terms and definitions
4 Principle
5 Reagents
6 Instruments, apparatus and working conditions
7 Collection and preservation of water samples
8 Conditioning of water samples
9 Elimination of interference
10 Steps
11 Calculation of result
12 Precision and accuracy
