This standard is applicable to determination of nitrite-nitrogen in surface water, underground water, seawater, drinking water, domestic sewage and industrial waste water. As for the method adopting the wavelength of 213.9nm, the minimum detection limit is 0.003mg/L, and the lower and upper limits of determination are 0.012mg/L and 10mg/L respectively; at the wavelength of 279.5nm, the upper limit is 500mg/L.
2 Terms and Definitions
For the purposes of this standard, the following definition applies:
gas-phase molecular absorption spectrometry
the method of measuring the characteristic spectrum absorption of the to-be-tested component by converting it to gas-phase molecular and loading into the measuring system under specified analysis conditions
3 Principle
Add ethanol (catalyst) in citric acid (0.15~0.3mol/L) medium to instantly convert the nitrite into NO2, then load the NO2 into the spectrum absorption tube of the gas-phase molecular absorption spectrometer with air, after which, the absorbance and nitrite-nitrogen concentration measured at the wavelength of 213.9nm and etc. shall comply with the Beer's law.
4 Reagents
Unless otherwise stated, analytically pure chemical reagents complying with national standard are used for the purpose of this standard; the water used in the experiment is newly prepared deionized water.
4.1 Citric acid solution c (C6H8O7?H2O)=0.3mol/L: weigh 64g of citric acid and dissolve it in water, scale the volume to 1,000mL and shake well.
