Method for determining nitrogen dioxide in workplace air by ion-exchange chromatography

Abstract

To evaluate the method for collecting NO2 in workplace air using a solid adsorbent and determining the concentration of NO2 by ion-exchange chromatography. NO2 in workplace air was collected using sampling tubes filled with 13X molecular sieve soaked with triethanolamine, and the samples were desorbed with a certain concentration of triethanolamine solution to obtain NO2(-). NO2(-) was separated with an anion exchange chromatography column and quantified by a conductivity detector. The concentration of NO2 was determined based on the conversion coefficient of NO2 and NO2(-). Different concentrations of NO2 (standard gas) was collected using the sampling tubes at different time points, and the sampling efficiency and desorption efficiency could reach more than 90%. The penetrating capacity of sampling tubes was more than 1.1 mg. The comparative test shows that there was no significant difference between the new method and national standard method (solution absorption) (P > 0.05). The samples could be stored at room temperature for more than 16 days. The calibration curve plotted in the new method was linear in the range of 0.1∼20.0 µg/ml, with a correlation coefficient of 0.9998; the detection limit was 0.01 µg/ml; the minimum detectable concentration was 0.05 mg/m(3) (V0 = 3.0 L). This determination method meets the requirements of Guide for establishing occupational heath standards-Part 4 Determination methods of air chemicals in workplace (GBZ/T 210.4-2008) and shows obvious advantages for determination of NO2 in workplace air.