Study On Filter Sampling And Fluorine Ion–selective Electrode Analysis For The Determination Of HF In Ambient Air

The best conditions of filter sampling and fluorine ion-selective electrode analysis to determine the mass concentration of HF in ambient air are obtained by the experiments of sampling and measuring HF in ambient air.The characteristic factors of fluorine ion-selective electrode analysis to determine fluorine ion are verified first. It shows that: the detection limit is 0.01 mg/L, the RQL is 0.04 mg/L, the standard deviation is 0.30～0.40, the RSD is 0.16%～0.30%, and the rate of recovery is between 97%～103%, this are accord with the requirements of national standard.The comparative research of characteristic factors between fluorine ion-selective electrode analysis and fluor reagent spectrophotometry are studied, It shows that: there is no remarkable distinction between these two methods, but the minimum quantitative detection concentration of fluorine ion-selective electrode analysis is low and the determination range is large, its precision and accuracy are also fine when compared with fluor reagent spectrophotometry, The standard samples are tested by fluorine ion-selective electrode analysis, and the statistical result shows that: there is no systematic error. So fluorine ion-selective electrode analysis can be selected as the base to determine the hydrogen fluoride in ambient air.The best sample conditiones are determined by comparative experiments using various membranes and various impregnants, that are: the organic membrane of 2μm aperture diameter is used as the first membrane to prevent the particle of above PM2.5, and the ultrafine glass fiber membrane dipped by K2HPO4 is used as the second membrane to absorb HF. The sampling flow is 70~120L/min, and the sampling time is more than 30 minutes.Aimed at the mathematical formula of the concentration of fluoride in ambient air, the main sources of the uncertainty are studied, and every sub-variable is calculated also, through the combination, the relative standard uncertainty is obtained, and so does the expanded uncertainty. The mass control diagram is drawn through more than 20 times analysis of mass control samples.