ON LINE MONITORING OF ELEMENTAL POLLUTANTS IN FLUE GASES: STANDARDIZATION, PRECISION AND ACCURACY

Several recent works have shown that it is possible to use Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) in the direct anal~sis of elemental pollutants in gases. The limits of detection range from 10 to 0.1 μg/m³ . The two crucial points in precision and accuracy are the control of the water content of the gases and the production of standard aerosols. The desolvation system used to produce standard aerosols consists of nebulizing a standard solution, volatilizing the droplets to evaporate the solvent, and removing the solvent by condensation. During the condensation process a partial re-solvation of the dry aerosol in the condensed solvent occurs. This re-solvation can induce systematic errors. Water content and re-solvation coefficient are closely linked, and both the design of the condenser, and the temperature condensation are critical.