AN IMPROVED AEROSOL GENERATION SYSTEM FOR THE PREPARATION OF XRF CALIBRATION FILTERS, C. Vanhoof, V. Corthouts and N. De Brucker, pp. 449-455

A fast and reliable method for the analysis of airborne loaded filters becomes more and more important for monitoring campaigns and inventory studies at sites with airborne pollution. Xray fluorescence spectroscopy (XRF) can perform quantitative analysis on filters without any pretreatment. Quantitative determination of various metals on loaded filters requires the use of calibration curves set up with synthetic filters. For accurate analysis, the calibration standards have to be prepared with a comparable matrix composition as the real filter samples. Therefore, cellulose nitrate filters were loaded by means of aerosol generation with various metals. The performance of an optimized aerosol generation system, based on the ultrasonic nebulization of a multi-element solution, is presented in this work. A multi-element solution is converted into a fine dense aerosol by ultrasonic action. The produced aerosol is dried and collected onto a filter. Filters can be loaded sequentially with a maximum standard deviation of 5 % for various metal concentrations. The influence of loading time and alteration of the initial metal concentration on the obtained elemental concentration have been investigated. Finally, the validation of the XRF measurement method is described. The linearity and sensitivity of the calibration curves are calculated for the various metals. The XRF detection limits, repeatability, and accuracy are determined. The XRF analysis of real filter samples is confirmed by subsequent analysis of filter samples with ICP-OES after acid digestion.