Determination of water soluble trace metals in airborne particulate matter using a dynamic extraction procedure with on-line inductively coupled plasma optical emission spectrometric detection

Abstract

A novel continuous-flow system for the dynamic extraction of water soluble metal fractions in airborne particulate matter (APM) with subsequent inductively coupled plasma optical emission spectrometric (ICP-OES) analysis of derived extracts is presented. The fully automated extraction system with on-line multi-element detection offers enhanced sensitivity when compared to batch-wise counterparts; additionally it provides information about the extraction process. With the developed procedure detection limits in the order of 1.5 (Ba) to 8.0 (Ni)ng extractable mass per investigated sample could be achieved, which translates to method detection limits for soluble metal concentrations in APM ranging from 0.2ngm−3 (Ba) to 0.9ngm−3 (Fe). Reproducibility of analysis was determined by replicate measurement (n=6) of an APM sample with an aerodynamic diameter ≤10μm (PM10), derived results varied between 3.5% (Mn) and 12.1% (Ni) relative standard deviation. Method validation was accomplished by comparison of extracted soluble and remaining non-soluble fractions with the total metal contents of the investigated PM10 samples, showing an excellent mass balance for all elements. Application of the developed procedure for the analysis of water soluble metal fractions in PM10 samples (n=16) from Linz (Austria) indicated a high variability of extractable fractions ranging from 11.7±7.2% (Fe) to 48.8±15.4% (Mn) of the total metal contents.