Development of an ETV-ICP-OES procedure for assessment of bio-accessible trace metal fractions in airborne particulate matter

Abstract

The present study describes an ETV-ICP-OES procedure for determination of bio-accessible fractions of Ba, Co, Cu, Mn, Ni and Pb in airborne particulate matter. The method is based on the preliminary extraction of trace metals with synthetic gastric juice using a physiologically based extraction test and the subsequent measurement of gastric extracts with ETV-ICP-OES. Signal quantification was based on external calibration with aqueous standard solutions using In as internal standard. The limits of detection (LOD) calculated as three times the standard deviation (3σ) of the signal derived from filter blank samples ranged from 1.8 ng (Mn) to 12.2 ng (Cu) for analyzed aliquots of 40 μl sample extracts which translates to a method detection limit of 0.11 ng m⁻³ (Mn) to 0.75 ng m⁻³ (Cu). The reproducibility of analysis is given as the relative standard deviation varied from 1.9% (Cu) to 5.7% (Ni). Compared to conventional ICP-OES measurement of sample extracts, the developed ETV-ICP-OES procedure was found to offer enhanced sensitivity. The accuracy of the developed method was assessed by analysis of the same sample set with the conventional ICP-OES procedure using liquid sample introduction as well as by comparison of total metal contents and the cumulated sum of extractable metal contents and those remaining after sample extraction, showing good recoveries for all investigated elements. Finally the developed procedure was applied for determination of bio-accessible trace metal fractions in PM10 samples collected from Graz-Süd (Austria) indicating that mean bio-accessible metal fractions varied between 32 ± 14% (Ni) and 97 ± 36% (Pb).