Comparison of the extraction efficiencies of different leaching agents for reliable assessment of bio-accessible trace metal fractions in airborne particulate matter

Abstract

Abstract. In present study, an in-vitro physiologically based extraction test has been applied for extraction of bio-accessible trace metal fractions in airborne particulate matter (APM) samples collected from different urban sites in Austria and Pakistan using the leaching agents H 2 O, sodium chloride, ammonium acetate, ammonium citrate, synthetic gastric juice and artificial lung fluids. Obtained extracts were then measured using an ETV-ICP-OES procedure which allowed highly sensitive measurement of dissolved analytes even in the presence of leaching agents. Derived results indicated that the investigated leaching agents extract different amounts of trace metals. In general, leaching agents with organic nature yielded comparatively greater extractable and thus bio-accessible trace metal fractions to that of simple solvents like H 2 O or aqueous NaCl solution. With water, only 26.3±4.0% of Cd was found to be bio-accessible whereas 88.4±24.

Methodological factors influencing inhalation bioaccessibility of metal(loid)s in PM2.5 using simulated lung fluid

“…In contrast, Pb bioaccessibility in ALF was 1.12, 1.20 and 1.30 fold higher (P < 0.05) in SRM 2710a, PP and CMW respectively compared to gastric phase alone; with the exception of SH15 where no significant difference (p > 0.05) was observed between methodologies. This result differs to results obtained by Mukhtar and Limbeck (2013), who reported higher Pb bioaccessibility using simulated gastric solutions compared to ALF. However, Mukhtar and Limbeck (2013) conducted extraction using both gastric solutions and ALF over a 1 h period, whereas in this study, a more biologically relevant extraction time was used (e.g.…”

“…This result differs to results obtained by Mukhtar and Limbeck (2013), who reported higher Pb bioaccessibility using simulated gastric solutions compared to ALF. However, Mukhtar and Limbeck (2013) conducted extraction using both gastric solutions and ALF over a 1 h period, whereas in this study, a more biologically relevant extraction time was used (e.g. 24 h extraction using ALF and 1 h extraction using gastric solution).…”

“…Additionally, significant knowledge gaps exist in methods currently used to determine metal(loid) bioaccessibility in PM 2.5 (Kastury et al, 2017). For example, the solid to liquid (S/L) ratio used ranges significantly (1:100 -1:1163) (Hamad et al, 2014a;Potgieter-Vermaak et al, 2012;Wiseman and Zereini, 2014) or is not reported because a part of the filter paper with which the particles were collected was used directly in assays (Mukhtar and Limbeck, 2013;Schaider et al, 2007); agitation varies from occasional (Wiseman and Zereini, 2014), continuous (Hamad et al, 2014b;Potgieter-Vermaak et al, 2012) or ultrasonic (Mukhtar and Limbeck, 2013); and extraction time varies from 1 (Mukhtar and Limbeck, 2013) to 120 h (Schaider et al, 2007). Furthermore, approximately 85 to 90% of deposited particles, including those engulfed by macrophages, may be cleared from the lung within 24 h, although clearance from the alveolar region is assumed to be slower (Hofmann, 2011).…”