Adaptation of the BCR sequential extraction procedure for fractionation of potentially toxic elements in airborne particulate matter collected during routine air quality monitoring

Abstract

The Community Bureau of Reference (BCR) four-step sequential extraction has been adapted for fractionation of potentially toxic elements (PTE) in simulant airborne particulate matter (APM) samples presented on 47 mm filter dynamics measurement system (FDMS) filters as used in routine air quality monitoring. Simulants were prepared from an urban soil reference material and from BCR CRM 701, which is certified for analytes extractable by the BCR procedure. Analysis was performed by inductively coupled plasma mass spectrometry using an Agilent 7700x instrument. Fractionation patterns similar to the full-scale protocol were obtained when test portions as small as 0.0625 g were extracted in 2-3 mL of reagents.However, changing the extraction vessel used was found to affect the outcome. This highlights the operational nature of sequential extraction procedures and the need carefully to evaluate the effects of procedural modifications. When the method developed was applied to blank FDMS filters, large amounts of Zn were detected, especially in step 3, the oxidisable fraction, and step 4, the residual fraction. Despite this, following blank-correction, fractionation patterns similar to certified values were obtained for BCR CRM 701, with overall recoveries ((steps 1-4)) of 84.2-113%. Given the increased awareness of public health risks associated with poor air quality, a sequential extraction procedure specifically designed for use with APM samples collected during routine air quality represents a valuable tool for use in source apportionment and to improve understanding of human exposure to PTE through inhalation.

Comparison of two non-specific flow-through sequential extraction approaches to identify the physico-chemical partitioning of potentially harmful elements in a certified reference material

“…The presence of a substantial PHE blank in TX40 FDMS filters has previously been reported [47,31]. As these "blank" components can be identified separately, they were able to be excluded from further data processing.…”

“…Calibration was with respect to solutions freshly-prepared by serial dilution of Agilent Technologies multi-element standard solution 2A. The nuclides quantified were: 27 Al, 137 Ba, 40 Ca, 52 Cr, 53 Cr, 63 Cu, 65 Cu, 56 Fe, 57 Fe, 39 K, 24 Mg, 55 Mn, 23 Na, 60 Ni, 31 P, 206 Pb, 207 Pb, 208 Pb, 28 Si, 29 Si, 88 Sr, 45 Ti, 51 V, 64 Zn, and 66 Zn. The internal standard was 115 In.…”

“…The combined data set was processed using a chemometric data processing method that has been described in detail by Cave et al [31,35]. This resolves chemical extraction data into components, defining the number of components and their composition.…”

“…Sequential extraction can provide valuable information when used appropriately [16]. The approach has been applied successfully to urban soils [12,13,[18][19][20][21]; street dusts [22][23][24][25][26]; and airborne particle matter [26][27][28][29][30][31]. However, it has limitations.…”

“…Despite interest in developing methods to assess the mobility of PHE bound to respirable airborne particles [43][44][45] little work has been carried out to apply the CISED approach in this context. The limited mass of airborne particulate matter samples available -typically just a few tens of mg, usually collected on a filter -is a key driver for miniaturization of sequential extraction techniques and/or the development of flow through extraction methods based on sample extraction directly from the collection filter [31].…”