The suitability of extraction solutions to assess bioaccessible trace metal fractions in airborne particulate matter: a comparison of common leaching agents.

The determination of bioaccessible metal concentrations and/or fractions is a prerequisite for reliable assessment of the hazardous potential of toxic trace metals present in airborne particulate matter (APM). For this purpose, the use of various leaching agents has been reported in literature. The applied reagents reveal severe differences in composition. Therefore, variations in the amounts of trace metals released from APM samples could be expected with the use of these agents, hampering comparison of literature data. In this work, bioaccessible metal fractions were determined in PM10 samples from Graz, Austria, and Karachi, Pakistan, using synthetic gastric juice (SGJ), artificial lysosomal fluid (ALF), Gamble's solution, aqueous solutions of sodium chloride, ammonium acetate, ammonium citrate, and water for sample extraction. Investigated trace metals showed distinct differences in extractable fractions for the same extractant. For example, bioaccessible contents ranged from 34.8 ± 13.3% for Ni (n = 12) to 77.9 ± 14.8% for Cd (n = 12) when SGJ was used for extraction. Furthermore, extraction yields for the applied leaching agents were determined, indicating for all investigated elements two to four times more efficient extraction with SGJ, ammonium citrate buffer, and ALF as compared to water and simple inorganic salt solutions, indicating that ammonium citrate buffer could be used as an alternative for synthetic body fluids with rather complex composition.

Recent developments in assessment of bio-accessible trace metal fractions in airborne particulate matter: a review.

In the last years a great deal of research has been focused on the determination of harmful trace metals such as Cd, Co, Cr, Cu, Ni or Pb in airborne particulate matter (APM). However, the commonly applied determination of total element concentrations in APM provides only an upper-end estimate of potential metal toxicity. For improved risk assessment it is important to determine bio-accessible concentrations instead of total metal contents. The present review gives an overview of analytical procedures reported for measurement of bio-accessible trace metal fractions in APM. The different approaches developed for extraction of soluble trace metals in APM are summarized. Furthermore the analytical techniques applied for accurate determination of dissolved trace metals in the presence of complex sample matrix are presented. Finally a compilation of published results for bio-accessible trace metals in APM is included.

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.

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 0.2 ng m(-3) (Ba) to 0.9 ng m(-3) (Fe). Reproducibility of analysis was determined by replicate measurement (n=6) of an APM sample with an aerodynamic diameter ≤10 µm (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.

Aerosol size distribution and mass concentration measurements in various cities of Pakistan.

During March and April 2010 aerosol inventories from four large cities in Pakistan were assessed in terms of particle size distributions (N), mass (M) concentrations, and particulate matter (PM) concentrations. These M and PM concentrations were obtained for Karachi, Lahore, Rawalpindi, and Peshawar from N concentrations using a native algorithm based on the Grimm model 1.109 dust monitor. The results have confirmed high N, M and PM concentrations in all four cities. They also revealed major contributions to the aerosol concentrations from the re-suspension of road dust, from sea salt aerosols, and from vehicular and industrial emissions. During the study period the 24 hour average PM(10) concentrations for three sites in Karachi were found to be 461 µg m(-3), 270 µg m(-3), and 88 µg m(-3), while the average values for Lahore, Rawalpindi and Peshawar were 198 µg m(-3), 448 µg m(-3), and 540 µg m(-3), respectively. The corresponding 24 hour average PM(2.5) concentrations were 185 µg m(-3), 151 µg m(-3), and 60 µg m(-3) for the three sites in Karachi, and 91 µg m(-3), 140 µg m(-3), and 160 µg m(-3) for Lahore, Rawalpindi and Peshawar, respectively. The low PM(2.5)/PM(10) ratios revealed a high proportion of coarser particles, which are likely to have originated from (a) traffic, (b) other combustion sources, and (c) the re-suspension of road dust. Our calculated 24 hour averaged PM(10) and PM(2.5) concentrations at all sampling points were between 2 and 10 times higher than the maximum PM concentrations recommended by the WHO guidelines. The aerosol samples collected were analyzed for crustal elements (Al, Fe, Si, Mg, Ca) and trace elements (B, Ba, Cr, Cu, K, Na, Mn, Ni, P, Pb, S, Sr, Cd, Ti, Zn and Zr). The averaged concentrations for crustal elements ranged from 1.02 ± 0.76 µg m(-3) for Si at the Sea View location in Karachi to 74.96 ± 7.39 µg m(-3) for Ca in Rawalpindi, and averaged concentrations for trace elements varied from 7.0 ± 0.75 ng m(-3) for B from the SUPARCO location in Karachi to 17.84 ± 0.30 µg m(-3) for Na at the M. A. Jinnah Road location, also in Karachi.

2-(2-Iodo-benzenesulfonamido)acetic acid.

The title compound, C(8)H(8)INO(4)S, is a halogenated sulfon-amide, a medicinally important class of organic compounds. In the crystal structure, inter-molecular O-H⋯O hydrogen bonds involving the carboxylic acid groups form characteristic centrosymmetric dimers. These dimers are further linked through centrosymmetric dimeric N-H⋯O inter-actions involving the amido H atom and a sulfonyl O atom. This leads to the formation of a ribbon-like polymer structure propagating in the b direction.