Urban dust

Some doubts were expressed on the second GC-AAS procedure used, which filtered the suspension and took back TriML in water. Indeed, TriML is not stable in water and it was suspected that losses could have occurred by adsorption on the filter. The extraction recovery was not necessary as standard additions were performed prior to extraction recovery values of 66 and 77% were obtained. 

The extraction recovery for the GC-MS method was not verified, which again allowed some doubts on the possibly low results. 

At this stage, it was hardly possible to confirm the doubts expressed on the extraction recovery of TriML in this material. The participants recommended that emphasis be put on the verification of extraction recovery in a further exercise, i.e. that a small batch of candidate reference material of urban dust be spiked with a known amount of TriML, left to equilibrate, homogenized and made available to the participants so that the extraction recovery may be verified. Recommendation was made to spike the dust in a slurry which should be freeze-dried, not dried, in order to avoid losses of TriML. 

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Figure 9. Reversed-phase HPLC analysis of PAH s extracted from SRM 1649, urban dust/organics, with UV detection, not preceded by normal-phase HPLC clean-up, (Reprinted from reference 72.

Coal ash, coal fly ash, power station fly ash, incinerator ash, vehicle exhaust particulates, urban dust, atmospheric dust, metal smelter dust, welding dust, diesel particulates, particulates on filter media Sewage sludge, wastewater... 

Quevauviller Ph, Ebdon L, Harrison RM, Wang Y (1999) Certification of trimethyl-lead in an urban dust reference material (CRM 605). Appl Organomet Chem 13 1-7. 

Trace elements in soils and sludges (CRMs 141R-146R 597) pp 225-232 (1998k) Chlorobi-phenyls in sewage sludge (CRM 392) pp 240-243 (1998I) Trimethyl-lead in urban dust (CRM 605) pp 274-278 In Production of Certified Reference Materials for Pollutants in Environmental Matrices. European Commission Report EUR 18157 EN, CCF Academic Press, Tarbes. 

Currently available CRMs A number of organolead (tetra- and triaUcyllead) compounds are commercially available to be used as calibrants. There are also a number of interesting CRMs an urban dust certified for trimethyUead and more appear to be in development The interest in organolead compotmds is, however, on the decline due to the gradual disappearance of the tetraethyl anti-knock agent from petrol. 

Fig, 3.2 Analytical scheme used for the certification of PAHs in NIST SRM 1649a Urban Dust. 

Tab. 3.14 Summary of analytical results from different methods for the determination of PAHs in SRM 1649a, Urban dust... 

Wise SA, Sander LC, Schantz MM, Hays MJ, and Benner BA Jr. 2000) Recertification of standard reference material (SRM) 1649, urban dust, for the determination of polycyclic aromatic hydrocarbons (PAHs). Polycyclic Aromat Compd, 13 419-456. 

SRM 1649A ( ) Urban Dust Organic Constituents NIST... 

Figure 6. X-ray elemental maps obtained using an electron microscope—urban dust sample containing automotive exhaust particles...

One particular type of source that should be studied carefully Is entrained soil. As shown above, this Is often the greatest contributor of TSP In urban areas. As there Is so much of It present, we need to know concentrations of all measured elements quite well to make an accurate determination of the residual amounts left to be accounted for by other sources. The composition of selved soil Is often used for the soil component, but there may be considerable fractionation Imposed by entrainment, e.g., preferential selection of very fine clay mineral particles. Such fractionation has been demonstrated In the very limited studies of entrainment of particles from soil of known composition (e.g.. Refs. 21, 49). These studies can probably best be done In controlled environments such as wind tunnels. One cannot simply collect ambient particles In the countryside and consider it to be soil, as there are anthropogenic contributions even at great distances from cities ( ). There Is further confusion betwen clean, "continental" dust and "urban" dust. The latter, which Is usually collected near city streets (21, 50), typically has a composition of soil contaminated by anthropogenic emissions, especially from motor vehicles. 

Cooper and Watson (21) reported finding about 0.1% manganese in both the fine (<2 pm) and coarse ( 2 pm) particle fractions, respectively, of urban dust in Portland and 0.2% and 0.085% in the fine and coarse fractions, respectively in continental dust. Thus, it should be possible to use this element in RSP samples as a soil tracer in New York City. However, during part of the period of this investigation, methylcyclopentadienyl tricarbonyl (MMT) was used as an octane booster for unleaded gasoline ( ). ... 

Bagley, S. T., S. L. Stoltz, D. M. Becker, and R. E. Keen, "Characterization of Organic Extracts from Standard Reference Materials 1649, Urban Dust/Organics, and 1650, Diesel Particulate Matter, Using a Microsuspension Assay. A WHO/IPCS/CSCM Study, Mutat. Res., 276, 81-86 (1992). 

Raisanen K, Kupiainen K, Tervahattu H (2005) The effect of mineralogy, texture and mechanical properties of anti-skid and asphalt aggregates on urban dust, stages II and III. Bull Eng Geol Environ 64 247-256... 

The presence of this non-exchangeable pool for PAHs is implied by the results of experiments which compared the extraction rates of native PAHs and spiked perdeuterated compounds from SRM 1649 urban dust (Burford et al., 1993). Extraction with supercritical C02 quantitatively recovered the deuterated PAHs within 30 min. C02 alone removed native PAHs more slowly and incompletely, C02/ methanol gave improved yields. Differences in volatilization of PAHs from urban particles into a clean airstream occurred, depending on whether the PAHs were native to the particles or added by surface coating (Poster et al., 1995). 

Following a feasibility study, it was found that trimethyllead (TML) would be of sufficient stability for the purpose of interlaboratory studies and possibly certifications of RMs whereas dialkyllead species and triethyllead were not stable enough. Interlaboratory studies were performed in 1992-1994 on TML in artificial rainwater and urban dust and enabled a significant improvement of the state-of-the-art to be achieved (Quevauviller et al., 1995b). These exercises were followed by a certification campaign aiming to certify TML in candidate RMs of artificial rainwater and urban dust. The between-laboratory agreement obtained was very satisfactory and both materials were proposed for certification. 

The urban dust RM (CRM 605) was successfully certified (Table 6.1). The stability of the material at +20°C was verified over 37 months and was found to be suitable for certification an instability was, however, noted at +40°C which justified the recommendation to store the material at +4°C in the dark (Quevauviller etai, 1999b). 

Wang, W.H., Wong, M.H., Leharne, S. and Fisher, B. (1998) Fractionation and biotoxicity of heavy metals in urban dusts collected from Hong Kong and London. Environ. Geochem. Health, 20, 185-198. 

Figure 11.2 Flow chart for urban dust fractionations and lead solid speciation.

Marvin et al. [14] compared sonication with Soxhlet for the extraction of PAHs from sediments, and from an urban dust standard reference material (SRM 1649). The sonication method required less than 5 g of sample. The amount of organic materials extracted by sonication with two solvents was 2.53 + 0.10% of the sediment samples (w/w), while 2.41 + 0.14% was extracted by Soxhlet. Sequential sonicaion with two solvents was much faster (45 minutes) than Soxhlet (2 days), with practically the same extraction efficiency. The variation of PAH extracted by sonication from the urban dust SRM was within 15%. 

The potential of ultrasonic extraction for field-based extractions has been put into use in the industrial hygiene and environmental single-element analysis of, for example, lead from glass fibre filter ambient air samples [13,14] or from lead-based paint, urban dust and river sediment [15] hexavalent chromium from coal fly ash and paint chips [16] and strontium from river sediment [17]. Ultrasonic extraction has also proved effective as a prior step in multi-element determinations of heavy metals. 

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