Application of capillary electrophoresis combined with a modified BCR sequential extraction for estimating of distribution of selected trace metals in PM2.5 fractions of urban airborne particulate matter

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

Two non-specific sequential extraction methods utilising chemometric data processing (chemometric identification of substrates and element distribution, CISED) have been developed and used to determine the physico-chemical partitioning of potentially harmful elements (PHE) in certified reference material BCR CRM 701 (lake sediment). A miniaturized centrifugation method in which the sample was extracted on a filter insert in a polypropylene centrifuging tube, and a quasi-flow through method in which the sample was supported on a TX40 filter in a 47 mm in-line polycarbonate filter holder, gave similar results. The CISED data processing identified nine components. Seven of these were of geochemical origin - two carbonate components, an Al/Fe oxide/hydroxide component, three Fe-dominated components and one Si-dominated component - while the others represented the TX40 filter blank. The overall extraction capabilities of the methods were similar to that of the well-established BCR sequential extraction (Σsteps 1-3). However, whilst the BCR extraction is operationally defined, the CISED provides information on associations between PHE and the geochemical components identified. The flow through CISED procedure has potential applications in investigating the chemical speciation of PHE associated with urban airborne particular matter.

Can washing-pretreatment eliminate the health risk of municipal solid waste incineration fly ash reuse?

Although the reuse of washing-pretreated MSWI fly ash bas been a hot topic, the associated risk is still an issue of great concern. The present study investigated the influence of washing-pretreatment on the total contents and bioaccessibility of heavy metals in MSWI fly ash. Furthermore, the study incorporated bioaccessibility adjustment into probabilistic risk assessment, to quantify the health risk from multi-pathway exposure to the concerned chemicals as a result of reusing washed MSWI fly ash. The results revealed that both water-washing and acid-washing process have resulted in the concentrated heavy metal content, and have reduced the bioaccessibility of heavy metals. Besides, the acid-washing process increased the cancer risk in most cases, while the effect of water-washing process was uncertain. However, both water-washing and acid-washing pretreatment could decrease the hazard index based on bioaccesilbility. Despite the uncertainties accompanying these procedures, the results indicated that, in this application scenario, only water-washing or acid-washing process cannot reduce the actual risk from all samples to acceptable level, especially for cancer risk.

Application of zirconium-iridium permanent modifier for the simultaneous determination of lead, cadmium, arsenic, and nickel in atmospheric particulate matter by multi-element electrothermal atomic absorption spectrometry

A novel and robust method for the simultaneous determination of lead, cadmium, arsenic, and nickel in atmospheric particulate matter by multi-element electrothermal atomic absorption spectrometry was developed, using zirconium-iridium coating as permanent modifier (140 μg Zr and 4 μg Ir). After 300 atomization cycles, it was necessary to add 2 μg of Ir. Due to the varying concentrations of Pb in atmospheric particulate matter, lead was monitored at two wavelengths, at the less sensitive line of 261.4 nm for high concentration samples (>20 μg L(-1)) or at 283.3 nm for the low concentration samples. Matrix-matched calibration had to be performed for quantitative recoveries (96-102 %). Following this approach, the four elements were determined in atmospheric particulate matter samples from an industrial area near the city of Athens in two different time periods (cold-warm) with limits of detection of 5.5 ng m(-3) for Pb at 261.4 nm and 0.29 ng m(-3) at 283.3 nm, 0.019 ng m(-3) for Cd, 0.14 ng m(-3) for As, and 0.22 ng m(-3) for Ni. Lead, Cd, and As levels were very low, whereas Ni content was at comparable levels with other areas worldwide.

PM(2.5) in the central part of Upper Silesia, Poland: concentrations, elemental composition, and mobility of components

The paper discusses ambient concentrations of PM(2.5) (ambient fine particles) and of 29 PM(2.5)-related elements in Zabrze and Katowice, Poland, in 2007. The elemental composition of PM(2.5) was determined using energy dispersive X-ray fluorescence (EDXRF). The mobility (cumulative percentage of the water-soluble and exchangeable fractions of an element in its total concentration) of 18 PM(2.5)-related elements in Zabrze and Katowice was computed by using sequential extraction and EDXRF combined into a simple method. The samples were extracted twice: in deionized water and in ammonium acetate. In general, the mobility and the concentrations of the majority of the elements were the same in both cities. S, Cl, K, Ca, Zn, Br, Ba, and Pb in both cities, Ti and Se in Katowice, and Sr in Zabrze had the mobility greater than 70%. Mobility of typical crustal elements, Al, Si, and Ti, because of high proportion of their exchangeable fractions in PM, was from 40 to 66%. Mobility of Fe and Cu was lower than 30%. Probable sources of PM(2.5) were determined by applying principal component analysis and multiple regression analysis and computing enrichment factors. Great part of PM(2.5) (78% in Katowice and 36% in Zabrze) originated from combustion of fuels in domestic furnaces (fossil fuels, biomass and wastes, etc.) and liquid fuels in car engines. Other identified sources were: power plants, soil, and roads in Zabrze and in Katowice an industrial source, probably a non-ferrous smelter or/and a steelwork, and power plants.

Differential Individual Particle Analysis (DIPA): applications in particulate matter characterization

Operator-controlled and computer-controlled scanning electron microscopy (CCSEM) are used extensively to characterize particulate matter in environmental media. Analysis in a scanning electron microscope (SEM) coupled with chemical extraction is a potentially powerful tool that is capable of determining how various sample components are associated at the individual particle level. This involves initial characterization in a SEM, after which the material is exposed to a liquid or gas phase reaction for a specified time, and once exposure is concluded, the particles are reanalyzed in the SEM. This particle analysis by difference, or differential individual particle analysis (DIPA), possesses considerable potential for describing the behavior of environmental particles under changing chemical conditions. Here we describe DIPA applications with illustrative examples drawn from the analysis of particulate matter modified by reactions in a fluid environment. In situ DIPA permits the same particles to be analyzed in the SEM before and after modification. Repeated exposure to the same, or different modifying conditions, provides information on the time dependence of specific reactions. Significant numbers of particles can be analyzed using CCSEM, and the same particles can be analyzed after the reaction by accurate sample relocation in the SEM. Ex situ DIPA, which involves a bulk sample modification, uses CCSEM to characterize significant numbers of particles pre- and postreaction. The CCSEM approach is extremely efficient; recent developments in silicon drift detectors have increased the speed of characteristic X-rays detection, and very large numbers of particles can be analyzed in a short period of time.

Recent trends in CE of inorganic ions: From individual to multiple elemental species analysis

The major methodological developments in CE related to inorganic analysis are overviewed. This is an update to a previous review article by the author (Timerbaev, A. R., Electrophoresis 2004, 25, 4008-4031) and it covers the review work and innovative research papers published between January 2004 and the first part of 2006. As was underlined in that review, a growing interest of analytical community in providing elemental speciation information found a sound response of the CE method developers. Presently, almost every second research paper in the field of interest deals with element species analysis, the use of inductively coupled plasma MS detection and biochemical applications being the topics of utmost research efforts. On the other hand, advances in general methodology traditionally centered on a CE system modernization for improvements in sensitivity and separation selectivity have attracted less attention over the review period. While there is no indication that inorganic ion applications would surpass by the developmental rate the more matured analysis of organic analytes, CE can now be seen as an analytical technique to be before long customary in a number of inorganic analysis arenas.

Is there a future for sequential chemical extraction?

Since their introduction in the late 1970s, sequential extraction procedures have experienced a rapid increase in use. They are now applied for a large number of potentially toxic elements in a wide range of sample types. This review uses evidence from the literature to consider the usefulness and limitations of sequential extraction and thereby to assess its future role in environmental chemical analysis. It is not the intention to provide a comprehensive survey of all applications of sequential extractions or to consider the merits and disadvantages of individual schemes. These aspects have been covered adequately in other, recent reviews. This review focuses in particular on various key issues surrounding sequential extractions such as nomenclature, methodologies, presentation of data and interpretation of data, and discusses typical applications from the recent literature for which sequential extraction can provide useful and meaningful information. Also covered are emerging developments such as accelerated procedures using ultrasound- or microwave energy-assisted extractions, dynamic extractions, the use of chemometrics, the combination of sequential extraction with isotope analysis, and the extension of the approach to non-traditional analytes such as arsenic, mercury, selenium and radionuclides.

Separation of common organic and inorganic anions in atmospheric aerosols using a piperazine buffer and capillary electrophoresis

The ability to monitor and quantify anionic components of aerosols is important for developing a better fundamental understanding of temporal and spatial variations in aerosol composition. Of the many methods that can be used to detect anions, capillary electrophoresis is among the most attractive ones because of its high separation efficiency, high resolving power for ionic compounds, and ability to be miniaturized for in-field monitoring. Here we present a method to baseline resolve common aerosol components nitrate, sulfate, chloride, and over two dozen organic acids in a single separation. A capillary electrophoresis separation utilizing a pH 5.78 piperazine buffer with 1,5-naphthalenedisulfonic acid as a probe for indirect UV absorbance detection was developed for this analysis. Previously, two different buffers were required to adequately separate all of these compounds. Electrophoretic mobilities, limits of detection, and migration time reproducibilities were measured for 38 organic and 8 inorganic anions. For solutions of low conductivity, detection limits for electrokinetic injections were found to be up to two orders of magnitude lower (0.2-0.4 microM) than those for pressure injection (1-45 microM). This separation was optimized and used for routine analysis of aqueous extracts of ambient atmospheric aerosols, but may be extended to other samples containing similar mixtures of anions.

Recent advances in capillary electrophoresis and capillary electrochromatography of pollutants

Recent advances in the CE and CEC separation, detection, and sample preparation methodologies applied to the determination of a variety of compounds having current or potential environmental relevance have been overviewed. The reviewed literature has illustrated the wide range of CE applications, indicating the continuing interest in CE and CEC in the environmental field.

Fractionation of eleven elements by chemical bonding from airborne particulate matter collected in an industrial city in Argentina

A four-step chemical sequential extraction procedure was used to evaluate the distribution of Al, As, Cr, Cu, Fe, Mn, Ni, Pb, Ti, V and Zn in airborne particulate matter collected on glass fibre filters using a high-volume sampler. Two sets of samples were collected in 2001 (winter and summer campaigns) in representative zones of an industrial city of Argentina. The leaching scheme was applied to PM-10 particles and consisted in extracting the elements in four fractions, namely soluble and exchangeable elements; carbonates, oxides and reducible elements; bound to organic matter and sulfidic metals; and residual elements. Metals and metalloids at microg g(-1) level were determined in each fraction by inductively coupled plasma optical emission spectrometry (ICP OES). Analyte concentration varied from 14 microg g(-1) (equivalent to 1.0 ng m(-3)) for As to 11.8 mg g(-1) (equivalent to 2,089 ng m(-3)) for Al. Seven elements, namely Al, Cr, Fe, Mn, Pb, Ti and Zn showed similar distributions in both seasons while As was distributed in a significantly different manner in each season. The results exhibited low As contents in the first and second fractions that could be associated with routine coal combustion and a high content in the third and fourth fractions of the summer samples that could be linked to the use of pesticides. Aluminium, As, Cu, Mn, Ni, Ti, V and Zn were found in different percentages in the more bioavailable aqueous fraction with As, Mn, V and Zn exhibiting solubilities greater than 1% while Cr and Pb being insoluble. The content of Al, Cr, Cu, Fe, Ni, Pb, and Zn in the residual fraction was, in average, higher than 50%. A comparative assessment of the use of the underlying information available from fractionation studies compared to that obtained from total element content was done for Fe and Mn. It showed that the results obtained using chemical sequential extraction procedures allowed further discrimination of the potential air pollution sources.

Characterization of trace metal particles deposited on some deciduous tree leaves in an urban area

In 1996 and 1997 horse chestnut (Aesculus hippocastanum L.) and Turkish hazel (Corulys colurna L.) leaves were sampled at 2 m height in the Belgrade Botanic Garden, located in an urban area with heavy traffic. Using a scanning electron microscope with an energy dispersive X-ray spectroscopy (SEM-EDAX), the size, size distribution, morphology and chemical composition of individual particles were examined on the adaxial and abaxial surfaces of leaf discs of both species. The majority of particles observed on leaves belonged to a class of fine particles (D < 2 microm). Morphological and chemical composition indicated that the most abundant particles were soot and dust with minor constituents such as Pb, Zn, Ni, V, Cd, Ti, As and Cu. Using an electrochemical technique (DPASV), it was possible to measure trace metal concentrations (Pb, Cu, Zn) in a water-soluble fraction of deposits on each single leaf. Trace metal contents in the leaf deposits, increased during the vegetation period for both species and were considerably higher in A. hippocastanum due to different epidermal characteristics. The higher trace metal concentrations in deposits in 1997 reflected greater atmospheric pollution in the Belgrade urban area.