Inductively coupled plasma optical emission spectrometric determination of trace element in PM10 airborne particulate matter collected in an industrial area of Argentina

Trace metals of relevance from the environmental and toxicological point of view were quantified in the city of Campana, Buenos Aires, Argentina. The collection of particulate matter was performed on ash-free fiber glass filters using high-volume samplers with a PM₁₀ sampling head, during a 3-month period in 2002. An acid leaching of elements deposited on the filters was adopted paying special attention to the recovery of volatile elements. Analysis was performed by inductively coupled plasma optical emission spectrometry (ICP OES) to ascertain the concentrations of 12 key elements, namely, Al, As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Ti, V and Zn. The validation of the procedure was performed by the analysis of the standard reference material NIST 1648, urban particulate matter, and good agreement between concentrations found and the reported certified values was achieved. Blank filters were spiked with the analytes investigated and the recoveries varied between 83% and 92%. Metal concentrations spanned the range 0.03 ng m⁻³ (equivalent to 0.42 μg g⁻¹) for Cd to 1.9 μg m⁻³ (equivalent to 29.7 mg g⁻¹) for Fe. The results obtained show that the pollutants of special environmental and health concern are As and Pb. Mean As concentration was higher than the guideline value associated with an excess cancer risk of 1:10⁻⁶, reported by the World Health Organization (WHO). Lead is the only element that showed higher concentrations than those recently measured in the large and heavily trafficked metropolitan area of Buenos Aires. Cadmium>Pb>As>Zn>Cu are the elements more enriched in airborne PM₁₀.     

飞机交流电源特性参数测量研究

飞机机载电源系统供电品质直接关系到飞机用电设备可靠工作和飞行安全,为此,2006年国际标准组织推出了新的机载电源标准ISO1540-2006;本文根据该标准要求,提出了一种机载电源的稳态和瞬态特性的测试的实用方法;建立了测量的数学模型;采用虚拟仪器技术,设计硬件测试平台,包括功率因数可调的大功率数字化程控负载和计算机数据采集系统;基于LabVIEW开发了测试软件;为满足暂态特性的测量要求和精度要求,采用了NI高速高精度数据采集卡,实现了较高的测量精度,综合测量误差小于0.5%,并在暂态测量中,考虑了负载接触器吸合时间;该测试系统可以用来检验恒频机载交流电源的特性是否符合国际标准要求,以保证飞行安全。     

Determination of metals, metalloids and non-volatile ions in airborne particulate matter by a new two-step sequential leaching procedure Part A: Experimental design and optimisation

The optimisation of a micro-analytical two-step sequential leaching procedure for the determination of non-volatile ions (NO₃⁻, SO₄²⁻, Cl⁻, Na⁺, Mg²⁺, NH₄⁺ and Ca²⁺) and of 17 elements (Al, As, Cd, Cr, Cu, Fe, Mg, Mn, Ni, Pb, S, Se, V, Zn, Sb, Si and Ti) in two fractions—extract and residue—on the same sample of air particulate matter is described. The two-step method was tested on the SRM NIST 1648 for equivalence with two reference methods, the EMEP procedure for ions extraction and the EN 12341 standard for the elemental determination of the PM₁₀ and is suitable for application to small sample amounts (less than 1 mg of particulate matter is needed), i.e. those collected by daily low volume filter-sampling. Performance times of the procedure were optimised to meet the target of routine application for large scale monitoring samples. A single ultrasonic-assisted extraction of air particulate matter is performed in 0.01 M acetate buffer at pH 4.5, followed by IC ions analysis and ICP-OES elemental analysis of the extract and by ICP-OES elemental analysis of the mineralized residue after dissolution by microwave-assisted digestion with a HNO₃/H₂O₂ mixture. Using a pH buffered extracting solvent was preferred to water or diluted acid solutions to improve the reproducibility of metals extraction with respect to existing leaching methods; the influence of pH, nature and concentration of the buffer solution and extraction time on analytes concentration in the extract is discussed. Values of ions extraction and elements recoveries resulted fairly equivalent with those obtained by the reference methods. The study was also extended to some non-certified elements (Mg, S, Sb, Si and Ti) for their environmental significance. Elements recoveries were obtained as sum of the extract and residue fractions and were comparable with those obtained by direct dissolution. Standard deviations were within 10% for almost all detected ions and elements.     

A study of uniformity of elements deposition on glass fiber filters after collection of airborne particulate matter (PM-10), using a high-volume sampler

A study was conducted to evaluate the homogeneity of the distribution of metals and metalloids deposited on glass fiber filters collected using a high-volume sampler equipped with a PM-10 sampling head. The airborne particulate matter (APM)-loaded glass fiber filters (with an active surface of about 500 cm²) were weighed and then each filter was cut in five small discs of 6.5 cm of diameter. Each disk was mineralized by acid-assisted microwave (MW) digestion using a mixture of nitric, perchloric and hydrofluoric acids. Analysis was performed by axial view inductively coupled plasma optical emission spectrometry (ICP OES) and the elements considered were: Al, As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Sb, Ti and V. The validation of the procedure was performed by the analysis of the standard reference material NIST 1648, urban particulate matter. As a way of comparing the possible variability in trace elements distribution in a particular filter, the mean concentration for each element over the five positions (discs) was calculated and each element concentration was normalized to this mean value. Scatter plots of the normalized concentrations were examined for all elements and all sub-samples. We considered that an element was homogeneously distributed if its normalized concentrations in the 45 sub-samples were within ±15% of the mean value ranging between 0.85 and 1.15. The study demonstrated that the 12 elements tested showed different distribution pattern. Aluminium, Cu and V showed the most homogeneous pattern while Cd and Ni exhibited the largest departures from the mean value in 13 out of the 45 discs analyzed. No preferential deposition was noticed in any sub-sample.     

Analysis of airborne substances by means of microwave thermal desorption

A method has been developed to enable thermal desorption of airborne substances from solid adsorbents based on active charcoal by means of microwave energy, followed by on-line GC-FID analysis. Ceramic traps were filled with 50 mg of commercially available graphitized carbon black. Adsorption efficiency and desorption conditions for three substances covering a broad range of vapor pressure were investigated. The recovery rate, breakthrough, and linearity of the system were determined by direct fortification with standard solutions, followed by microwave thermal desorption and gas chromatographic separation. The recovery efficiencies were 80–84 %, with a standard deviation of 3–6 %. The correlation coefficient of the linear range between 1 (10 for one of the compounds) and 1000 ng was > 0.999. Initial experiments were performed to investigate the enrichment of the standards from the gaseous state. The recovery rates of the most volatile compound was increased by optimizing the density of the packing.     

Metal fractionation of atmospheric aerosols via sequential chemical extraction: a review

This review surveys schemes used to sequentially chemically fractionate metals and metalloids present in airborne particulate matter. It focuses mainly on sequential chemical fractionation schemes published over the last 15 years. These schemes have been classified into five main categories: (1) based on Tessiers procedure, (2) based on Chesters procedure, (3) based on Zatkas procedure, (4) based on BCR procedure, and (5) other procedures. The operational characteristics as well as the state of the art in metal fractionation of airborne particulate matter, fly ashes and workroom aerosols, in terms of applications, optimizations and innovations, are also described. Many references to other works in this area are provided.     

Evaluation of a microwave-assisted extraction technique for determination of water-soluble inorganic species in urban airborne particulate matter

A simple and rapid microwave-assisted extraction (MAE) technique has been developed for the determination of water-soluble inorganic species (cations: Na⁺, NH₄⁺, K⁺, Ca²⁺ and Mg²⁺ and anions: F^–, Cl^–, NO₃^–, PO₄^3– and SO₄^2–) in airborne particulate matter. The analytes were extracted under different treatment conditions such as microwave power and extraction time. They were quantified using ion chromatography. The observed concentrations and recovery yields obtained under different conditions were compared. The results of a comparison between this MAE and sonication using NIST SRM 1648 are also given in this paper. The optimized MAE technique gave results in good agreement with the values obtained by the sonication. For some ions, for example Mg²⁺ and K⁺, recovery was low with both techniques. The results demonstrated that the optimized MAE is fast and efficient compared with conventional ultrasonic extraction. Urban airborne particles were collected and subjected to the MAE followed by the IC analysis to determine the relative proportions of different water-soluble inorganic species. These results are briefly discussed.     

Detection of PAH of molecular weight between 300 and 402 in airborne particulate matter by fused silica capillary GC and GC/MS

Gas chromatography (GC), low-voltage mass spectrometry (LV MS), and gas chromatography/mass spectrometry (GC/MS) have been used for detecting polycyclic aromatic hydrocarbons (PAH) of molecular weight between 300 and 402 in airborne particulate matter. Nearly 200 high molecular PAH separated by fused silica capillary columns could be characterized by their El mass spectra. The lack of reference substances precluded further structure elucidation.     

Analytical methods for assessing metal bioaccessibility in airborne particulate matter: A scoping review

In contrast to the existence of standardized methods to assess metal bioaccessibility via the gastrointestinal route, there are no widely-accepted, established in vitro testing protocols to measure elemental solubility in the human lung. This may be attributed, in part, to the difficulty associated with simulating the lung’s complex in vivo conditions. The purpose of this review is two-fold: (1) to determine how the bioaccessibility of metals associated with ambient particulate matter (PM) in the human lung has been assessed in the literature, and (2) examine the suitability and biological relevance of applied methods for the measurement of metal bioaccessibility employed to date.     

Critical review on the development of analytical techniques for the elemental analysis of airborne particulate matter

Among all environmental pollutants, particulate matter (PM) poses the major threat to our health. These tiny airborne particles vary in shape and composition, which is reflected in their hazardous potential. The particles are small enough to penetrate deep into the lungs and even enter the bloodstream, causing severe diseases. Therefore, their regular monitoring is required. Toxic metals and other elements are often measured by regulatory agencies as well as in research laboratories, either to compare ambient concentrations with prescribed limit values or to study provenance of air pollution sources in order to target PM pollution mitigation strategies. The most established method for the determination of regulated Pb, Cd, As, Ni and other elements in PM is microwave digestion inductively coupled plasma mass spectrometry (MW/ICPMS), whereas X-ray fluorescence (XRF) techniques have also often been used, especially in research. In this review paper we critically assess these two and three other analytical techniques (i.e., LA-ICPMS, PIXE and INAA) for element determination in PM deposited on filter media. All aspects from sample treatment to measurement range and limitations, costs and waste management are considered. In conclusion we identify XRF and LA-ICPMS as two promising surface techniques for the analysis of a PM deposit on a filter, which could replace the laborious wet MW/ICPMS method, which is – considering its wide use, very incriminating to the environment. In short, EDXRF is the cheapest, simplest for use and already customized for PM samples, whereas LA-ICPMS is promising, but still needs some development in the direction of autosamplers and matrix-matched standards for calibration.