PIXE analysis of Tillandsia usneoides for air pollution studies at an industrial zone in Central Mexico

In order to find out if there is a relation between atmospheric particulate matter composition and human health effects, metals and other elements measurement are performed. Analysis of atmospheric aerosols collected in filters is the usual method to achieve this task. Biological monitors provide an advantageous alternative way of sampling, since there is no need of special sampling devices, and accumulation time can be as long as desired. In this study, Tillandsia usneoides a reliable air pollution biological monitor that occurs naturally throughout Mexico was used to monitor air quality of Tula–Tepeji corridor at central Mexico. This area is considered critical zone because of atmosphere contaminants high concentration. Some biomonitors were transplanted from a clean environment to four sites at the Tula corridor. Plants samples were collected every two weeks from February to April 2008. PM₁₀ sampling in filters was also performed simultaneously at three locations where T. usneoides was transplanted, for a comparison. Chemical composition was determined by PIXE. Results showed that T. usneoides incorporates anthropogenic elements reaching maximal levels after 6 to 10 weeks approximately. Since results obtained with biomonitors agree with those obtained with aerosol filters, T. usneoides could be employed as a first approximation to provide insights of the atmospheric pollution level previous to a detailed study using filters.     

质子激发X射线荧光法测定高纯空气中痕量金属杂质Cr、Cu、Fe、Zn

本实验用质子激发X射线荧光法(简称PIXE法)测定了高纯空气中的痕量元素。空气样品用过滤法采集,将过滤装置与空气气路联结,微粒法采集在核孔滤膜上,后端接空气流量计,控制流量在0.5 L/min,采集2～4 h。然后用PIXE测定。此法适于分析微区样品中的痕量金属杂质。Cr、Fe、Cu、Zn的检测下限小于0.1ng/cm~2,标样由美国微物质公司(Micromatter Co.U.S.A.)提供。     

Proton induced X-ray emission (PIXE) analysis on thick samples exemplified on the rare earth elements

Summary Proton Induced X-ray Emission (PIXE) analysis calibration curves (i.e. intensity of analytical signal as a function of concentration c _i ) are determined on thick solid samples with rare earth element concentrations c _i 0.3g/g. The calibration curves are linear at low concentrations c _i 0.3 weight% at proton energies 1.7E _PO 2.5MeV. The precision of the quantitative analysis amounts to ±4 %. The shape of the curves at higher concentrations may be understood by simple qualitative considerations.Distortions by interelement-effects caused by additional other rare earth elements j in concentrations c _j 2 weight% are not detectable. The agreement between the experimental and the calculated intensities for different matrices is very good at low concentrations c _i 1 weight% of analyte.

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Protoneninduzierte Röntgenspektralanalyse (PIXE) dicker Proben am Beispiel der Seltenen ErdelementeI. Experimentelle Bestimmung von Eichkurven, Genauigkeit und Matrixeffekten

Zusammenfassung Es werden Eichkurven (d. h. Intensität des Analysensignals in Abhängigkeit von der Analytkonzentration c _i ) für die protoneninduzierte Röntgenspektralanalyse (PIXE) dicker Festkörperproben mit Seltenen Erdelementen im Konzentrationsbereich c _i 0,3g/g aufgenommen. Diese Eichkurven verlaufen bei niedrigen Konzentrationen c _i 0,3 Gewichts-% und Protonenenergien 1,7E_PO2,5MeV linear. Die Genauigkeit der quantitativen Analyse beträgt ±4 %. Der Verlauf der Eichkurven bei höheren Konzentrationen kann durch einfache qualitative Überlegungen verstanden werden.Es werden keine Störungen durch Interelementeffekte beobachtet, die durch zusätzliche andere Seltene Erdelemente j in Konzentrationen c _j 2 Gewichts-% hervorgerufen werden. Die Übereinstimmung der experimentellen und berechneten Intensitäten für verschiedene Matrices ist bei niedrigen Analytkonzentrationen c _i 1 Gewichts-% sehr gut.

Dedicated to Karl Gleu at the occasion of his 80th birthday     

Proton induced X-ray emission (PIXE) analysis on thick samples exemplified on the rare earth elements

Summary A semiempirical procedure is developed for the calculation of the signal intensity for thick sample PIXE experiments. The calculated X-ray intensity emerged out of a thick sample is factorized into the overall produced intensity within a thick sample and an effective transmission factor for the X-ray self-absorption.The accuracy of this procedure is limited by the reliability of the experimental input parameters to about ±25%.We find as an important result of this study: The signal intensity is calculated as a function of the various experimental parameters, i.e. proton energy and sample composition including interelement- and matrix effects. This function is presented as a closed equation, which can be applied very easily, i.e. without large scale computers, to calculate the sample elemental concentration. The mass absorption coefficient of the sample most strongly influences the effective transmission term.Enhancement corrections are calculated for additional interfering rare earth elements j. No significant interelement-effects appear at concentrations c _j 2 weight%, where analysis by PIXE may be interesting. The calculated results agree well with experimental data for the rare earth elements in different matrices.Dedicated to Karl Gleu on the occasion of his 80th birthday     

冠心病（心肌纤维化）微量元素谱的多元分析

用ＩＣＰ－ＡＥＳ分析了冠心病中心肌纤维化男、女患者血液中的１９种元素含量，结果通过因子分析得到男女不同性能别的判别元素谱、应用非线性映射得以二维空间图、男性分辨率达９６．６％，女性达８７．３％。     

Trace elemental analysis of rice grown in two regions of Tanzania

The concentrations of elements in rice, locally cultivated in two regions of Tanzania (Mbeya and Morogoro), were determined using Instrumental Neutron Activation Analysis (INAA) for Na, Mg, Al, Cl, K, Ca, V, Mn, Cu and Br, and Particle-Induced X-Ray Emission (PIXE) for P, Fe and Zn. There were no statistical differences in concentrations of the essential elements Fe, Zn, Cu and P in rice from both regions. There was also no significant correlation between grain P and Fe content, suggesting the possibility of growing Tanzanian rice with low phytic acid and high Fe contents.     

Graves氏病骨髓微量元素的探讨

通过原子吸收光谱技术探讨Gretves氏病人骨髓Zn、Cu、Mn、Se、Cr及Cu／Zu、Cu／Mn、Cu／Se、Cr／Zn、Cr／Mn、Cr／Se的变化，结果表明：患病组骨髓Cu、Cr、Cu／Zn、Cu／Mn，Cu／Se、Cr／Zn、Cr／Se较正常组明显升高，而Zn、Mn，Se明显降低，Cr／Mn两组比较无差异。计算机多因素逐步回归分析结果显示五种元素中Cu与T3关系最密切，六组元素比值中Cu／Se、Cr／Mu与T3关系量密切，Se元素与患者病程长短关系密切。     

Space-resolved analysis of trace elements in fresh vegetables using ultraviolet nanosecond laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy (LIBS) has been applied to analyze trace elements contained in fresh vegetables. A quadrupled Nd:YAG laser is used in the experiments for ablation. Analyzed samples come from local markets and represent frequently consumed vegetables. For a typical root vegetable, such as potato, spectral analysis of the plasma emission reveals more than 400 lines emitted by 27 elements and 2 molecules, C₂ and CN. Among these species, one can find trace as well as ultra-trace elements. A space-resolved analysis of several trace elements with strong emissions is then applied to typical root, stem and fruit vegetables. The results from this study demonstrate the potential of an interesting tool for botanical and agricultural studies as well for food quality/safety and environment pollution assessment and control.     

Raman piezo-spectroscopic analysis of natural and synthetic biomaterials

Raman piezo-spectroscopy of bone, teeth, and artificial joints is reviewed with emphasis placed on confocal microprobe techniques. Characteristic spectra are presented and quantitative assessments of their phase structure and stress dependence are shown. Vibrational spectroscopy is used here to study the microscopic stress response of cortical bone to external stress (with or without internal damages), to define microscopic stresses across the dentine–enamel junction under increasing external compressive load, and to characterize interactions between prosthetic implants and biological environment. Confocal spectroscopy allows acquisition of spatially resolved spectra and stress imaging with high spatial resolution.     

Fractionation analysis of trace metals in humic substances of soils irrigated with wastewater in Central Mexico by particle induced X-ray emission

The Mezquital Valley in Central Mexico has received wastewater from Mexico City for nearly 100 years. Wastewater brings in organic matter and nutrients but also trace metals. Humic substances, the main components of organic soil matter, are responsible for retaining and regulating the mobility of trace metals in soils. In this study, humic substances were extracted from the soil and separated into distinct fractions (humic acids, fulvic acids and humins). The particle induced X-ray emission (PIXE) technique was applied to determine the metal content in bulk soil as well as in humic acids and fulvic acids not soluble in H₃PO₄. In order to assess whether the long-term input of organic matter and metals modifies the metal association with these humic substances, parcels irrigated for three time periods (5, 47 and 89 years) were selected for this study. It was observed that metals such as Zn and Cu are mainly associated with the humic acids. Fulvic acids retain mainly Cr while Pb is distributed among humic and fulvic acids. It was also observed that in general, metal retention by humic substances increases with irrigation time. Depth also affects metal association with the humic substances.     

Elemental analysis of size-fractionated particulate matter sampled in Göteborg,Sweden

The aim of the study was to investigate the mass distribution of trace elements in aerosol samples collected in the urban area of Göteborg, Sweden, with special focus on the impact of different air masses and anthropogenic activities. Three measurement campaigns were conducted during December 2006 and January 2007. A PIXE cascade impactor was used to collect particulate matter in 9 size fractions ranging from 16 to 0.06 µm aerodynamic diameter. Polished quartz carriers were chosen as collection substrates for the subsequent direct analysis by TXRF. To investigate the sources of the analyzed air masses, backward trajectories were calculated. Our results showed that diurnal sampling was sufficient to investigate the mass distribution for Br, Ca, Cl, Cu, Fe, K, Sr and Zn, whereas a 5-day sampling period resulted in additional information on mass distribution for Cr and S. Unimodal mass distributions were found in the study area for the elements Ca, Cl, Fe and Zn, whereas the distributions for Br, Cu, Cr, K, Ni and S were bimodal, indicating high temperature processes as source of the submicron particle components. The measurement period including the New Year firework activities showed both an extensive increase in concentrations as well as a shift to the submicron range for K and Sr, elements that are typically found in fireworks. Further research is required to validate the quantification of trace elements directly collected on sample carriers.     

Total reflection X-ray fluorescence analysis of trace-elements in candies marketed in Mexico

Trace metals concentrations in food are significant for nutrition, due either to their nature or toxicity. Sweets, including chewing gum and candies, are not exactly a food, but they usually are unwearied consumed by children, the most vulnerable age-group to any kind of metal contamination in the food chain. The presence of relatively high concentrations of heavy metals such as Lead elicits concern since children are highly susceptible to heavy metals poisoning. Trace-metals concentrations were determined for six different flavors of a Mexican candy by means of Total X-ray Fluorescence Spectrometry. Triplicate samples of the various candy's flavours (strawberry, pineapple, lemon, blackberry, orange and chilli) were digested in 8 mL of a mix of supra-pure HNO₃ and H₂O₂ (6 mL: 2 mL) in a microwave oven MARS-X. Results show the presence of essential and toxic elements such as Ti, Cr, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr, and Pb. All metal concentrations were higher and significantly different (α = 0.05) in chilli candy, compared to other candy flavours. Lead concentration fluctuated in the range of 0.102 to 0.342 μg g^− 1. A discussion about risk consumption and concentration allowed by Mexican and International Norms is made. As a part of the Quality Control Program, a NIST standard of “Citrus Leaves” and a blank were treated in the same way.     

Elemental characterization of mineral supplements by neutron activation analysis

Instrumental neutron activation analysis (INAA) was applied to assess element concentrations in eleven samples of mineral supplements/multivitamins acquired in drugstores and pharmacies in São Paulo city, SP, Brazil. Concentrations of Ca, Co, Cr, Cu, Fe, K, Na, Se and Zn were determined. A comparison was made between the results obtained with the labels of the mineral supplents. Certified reference materials, NIST SRM1400 Bone Ash and NIST SRM 1633b Coal Fly Ash were analyzed for quality control of the analytical results.     

Instrumental neutron activation analysis of trace element contents in the rib bone of healthy men

The effect of age on trace element contents in rib bone of 24 healthy 16–55-year old men was investigated by INAA. Mean values (M ± SΕΜ) for mass fraction of Co, Fe, Rb, Sr, and Zn (mg/kg on dry weight basis) were: 0.0030 ± 0.0005, 150 ± 20, 1.70 ± 0.30, 260 ± 30, and 76 ± 4, respectively. The upper limit of mean contents of Ce, Cs, Eu, Hg, and Se were: ≤0.03, ≤0.01, ≤0.001, ≤0.008, and ≤0.03, respectively. The contents of Ag, As, Au, Ba, Br, Cd, Cr, Gd, Hf, La, Lu, Nd, Sb, Sc, Sm, Ta, Tb, Th, U, Yb, and Zr were under detection limits. No changes of trace element contents with age were found.     

Relevance of NH4F in acid digestion before ICP-MS analysis

In order to implement a simpler, less expensive and more safe sample dissolution procedure, we have substituted the HF-HClO₄ mixture by NH₄F. By testing three certified reference materials, lichen 336, basalt BE-N, soil 7, it was found that the three-reagents digestion without HF and HClO₄ (HNO₃ + H₂O₂ + NH₄F was used) was very effective for the pretreatment of ICP-MS measurement. The comparison was based on the measurement results and their uncertainties. All are reference material for amount contents of different trace elements. The accuracy and precision of the developed method were tested by replicate analyses of reference samples of established element contents. The accuracy of the data as well as detection limits (LODs) vary among elements but are usually very good (accuracy better than 8%, LODs usually below 1 μg/g in solids). ICP-MS capabilities enable us to determine routinely 13 and 16 minor and trace elements in basalt and soil.     

On the possibilities of inductively coupled plasma mass spectrometry for analysis of archaeological bones for reconstruction of paleodiet

The possibilities of inductively coupled plasma atomic mass spectrometry for determination of elemental composition of archaeological bones for reconstruction of paleodiet are discussed. The interferences of different polyatomic ions on the determination of Fe, Cu, Mg, Mn, Zn, and Zr are investigated and evaluated. Thus, a method for the determination of Al, As, Ba, Mg, Pb, Sr, V, Zn, and Zr is proposed and is validated by analysis of IAEA-SRM-H-5 (animal bone). The applicability of the proposed procedure is demonstrated analyzing real archaeological bone samples dated to 4th century b.c. and the results are compared with the data obtained by inductively coupled plasma atomic emission spectrometry.     

Occupational exposure of goldsmith workers of the area of Rome to potentially toxic metals as monitored through hair analysis

In continuation of an investigation recently carried out to monitor through hair analysis the occupational exposure of goldsmith workers to potentially toxic elements, another study was performed to extend the same methodological approach to the goldsmiths of Rome. This research was part of the project P.R.O.Art. undertaken by the Italian National Research Council in cooperation with the Ministry of Industry and the National Craftsmen's Federation with the purpose of supporting goldsmith activities and trade. Sampling of hair, washing and sample digestion followed well-established procedures. Silver, Au, Cd, Co, Cr, In, Ni, Pb and Pt were determined by means of inductively coupled plasma mass spectrometry (ICP-MS), whereas Hg was analyzed using the flow injection mercury system (FIMS). On the other hand, the expected relatively high concentrations of Cu and Zn in hair allowed for the use of inductively coupled plasma atomic emission spectrometry (ICP-AES). Data obtained were statistically treated by applying the non-parametric Kruskal–Wallis test. A significant difference, at the level of P<0.05, between exposed and unexposed subjects in the Rome area was observed only for Au.     

Alteration of biological samples in speciation analysis of metalloproteins

For investigations of metalloproteins by speciation analysis, the integrity of the protein–metal complexes before and during separation is crucial. Knowledge about potential alterations of the samples is thus essential to avoid misinterpretations of the analytical results. Chromatographic element profiles of different cytosolic samples from animal tissues were measured repeatedly to estimate the sample stability. The dependence of the signals on the dwell time of the sample in an autosampling device at 4 °C for a period of 10 h was observed. Alterations in the element content of different metal-containing fractions were quantified by means of recovery values. Some metalloprotein fractions (e.g. ≈27-kDa arsenic, ≈27-kDa iron and different zinc fractions) were stable or only minor alterations were observed and for their investigation an autosampling device is therefore suitable. However, most of the other metalloprotein fractions, especially nickel-containing proteins, showed major alterations: these samples should therefore be analysed immediately after preparation or directly after thawing. Figure Chromatographic manganese-profiles of 11 repeated SEC-ICP-MS-separations of rat brain cytosol. The first sample at time 0 h was the run immediately started after thawing of the prepared cytosol; the other samples were measured hourly, taken from the same sample vial. In addition to the time axis the estimated molecular mass axis is plotted Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Vacuum ultraviolet laser-induced breakdown spectroscopy analysis of polymers

Laser-induced breakdown spectroscopy (LIBS) in the vacuum ultraviolet range (VUV, λ < 200 nm) is employed for the detection of trace elements in polyethylene (PE) that are difficult to detect in the UV/VIS range. For effective laser ablation of PE, we use a F₂ laser (wavelength λ = 157 nm) with a laser pulse length of 20 ns, a pulse energy up to 50 mJ, and pulse repetition rate of 10 Hz. The optical radiation of the laser-induced plasma is measured by a VUV spectrometer with detection range down to λ = 115 nm. A gated photon-counting system is used to acquire time-resolved spectra. From LIBS measurements of certified polymer reference materials, we obtained a limit of detection (LOD) of 50 µg/g for sulphur and 215 µg/g for zinc, respectively.The VUV LIBS spectra of PE are dominated by strong emission lines of neutral and ionized carbon atoms. From time-resolved measurements of the carbon line intensities, we determine the temporal evolution of the electronic plasma temperature, T_e. For this, we use Saha–Boltzmann plots with the electron density in the plasma, N_e, derived from the broadening of the hydrogen H-α line. With the parameters T_e and N_e, we calculate the intensity ratio of the atomic sulphur and carbon lines at 180.7 nm and at 175.2 nm, respectively. The calculated intensity ratios are in good agreement with the experimentally measured results.