Določevanje nekaterih elementov v sledovih v atmosferskih delcih

Determination of trace element concentrations in atmospheric aerosols is important because of their toxic effects on human health. Additionally, they are now widely used in source apportionment studies. There is a number of methods for sample preparation of ambient particulate matter. One of the most widely used is microwave-assisted digestion of filter-based samples. Since the water-soluble fraction is bioavaliable, the aim of our study was to determine the concentration of selected trace elements (V, Cr, Mn, Ni, Cu, Zn, As, Cd, Sb, Tl, and Pb) in this fraction and compare it to the amounts obtained by two different microwave digestion procedures – one using a mixture of H2O2 and HNO3 and the other using a mixture of HF, HCl, and HNO3. The recoveries of the digestion procedures used were tested on certified reference material (NIST SRM 1648 Urban Particulate Matter). The procedures were applied to filters containing PM10 particles collected at an urban background location in Ljubljana, Slovenia. Among the elements analysed, V, Zn, As, and Cd displayed the highest concentration within the water-soluble fraction, with Cr, Ni, Tl and Pb displaying the lowest concentrations. The comparison between the two applied digestion procedures showed that Cr, Ni, Sb and Tl were strongly bound to the sample matrix.Določevanje elementov v sledovih v atmosferskih delcih je pomembno zaradi njihovega toksičnega vpliva na človekovo zdravje. V zadnjem času se koncentracije teh elementov tudi zelo pogosto uporabljajo v študijah povezanih s porazdelitvijo po virih. Za določevanje elementov v sledovih se uporabljajo različne priprave vzorcev. Najpogostejši je razklop filtrov s pomočjo mikrovalovne peči. Ker je vodotopen delež tudi biološko dostopen, je bil namen naše študije določitev te frakcije posameznih elementov (V, Cr, Mn, Ni, Cu, Zn, As, Cd, Sb, Tl and Pb) in primerjava s koncentracijami po dveh različnih razklopih – prvi z mešanico H2O2 in HNO3 ter drugi z mešanico HF, HCl in HNO3. Izkoristke uporabljenih razklopov smo preverili s standardnim referenčnim materialom (NIST SRM 1648 Urban Particulate Matter). Preverjena postopka smo uporabili na filtrih, ki so vsebovali delce PM10, vzorčevane v Ljubljani, Slovenija. Med analiziranimi elementi so bili izrazito dobro topni v vodi V, Zn, As in Cd, najmanj pa Cr, Ni, Tl, in Pb. Primerjava med obema uporabljenima razklopoma je pokazala, da so Cr, Ni, Sb in Tl v delce izredno stabilno vezani

Bibliometric analysis of research on secondary organic aerosols: A Science Citation Index Expanded-based analysis (IUPAC Technical Report)

This study was conceived to evaluate the global scientific output of secondary organic aerosol (SOA) research over the past 20 years and to assess the characteristics of the research patterns, tendencies, and methods in the papers. Data were based on the online version of Science Citation Index Expanded from 1992 to 2011. Publications referring to SOAs were assessed by distribution of the number of publications and times cited, source categories, source journals, author keywords, Key Words Plus, and the most cited publications in these years. By synthetic analysis of author keywords, Key Words Plus, titles, and abstracts, it was concluded that modeling is currently and will at least over the next decade continue to be the predominant research method to validate state-of-the-art knowledge of SOAs, and that the foci of SOA research will be the key precursors terpenes and isoprene, the mechanisms of oxidation and gas-phase reactions, and emission inventories

Using Variable and Fixed Topological Indices for the Prediction of Reaction Rate Constants of Volatile Unsaturated Hydrocarbons with OH Radicals

mVolatile organic compounds (VOCs) play an important role in differentphotochemical processes in the troposphere. In order to predict their impact on ozoneformation processes a detailed knowledge about their abundance in the atmosphere as wellas their reaction rate constants is required. The QSPR models were developed for theprediction of reaction rate constants of volatile unsaturated hydrocarbons. The chemicalstructure was encoded by constitutional and topological indices. Multiple linear regressionmodels using CODESSA software was developed with the RMSCV error of 0.119 log units.The chemical structure was encoded by six topological indices. Additionally, a regressionmodel using a variable connectivity index was developed. It provided worse cross-validation results with an RMSCV error of 0.16 log units, but enabled a structuralinterpretation of the obtained model. We differentiated between three classes of carbonatoms: sp2-hybridized, non-allylic sp3-hybridized and allylic sp3-hybridized. The structuralinterpretation of the developed model shows that most probably the most importantmechanisms are the addition to multiple bonds and the hydrogen atom abstraction at allylicsites

Accumulation of heavy metals from soil in medicinal plants

Medicinal plants accumulate heavy metals from contaminated soil, and their consumption can cause poisoning. Our objective was to determine the levels of Pb, Cd, Zn, Cu, Fe, and Mn in four medicinal plant species (Achillea millefolium, Hypericum perforatum, Plantago lanceolata, and Urtica dioica) and their native soil, all sampled at a former smelter. The highest soil Cd, Pb, and Zn levels surpassed the maximum allowed limit 75-fold, 48-fold, and 14-fold, respectively. Their soil levels correlated with those in the plants, but this was not the case with Cu, Fe, and Mn. Heavy metal accumulation seems to depend on the plant species, yet even so, medicinal herbs should be cultivated and gathered only from controlled (uncontaminated) areas. Polluted areas should be monitored on a regular basis, while further research should investigate the connection between the heavy metal levels in the soil, their levels available for plants, and the levels extractable from plants

Vsebnost Cu, Mn, Zn, Cd, Cr in Pb v različnih stopnjah pridelave vina

In samples taken during different stages of winemaking process (from grapes, crushed grapes, pressed pomace, must deposit, deposit of lees, must before and after clarification and wine) the Cu, Mn and Zn contents were determined by flame atomic absorption spectrometry (FAAS) and the Cd, Pb and Cr contents were determined by electrothermal atomic absorption spectrometry (ETAAS). Grapes, crushed grapes, pressed pomace, must deposit and deposit of lees were microwave digested with nitric acid, hydrofluoric acid and hydrogen peroxide solution, while for must and wine no special treatments were necessary. The highest contents of Cu, Mn, Zn, Pb, Cd and Cr were determined in the pressed pomace, lees, and in white grape varieties also in must deposit. Mean values obtained of dry weight (pressed pomace, lees, must deposit) were 63 mg/kg, 300 mg/kg, 184 mg/kg for Cu, 11 mg/kg, 15 mg/kg, 134 mg/kg for Mn, 14 mg/kg, 35 mg/kg, 17 mg/kg for Zn, 0.3 mg/kg, 0.5 mg/kg, 0.6 mg/kg for Pb, 0.5 mg/kg, 1.0 mg/kg, 1.8 mg/kg for Cr, 15.4 µg/kg, 24.4 µg/kg, 13.0 µg/kg for Cd. The Cu content was decreasing from the grapes to the bottled wine, whereas the Mn, Zn, Cd, Cr and Pb contents in the bottled wine were higher than in musts in all investigated white and red grape varieties. In ten wine samples the following contents were determined: Cumean 0.12 mg/L (range: 0.06-0.30 mg/L), Mnmean 1.04 mg/L (range: 0.60-1.78 mg/L), Znmean 0.50 mg/L (range: 0.13-1.03 mg/L), Cdmean 0.34 µg/L (range: 0.08-1.04 µg/L), Crmean 17.0µg/L (range: 5.2-25.1 µg/L) and Pbmean 25.3 µg/L (range: 16.4-37.8 µg/L).V vzorcih odvzetih v različnih stopnjah predelave grozdja (v grozdju, drozgi, tropinah, usedlini po razsluzu mošta, v drožeh, v moštu pred in po razsluzu in v vinu) smo določili vsebnost Cu, Mn in Zn s plamensko atomsko absorpcijsko spektrometrijo (FAAS) in vsebnost Cd, Pb in Cr z elektrotermično atomsko absorpcijsko spektrometrijo (ETAAS). Vzorce grozdja, drozge, tropin, usedline po razsluzu mošta in droži smo razkrojili v mikrovalovni peči z dušikovo (V) kislino, fluorovodikovo kislino in vodikovim peroksidom. Za mošt in vino predhodna priprava vzorcev ni bila potrebna. Najvišje vsebnosti Cu, Mn, Zn, Pb, Cd in Cr smo določili v tropinah, drožeh in pri belih sortah grozdja tudi v usedlini po razsluzu mošta. Srednje vrednosti preračunane na suho snov (tropin, droži, usedline po razsluzu mošta) so bile 63 mg/kg, 300 mg/kg, 184 mg/kg za Cu, 11 mg/kg, 15 mg/kg, 134 mg/kg za Mn, 14 mg/kg, 35 mg/kg, 17 mg/kg za Zn, 0.3 mg/kg, 0.5 mg/kg, 0.6 mg/kg za Pb, 0.5 mg/kg, 1.0 mg/kg, 1.8 mg/kg za Cr, 15.4 µg/kg, 24.4 µg/kg, 13.0 µg/kg za Cd. Vsebnost Cu je padala od grozdja do stekleničenega vina. Pri vseh analiziranih belih in rdečih sortah so bile vsebnosti Mn, Zn, Cd, Cr in Pb v stekleničenih vinih višje kot v moštih. V desetih vzorcih vina smo določili naslednje vrednosti: Cusrednja vrednost 0.12 mg/L (območje: 0.06-0.30 mg/L), Mnsrednja 1.04 mg/L (območje: 0.06- 1.78 mg/L), Znsrednja 0.50 mg/L (območje: 0.13-1.03 mg/L), Cdsrednja 0.34 µg/L (območje: 0.08-1.04 µg/L), Crsrednja 17.0 µg/L (območje: 5.2-25.1 µg/L), Pb25.3µg/L (območje: 16.4-37.8 µg/L)

Determination of Cd, Pb and As in sediments of the Sava River by electrothermal atomic absorption spectrometry

Abstract: The applicability of nitric acid, palladium nitrate and a mixture of palladium and magnesium nitrate as matrix modifiers was estimated for the accurate and reproducible determination of cadmium (Cd), lead (Pb) and arsenic (As) in sediments of the Sava River by electrothermal atomic absorption spectrometry, ETAAS. Decomposition of the samples was done in a closed vessel microwave-assisted digestion system using nitric, hydrochloric and hydrofluoric acids, followed by the addition of boric acid to convert the fluorides into soluble complexes. The parameters for the determination of Cd, Pb and As in sediments were optimised for each individual element and for each matrix modifier. In addition, two sediment reference materials were also analysed. In determination of Cd and Pb, nitric acid was found to be the most appropriate matrix modifier. The accurate and reliable determination of Cd and Pb in sediments was possible also in the presence of boric acid. The use of a mixture of palladium and magnesium nitrate efficiently compensated for matrix effects and enabled the accurate and reliable determination of As in the sediments

Determination of Cd, Pb and As in sediments of the Sava River by electrothermal atomic absorption spectrometry

The applicability of nitric acid, palladium nitrate and a mixture of palladium and magnesium nitrate as matrix modifiers were estimated for the accurate and reproducible determination of cadmium (Cd), lead (Pb) and arsenic (As) in sediments of the Sava River by electrothermal atomic absorption spectrometry, ETAAS. Decomposition of the samples was done in a closed vessel microwave-assisted digestion system using nitric, hydrochloric and hydrofluoric acids, followed by the addition of boric acid to convert the fluorides into soluble complexes. The parameters for the determination of Cd, Pb and As in sediments were optimised for each individual element and for each matrix modifier. In addition, two sediment reference materials were also analysed. In determination of Cd and Pb, nitric acid was found to be the most appropriate matrix modifier. The accurate and reliable determination of Cd and Pb in sediments was possible also in the presence of boric acid. The use of a mixture of palladium and magnesium nitrate efficiently compensated for matrix effects and enabled the accurate and reliable determination of As in the sediments. Quantification of Cd and As was performed by calibration using acid matched standard solutions, while the standard addition method was applied for the quantification of Pb. The repeatability of the analytical procedure for the determination of Cd, Pb and As in sediments was ±5 % for Cd, ±4 % for Pb and ±2 % for As. The LOD values of the analytical procedure were found to be 0.05 mg/kg for Cd and 0.25 mg/kg for Pb and As, while the LOQ values were 0.16 mg/kg for Cd and 0.83 mg/kg for Pb and As. Finally, Cd, Pb and As were successfully determined in sediments of the Sava River in Slovenia