Žilvinas Ežerinskis

Determination of 129I in Arctic snow by a novel analytical approach using IC-ICP-SFMS

The environmental radiation background has increased in the last century due to human nuclear activities and in this context 129I may be used to evaluate the anthropogenic contribution to global nuclear contamination. We present a fast and novel method for iodine-129 measurements. Coupling ion chromatography and inductively coupled plasma sector field mass spectrometry (IC-ICP-SFMS) allows the determination of iodine-129 at picogram per gram levels. The capability of the Dionex IONPAC® AS16 column to retain iodine species in the absence of NaOH has been used to pre-concentrate 5 mL samples. Although 129I suffers from isobaric spectral interference due to the presence of 129Xe, the IC-ICP-SFMS technique allows 129I to be determined by removing all other isobaric interferents. Furthermore, the 129Xe interference is sufficiently small and stable to be treated as a background correction. This strategy permits the evaluation of 129I speciation at sub-picogram per gram levels with a limit of detection (LOD) of 0.7 pg g−1. Thus the range of possible applications of this technique is expanded to low-concentration environmental samples such as polar snow. Preliminary results obtained from Greenland (NEEM) snow pit samples confirm its applicability in environmental research.

Method of standard additions for arsenic measurements in water by ICP sector field mass spectrometry at accuracy comparable to isotope dilution

Mathematical model of the method of additions was reviewed to exclude the dilution and mass irreproducibility effects and assure the linear calibration. Selenium was identified as a high quality internal standard for arsenic measurements. At increased ratio measurement accuracy instrumental effects are important, and capabilities of the instrument must be carefully tested and accounted for. In measurements with double focusing electric and magnetic fields mass spectrometer Element 2 at medium mass resolution need for full integration of the peaks and role of the low frequency noise was evident. Averaging of the final results provided better accuracy of determination in comparison to the mean values of the intermediate data. If suitable internal standards can be selected, the method of standard additions is found to provide measurement accuracy comparable to that of isotope dilution. Comparison of the analytical signal of the test sample from direct measurements and the calibration graph is recommended as a test of the level of compensation for the possible matrix effects.

Aerosol source (biomass, traffic and coal emission) apportionment in Lithuania using stable carbon and radiocarbon analysis

ABSTRACT In the present study, a combination of the stable carbon isotope ratio (13C/12C) with radiocarbon data (14C) allowed us to perform the aerosol source apportionment. Filter samples of PM1 were collected during the warm and cold periods in rural and urban sites in Lithuania. The 14C/12C ratio of total carbon (TC) was measured using the single stage accelerator mass spectrometer quantifying of fossil and non-fossil derived aerosol emissions. The δ13C value was measured using an elemental analyser interfaced with an isotope ratio mass spectrometer. We have found that the highest fraction of contemporary carbon (fc = 0.82) was measured during a warm period in a rural location. A higher fraction of fossil fuel-derived carbon was observed for air masses transported from highly industrialized Western European regions during both seasons. Isotope mass balance calculations revealed that the traffic emissions composed 15 and 25 % in rural and urban sites, respectively, and did not change during either season. Input from coal-derived aerosol particles was estimated to be 15 % at an urban site during the cold period. The combination of the stable carbon isotope ratio with the radiocarbon data allowed us to distinguish coal, liquid fossil fuel combustion, and non-fossil derived aerosol particle emissions.

Effect of matrices with low second ionization potentials on analytical signals in inductively coupled plasma mass spectrometry

A low second ionization potential element matrix reduces the mass spectrometric analytical signals at matrix concentrations as low as milimoles. The matrix effects on different analytes and argon are similar and can be accounted for by application of a single internal standard at an accuracy of about 20%. For a higher accuracy, the analyte specific internal standards have to be selected and/or proper matrix reference materials and dilution of samples should be used. Typically, the degree of the double to single ionization is also suppressed in the presence of the matrix while a small increase in the ionization temperature is observed. The increase of the temperature can be caused by the lower energy losses to ionization in the presence of a matrix. We discuss secondary effects such as an increase of the temperature gradients, the ionization degree and ambipolar diffusion. We point out the possibility of charge transfer from argon to the doubly ionized ions in lanthanides and in some transition group elements and discuss the role of this phenomenon to the matrix effect.

Dietary aspects of the West Lithuanian people during the Late Roman and Early Migration periods with reference to household and funerary pottery

Zusammenfassung Die vorliegende Studie präsentiert die Ergebnisse einer integrierten interdisziplinären Untersuchung von Rückständen verkohlten organischen Materials bzw. Lebensmittelkrusten, die auf der inneren Keramikoberfläche haften und eine wertvolle Informationsquelle für die menschliche Ernährung darstellen. FTIR und Isotopenverhältnis-Massenspektrometrie wurden verwendet, um Haushaltsgefäßen und Miniaturtöpfen zu analysieren, die in der Zeit zwischen dem 3. und der Mitte des 5. Jahrhunderts in Westlitauen mit Toten als Beigaben in Vestattungen gelangten. Die δ13C-Isotopenanalyse zeigt einen beträchtlichen Unterschied zwischen den Rückständen von Haushalts- und Grabkeramik. Die δ13C-Isotopenverhältnisse in den Proben von Miniaturpotentiometern variieren von −28,0 ‰ bis −28,8 ‰. Isotopenwerte in einem relativ engen Bereich weisen darauf hin, dass in den Töpfen vorhandenes organisches Material ähnlichen Ursprungs war. δ13C-Isotopenverhältniswerte lassen vermuten, dass niedergelgte Miniaturtöpfe mit Bier aus Gerste und/oder Hafer gefüllt waren. Der δ15N-Isotopenwert (δ15N = 8,0 ‰) und die Carboxyl-Gruppe der C-O-Gruppe sowie die Polysaccharide zeigen das Vorhandensein von Proteinen in einigen der Miniaturtöpfen an, so dass außerdem angenommen werden kann, dass diese mit fermentiertem Milchgetränk gefüllt waren. Die Miniaturtöpfe wurden in den Bestattungen platziert und mit einer symbolischen Menge Bier oder fermentierten Getränken auf Milchbasis gefüllt (40/50 bis 100 ml). Das Kohlenstoffisotopenverhältnis der Haushaltsgefäße variierte von −23,9 ‰ bis −27,9 ‰, was auf eine auf Getreide vom Typ C3 basierende Ernährung hindeutet. Die aus organischen Rückständen gewonnenen δ15N-Werte liegen zwischen 3,1 ‰ und 9,9 ‰, was als Hinweis zu verstehen ist, dass Bestandteil der menschlichen Ernähung auch Pflanzen- und Allesfresser waren. Zusammenfassend zeigt die Analyse, dass die konsumierte Nahrung terrestrischen Ursprungs ist und aus der Landwirtschaft und der Tierzucht stammt.