Heinrich Baumann

Rapid and sensitive determination of iodine in fresh milk and milk powder by inductively coupled plasma - mass spectrometry (ICP-MS)

SummaryA rapid and sensitive method for the determination of iodine in fresh milk and milk powders by inductively coupled plasma — mass spectrometry is described. The method is applied to the analysis of the two standard reference materials BCS-CRM Nos. 63 and 150. The iodine concentrations found in these materials are 0.28±0.01 μg/g and 1.21±0.01 μg/g, respectively. In fresh milk, iodine concentrations between 50 and 2300 ng/ml were determined. The ICP-MS results for these milk samples are compared to the results which were obtained by a chemical method and by X-ray fluorescence analysis. Because of the simple sample preparation and the good sensitivity and selectivity ICP-MS is the only method which allows the determination of iodine in milk samples down to the lower ng/ml range together with a high sample throughput.

Solid sampling with inductively coupled plasma-mass spectrometry — a survey

SummaryThis survey presents the approaches to solid sample introduction with ICP-MS, including electrothermal vaporization, direct sample insertion, laser ablation, arc nebulization, and slurry nebulization. The main characteristics of these sample introduction techniques with regard to their combination with ICP-MS are discussed and examples of applications are given. The analytical aspects of these relatively new techniques are critically evaluated.

Atmospheric distribution of particulate lead over the Atlantic Ocean from Europe to Antarctica

Concentrations of lead in aerosols over the Atlantic Ocean were measured between 50 °N and 70°S during different expedition legs of the German polar research ship FS Polarstern in 1984 and 1985. The Pb concentrations varied from 0.008 to 66 ng m−3. High Pb concentrations have been found near regions with high industrial activities. The highest values were detected near the west coast of Europe and in some coastal regions of South America. Measurements where Fe beside Pb was determined as a crustal element, show in their Pb/Fe ratio that anthropogenic and other non-crustal sources significantly influence the atmospheric lead concentration near the coast of West Africa (south of Dakar) and South America. The measured Pb/Fe ratios over the ocean between both continents are much lower, but still higher than the crustal Pb/Fe ratio. Very low Pb concentrations in the range of 0.1–3 ng m−3 were measured between the African and South American continents near the equator and around the South Shetland Islands near the Antarctic Peninsula. However, the lowest Pb concentrations of 8–25 pg m−3 were found in aerosols over the Ekstrom ice shelf in Antarctica, near the ice edge. The present study has resulted in one of the most extensive global distribution patterns of this important trace element so far. In addition, the analysis by isotope dilution mass spectrometry guarantees accurate results down to an atmospheric level of a few pg Pb m−3 if contamination is under control.

Analysis of organobromine compounds and HBr in motor car exhaust gases with a GC/microwave plasma system

SummaryIn this investigation an analytical procedure for the determination of different organobromine compounds in motor car exhaust gases is developed in order to obtain a total balance of these compounds in this type of exhaust gas. For this purpose, adsorption sampling on Tenax GC combined with thermal desorption and a fast cold trap injection into the GC column system is used. A special capillary cold trap/thermodesorption system for a fast injection within 1 s is developed. The chromatographically separated fractions are identified by their retention times and elementspecific detection with a microwave plasma detector. Methyl bromide, 1,2-dibromoethane, and vinyl bromide are analysed in exhaust gases in cases where the gasoline contains 1,2-dibromoethane as an additive (leaded gasoline). The analysed bromine contents, which correspond to these organobromine compounds, are in the range of 90–190 μg/m3, 15–85 μg/m3, and 5–20 μg/m3, respectively. The portion of the organobromine compounds is 22–44% of the total bromine which is emitted by the exhaust gases. The other portion contains mainly inorganic particulate bromide, which can be separated by filters. The concentration of the organobromine compounds decreases with increasing motor temperature. After conversion into 2-bromocyclohexanol and after gas chromatographic separation HBr is detected to be 5.8 μg bromine per m3 exhaust gas, which corresponds to approximately 1% of the total bromine emission. 1,2-Dichloroethane is analysed in the range of 5–35 μg Cl/m3, whereas the concentration of tetraalkyl lead in the exhaust gases is less than the detection limit of 6.7 μg Pb/m3. The average bromine/lead ratio found in the filterable portion of the exhaust gases is 0.30 (by weight); the same ratio calculated for total bromine emission including the organobromine compounds is 0.47. Compared with the bromine/ lead ratio in gasoline of 0.39 this means that at least 17% of the total lead in the gasoline is not directly emitted with the motor car exhaust gases.

Determination of trace impurities in electronic grade quartz: Comparison of inductively coupled plasma mass spectroscopy with other analytical techniques

An analytical procedure for the determination of uranium and thorium in the sub-ng/g range as well as of other trace elements in the ng/g to μg/g range in high purity quartz samples is described. The results obtained by inductively coupled plasma mass spectroscopy (ICP-MS) are compared to those obtained by other analytical techniques (instrumental neutron activation analysis, INAA; flame atomic absorption spectrometry, AAS; Zeeman graphite furnace atomic absorption spectrometry, ZGFAAS; total reflection X-ray fluorescence analysis, TRFA; direct current arc optical emission spectrometry, DC-arc OES; and X-ray fluorescence analysis, XRFA). For the ICP-MS measurements, the decomposition of the samples is carried out with HF/HNO3/H2SO4-mixtures. The results obtained by the different methods show reasonable agreement. For uranium and thorium, ICP-MS proves to be the most sensitive method: detection limits of about 50 pg/g can be achieved for both elements.

Sequential multielement analysis of a single aerosol filter by different instrumental and wet-chemical methods

SummaryThe direct instrumental methods X-ray fluorescence spectrometry (XRFS) and instrumental neutron activation analysis (INAA), and, after digestion of the sample, inductively coupled plasma mass spectrometry (ICP-MS) were applied in sequence to analyse small single aerosol filters. XRFS detected up to 19, INAA up to 22, and ICP-MS up to 33 elements. In total, up to 45 elements were determined, and, for a number of additional elements limits of detection could be given. For many elements, the data quality could be checked by cross-comparison of the results of two or all three methods. These methods very meaningfully complement each other and, in the manner used, allow the determination of all elements of interest in a small aerosol filter sample.

Brom/Blei-Verhältnisse in Aerosolen und Autoabgasen

SummaryIn principle, the determination of Br/Pb- ratios in aerosols opens the possibility to get information on the source of the corresponding emission or on the history of the aerosol. Up to now, different results were obtained in a number of investigations where the Br/Pb-ratio in aerosols was analysed and compared with the same ratio in gasoline. In order to exclude analytical errors during the investigations of this work, the definitive method of isotope dilution mass spectrometry is used to determine the Br/Pb ratios. It could be shown that in aerosols and motorcar exhausts the Br/Pb-ratio is lower than it is given by the additives included in gasoline. In aerosols a Br/Pb-ratio is found in summer time which is lower than in autumn. Additionally, the same is true for aerosols which were collected during rainfalls compared with dry weather. Model experiments have shown that a wrong Br/Pb-ratio can be determined with filters where lead bromide is deposited. Different transportation mechanisms take place for lead and bromine by sucking air mixed with CO2, SO2 or NOx through the filter which leads to a decrease of the Br/Pb ratio. It was also found that bromoorganic compounds which have not been converted into inorganic bromide in the motor can result in a lower Br/Pb-ratio in the inorganic part of the exhaust compared with the composition of gasoline.ZusammenfassungDie Bestimmung von Br/Pb-Verhältnissen in Aerosolen eröffnet grundsätzlich die Möglichkeit, auf die Verursacherquelle einer entsprechenden Emission schließen zu können oder eine Aussage über die Vorgeschichte der Aerosole zu erhalten. Im Vergleich zu den Br/ Pb-Verhältnissen im Benzin haben bisherige Untersuchungen von Aerosolen zu sehr unterschiedlichen Ergebnissen geführt. Um bei solchen Untersuchungen Analysenfehler weitgehend auszuschließen, wird im Rahmen dieser Arbeit erstmals die definitive Methode der massenspektrometrischen Isotopenverdünnungstechnik zur Bestimmung der Br/ Pb-Verhältnisse angewandt. Dabei zeigt sich, daß sowohl bei Aerosolen als auch bei Autoabgasen stets ein niedrigeres Br/Pb-Verhältnis gefunden wird, als dies durch die im Benzin enthaltenen Additive vorgegeben ist. In Aerosolen der Luft wird im Sommer ein niedrigeres Br/Pb-Verhältnis gemessen als im Herbst. Gleiches gilt für Aerosolproben, die bei regnerischem im Vergleich zu trockenem Wetter gesammelt werden. Modellversuche zeigen, daß man leicht Fehler in der Br/Pb-Bestimmung dadurch machen kann, daß primär auf Filtern deponierte Blei- und Bromidionen durch die in der Luft vorhandenen Gase CO2, SO2 und NOx in unterschiedlichem Maße wieder vom Filter verflüchtigt werden können, was zu niedrigeren Br/Pb-Verhältnissen führen kann. Weiterhin ergibt sich, daß vom Motor nicht umgesetzte bromorganische Verbindungen offensichtlich bereits für eine Ernie drigung des Br/Pb-Verhältnisses im anorganischen Teil des Abgases gegenüber der Benzinzusammensetzung sorgen.