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Für die vom Bundesumweltministerium vorgesehene Mantelverordnung sind validierte Unter-suchungsmethoden erforderlich. Dazu gehört auch die Herstellung von wässrigen Eluaten, z.B. zur Beurteilung der Mobilität von Schadstoffen und der Ableitung von Grenzwerten.
Ziel des Vorhabens war es, auf der Grundlage geeigneter Testmaterialien (mit prioritären organischen Schadstoffen kontaminierte Böden und Bodenmaterialien) Ringversuche zur Validierung des Schüttelverfahrens nach E DIN 19527 und des Säulenverfahrens für die Übereinstimmungs-untersuchung nach DIN 19528 durchzuführen. Auf der Grundlage der Untersuchungsergebnisse sollten beide Normen bezüglich der Vorgehensweise präzisiert werden und es sollten die während des Ringversuchs ermittelten Verfahrenskenndatenn zur Validierung der Normen herangezogen werden. Darüber hinaus sollten Säulen- und Schüttelverfahren als Übereinstimmungstest vergleichend bewertet werden.
Es wurden vier geeignete Ringversuchsmaterialien hergestellt und an insgesamt 18 Ringversuchsteilnehmer ausgegeben. Die Auswertung der Ringversuche erfolgte auf der Grundlage klassischer Statistik nach DIN ISO 5725 mit Hilfe der AuswertesoftwareProLab 2011 (quo data).
Auf der Grundlage der Validierungsringversuche wurden die Verfahrenskenndaten für die Norm DIN 19527 ermittelt. Die statistische Auswertung der eingereichten Datensätze war aufgrund der großen Streubreite der Daten schwierig. Die vorgeschriebenen statistischen Methoden zur Datenauswertung adressieren die Behandlung nicht gleichverteilter Datensätze nur ungenügend. Das muss bei der Bewertung der Ergebnisse und deren Zuverlässigkeit berücksichtigt werden.
Generell kann festgestellt werden, dass keine signifikanten Unterschiede zwischen den Ergebnissen der Schüttel- und Säulenelution beobachtet werden. Dabei werden beim Schüttelverfahren tendenziell etwas geringere Gesamtmittelwerte erzielt als beim Säulenverfahren, die berechneten Vergleichsvariationskoeffizienten sind für das Schüttelverfahren meist etwas niedriger. Dennoch erweisen sich beide Elutionsverfahren bei den eingesetzten Ringversuchsmaterialien als gut vergleichbar.
The occurrence of persistent organic pollutants like polychlorinated biphenyls (PCB) and organochlorine pesticides (OCP) in the environment is still a matter of concern, even years after their use was abolished. Hence, threshold values are regulated by law which reference a number of national and international standards for determination of said contaminants. In this context, soil is an especially difficult matrix, because several defining parameters can vary in a wide range. Organic matter content in particular has a crucial influence on extractability of contaminants because it largely governs formation of non-extractable or bound residues.
For this study, four soils of different total organic carbon (TOC) content were generated from uncontaminated reference soil (RefeSol 01-A) and compost which were spiked to contaminant levels representative of the Bundes-Bodenschutz-Verordnung (BBodSchV). These test materials were extracted using accelerated solvent extraction (ASE), Soxhlet extraction, and liquid-liquid extraction. For the latter method, samples were initially extracted for 15 minutes employing acetone. The follow-up extraction step was carried out using cyclohexane and the extraction time varied between 15 minutes and 16 hours. After clean-up, extracts were analysed via gas chromatography-mass spectrometry (GC MS) and with a gas chromatograph equipped with an electron capture detector (GC ECD).
Statistical analysis of the experimental values showed that recovery was not dependent on matrix TOC content. Also, no clear preference for a single method could be detected. Concerning liquid-liquid-extraction, it is merely observed that prolonged extraction time results in slightly higher recoveries, while moderate extraction times appear to yield the most robust results. Although Soxhlet and ASE show high recoveries, they also lead to larger standard deviations and are not suitable for determination of thermolabile pesticides.
In addition to recovery by different extraction methods, the agreement of values obtained by ECD and MS was evaluated. For ECD, standard deviations are generally higher but overall the values obtained by MS and ECD are comparable.
The determination of organochlorine pesticides (OCP) and polychlorinated biphenyls is challenging because they are strongly physical and chemical bound to soil organic matter. There are various valid standards for the determination of these analytes in soil that differ especially in the extraction method and extraction time. In order to make profound assessments concerning the extraction efficiency seven extraction procedures namely pressurized liquid extraction (PLE), soxhlet and shaking with different extraction times 0.5 h, 1 h, 3 h, 6 h and 16 h were compared. For the study four soils of different total organic carbon (TOC) content were generated from uncontaminated reference soil and compost which were spiked to contaminant levels representative of the Bundes-Bodenschutz-Verordnung. Clean-up and measurement conditions using gas chromatography with mass spectrometry (GC-MS) were kept constant. Statistically analysis of the experimental values showed that recovery rates were not dependent on matrix TOC content. In consideration of measurement uncertainties of 10% - 20% for the determination of OCP and PCB in soil no differences in the efficiency between the tested extraction procedures could be observed.
Ziel des Vorhabens ist es, die Robustheit des Schüttelverfahrens nach E DIN 19527 mit einem Wasser-/Feststoffverhältnis von 2 l/kg für unterschiedliche Bodenarten und Bodenmaterialien zu überprüfen. Gleichzeitig soll bei diesen Untersuchungen das Stoffspektrum auf weitere prioritäre organische Kontaminanten erweitert werden. Dies stellt die Voraussetzung für die Durchführung von Ringversuchen zur Validierung der Norm DIN 19527 dar.
A procedure for the quantification of the PCB marker congeners 28, 52, 101, 138, 153, 180 in plastic waste form the recycling of cables in the range of content between 0.1 mg kg-1 and 20 mg kg-1 was validated. Representative reference materials for laboratory analyses were produced using granulates from different recycling processes. The method development included aspects of grinding, sieving, homogenising as well as the comparison of extraction methods and chromatographic conditions. The validated procedure foresees grinding of the technical sample to an upper particle size limit of 0.50 mm followed by extraction with an unpolar solvent such as n-hexane and gas chromatographic determination. LOD and LOQ for individual congeners ranged between 0.01 mg kg-1 and 0.08 mg kg-1. Electron capture detection (ECD) and mass selective detection (MS) were equivalent if chromatographic conditions were appropriately selected. The application of MS was advantageous in presence of significant amounts of interfering components which have been found in some cables.
Three reference materials containing the marker congeners in the range of 0.1 mg kg-15 mg kg-1 were submitted to a final validation intercomparison with 23 selected field laboratories using the developed method. Relative reproducibility standard deviations varied between 15% and 33%.
Evaluation of methods for the analysis of soils according to § 8 of the German Federal Soil Protection Act (BBodSchG)
The German Federal Soil Protection Act establishes the conditions for effective soil protection and remediation of contaminated sites. In the German Federal Soil Protection and Contaminated Sites Ordinance (BBodSchV) limiting values and methods for the determination of environmentally harmful substances in soils are fixed. The aim of this project was to evaluate selected methods by comparative investigations and proficiency testing schemes. New methods for the determination of inorganic and organic pollutants should be developed and compared with the existing standard
methods. Despite the widespread use of ICP-OES up to now no national or international standard is available for the determination of heavy metals in soil extracts with this analytical method. The influence of spectral and non spectral interferences on the accuracy of the results was systematically investigated, especially based on aqua regia soil extracts. Analyte concentration equivalents were determined, too. Based on these results a proposal for a standard was submitted to the corresponding working group of ISO TC 190.[...]