570 Biowissenschaften; Biologie
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- Explosives (2)
- 2,4,6-trinitrotoluene (1)
- Heatmap (1)
- MALDI-TOF MS (1)
- Matrix-assisted laser desorption/ionization quantification (1)
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The use of explosives has led to a widespread distribution of 2,4,6-trinitrotoluene (TNT) and its by- and degradation products in the soil on former production and testing sites. The investigation of those large contaminated sites is so far based on a few selected soil samples, due to high costs of conventional HPLC and GC analysis, although huge differences in concentrations can already be found in small areas and different collection depths. We introduce a novel high-throughput screening system for those areas, which combines a smartphone-based collection of GPS data and soil characteristics with a fast MALDI-TOF MS quantification of explosives in soil sample extracts and finally a heatmap visualization of the explosives’ spread in soil and an analysis of correlation between concentrations and soil characteristics. The analysis of a 400 m2 area presented an extensive contamination with TNT and lower concentrations of the degradation and by-products aminodinitrotoluenes (ADNT) and dinitrotoluenes (DNT) next to a former production facility for TNT. The contamination decreased in deeper soil levels and depended on the soil type. Pure humus samples showed significantly lower contaminations compared to sand and humus/sand mixtures, which is likely to be caused by an increased binding potential of the humic material. No correlation was found between the vegetation and the concentration of explosives. Since the results were obtained and visualized within several hours, the MALDI-TOF MS based comprehensive screening and heatmap analysis might be valuable for a fast and high-throughput characterization of contaminated areas.
Quantification of nitroaromatic explosives in contaminated soil using MALDI-TOF mass spectrometry
(2019)
Contamination from various sources is a global environmental and health threat, with mining and military activities in particular having spread nitroaromatic compounds, such as 2,4,6-trinitrotoluene and its degradation products and by-products, to the soil. The investigation and monitoring of large contaminated areas requires new detection methods since the established ones are expensive and time-consuming. Hence, we established a matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI--TOF MS) method using 1,5-diaminonaphthalene as the matrix substance and an internal standard for quantification. Analyzing standard substances, we found specific signals for radical and fragment ions of different nitrotoluenes and nitrobenzenes with good reproducibility and detection limits down to 0.25 ng/μL. The analysis of soil sample extracts from a former production site showed clear signals for 2,4,6-trinitrotoluene and the primary degradation products aminodinitrotoluenes. Furthermore, quantification gave results comparable to those obtained by conventional liquid chromatography--tandem mass spectrometry analysis. The MALDI-TOF MS method has a comparatively lower reproducibility, with relative standard deviations of 6% to 20% for multiple measurements of standard solutions and soil sample extracts. Nevertheless, a comparison of both methods revealed the advantages of MALDI-TOF MS analysis of explosive-contaminated areas with regard to costs, time, and handling. Finally, our MALDI-TOF MS method fulfills all the needs for high sample throughput and can therefore be a valuable screening tool for explosive-contaminated areas.
Kaffee ist das wohl populärste Heißgetränk weltweit. Zwei botanische Arten sind für den Weltmarkt von Bedeutung und unterscheiden sich bezüglich ihres Anbaugebietes und der Inhaltsstoffe. Kaffee enthält über 850 bisher identifizierte Aromastoffe, welche den Geschmack bilden. Außerdem haben die Prozessierung der geernteten Kirsche bis zur Bohne, das Röstprofil und das Aufbrühen einen großen Einfluss darauf. In dieser Arbeit wurde die Auswirkung der Prozessierungsmethode auf ausgewählte Inhaltsstoffe mit Hilfe der Flüsssig-Chromatographie-Tandem-Massenspektroskopie (LC-MS/MS) untersucht. Dafür wurden drei Prozessierungsmethoden, die unterschiedlich viel Wasser für das Ablösen des Fruchtfleisches von den Kaffeekirschen benötigen, und zwei Kultursorten miteinander verglichen. Die Ergebnisse zeigten einen geringfügig höheren Gehalt der zwei wichtigsten Inhaltsstoffe Koffein und Chlorogensäure in den Bohnen, bei deren Prozessierung im Eco-Pulper-Verfahren weniger Wasser eingesetzt wurde. Bis auf einen verringerten Gehalt an Saccharose wurde für weitere wichtige Inhaltsstoffe (Acrylamid, Niacin, Zitronensäure und Vanillin) kein signifikanter Unterschied bei höherem Wassereinsatz gefunden. Insofern man die untersuchten Inhaltsstoffe als Qualitätsmarker betrachtet, ist im Vergleich zu den anderen Prozessierungsmethoden das Eco-Pulper-Verfahren die beste Wahl, insbesondere da es als wassersparende Methode einen entscheidenden Beitrag zur Nachhaltigkeit des Kaffeeanbaus leistet.