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Cordeiro F.,European Commission | Robouch P.,European Commission | De La Calle M.B.,European Commission | Emteborg H.,European Commission | And 2 more authors.
Journal of AOAC International | Year: 2011

A collaborative study, International Evaluation Measurement Programme®-25a, was conducted in accordance with international protocols to determine the performance characteristics of an analytical method for the determination of dissolved bromate in drinking water. The method should fulfill the analytical requirements of Council Directive 98/83/EC (referred to in this work as the Drinking Water Directive; DWD). The new draft standard method under investigation is based on ion chromatography followed by post-column reaction and UV detection. The collaborating laboratories used the Draft International Organization for Standardization (ISO)/Draft International Standard (DIS) 11206 document. The existing standard method (ISO 15061:2001) is based on ion chromatography using suppressed conductivity detection, in which a preconcentration step may be required for the determination of bromate concentrations as low as 3 to 5 μg/L. The new method includes a dilution step that reduces the matrix effects, thus allowing the determination of bromate concentrations down to 0.5 μg/L. Furthermore, the method aims to minimize any potential interference of chlorite ions. The collaborative study investigated different types of drinking water, such as soft, hard, and mineral water. Other types of water, such as raw water (untreated), swimming pool water, a blank (named river water), and a bromate standard solution, were included as test samples. All test matrixes except the swimming pool water were spiked with high-purity potassium bromate to obtain bromate concentrations ranging from 1.67 to 10.0 μg/L. Swimming pool water was not spiked, as this water was incurred with bromate. Test samples were dispatched to 17 laboratories from nine different countries. Sixteen participants reported results. The repeatability RSD (RSDr) ranged from 1.2 to 4.1%, while the reproducibility RSD (RSDR) ranged from 2.3 to 5.9%. These precision characteristics compare favorably with those of ISO 15601. A thorough comparison of the performance characteristics is presented in this report. All method performance characteristics obtained in the frame of this collaborative study indicate that the draft ISO/DIS 11206 standard method meets the requirements set down by the DWD. It can, therefore, be considered to fit its intended analytical purpose. © 2012 Publishing Technology. Source


Salem M.,Cairo University | Salem M.,Justus Liebig University | Heydel C.,Justus Liebig University | El-Sayed A.,Cairo University | And 3 more authors.
Tropical Animal Health and Production | Year: 2012

Mycobacterium avium subspecies paratuberculosis is considered as one of the most serious problems affecting the world's ruminant industry due to its significant impact on the global economy and the controversial issue that it may be pathogenic for humans. M. avium subspecies paratuberculosis is the causative agent of Johne's disease in animals and might be implicated in cases of human Crohn's disease. We provide an insight into M. avium subspecies paratuberculosis from some bacteriological, clinical, and molecular epidemiological perspectives. © 2012 Springer Science+Business Media Dordrecht. Source


Riemenschneider C.,Landesbetrieb Hessisches Landeslabor LHL | Riemenschneider C.,Justus Liebig University | Zerr W.,LHL | Vater N.,Landesbetrieb Hessisches Landeslabor LHL | And 3 more authors.
Bioresource Technology | Year: 2014

A new analytical method for the determination of colistin in fermenter samples was developed followed by a study on the behavior of this substance during anaerobic fermentation. Analysis of colistin A and B was carried out by liquid chromatography-tandem mass spectrometry. Separation of the analytes was performed on a Security Guard column (4. ×. 3. mm). Fourteen fermentation tests in batch as well as in continuous reactors were carried out. After 44. days of anaerobic digestion of cattle manure, initially spiked with 500. mg/kg of colistin sulfate, a considerable decrease of the colistin concentration to less than 1. mg/kg could be observed. Furthermore, the daily production of biogas and methane was measured. A correlation between gas production and colistin concentration could not be determined. However, an increase of 10% of the cumulative methane production was observed in those fermenters spiked with an initial bolus of 500. mg/kg colistin. © 2014 Elsevier Ltd. Source


Kampmann K.,Justus Liebig University | Ratering S.,Justus Liebig University | Geissler-Plaum R.,Justus Liebig University | Schmidt M.,Landesbetrieb Hessisches Landeslabor LHL | And 2 more authors.
Bioresource Technology | Year: 2014

Two parallel, stable operating biogas reactors were fed with increasing amounts of maize silage to monitor microbial community changes caused by overloading. Changes of microorganisms diversity revealed by SSCP (single strand conformation polymorphism) indicating an acidification before and during the pH-value decrease. The earliest indicator was the appearance of a Methanosarcina thermophila-related species. Diversity of dominant fermenting bacteria within Bacteroidetes, Firmicutes and other Bacteria decreased upon overloading. Some species became dominant directly before and during acidification and thus could be suitable as possible indicator organisms for detection of futurity acidification. Those bacteria were related to Prolixibacter bellariivorans and Streptococcus infantarius subsp. infantarius. An early detection of community shifts will allow better feeding management for optimal biogas production. © 2014 Elsevier Ltd. Source


Kampmann K.,Justus Liebig University | Ratering S.,Justus Liebig University | Baumann R.,Justus Liebig University | Schmidt M.,Landesbetrieb Hessisches Landeslabor LHL | And 2 more authors.
Systematic and Applied Microbiology | Year: 2012

Methanogenic communities in 200L biogas reactors containing liquid manure were investigated for 33d. The reactors were consecutively fed with casein, starch and cream. Real-time PCR with primers targeting the gene for methyl coenzyme-M reductase (mcrA) resulted in copy numbers of up to 2.1×109gdrymass-1. Single strand conformation polymorphism (SSCP) analysis revealed a stable community consisting of few hydrogenotrophic methanogens. One of the two most abundant species was closely related to Methanospirillum hungatei, whereas the other one was only distantly related to other methanogens, with Methanopyrus kandleri being the closest cultivated relative. Most probable number (MPN) cultivations were accomplished with a sample from a 600m3 reactor from which all manures used in the experiments originated, and equal cell counts of ca. 109gdrymass-1 were found for cultivations with acetate, H2 and methanol. SSCP analysis of these samples and sequencing of the DNA bands identified different hydrogenotrophic methanogens in all samples, and acetoclastic methanogens closely related to Methanosarcina mazei in the samples cultivated with acetate and methanol. As the acetoclastic species were not found in any other SSCP sample, it was supposed that the ammonia values in the manure of the laboratory biogas reactor, which ranged from 2.48 to 3.61gNH4-NL-1, inhibited the growth of the acetoclastic methanogens. © 2012 Elsevier GmbH. Source

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