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Roskilde, Denmark

Kenessov B.N.,Al-Farabi Kazakh National University | Kenessov B.N.,Wageningen University | Koziel J.A.,Iowa State University | Koziel J.A.,Wageningen University | And 2 more authors.
Analytica Chimica Acta | Year: 2010

The paper describes a novel SPME-based approach for sampling and analysis of transformation products of highly reactive and toxic unsymmetrical dimethylhydrazine (UDMH) which is used as a fuel in many Russian, European, Indian, and Chinese heavy cargo carrier rockets. The effects of several parameters were studied to optimize analyte recovery. It was found that the 85μm Carboxen/polydimethylsiloxane fiber coating provides the highest selectivity for selected UDMH transformation products. Optimal sampling/sample preparation parameters were determined to be 1-h soil headspace sampling time at 40°C. The GC inlet temperature was optimized to 170°C held for 0.1min, then 1°Cs -1 ramp to 250°C where it was held for 40min. Temperature programing resulted in a fast desorption along with minimal chemical transformation in the GC inlet. SPME was very effective extracting UDMH transformation products from soil samples contaminated with rocket fuel. The use of SPME resulted in high sensitivity, speed, small labor consumption due to an automation and simplicity of use. It was shown that water addition to soil leads to a significant decrease of recovery of almost all target transformation products of UDMH. The use of SPME for sampling and sample preparation resulted in detection of the total of 21 new compounds that are relevant to the UDMH transformation in soils. In addition, the number of confirmed transformation products of UDMH increased from 15 to 27. This sampling/sample preparation approach can be recommended for environmental assessment of soil samples from areas affected by space rocket activity. © 2010 Elsevier B.V. Source

Sailaukhanuly Y.,Al-Farabi Kazakh National University | Sarossy Z.,Technical University of Denmark | Carlsen L.,Awareness Center | Egsgaard H.,Technical University of Denmark
Chemosphere | Year: 2014

Chloromethane, accounting for approximately 16% of the tropospheric chlorine, is mainly coming from natural sources. However anthropogenic activities, such as combustion of biomass may contribute significantly as well. The present study focuses on the thermal solid state reaction between pectin, an important constituent of biomass, and chloride ions as found in alkali metal chlorides. The formation of chloromethane is evident with the amount formed being linear with respect to chloride if pectin is in great excess. Thus the reaction is explained as a pseudo first order SN2 reaction between the chloride ion and the methyl ester moiety in pectin. It is suggested that the polymeric nature of pectin plays an active role by an enhanced transport of halides along the carbohydrate chain. Optimal reaction temperature is around 210°C. At higher temperatures the yield of chloromethane decreases due to a thermal decomposition of the pectin. The possible influence of the type of cation is discussed. © 2014 Elsevier Ltd. Source

Bruggemann R.,Leibniz Institute of Freshwater Ecology and Inland Fisheries | Carlsen L.,Awareness Center | Carlsen L.,Kazakh-British Technical University
Match | Year: 2011

Comparison of objects characterized by a multitude of criteria will typically not lead to a linear order, but to a partial order. However, often a linear order is desirable or even required. The present paper presents an improved - extended - approximate local partial order model to estimate a weak or linear order based on averaged ranks of the studied objects originally being partially ordered. The paper analyses various possible partial order scenarios by means of the new local partial order model, the results being compared to the original approach as well as to exact values (their calculation can be extremely time consuming), demonstrating a distinct improvement of the extended method compared to the original local partial order ranking method. By the approximate methods the values of averaged ranks can be understood in terms of three basic partial order parameters. The method is applied to current research on human health effects of rocket fuel transformation products. Source

Sailaukhanuly Y.,Al-Farabi Kazakh National University | Zhakupbekova A.,Al-Farabi Kazakh National University | Amutova F.,Al-Farabi Kazakh National University | Carlsen L.,Al-Farabi Kazakh National University | Carlsen L.,Awareness Center
Chemosphere | Year: 2013

Knowledge of the environmental behavior of chemicals is a fundamental part of the risk assessment process. The present paper discusses various methods of ranking of a series of persistent organic pollutants (POPs) according to the persistence, bioaccumulation and toxicity (PBT) characteristics. Traditionally ranking has been done as an absolute (total) ranking applying various multicriteria data analysis methods like simple additive ranking (SAR) or various utility functions (UFs) based rankings. An attractive alternative to these ranking methodologies appears to be partial order ranking (POR). The present paper compares different ranking methods like SAR, UF and POR. Significant discrepancies between the rankings are noted and it is concluded that partial order ranking, as a method without any pre-assumptions concerning possible relation between the single parameters, appears as the most attractive ranking methodology. In addition to the initial ranking partial order methodology offers a wide variety of analytical tools to elucidate the interplay between the objects to be ranked and the ranking parameters. In the present study is included an analysis of the relative importance of the single P, B and T parameters. © 2012 Elsevier Ltd. Source

Carlsen L.,Awareness Center | Bruggemann R.,Leibniz Institute of Freshwater Ecology and Inland Fisheries
Journal of Chemometrics | Year: 2016

A priori in partial ordering methodology the input data are understood as exact and true values, which is denoted as the "original data matrix". As such even minor differences between values are regarded as real. However, in real life data are typically associated with a certain portion of noise or uncertainty. Hence, introducing noise may cause changes in the overall ordering of objects. The present paper deals with the effects of data noise or uncertainties on the partial ordering of a series of objects, a series of obsolete pesticides being used as an illustrative example. The approach is fuzzy like, and partially ordered sets are obtained as function of noise. A main focus of the work is to identify the range in terms of noise, where the original partial order is retained. We call this range the "stability range". It is demonstrated that by increasing data noise the range where the "original partial order" is obtained decreases. The original partial order is based on the original data matrix. Further, it is found that significant changes in the partial ordering appear outside of this stability range. The possible relation between data noise and the stability range is discussed on an empirical basis. © 2016 John Wiley & Sons, Ltd. Source

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