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Ostrowiec Świętokrzyski, Poland

Buszewski B.,Nicolaus Copernicus University | Michel M.,Plant Protection Institute NRI
Journal of AOAC International | Year: 2010

Crop models use mathematical equations to simulate the physical and chemical processes that generally control the uptake, translocation, and sorption of pesticides in all parts of plants. Our interest is focused on method optimization to determine the new compounds using stationary and mobile phases with different physicochemical properties. The work deals with five fungicides composed of nitrogen-containing heterocycles, 1,2,4-triazoles. The sample preparation liquid extraction and solid-phase-based methods are used to determine and model the pesticide residues in plants organisms. Analysis of these compounds is generally carried out by GC or HPLC coupled to different detectors, especially to mass spectrometers, in hyphenated techniques that have been extremely developed in recent years. The relationships between the chromatographic retention factor (k) and those physicochemical properties that are relevant in quantitative structure-retention relationship (QSRR) studies were investigated. The accuracy of the simple linear regressions between the chromatographic retention and the descriptors for all of the compounds was satisfactory (correlation coefficient 0.83 ≤ R2 ≤ 0.99). The QSRR models of these nitrogen-containing heterocyclic compounds could be predicted with a multiple linear regression equation having the statistical index R2 = 1.00. Evaluation of chromatographic properties of the new stationary phases and description of the molecular separation mechanism using the QSRR method, including molecular modeling, were performed. A universal model is presented that links the physicochemical parameters describing the fungicide compounds with the anatomical, physiological, and biochemical properties of the plant. Source


Buszewski B.,Nicolaus Copernicus University | Michel M.,Plant Protection Institute NRI
Talanta | Year: 2011

Poland's Senate establishes 2011 as the Year of Maria SkÆodowska- Curie, in order to promote awareness of her great contribution to the development of global science. Maria SkÆodowska-Curie is the only scientist in history to receive the Nobel Prize twice, once in physics (1903) for the discovery of radioactivity and once in chemistry (1911) for the discovery of polonium and radium and studies concerning the nature of these elements. The Royal Swedish Academy of Sciences awarded Pierre Curie, Maria Curie, and Henri Becquerel the Nobel Prize in Physics, in recognition of the extraordinary services they have rendered by their joint research on the radiation phenomena discovered by Professor Henri Becquerel. Maria SkÆodowska-Curie was awarded the Nobel Prize in Chemistry in 1911. The citation by the Nobel Committee was, in recognition of her services to the advancement of Chemistry by the discovery of the elements radium and polonium, by the isolation of radium and the study of the nature and compounds of this remarkable element. Source


Michel M.,Plant Protection Institute NRI
Journal of Liquid Chromatography and Related Technologies | Year: 2010

Author interest is focused on method optimization to determine the new compounds using stationary and mobile phases with different physicochemical properties. This work deals with 5 substances composed of nitrogen containing heterocycles, 1,2,4-triazoles. The relationships between the chromatographic retention factor (k) and those physicochemical properties which are relevant in quantitative structure retention relationship (QSRR) studies were investigated. The accuracy of the simple linear regressions between the chromatographic retention and the descriptors for all of the compounds was satisfactory (correlation coefficient, 0.8≤r2≤1.0). The QSRR models of compounds could be predicted with a multiple linear regression equation having the statistical index, r2=1.000. Evaluation of chromatographic properties of the new stationary phases and description of the molecular separation mechanism using the QSRR method including molecular modeling will be suggested. Source


Buszewski B.,Nicolaus Copernicus University | Gadzala-Kopciuch R.,Nicolaus Copernicus University | Michel M.,Plant Protection Institute NRI
Accreditation and Quality Assurance | Year: 2011

The chemical and physical properties of the stationary and the mobile phase determine the retention and selectivity of the separated molecules in chromatographic process. It should explain the specific and non-specific interactions in the chromatographic system. Special emphasis should be placed on column selection through the adequate choice of column dimensions (diameter and length) and the type of stationary phase with required parameters, which contributes the system effectiveness. However, column effectiveness is unable to guarantee a satisfactory level of substance separation. For this reason, the interactions between the analyte, the stationary and the mobile phase need to be investigated to determine the retention factors of the separated substances and the optimal parameters of the chromatographic system. According to the principles of thermodynamics, in particular molecular interactions, the chromatographic process has to be carried out with a high level of control. This work can be treated a brief tutorial devoted to thermodynamics of liquid chromatography process with a special emphasis on molecular interactions between analyte species and the components of the mobile and stationary phases. © 2011 Springer-Verlag. Source


Michel M.,Plant Protection Institute NRI | Chimuka L.,Nicolaus Copernicus University | Chimuka L.,University of Witwatersrand | Kowalkowski T.,Nicolaus Copernicus University | And 2 more authors.
Journal of Separation Science | Year: 2013

An artificial neural network model of supported liquid membrane extraction process with a stagnant acceptor phase is proposed. Triazine herbicides and phenolic compounds were used as model compounds. The model is able to predict the compound extraction efficiency within the same family based on the octanol-water partition coefficient, water solubility, molecular mass and ionisation constant of the compound. The network uses the back-propagation algorithm for evaluating the connection strengths representing the correlations between inputs (octanol-water partition coefficients logP, acid dissociation constant pKa, water solubility and molecular weight) and outputs (extraction efficiency in dihexyl ether and undecane as organic solvents). The model predicted results in good agreement with the experimental data and the average deviations for all the cases are found to be smaller than ±3%. Moreover, standard statistical methods were applied for exploration of relationships between studied parameters. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

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