Jolanta Szczygelska-Tao

Use of porous glass and silica gel as support media of a surface compound for generation of analytes in gaseous standard mixtures. New method for the determination of the amount of analyte generated.

The paper presents a new method for the determination of a volatile component of a gaseous standard mixture obtained by thermal decomposition of a suitable surface compound. The amount of the analyte generated (under given conditions of thermal decomposition) per unit of mass of the chemically modified material has been determined exclusively on the basis of measuring generation time. Therefore, the total error of the determination of the amount of a standard compound depends solely on the respective errors of weighing the material and measuring its decomposition time (both being direct measurements). This new method permits obtaining a few measuring points on the basis of a single sample of the material with chemically modified surface.

Chromogenic azole diazothiacrown ethers

Azocrown ethers with sulphur atoms and pyrrole or imidazole residue as a part of macrocycle have been synthesised. Their metal complexation abilities in acetonitrile were studied using UV–vis spectrophotometry. The largest spectral changes were observed for both pyrrole- and imidazole-azothiacrown ethers on complexation with Pb2 + , Cu2 + , Zn2 + , Ni2 + , Co2 + and Ag+ ions. In the case of alkali and alkaline earth metal ions no spectral changes were found. Preliminary studies of ion-selective membrane electrodes with synthesised ionophores are presented. In the measurement for transition/heavy metal cations, only copper and lead give high responses. X-ray structure of 18-membered pyrrole azothiacrown ether is described.

Generation of gaseous mixtures of ethene on the basis of thermal decomposition of compound bonded to silica gel surface – Single and multipoint calibration of a thermal decomposition‐gas chromatography system

The paper presents a new method of determination of a volatile component (ethene) of gaseous standard mixtures obtained by thermal decomposition of a suitable surface compound. This method is based on a simple mathematical relationsphip (function of a single variable). The amount of the analyte generated (under given, chosen conditions of thermal decomposition) per unit of mass of the source material has been determined exclusively on the basis of measuring the standard generation time.V

Crown ethers with an azo or azoxy unit and sulfur atom(s) in a 13-membered macrocycle

Abstract 13-Membered crown ethers bearing oxygen and sulfur atom(s) and an azo- or azoxy group in the macrocycle have been synthesized by reductive macrocyclization of dinitropodands. The structure of a 13-membered azoxydithiacrown ether has been studied by X-ray analysis. Preliminary studies of these compounds as ion carriers in ion-selective membrane electrodes is reported.

Preparation of Gaseous Standard Mixtures: Methods for Controlling the Amount of Components Generated in the Process of Thermal Decomposition of Immobilized Compounds

Gaseous standard mixtures play an important role in characterizing and checking the applicability of new analytical procedures. In this case gaseous standard mixtures can be treated as a special kind of reference material (validation process requires the use of so-called matrix reference materials). The selection of a method of generation of gaseous standard mixtures with the desired characteristics depends on the nature of the analyte and diluent gas, as well as on the required concentration of analytes in the mixture. Recently, dynamic methods of generation of gaseous standard mixtures are becoming more and more common. These include the method based on thermal decomposition of immobilized compounds. The generation of the measured component takes place as a result of heating of a sample of solid support with chemically modified surface. During a chemical reaction initiated by sufficiently high temperature, the immobilized compound undergoes decomposition or rearrangement accompanied by the release of a specific volatile compound. Various amounts of the analyte per unit time can be obtained by adjusting the conditions of the thermal decomposition process. This article describes the possibility of varying the amount of a measured component through the adjustment of conditions of drying the solid support or of the process of chemical modification of its surface. The principle of this technique is exemplified by the generation of a mixture containing ethene as the analyte. Porous glass was used as a solid support. The proposed technique was used for the generation of gaseous standard mixtures for the calibration of a thermal desorber-gas chromatograph-flame ionization detector (TD-GC-FID) system.

Studies on 16-Membered Azothia- and Azoxythiacrown Ethers as Ion Carriers in Ion Selective Membranes

Abstract16-Membered azothia- and azoxythiacrown ethers have been studied as ion carriers in ion-selective membranes. Their selectivities towards alkali, alkaline earth, transition and heavy metal cations were evaluated. The complex formation constants for these compounds with chosen cations have been determined using segmented sandwich membranes method.

Exploration of optical fibres as a carrier for new benzene and toluene matrix-free reference materials

To meet high expectations concerning precision and accuracy of reference materials, preparation of matrix-free reference materials using thermal decomposition-gas chromatography-mass spectrometry (TD-GC-MS) was proposed in this study. In the paper, the results obtained in preparation of the new reference materials for benzene and toluene are presented, based on the thermal decomposition technique of compounds chemically bound to the surface of optical fibre segments. The results obtained at various stages of the research procedure (homogeneity, stability) confirmed the possibility of using prepared laboratory samples of materials as reference materials for benzene and toluene. For the prepared batch of materials, reference values 1.26 ± 0.91 (ng/fibre) for benzene and 11.3 ± 7.4 (ng/fibre) for toluene were determined.