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A rapid and low-cost sample preparation method modifying the so-called QuEChERS (quick, easy, cheap, effective, rugged and safe) method was developed for the determination of H2SO4 stable organic compounds in fish samples. The method involves acetonitrile salting-out extraction and a novel clean-up procedure combining the pH-tuned dispersive liquid-liquid microextraction (DLLME) with conc. H2SO4 digestion. The H2SO4 treatment is carried out by a simple operation in contrast to laborious and time-consuming procedures reported in the literature. The method was developed, optimised and validated using selected polybrominated diphenyl ethers (PBDEs) as representatives of H2SO4 stable compounds. For instrumental analysis of sample extracts, thermal desorption-gas chromatography-triple quadrupole tandem mass spectrometry (TD-GC-QqQ-MS/MS) was used. The proposed sample preparation method provides better co-extractives removal efficiency as compared to the original QuEChERS method and, unlike the QuEChERS dispersive solid-phase extraction (dSPE), allows complete removal of fatty acids. The sample preparation is low-cost due to the employment of small amounts of low-cost chemicals (no need of expensive sorbents), and it does not require special instrumentation. The whole analytical method showed satisfactory performance (linearity, recovery, repeatability, accuracy, limits of the method), and its applicability was confirmed by determination of PBDEs in samples of four fish species with variable lipid content in the range of 0.7-19%. The obtained recoveries for six PBDEs in the NIST standard reference material SRM 1946 were in the range of 81-95%, and relative standard deviations were in the range of 3-13%. [ABSTRACT FROM AUTHOR]

Sorption of hazardous pyridine derivates by copper forms of synthetic zeolite ZSM5 and natural zeolite of the clinoptilolite type (CT) has been investigated. Sorption of 2-chloropyridine (clpy) and 2-ethylpyridine (ethylpy) from liquid and gas phase by copper forms of zeolites (Cu-ZSM5 and Cu-CT) has been studied by CHN analysis, thermal (TG, DTG and DTA) analysis, FTIR spectroscopy, X-ray powder diffractometry and determination of the surface areas and the pore volumes by low-temperature adsorption of nitrogen. The results of thermal analyses of Cu-ZSM5, Cu-(clpy)-ZSM5, Cu-(ethylpy)-ZSM5, Cu-CT, Cu-(clpy)-CT and Cu-(ethylpy)-CT zeolitic products with different composition ( x depends on the experimental conditions of sorption of pyridine derivates) clearly confirmed their different thermal properties and the sorption of pyridine derivates. The main part of the decomposition process of zeolitic samples containing pyridine derivates occurs at considerably higher temperatures than the boiling point of pyridine derivates proving strong bond and irreversibility of clpy- and/or ethylpy-zeolite interaction. FTIR spectra showed well-resolved bands for pyridine derivates in the Cu-(clpy)-zeolite and Cu-(ethylpy)-zeolite. Surface area and pore volumes of the samples Cu-clpy-ZSM5, Cu-ethylpy-ZSM5, Cu-clpy-CT and Cu-ethylpy-CT in comparison with Cu-ZSM5 and Cu-CT decreased due to the adsorption of pyridine derivates. [ABSTRACT FROM AUTHOR]

Thermochemical properties of two kinds of composite material of synthetic zeolite ZSM5 in potassium form (K-ZSM5) with AgI have been studied. The composites have been prepared by treating the silver form of synthetic zeolite ZSM5 (Ag-ZSM5) with potassium iodide solution under different experimental conditions. One of the composites was additionally sintered at temperature 500°C for 20 h. Both composites have been characterized by TG, DTG, DTA, EDS analysis, X-ray powder diffractometry and X-ray photoelectron spectroscopy. The methods of thermal analysis as well as X-ray powder diffractometry and XPS confirmed the differences between the two composites caused by sintering during the synthesis. The content of AgI in the surface layer was different. No changes of the zeolitic mineral dimensions are observed. [ABSTRACT FROM AUTHOR]

Copper forms of synthetic zeolite ZSM5 containing ethylenediamine (en) were characterised by methods of thermal analyses - TG, DTA and DTG in the temperature range 20-1000°C, in air and in argon atmosphere. Mass spectroscopy was used for the study of the released gas products of thermal decomposition. The results of thermal analyses of three Cu(en)xZSM5 zeolitic products with different composition (x depends on the mode of preparation) checked their different thermal properties. The main part of the decomposition process occurs at considerably higher temperatures than the boiling point of ethylenediarnine of all three products, it proves strong bond and irreversibility of en-zeolite interaction. According to the results of the mass spectroscopy method the decomposition process in inert atmosphere is characterised by the development of a large spectrum of products with atomic mass from 28 to 178 atomic mass units, and there is a correlation between the mode of sample preparation and the spectrum of the released products. [ABSTRACT FROM AUTHOR]