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Simultaneous determination of Ne, Ar, CFC-11, CFC-12 and SF6 in grounwater samples by gas chromatography

Mochalski P., Śliwka I.

Chemia Analityczna

2008

Vol. 53, No. 5

651-658

Ne, Ar, CFC-11, CFC-12 and SF6 are widely used as markers in the studies of ground-water systems. Usually, their analysis involves a use of two or three separate instrumental methods and separate sets of water samples. In this work a gas chromatographic method for simultaneous determination of Ne. Ar, SF6, CFC-11 and CFC-12 in one groundwater sample has been presented. The analytes of interest were extracted from the water sample using the headspace method and analyzed employing a system consisting of four chromatographic channels. Limits of detection for the measured tracers were: 0.06 fmol L-1 (0.0081 pg kg-1) for SF6,15 fmol L-1 (2.1 pg kgpg kg-1) for CFC-11, 10 fmol L-1 (1.23 pgkg-1) for CFC-12,0.84 nmol L-1 ( 1.9x 10 cm3 STP cm-3) for Ne, and 0.15 &mumol L-1 (3.1 x 10-6 cm-3 STP cm-3) for Ar.

Ne, Ar. CFC-11, CFC-12 i SSF⁶ sąpowszechnie stosowane jako znaczniki w badaniach wód podziemnych. Pomiar stężenia tych związków przeprowadza się zazwyczaj dwiema lub trzema różnymi metodami analitycznymi z wykorzystaniem oddzielnych zestawów próbek wód. W niniejszej pracy przedstawiono opis chromatograficznej metody jednoczesnego oznaczania Ne, Ar, SF₆ oraz freonów F-11 i F-12 w pojedynczej próbce wód podziemnych.Poziomy wykrywalności mierzonych związków wynoszą 0,06 fmol L^-1 (0.0081 pg kg w przypadku SF₆; 15 fmol L^{-1 (2,1 fg cm^-3 w przypadku F-ll; 10 fmol L<-1} (1,23 pg kg^-1 w przypadku F-12; 0,84 nmol L^-1 (l ,9 x 10^-8 cm³ STP cm-') w przypadku Ne i 0,15 μmol L^-1 (3,1 x 10^-6 cm³ STP cm^-3) w przypadku Ar.

Catalytic removal of chlorine from organic compounds.

Karpiński Z., Pielaszek J., Bonarowska M.

Prace Naukowe Instytutu Chemii i Technologii Nafty i Węgla Politechniki Wrocławskiej. Konferencje

2002

Vol. 10, nr 57

137-142

Several carbon-supported, bimetallic palladinum-gold systems were prepared and screened as catalysts for the hydrodechlorination of dichlorodifluoromethane (CFC-12). Since catalytic behavior depends very much on the extent of Pd-Au alloying, it was necessary to ensure proper conditions for mutual interaction of both alloy components after their deposition on the support. The direct redox reaction, which involves a reductive deposition of gold ions on pre-reduced palladinum material appeared very useful. Characterizing these catalysts by x-ray diffraction and other methods showed a higher degree of Pd-Au interaction than that in Pd-Au/C catalysts prepared by impregnation. Kinetic studies indicated an intimate contact of Pd and Au is essential to improve selectivity to difluoromethane (from ~70% for Pd/C to ~90% for Pd-Au/C catalysts prepared by direct redox method). Large amounts of carbon originated from the CFC-12 molecule enter palladinum lattice during hydrodechlorination. During reaction part of this carbon can be hydrogenated from the catalyst, giving rise to higher selectivity towards methane. Well-mixed, highly selective toward CH2F2, Pd-Au catalysts absorb much less carbon.