High-pressure hydrogenated carbon hydrogen isotope

Isotope fractionation between the vapor phase and the dissolved aqueous phase has been studied only for toluene and trichloroethylene (carbon only [545, 690]). Fractionation associated with adsorption has been quantified only for toluene in regard to sample extraction using a poly(dimethylsilo-xane)-coated solid-phase microextraction fiber [373] and qualified for benzene, toluene, and ethylbenzene based on high-pressure liquid chromatography analyses of isotopically labeled and unlabeled compounds (carbon and hydrogen [692]). Isotope fractionation associated with the reductive dechlorination of chlorinated ethylenes by zero-valent iron and zinc has been... 

The occurrence of [Mh-H] ions due to bimolecular processes between ions and their neutral molecular counterparts is called autoprotonation or self-CI. Usually, autoprotonation is an unwanted phenomenon in EI-MS. [M-i-1] ions from autoprotonation become more probable with increasing pressure and with decreasing temperature in the ion source. Furthermore, the formation of [M-i-1] ions is promoted if the analyte is of high volatility or contains acidic hydrogens. Thus, self-CI can mislead mass spectral interpretation either by leading to an overestimation of the number of carbon atoms from the C isotopic peak (Chap. 3.2.1) or by... 

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