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Coupling Gas Chromatography to FI-MS

In the early 1970s, the coupling of gas chromatography (GC) to FI-MS suffered from poor instrument capabilities of that time [84,85]. Recent advances with oaTOF instrumentation allow for fast acquisition of spectra, high resolution, and straightforward accurate mass measurements in GC-FI-MS. Thus, GC-FI-MS has become a trusted tool in many laboratories, especially in the petroleum industry [31,32,86,87]. To maintain full ionization efficiency, it is common that an accumulation period of 1 s per spectrum is followed by flash-heating the emitter for 0.1-0.2 s [31,32]. These applications have also been driving the development of EI/Fl/FD [39] and EFCI/FI combination sources for GC-oaTOF instruments [88]. [Pg.391]

FD can be regarded the softest ionization method in mass spectrometry, even though electrospray ionization and matrix-assisted laser desorption ionization can transfer much larger ions into the gas phase [27,89], This is mainly because the ionization process itself does not transfer any extra energy to the incipient ions. Problems normally arise above molecular weights of 3000 u where the heated emitter causes thermal decomposition of the saiiple. [Pg.392]

Example The extraordinarily stable trityl ion, PhsC, m/z 243, tends to dominate mass spectra (Chap. 6.6.2). Thus, neither the El spectrum of chlorotriphenylmethane nor that of its impurity triphenylmethanol show molecular ions [Pg.392]

Example D-Glucose evaporates into the ion source without conplete decomposition as demonstrated by its H spectrum (Fig. 8.13). HD yields a spectrum with a very low degree of fragmentation that is most probably due to the required slight [Pg.393]

Analytes of very high polarity are not further ionized by field ionization. Here, the prevailing pathways are protonation or cationization, i.e., the attachment of alkali ions to molecules [93]. The subsequent desorption of the ions from the surface is effected by the action of the electric field. As [M+Na] and [M+K] ions are already present in the condensed phase, the field strength required for their desorption is lower than that for field ionization or field-induced [M+H] ion formation [43,94]. The desorption of ions is also effective in case of ionic analytes. [Pg.394]


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