Typical total ion current

Fig. 24a, b. Typical total ion current mass chromatograms for LAS, coproducts, and their intermediates in a effluent b influent samples of an activated sludge sewage treatment plant (after [322] with permission)... 

A typical total ion current chromatogram of the Tenax trapped canned black truffle (Tuber Melanosporum) juice volatiles is shown in Figure 2. The compounds identified by GC-MS are listed in Table I in the order of elution from the GC column with their characteristic mass spectral data. The identification of these compounds was based on comparison of the mass spectra obtained with those stored in the NIH/EPA library and also with those of authentic compounds. Moreover, an additional search of published standard mass spectra to confirm the identity of unknowns was undertaken (16). 

Identification of volatiles compounds A typical total ion current chromatogram of the Tenax trapped Black Truffle (Tuber Melanosporiim) volatiles is shown in Figure 4. 

Examples of GC-MS data for typical total extracts from rural and urban aerosol particle samples (analyzed as silylated derivatives) (a) total ion current (TIC) trace for Oakridge, OR, rural aerosol (Jan/Feb. 1985) and (b) TIC trace for Pasadena, CA, aerosol (Feb. 1989), DEHP = diethylhexyl phthalate, lA = carbon chain length of -alkanoic acids. 

These data for successive scans are then stored for subsequent manipulation. The reconstructed total ion current trace, equivalent to that obtained from a flame ionisation detector in gas chromatography, shows the variation of total ion current with time and allows spectra of interest to be identified. A typical example is shown in Fig. 6A. The background may be subtracted to give clean spectra, and their identification may be attempted using libraries of standard spectra. If a composite spectrum is obtained from two unresolved peaks, complex subtraction routines may be used to obtain a pure spectrum of each of the components. These may be separately submitted for library searching. The spectra may then be plotted or obtained as a mass versus intensity listing. 

Fig. 6. Reconstructed total ion current trace (A) and a single ion chromatogram from mjz 91 (B) for a typical GC-MS run.

FIGURE 27-15 Typical outputs for a GC/MS system, in (a), the total ion current chromatogram of a five-component mixture is shown. The components were 1, A/-nitrosodimethylamine. 

Based on the above analysis, total ion current of acetylated D-glucose ester and mass spectrogram of pieces are screened and calculated in detail. Mass spectrogram of pieces should have peaks a (m/z= 117), b (m/z = 233), c (m/z= 161) and d (m/z = 45) if the hydroxypropyl does not exist. Figure 5.9 is the typical mass spectrogram which does not have hydroxypropyl. From the total ion current, the peaks where the retention time was before 21 min were formed by unsubstituted... 

FIGURE 29, The GC/MS/C analysis of the saturated hydrocarbon fraction of an Israeli crude oil (a) total ion current (TIC) (b) trace of fragment mjz 133.133, typical of open-chain alkanes (c) trace of fragment (mass fragmentogram) m/z 133.133, typical for most tri-, tetra- and pentacyclic terpanes, dominated by the hopanes (d) the m/z 217.196 mass fragmentogram, steranes, and (e) the m/z 218.203 fragmentogram, also steranes Traces b-e are SIM of accurate mass (AM) with RP of 5000... 

Fig. 8.25. Comparison of (a) total ion currents and (b) of molecular ion or quasimolecular currents of analytes typical for GC-MS as obtained by 70-eV El, H, positive-ion Cl and negative-ion Cl both using methane reagent gas. Reproduced from Ref. [88] with permission. John Wiley Sons, Ltd., 2009.

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