Total-ion chromatogram

Computers, often combined with transputers, are used for three main functions when connected to a mass spectrometer. The foremost requirements involve the acquisition and preprocessing of basic data and the control of the instrument s scanning operations. Additional software programs are available to manipulate the preprocessed data in a wide variety of ways depending on what is required, e.g., a mass spectrum or a total ion chromatogram. 

Fig. 4. Chromatograms of Russian coriander oil injected into a serially configured gc /ir /ms ( a) total ion chromatogram (TIC) (b) total response...

Figure 15.10 Primary (a) and secondary (b) separation of unleaded gasoline, where (a) shows the IRD chromatogram, and (b) shows the MSD total ion chromatogram of heart cut c. Adapted from Analytical Chemistry, 65, N. Ragunathan et al., Multidimensional gas chromatography with parallel cryogenic tr aps , pp. 1012-1016, copyright 1993, with permission from the American Chemical Society.

Figure 5.28 LC-electrospray-MS total ion chromatogram of sulfated oligosaccharides from mucins purified from the porcine large intestine, where the annotations indicate the molecular ions observed from each component. Reprinted with permission from Thoms-son, K. A., Karlsson, H. and Hansson, G. C., Anal. Chem., 72, 4543-4549 (2000). Copyright (2000) American Chemical Society.

Figure 5.4 Typical total ion chromatogram by pyrolysis MAB/Tof MS for deposition of 0.5 pi of suspension (about 50,000 cells). The cells were a thermostable direct hemolysin producing V. parahaemolyticus serotype 04 K12. Peak width at half maximum intensity is 20 scans ( 4 seconds).

FIGURE 5.4 Chromatograms of 2DLC (affinity/SEC/MS). Bottom trace is affinity separation with UV detection and 2 min fraction specified. Middle trace is MS total ion chromatogram showing protein elution and salts diverted to waste. Top trace in MS extracted ion chromatogram of protein of interest. 

Because online separations provide such a wealth of information about target proteins, interpretation becomes of critical importance in order to make full use of the data. The first step in any analysis of LC-MS data involves integration and deconvolution of sample spectra to determine protein mass and intensity. In manual analysis (Hamler et al., 2004), users identify protein umbrellas, create a total ion chromatogram (TIC), integrate the protein peak, and deconvolute the resulting spectrum. Deconvolution of ESI spectra employs a maximum entropy deconvolution algorithm often referred to as MaxEnt (Ferrige et al., 1991). MaxEnt calculates... 

FIGURE 13.4 Total ion chromatograms from the ID LC/MS analysis of a yeast ribosomal protein fraction separated using 0.1% TFA (Panel a) and 0.1% formic acid (Panel b) as mobile phase modifiers. TFA produced narrower, more concentrated, peaks for mass analysis that did not overcome the significant electrospray ionization suppression associated with using this modifier for LC/MS studies, resulting in an overall reduction in component intensities. 

FIGURE 13.5 The total ion chromatogram and deconvoluted protein mass map for a ID LC/MS analysis of yeast ribosomal proteins. The bubble size is proportional to component intensity. 

FIGURE 13.7 Total ion chromatogram reproducibility for three 2DLC (S AX-Step Gradient/ RP)/MS analyses of an E. coli cytosolic fraction. 

Figure 25 Total ion chromatogram (pyrogram) of PVC. Reproduced with permission from Wampler [71]. 2005, Perkin Elmer, Inc.

Figure 2 Linear representation of the total ion chromatogram (TIC) of the Grob mix .

The spray paint can was inverted and a small amount of product was dispensed into a 20 mL glass headspace vial. The vial was immediately sealed and was incubated at 80°C for approximately 30 min. After this isothermal hold, a 0.5-mL portion of the headspace was injected into the GC/MS system. The GC-MS total ion chromatogram of the paint solvent mixture headspace is shown in Figure 15. Numerous solvent peaks were detected and identified via mass spectral library searching. The retention times, approximate percentages, and tentative identifications are shown in Table 8 for the solvent peaks. These peak identifications are considered tentative, as they are based solely on the library search. The mass spectral library search is often unable to differentiate with a high degree of confidence between positional isomers of branched aliphatic hydrocarbons or cycloaliphatic hydrocarbons. Therefore, the peak identifications in Table 8 may not be correct in all cases as to the exact isomer present (e.g., 1,2,3-cyclohexane versus 1,2,4-cyclohexane). However, the class of compound (cyclic versus branched versus linear aliphatic) and the total number of carbon atoms in the molecule should be correct for the majority of peaks. 

Figure 10.6 Total ion chromatograms obtained for frankincense showing comparison between (a) SPME and (b) dichloromethane extraction. Reproduced from S. Hamm, E. Lesellier, j. Bleton, A. Tchapla, J. Chromatogr., A, 1018, 73 83.Copyright 2003 Elsevier Limited...

In order to confirm the relative retention times established for DBDPO using only CGC, additional sets of partially brominated diphenyl oxides and dibenzofurans were synthesized using the Fe°/ Br2 procedure. The course of these reactions was followed by both CGC and CGC/MS. As a result, it was possible to simultaneously confirm the previous relative retention time peak assignments as well as to correlate the retention times between the two instruments. Some of the pertinent comparative retention time data obtained from these experiments is summarized in Table I. Upon completion of the individual reactions, a cocktail containing both partially brominated furans and diphenyl oxides was mixed. A typical CGC chromatogram and a CGC/MS total ion chromatogram for this cocktail are shown in Figures 1 and 2, respectively. 

Fig. 1.2 A comparison of total ion chromatograms (GC-MS TIC) of selected axillary skin surface compounds for A a female, B a male (1), C a male (2) human subjects...

The Excel macro findpeak.xls imports the data from the. CSV files into an Excel spreadsheet. This imports all of the. CSV files containing all the mass spectra of one Total Ion Chromatogram. The user may import as many data files as desired for comparisons. 

Fig. 15.2 Patterns of volatiles emitted from hairs during the breeding season. The comparison was carried out using SPME and GC-MS showing the total ion chromatograms (TIC) of four hair samples from one male including the throat region (a), the sternal region (b), the region of the lateral abdomen (c), and the tail region (d)...

Total ion chromatogram, mass spectrometer, 6 431 Total ion electrolyte concentration, determination of, 14 423 Total lime, 15 29... 

Fig. 11.17. Simulated mass chromatograms resulting from precursor ion and constant neutral loss tandem mass spectra (middle and bottom traces), illustrating the selectivity that those MS/MS scan modes can bring to chromatographic analyses. The top trace in the figure represents a total ion chromatogram obtained using a conventional single stage of mass analysis.

Fig. 21.14. Temperature-programmed capillary GC-MS total ion chromatograms for kerosene (upper trace) and Moth-Knox pesticide (lower trace). Note the similarity in the pattern of peaks, with the exception of the large peak in the pesticide sample (at a retention time of about 12.5 min). The mass spectrum and the retention time of this peak both corresponded to a standard of naphthalene.

---