TIC—See Total ion current

From a mass spectrometry perspective, the pump must be pulse free, i.e. it must deliver the mobile phase at a constant flow rate. Pulsing of the flow causes the total ion current (TIC) trace (see Chapter 3) - the primary piece of information used for spectral analysis - to show increases in signal intensity when analytes are not being eluted and this makes interpretation more difficult. 

Figure 11.7 Pyrogram of a beeswax sample obtained with a microfurnace pyrolyser at 600°C, in the presence of HMDS. TIC total ion current m/z 117 profile of carboxylic acid trimethylsilyl esters, showing a maximum with palmitic acid m/z 57 profile of hydrocarbons, showing a maximum with heneicosane m/z 103 profile of alcohol trimethylsilyl ethers, showing a max imum with docosanol. For the identification of all peaks, see Bonaduce and Colombini [70]...

Figure 7.1 Total ion current (TIC) chromatogram obtained by GC-MS analysis of a resin (Pinus sylvestris). The diterpenoid resin acids were methylated (using diazomethane) to improve chromatographic performance. Peak identities 1, Methyl pimarate 2, Methyl sandaracopimarate 3, Methyl isopimarate 4, Methyl palustrate 5, Methyl dehydroabietate 6, Methyl abietate 7, Methyl neoabietate. For GC-MS operating conditions, see Heron and Pollard (1988).

Fig. 2.2.2. Total ion current (TIC) CE-ESI-MS electropherogram of the simultaneous separation of LAS and SPC in an extract from the influent of a STP. For experimental conditions see Ref. [10]. Reprinted with permission from Ref. [10] 2001 The Royal...

Fig. 3.159. IP-UV-DAD (a) and total-ion current (TIC)-ESI-MS (b) chromatogram of a 22-compound aromatic sulphonate standard mixture of 4 mf/1 in the SIM-NI mode. Injection volume 50 jA, fragmentation voltage 80 V. Superspher RP-18 fast and short column (75 x 4 mm i.d., 4 pm particle diameter). For peak identification see Table 3.44. Reprinted wih permission from R. Loos et al. [197].

This problem was at least partially solved using a spectrum-normalization procedure with total ion current (TIC) (Figure 3.33). We previously studied the effectiveness of spectrum normalization with TIC the obtained spectra were multiplied with arbitrary variables such that all spectra had equal TIC values (i.e., equal integral values of the measured mJz region m/z 400-900]). Such TIC normalization is available with the Normalize Spectra function of Fleximaging 2.0 software (Bruker Daltinics) with filter function to exclude a number of noise spectra from the normalization process (see details in the software manual). 

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