Selected-ion monitoring chromatogram

Figure 4.10 Selected ion-monitoring chromatograms of the thiocyanate and isothiocyanate derivatives of methyl, ethyl and isopropyl mesylates (final concentrations 0.25 pg/ml). Reproduced from [60] by permission of the Royal Society of Chemistry.

Figure 15.8 Multidimensional GC-MS separation of urinary acids after derivatization with methyl chloroformate (a) pre-column chromatogram after splitless injection (b) Main-column selected ion monitoring chromatogram (mass 84) of pyroglutamic acid methyl ester. Adapted from Journal of Chromatography, B 714, M. Heil el al., Enantioselective multidimensional gas chromatography-mass spectrometry in the analysis of urinary organic acids , pp. 119-126, copyright 1998, with permission from Elsevier Science.

Selected ion monitoring chromatograms of clozapine standard and hair sample extract using the masses 243 and 256. 

The isomer profiles of TeCDTs in the selected-ion monitoring chromatograms of stack gas samples from waste incineration and from pulp mill effluents are quite different. Still, the concentrations of TeCDTs in the stack gas samples were quite high, while the concentrations in pulp mill effluents were very low. The stack emissions contain more isomers which have shorter retention times in the HP-5 column than the pulp mill effluents. This may indicate that the TeCDTs are formed in a different way in waste combustion and in pulp bleaching [15]. SIM chromatograms with the exact value of the (M+2)+ ion of TeCDTs (321.8759) from a stack gas sample and from a pulp mill effluent sample are shown in Fig. 1. 

Fig. 5 a, b. Selected ion monitoring chromatograms with a resolution of 20,000 with the values a 319.8788 and 321.8758 for TeCDTs [exact values of the M+ and (M+2)+ ions of TeCDTs] b 353.8398 and 355.8369 for PeCDTs [exact values of the M+ and (M+2)+ ions of PeCDTs] from a waste incineration sample and with the exact values of M+ from some model compounds. From [13]... 

An example of MS of the selected ion-monitored chromatograms (SIM) from the TMS derivatives of alkali-decomposed puffer T. oblongus poison TTX ( Cg-base ) is shown in Figure 10. Sharp fragment ions appear at m/z 407 (parent peak), 392 (base peak), and 376, indicating the presence of the quinazoline skeleton in the toxin (Narita et ah, 1981). 

Figure 6.3 Selected ion monitoring chromatogram of four amphetamine-type substances, phenylethylamine, and ketamine from extracted whole blood. From Apollonio, L.G., et al. J. Chromatogr. B. 2006, Figure lb, with permission.

This set-up, or a very similar one, has been used to determine different group of pollutants in environmental waters (45, 83, 93). For example, with 10 ml of sample the limits of detection of a group of pesticides were between 2 and 20 ng 1 (92) in tap and river water, with this system being fully automated. Figure 13.19 shows the chromatograms obtained by on-line SPE-GC-MS under selected ion-monitoring conditions of 10 ml of tap water spiked with pesticides at levels of 0.1 pig 1 (92). 

Why is the sensitivity obtained when using reconstructed ion chromatograms (RICs) for quantitation less than that achieved when employing selected-ion monitoring (SIM) to monitor the same ions ... 

Figure 5.10 Reconstructed ion chromatograms used to quantify the levels of the principal oligosaccharides found in rituximab process samples. Reprinted from J. Chromatogr., A, 913, Wan, H. Z., Kaneshiro, S., Frenz, J. and Cacia, J., Rapid method for monitoring galactosylation levels during recombinant antibody production by electrospray mass spectrometry with selective-ion monitoring , 437-446, Copyright (2001), with permission from Elsevier Science.

Selecting an approach Since the chromatograms appeared identical using the FID, a different technique is needed to allow detection of the off-flavor. GC-mass spectrometry (GC-MS) provides more information than GC-FID and, in selected ion monitoring mode, can detect lower concentrations. 

Fig. 21.10. Total ion (TIC) and selected ion monitoring (at m/z = 104) chromatograms of the headspace of the acceptable and unacceptable flavor samples. (Redrawn/redrawn from J. Chromatogr., 351, R.A. Sanders, and T.R. Morsch, Ion profiling approach to detailed mixture comparison. Application to a polypropylene off-odor problem, 525-531, Copyright (1986) with permission from Elsevier.)...

Figure 4.7 Chromatograms from selected ion monitoring (a) VA-dimethylaminoethyl chloride (DMC), 200 pg corresponding to 0.2 ppm, operator 1 (b) dimethylaziridinium (DMA), 1 ng corresponding to 1 ppm, operator 1 (c) DMC, 200 pg, operator 2 (d) batch of diltiazem hydrochloride estimated to contain 0.06 ppm DMC (operator 1). Normal day-to-day variation in retention times is illustrated DMA elutes later than DMC (Rs = 1.6). Reproduced from [22] by permission of the Royal Society of Chemistry.

Fig. 17.13 Precolvimn (a, flame ionisation detection) and main column (b, selected ion monitoring detection)-chromatograms of a raspberry extract [71]...

Figure 22-20 Chromatograms of herbicides (designated 1-6) spiked into river water at a level near 1 ppb demonstrate increased signal-to-noise ratio in selected ion monitoring, (o) Ultraviolet detection at 240 nm (b) Electrospray reconstructed total ion chromatogram, (c) Electrospray selected ion monitoring at m/z 312. [From A. Lagana. G. Fago, and A. Marino, "Simultaneous Determination of imidazoiinone Herbicides from Soil and Natural Waters."Anal. Chem. 1998, 70.121.]...

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