GC-MS-selected ion monitoring

As an example of typical experimental data, Fig. 10.32 is a GC-MS selected ion monitoring (SIM) profile (m/z 247) for the nitrofluoranthenes and nitropy-renes in an extract of ambient particles collected in southern California (Arey et al., 1988b). The 1-nitropyrene (1-NP) and 3-nitrofluoranthene (3-NF) presumably are from diesel emissions (Tables 10.33 and 10.34), but the dominance of 2-nitrofluoranthene and 2-nitropyrene reflects a second major source. 

FIGURE 10.32 GC-MS selected ion monitoring (SIM) scan of the molecular ions (m/z 247) of nitrofluoranthene (NF) and nitropy-rene (NP) isomers in extracts of ambient particles collected in Torrance, California, January 1986 (adapted from Arey et at., 1988b, and Atkinson and Arey, 1997). 

Table 3.1.4 Preparation of stock and working solutions for gas chromatography-mass spectrometry (GC-MS) selected ion monitoring (SIM) analysis. 2MBG 2-methylbutyrylglycine, BG butyrylglycine, DCA dicarboxylic acid, EMA ethylmalonic acid, GLUT glutaric acid, HG hexanoylglycine,...

For quantitative analysis, GC peak area ratios (Grob 1985), using the added pentaerythritol or some other suitable compound as internal standard, or GC-MS selected ion monitoring (Chapman 1985) may be used when authentic samples of the compounds of interest are available. 

HA, heterocyclic amine AA, aromatic amine PA, polyamine Al, aliphatic amine N, nitrosamine MAM, Musk amino metabolities ABDACs, alkylbenzyldimethylammonium chlorides BCD, electron capture detection AED, atomic emission detection FID, flame ionization detection FPD, flame photometric detection GC-MS-SIM, GC-MS selected ion monitoring NPD, nitrogen phosphorus detection NlCl, negative-ion chemical ionization El, electron ionization CGC, capihary GC A, air H, water W, waste. 

Murray and Whitfield (11), in their extensive survey of 3-alkyl-2-methoxypyrazines in raw vegetables, reported finding 3-isobutyl-, 3-lsopropyl-, and 3-(Sec-butyl)-2-methoxypyrazines in red, or chili peppers. Combining gc effluent sniffing and gc-ms selected ion monitoring, Huffman e al. (12) detected 3-lsobutyl-2-methoxypyrazlne in both fresh and processed Jalapeno pepper volatiles. They attributed most of the fresh Jalapeno aroma to the presence of the bell pepper pyrazlne. 

Fig. 3. GC-MS selected ion-monitoring trace of pHj] and [ Hg] p-octopamine (as their DTFMB-TMS derivatives) from 50 DUM cells incubated with pHg] p-tyramme (A) Detection of endogenous p-octopamine (mass-to-charge ration 537) (B,C) Deu-terated pHg] p-octopamine (mass-to-charge ratio 542) and pHgjp-octopamine (mass-to-charge ration 543), respectively. These deuterated products must have been synthesized by the DUM cells from [ Hg] p-tyramine, because they are not present m the controls. Int. Std. Internal stan d (PH3] m-octopamine) added at the time of derivatization to allow quantification of amines recovered. The y-axis of the figine represents instrument response in arbitrary units. M/Z Mass-to-charge ratio for the particular 10ns being monitored, which in each case corresponds to the molecular weights of the derivatives of the species present.

MSTFA was also the derivatizing agent of choice for the direct derivatization of flutroline in plasma extracts on the tip of a moving needle injector prior to GC-MS selected ion monitoring (SIM) assay [22]. TMS derivatives of formaldehyde condensates, formed in a gas phase reaction with BSTFA, were used for the separation and quantification of methylal (dimethoxymethane), methylene glycol and a series of poly(oxymethylene) glycol monomethyl ethers by capillary GC-MS using ammonia chemical ionization [23]. The possibility of accelerated... 

Screening C. 2 ml anabolic steroids, some diuretics, some S-blockers and S-2-agonists - purification - enzymatic hydrolysis - extraction - concentration - TMS, trifluoroacetyl (TFA) derivatization -GC-MS selected ion monitoring (SIM) analysis ... 

A GC-MS-selected ion monitoring (SIM) method for the simultaneous detection of Sarin, Soman, Tabun, GF, VX, Russian VX and Sulfur Mustard in water was reported in 1999 [62]. Water samples were extracted twice with dichloromethane. The combined extracts were concentrated to 1 mL under a gentle stream of nitrogen and an internal standard solution was added. Selected ion monitoring for... 

Louchouam, R, Opsahl, S., and Benner, R. (2000). Isolation and quantification of dissolved lignin from natural waters using solid-phase extraction (SPE) and GC/MS selected ion monitoring (sim). Anal Chem., 13, 2780 -2787. 

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