Multiple ion detection

Selected-ion monitoring (SIM). Describes the operation of a mass spectrometer in which the ion currents at one (or several) selected m/z values are recorded, rather than the entire mass spectrum. The use of the terms multiple-ion detection (MID), multiple-ion (peak) monitoring (MPM), and mass fragmentography are not recommended. 

By CH4-chemical ionization two predominant ions from DDS were formed in the ion source m/z 163 (M + 1) and m/z 165 (M + 3), which were accelerated and separated in the first quadrupole. Decomposition by collision activation with argon then occurred in the second quadrupole and the resulting daughter ions were separated in the third quadrupole to give rise to collision-induced spectra (equations 41-43). When carrying out the analysis with a solid inlet MS-MS system (TSQ) it was observed that, when operating TSQ in the multiple ion detection mode and selecting the ions m/z 63, 83, 85,99 and 101, only in the third quadrupole was there no interference from other m/z 163 and 165 precursor ions . ... 

Odanake et al. [1] have reported the application of gas chromatography with multiple ion detection after hydride generation with sodium borohydride to the determination of mono and dimethyl arsenic compounds, trimethyl arsenic oxide and inorganic arsenic in soil and sediments. Recoveries in spiking experiments were 100-102% (mono and dimethyl arsenic compounds and inorganic arsenic) and 72% (trimethyl arsenic oxide). 

Therefore, a C13-AE, a cationic (quaternary ammonium) surfactant (quat), an amphoteric Ci2-alkylamido betaine, and the non-ionic fatty acid diethanol amide (FADA) as presented with their FIA-MS spectra in Fig. 2.5.12(a)-(d) were analysed as pure blends and as mixtures always obtained from two blends in FIA-MS multiple ion detection mode (MID). Mixtures as well as pure blends contained identical concentrations of surfactant homologues. For AE quantitation the mass traces of all A m/z 44 equally spaced homologues (m/z 306-966) of the C13-AE were recorded. The cationic (quaternary ammonium) surfactant, the amphoteric Ci2-alkylamido betaine, and the non-ionic FADA were quantified recording the mass traces at m/z 214 and 228, or 184, 212, 240, 268, 285, 296, 313, 324 and 341, or 232,260, 288, 316 and 344, respectively. 

Fig. 2.5.13. Ion current traces of APCI-FIA-MS(+) examinations of compound interferences performed in multiple ion detection mode applied for quantification of pure AE blend (A AE b,d,f recorded between 0 and 4.0 min), pure quat (B a), betaine (B c) and FADA (B e) blend (cf. B Selected compounds a,c,d recorded between 4.0 and 8.5 min). In mixtures of AE with quat, betaine or FADA, respectively, all constituents were determined by MID (cf. C Mixture AE/quat (a,b), AE/betaine (c,d), and AE/FADA (e,f) (recorded between 8.5 and 14.0 min, respectively). Ions recorded in MID mode for quantification AE (all ions starting at m/z 306 + A 44 and ending at 966), quat m/z 214 and 220, betaine m/z 184, 212, 240, 268, 285, 296, 313, 324 and 341, FADA m/z 232, 260,...

ECD = electron capture detection EPA = Environmental Protection Agency GC = gas chromatography GPC - gel permeation chromatography HRMS = hihg-resolution mass spectrometry MID = multiple ion detection MS = mass spectrometry SIM = selected ion monitoring... 

The operation of magnetic sector (Chap. 4.3), linear quadrupole (Chap. 4.4), or quadrupole ion trap (Chap. 4.5) mass spectrometers in the repetitive scanning mode is useful for the identification of the components of a mixture. If quantitation is a major issue (below), selected ion monitoring (SIM) is preferably employed the term multiple ion detection (MID) and some others are also in use. [33] In the SIM mode, the mass analyzer is operated in a way that it alternately acquires only the ionic masses of interest, i.e. it jumps from one m/z value to the next. [34-39] The information obtained from a SIM trace is equivalent to that from a RIC, but no mass spectra are recorded. Thus, the scan time spent on a diagnostically useless m/z range is almost reduced to zero, whereas the detector time for the ions of interest is increased by a factor of 10-100. [40] An analogous improvement in sensitivity (Chap. 5.2.3) is also observed. 

Multiple ion detection bVariable due to daily fluctuations CNot determined... 

Urine As Multiple ion detection. Hydride generation heptane cold trap, Extraction Inorganic, monomethyl-, dimethyl- and trimethylarsenic compounds were detected by this combination of techniques 8o)... 

Air, gloves (surrogate for dermal exposure) Preconcentration from air sample using polyurethane foam (PUF). Soxhlet extraction of PUF or gloves with 5% ethyl ether/hexane. Addition of deuterated internal standards and concentration using K-D and nitrogen blowdown. Capillary GC/MS (can use multiple ion detection) 55 ng/m3 (5.5 nr sample) 73 (14% RSD) Hsu et al. 1988... 

MS, Mass spectrometry El, electron impact Cl, chemical ionization MID, multiple ion detection PICI, positive-ion chemical ionization NICI, negative-ion chemical ionization SIM, selected ion nmonitoring TSP, thermospray PPINICI, pulsed positive ion-negative ion chemical ionization ECD, electron-capture detector NPD, nitrogen/phosphorous detector NSTD, nitrogen-selective thermionic detector FT-IR, Fourier transform infrared spectrometry. 

TD-IT, Thermal desorption-ion trap CAD MIKE, collisionally activated decomposition mass-analyzed ion kinetic energy MID, multiple ion detection FID, flame ionization detector NPD, nitrogen/phosphorus detector SIM, selected ion monitoring El, electron impact TMS, trimethylsilane MTBSTFA, N-methyl-N-(tetr.-butyldimethylsilyl)trifluoroacetamide. 

Vinyl chloride Mass fragmentography then GC-MS recording m/e 62 and 64 peaks. Quadrupole m/s equipped with multiple ion detection sub pg L1 [18]... 

Also the derivatization produced electron capturing impurities which occasionally interfered with the tetradecenal peak. Our present method of analysis involves quantitation of TDAL using a capillary column GC/MS technique. The GC/Mass Spectrometer (Finnigan 4021) is used in the multiple ion detection (MID) mode under computer control. Specific ions in both the internal standard (decylbenzene) and the pheromone are recorded. The combination of high resolution capillary gas chromatography and the specificity of the mass spectrometer in the MID mode, makes this technique superior to the oxime method, albeit, a little less sensitive. (EC v-lOO peg MID 500 peg)... 

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