Curved linear ion trap

FTMS/MS data are acquired at a resolving power of 60,000 ( m/z 400). Both collision-induced dissociation (CID) and higher energy collisional dissociation (HCD) are performed for structural identification of analyte molecules. For the latter, the collision cell placed in elongation to the curved linear ion trap is used see 6). Precursor ion isolation is achieved in the linear ion trap for both kinds of fragmentation techniques. As for the molecular (MS mode) ions, also the fragment (MS/MS mode) ions are analyzed in the Orbitrap detector in these experiments. 

The scan speed, the pulse amplitude in DPV was optimized and an inhibition calibration curve was obtained using carbofuran as reference pesticide. The linear range was observed to be 1 nM to 1 pM. A lowest detection limit of 9 nM has been achieved using this AChE immobilized tetracyanoquinodimethane (TCNQ)/NF modified SPE. In the case of carbofuran contaminated water samples, the detection limit was observed to be 20 nM and the developed sensor has a good analytical performance in comparison with the results obtained by standard methods using gas chromatography coupled to a Finningan Mat 800 ion trap detector mass spectrometer (GC-ITDMS). 

When the calibration curves were compared, several compounds at the low end of the calibrated concentration range were affected by components already present in the diesel/oil extract. For example, low-levels of some PNAs and phthalates, present naturally in these refined petroleum products, were detected in the unspiked diesel/oil extract. Also, some of the phenols in this dirty matrix were reactive in the injection liner indeed, the matrix itself can passivate the liner for some target compounds. Passivation in this sense means that the liner surface becomes coated with non-volatile components, forming a barrier between the analyte and the bare, more reactive glass surface. While this issue is not related to ion trap mass spectrometry per se, it will be present in any analytical GC/MS system. As illustrated in the example below, calibration curve linearity (as represented by relative percent standard deviation, or RSDs, of the relative response factor at each calibration concentration level) and correlation coefficients for most compounds in the pure solvent were identical statistically to those prepared in the 3000 ppm diesel/oil matrix spikes, as are shown in Figures 15.36 and 15.37. 

In recent years, GC-ion-trap detection (ITD) systems that can perform tandem MS (MS-MS) on a routine basis have become commercially available [86]. Because ITD provides good sensitivity as well as increased selectivity in the MS-MS mode, an on line SPE-GC ITD system was optimized for the trace-level determination of polar and apolar pesticides [53]. The Autoloop interface (see section 3.2.3) was operated at an injection temperature of 90X, which permitted the determination of thermolabile pesticides such as carbofuran and carbaryl. With sample volumes of 10 to 30 ml and a copolymer SPE cartridge, linear calibration curves were obtained for several pesticides over the range of 0.1 to 500 ng/L. Fully satisfactory tandem mass spectra were obtained at levels as low as 0.1 ng/L level in tap and river water. The system was used to analyze water from European and Asian rivers, and the determination of microcontaminants at 8 to 16 ng/L levels did not cause any problems (Fig. 11). Relevant analytical data are presented in Table 7. One conclusion may be that, for this target-compound type of analysis, a sample volume of 1 ml or less will be sufficient to comply with governmental directives. 

Major ion trap developments have occurred over the last 15 years. In 1995, Bier and Syka patented the use of the mass selective instability scan from high-charge-capacity ion trap geometries such as the linear quadmpole ion trap (LQIT), toroidal trap (TQIT), curved or banana traps (CQIT), and elliptical traps (EQIT). The LQIT with radial ejection was eventually commercialized in 2002, and it is used as a stand-alone mass analyzer and has been combined with QMFs, Fourier transform ion cyclotron resonance (FT ICR), and the orbitrap to form hybrid instmments. The LQIT analyzer has eclipsed the conventional ... 

Quadnipole fundamentals that can be applied to 3D- and 2D-quadmpole field ion traps can be found in the book by Dawson. We will use the acronym XQIT in this text, where X is a variable that refers to all quadrupole field ion traps whether they have 2D- or 3D-quadrupole fields. For the 2D traps, X will be replaced by L for linear, RL for rectilinear, T for toroidal, and C for curved, allowing for a nomenclature system for future geometries. 

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