Tube lens

In order to parallel solution-phase reactivity and ion-molecule reactions in the gas phase, the reactivity of a typical homogeneous catalyst, described earlier by Grubbs and co-workers [128], was studied by ESMS [129]. Electrospray of the dichloride salt of 15 and increasing the collisional activation potential first yielded predominantly the monocation 16, but with raising the tube lens potential even higher the intensity of 16 decreased due to loss of the second phosphine ligand, loss of trimethylamine, and loss of HCl. The observed fragmentation pattern was consistent with the assumed structure of the ruthenium complex. 

In some API source designs, an additional focussing device is applied, e.g., a tube lens at the outlet side of the heated capillary (Figure 5.9), and a ring electrode between nozzle and skimmer (Figure 5.6). 

Figure 3.9 Fragmentation patterns in positive-ion mode of PCs. ESI-MS conditions spray voltage 4.5 kV sheath gas nitrogen 0.9L/min capillary voltage 35 V capillary temperature 200 °C tube lens offset voltage 15 V. (Reprinted from Pad et al., 2006. Simultaneous separation and identification of oligomeric procyani-dins and anthochyanidins-derived pigments in raw red wine by HPLC-UV-ESI-MSn, Journal of Mass Spectrometry 41, p. 869, with permission from John Wiley Sons Ltd)...

Table 3.14 Anthocyanins and their derivatives identified in a Primitivo wine by LC/ESI-MS analysis performing program D in Table 3.12. The characteristic fragment ions from the MS/MS and MS3 experiments of the most intense m/z signals of mass spectra, are reported. MS conditions positive ion mode spray voltage 4.5 kV sheath gas N2 0.9 L/min capillary voltage 35 V capillary temperature 200°C tube lens offset voltage, 15 V (Pati et al., 2006).

Advanced microscopes made since 1980 have a more complicated optical arrangement called infinity-corrected optics. The objective lens of these microscopes generates parallel beams from a point on the object. A tube lens is added between the objective and eyepiece to focus the parallel beams to form an image on a plane, which is further viewed and enlarged by the eyepiece. 

Figure 3 Ion abundances as a function of tube lens voltage in the ESI/MS.

Figure 4 In-source CID of P-BrC6H4N2+ in tube lens region of the LCQ followed by ion-molecule reactions with reactive gases derived from the ESI solvent (CH3CN). Ions are labeled according to Scheme 12.

The MS conditions positive-ion mode spray voltage 4.5 kV sheath gas N2 0.9L/min capillary voltage 35 V capillary temperature 200°C tube lens offset voltage, 15V (Pati et al.,2006). 

Fig. 3 Confocal fluorescence detection on a microchip. A laser was used as the excitation source. The laser light passed through a biconvex lens, was focused into an illumination pinhole, and was subsequently reflected by a dichroic mirror and focused in the channel on the capillary electrophoresis (CE) chip by a microscope objective. The fluorescence signal from the sample, collected by the microscope objective, was passed through the dichroic mirror, focused by the tube lens into a confocal pinhole, and then detected by a photomultiplier tube (PMT). To improve the signal-to-noise ratio, band-pass filter and notch filter were inserted above PMT for spectral filtering...

For nondescanned detectors it is important to use a field lens in front of the detector. The general optical principle is shown in Fig. 5.92. In this figure it was assumed that the fluorescence light is separated from the excitation before it passes the tube lens the lens diameters are exaggerated. 

If a tube lens is in the fluorescence detection path, the beam configuration may be slightly different than that shown in Fig. 5.90. The microscope may also have additional lenses in the beam path to project an image on a camera, or to increase the light-collection area of direct detection. In any case, there is a simple way to find the image of the microscope lens behind the field lens Turn on the microscope lamp in the transmission beam path, so that the condenser lens fully illuminates the aperture of the microscope lens. The image of the microscope lens can then easily be found by holding a sheet of paper behind the field lens. 

Fig. 15.5). An alkylphenolpolyglycolether blend (APEO) was submitted to in-source CID under variation of capillary tube lens voltages.

Experiments were performed with an LCQ Advantage ion trap mass spectrometer (Thermo Fisher, San Jose, CA) fitted with a standard orthogonal ESI source. Room temperature was kept constant at 295 1 K and we assumed that the ambient temperature inside the instrument was 298.6 0.4 K, as reported for the same instrument set-up [36], Xcalibur, version 1.5 (Thermo Fisher), was used for data acquisition. Mass spectra were obtained in positive ion mode by using a spray voltage of 4.5 kV, a capillary temperature of 130°C, a capillary voltage of 10 V, and a tube lens offset of 0 V. The q -vdiae was maintained at 0.25. Two microscans of 200 ms per scan were used. A10 Th isolation width was used for precursor ion selection in all experiments and the ions were monitored at their exact masses. MS/MS experiments in the ion trap used CID with helium gas at 0.1 Pa. 

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