Synapt instrument

This mode of mobility acquisition is one of the major advantages of the Synapt instrument. In one single experiment, both mass spectra and ATD profiles, for each ion in the mass spectrum, are recorded. Another advantage of this instrumentation is that CID experiments can be performed in either, or both, of the trap and transfer TWIGs. This facility allows a number of different experiments to be carried out, such as ... 

This procedure is similar to that of an MS experiment, with the difference that all product ions (MS and MS ) are recorded at the same time. The different modes of operation of the Synapt instrument are summarized in Table 8.1. 

Modes of Operation of the TWIG Components of the Triple-Stage TWIG Synapt Instrument... 

FIGURE 8.4 Normalized cross-sections vs corrected arrival times for myoglobin. Plot used to create a cross-section calibration for the Synapt instrument. The sample analyzed was equine myoglobin and charge states [M-h8H] +-[M-h 16H] + were used. 

McEwen et al. have utilized another ambient technique called atmospheric pressure solids analysis probe (ASAP) [84,85] and interfaced it with TWIM-MS [86], This source is now available commercially on the Synapt instrument. They have used m/z vi drift time plots to define compound classes in CTude oil analysis and to resolve isobaric compounds. Excellent agreement was demonstrated for drift times obtained from standards run individually and doped into the crude oil mixture. This work demonstrates the utility of mobility experiments to provide a degree of separation and classification in the study of very complex mixtures where chromatographic separation is either not possible or too time consuming. 

What is already clear is that the number of installed Synapt instruments has increased considerably and rapidly among the research community of IM practitioners. The enthusiastic acceptance of Synapt instruments will ensure that, as weU as building on the excellent work of the pioneers of the technique, new and exciting application areas will be explored and developed. 

The identical TSA approach using the S YNAPT G2 (higher mobility at 95 vs. low mobility at 125) instead of the first generation SYNAPT instrument (higher mobility at 89 vs. low mobility at 101) provided a drift resolution enhancement of 18 Bins for the doubly Uthiated palmitic acid over the isobaric ion. Palmitic acid is a saturated fatty acid and one C2 unit shorter as compared to oleic add (Scheme 9.2). 

Dissociated neuronal cultures provide a versatile system for analysis of mechanisms underlying neurotransmitter release. These cultures can be prepared from fetal or postnatal brain tissue. This preparation has been particularly instrumental in analysis of synapses deficient in key components of the release machinery. For instance, genetic deletion of synaptic SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptors) proteins such as synaptobrevin-2 and SNAP-25... 

Waters Corporation Synapt. The samples are solutions of biological material, and the ion sources are uniformly EIS, nanospray ionization, or matrix-assisted laser desorption and ionization as described in Chapters 4,9,15, and 18. Studies with the Synapt traveling wave instrument have revealed details of biomolecular ions in the gas phase that are not available by MS alone or by other methods. The full meaning of such studies and relevance for in vivo biomolecular activity is currently under discussion and debate " nonetheless, IM-MS for explorations of biomolecules certainly has affected the visibility of mobility as a measurement method and the level of technology that has been advanced through pharmaceutical and medical concerns. 

In addition to the number of types of spectrometers available for measuring ion mobility, numerous instruments are available for measuring mass. Thus, IMS-MS is combinatorial in nature. IMS instruments have been interfaced to quadrupole (Q) MSs, ion trap MSs, time-of-flight mass spectrometers (TOF-MSs), Fourier transform ion cyclotron resonance MSs, and most recently a Waters Synapt G-2 MS containing a quadrupole ion filter with a TW-IMS coupled with a TOF-MS. With these various IMS-MS configurations, high-resolution IMS-MS, IMS-MS, IMS-MS, IMS-MS-IMS-MS, IMS-MS -IMS-MS, and IMS-MS-IMS-MS spectrometry has been demonstrated. In the following sections, each type of ion mobility-MS is described. 

Figure 9.6 shows a schematic of an ion mobility MS called the Synapt, the only low-pressure IMS-MS that is commercially available. Known as the TW-IMS, this mobility cell is embedded in a Q-TOF-type MS with multiple capabilities. The figure depicts the ions traveling from left to right. On the far left is the ESI source, which introduces aqueous samples from a high-performance liquid chromatographic (HPLC) instrument or by direct infusion. As the electrosprayed ions enter the MS, they are bent in a Z manner to eliminate the solvent and focus the ions into a traveling wave ion transfer lens. From here, the ions enter a QMS, where a mass can... 

A protocol used to calibrate the TWIMS is presented here and an Excel spreadsheet simplifying its use is available online (http //www2.warwick.ac.uk/fac/sci/ bio/research/jscrivens/synapt calibration/). To create a calibration, values of absolute cross-sections obtained on DCIM-MS instrumentation are required. Such values have been published [23,59,63] and are available free from the Web site of Professor D.E. Clemmer (http //www.indiana.edu/-clemmer/). The procedure is as follows. 

Figure 8.4 Ion source designs and parameters affecting id/D scrambiing. (a) For Instruments with a heated capillary Ion source design, the capillary temperature, potential difference between transfer capillary and the first skimmer, and the DC voltage of the first multipole Ion guide can contribute to H/D scrambling, (b) For Instruments with a Z-type Ion source, the sample and extraction cone voltage and the velocity of the source F-wave Ion guide (Synapt) can contribute to H/D scrambling...

FIGURE 13.3 Instrument schematics for (a), Waters Synapt QTOF ( Waters), (b) Thermo Finnigan LTQ-Orbitrap, and (c) Thermo Finnegan LTQ FTICR mass spectrometers ( Thermo Finnegan). 

Figure 2.22 Schematic diagram of the MALDI Synapt C2-S HDMS instrument Illustration courtesy of Waters Corp.

---