Mobility analysis

Thus, the TDH method, by itself, is not good for determining impurity concentrations in SI material, although it can be somewhat more useful in conjunction with a mobility analysis. 

Because conformational changes in RNA or short DNAs typically cause small changes in electrophoretic mobility, analysis of nucleic acid folding requires careful optimization of electrophoresis conditions. By contrast, protein—nucleic acid interactions are typically easier to analyze by native PAGE because the molecular weight and positive charge of the protein produces a relatively large shift in gel mobility. 

Commercial instruments are available for a variety of applications in aerosol instrumentation, production of materials from aerosols, contamination control, etc. (ISO/CD 15900 2006, Determination of Particles Size Distribution—Differential Electrical Mobility Analysis for Aerosol Particles). 

YS Liu, SJ Valentine, AE Counterman, CS Floaglund, DE Clemmer. Injected-ion mobility analysis of biomolecules. Anal Chem 69 A728—A735, 1997. 

As noted from Table 2, the major contribution (91%) to the conductivity is derived from the acid, and in particular (80%) from the proton due to its high mobility. Analysis and experimental data indicate that by removing the acid, the conductivity drops by about a factor of 10. 

Capillary electrophoresis has become an attractive alternative to ion chromatography and atomic absorption spectrometry for measuring inorganic ions because of its multi-ion capability, high speed, high resolution and sensitivity, and relatively low cost. Because of their relatively high electrophoretic mobility, analysis times can be shortened for small ions by having them move electrophoretically in the... 

DDF analysis gives precise diffusion coefficients of target molecules. In this analysis, molecule displacements during a short lag-time are derived from trajectories in order to make the distribution function, which is used to obtain the diffusion coefficients. This method does not require any fitting processes in order to construct the DDF and hence is suitable for precise mobility analysis of target molecules on the membrane. Here we describe the DDF analysis method for cARl, which has one diffusion state. This analysis can be applied to other molecules that exhibit more complicated behaviors some molecules exhibit two different types of diffusion states and state transition between them. 

Hogan, C.J., Jr. de la Mora, J.R, Ion mobility measurements of non-denatured 12-150 kda proteins and protein multimers by tandem differential mobility analysis-mass spectrometry (DMA-MS), J. Am. Soc. Mass Spectrom. 2011, 22,158-172. 

Bacher, G. Szymanski, W. Kaufman, S. Zollner, R Blass, D. Allmaier, G., Charge-reduced nanoelectrospray ionization combined with differential mobility analysis of peptides, proteins, glycoproteins, noncovalent protein complexes and viruses. J. Mass Spectrvm. 2001, 36(9), 1038-1052. 

In laser ablation, a solid sample is irradiated with a laser pulse that ablates the point of laser-solid contact to produce a plume of ions and neutrals in the vapor space just above the point of laser-solid contact with the sample surface. If this plume is swept into an ionization source or if reactant ions are electrically focused into the ablated sample plume, product ions are formed. These ions can be electrically focused into an IMS for ion mobility analysis. Direct laser ablation followed by ionization from... 

FIGURE 6.8 Schematic of the first tandem ion mobility spectrometer from PCP Incorporated (a) in a configuration with a photodischarge lamp. Three ion shutters were employed to isolate ions of certain mobility for subsequent chemical reactions and then a final section for ion mobility analysis of products. A modem version of this is shown in (b) and is used for the determination of decomposition or fragmentation kinetics of thermalized ions in air at ambient pressure. (From Stimac et al. Tandem Ion mobility spectrometer for chemical agent detection, monitoring and alarm, Contractor report on CRDEC Contract DAAKll 84 C 0017, PCP, West Palm Beach, FL, May 1985. 

While time-dispersive ion mobility devices of the type used for drift tube IMS require aperture grids prior to the Faraday plate to preserve the resolving power of the instrument, ion filters and scanning mobility spectrometry such as differential mobility spectrometry (DMS), field asymmetric IMS (FAIMS), differential mobility analysis (DMA), and aspiration IMS (alMS) do not require an aperture grid and can efficiently detect ions with a simple Faraday plate. In these devices, ions do not travel as a discrete swarm, and the exact arrival time of the ions is not critical. Figure 7.3 shows a schematic of a typical differential ion mobility spectrometer (DIMS) in... 

FIGURE 8.4 DMA spectrum of 9.2-kDa polystyrene. The sharp peak to the left is from small background ions due to the electrospray process. The next peak to the right beginning at a 1/Z value of about 5 is the monomer, followed by the dimer, trimer, and so on. The resolving power of this spectrum is approximately 2. (From Ku et al.. Mass distribution measurement of water-insoluble polymers by charge-reduced electrospray mobility analysis. Anal. Chem. 2004, 76, 814-822. With permission.)... 

Ku, B.K. Fernandez de la Mora, J. Saucy, D.A. Alexander, J.N., Mass distribution measnrement of water-insolnble polymers by charge-rednced electrospray mobility analysis, A aZ. Chem. 2004, 76, 814—822. 

As described in previous chapters, there are many different types of ion mobility methods. These include drift tube ion mobility spectrometry (DTIMS), traveling wave ion mobility spectrometry (TW-IMS), differential mobility spectrometry (DMS), differential mobility analysis (DMA), and aspiration ion mobility spectrometry (alMS). All of these IMS methods have been interfaced to MSs. 

FIGURE 9.16 Sketch of a high-transmission ESI-DMA-MS interface. (From Fernandez de le Mora Ude, S. Thomson, B.A., The potential of differential mobility analysis coupled to MS for the study of very large singly and multiply charged proteins and protein complexes in the gas phase, Biotechnol. J. 2006, 1, 988-997. With permission.)... 

Eemandez de la Mora, J., de Juan, L., Eichler, T., RoseU, J., Differential mobility analysis of molecular ions and nanometer particles. TrAC 1998,17, 328. 

In Fig. 6, a typical gel mobility analysis of CCL2 binding to HS is presented. It clearly shows that upon increasing chemokine concentration, the HS band becomes weaker according to its immobilization in the chemokine-GAG complex, whereas the uncomplexed chemokine does not migrate at aU toward the anode and is thus not detected in this setup. 

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