Multidimensional "7 mass

J.C. Schwartz, A.P. Wade, C.G. Enke and R.G. Cooks, Systematic delineation of scan modes in multidimensional mass spectrometry, Anal. Chem., 62 (1990) 1809-1818. 

Hoke, S.H.IL Morand, K.L. Greis, K.D. Baker, T.R. Harbol, K.L. Dobson, R.L.M. Transformations in Pharmaceutical Research and Development, Driven by Innovations in Multidimensional Mass Spectrometry-Based Technologies. Int. J. Mass Spectrom. 2001, 212, 135-196. 

Yang, K., Cheng, H., Gross, R. W., and Han, X. 2009. Automated lipid identification and quantification by multidimensional mass spectrometry-based shotgun lipidomics. AnaZ. Chem. 81 4356-68. 

Figure 12.18. Shotgun lipidomics using ESI intrasource separation and multidimensional mass spectrometry of lipids from a complex extract. (From refs. 65 and 66.)...

Through global lipidomics, each distinct lipid species present in a cell s lip-idome can be identified. A shotgun lipidomics approach, which uses an ESI-intrasource separation of Upids from a complex extract, multidimensional mass spectrometry, and computer-assisted array analysis, is described. 

Multidimensional mass spectrometry (MS) involves the use of two or more mass analysis procedures one after the other in order to facilitate the selective fragmentation of specific ions in a complex mixture. Many different types and configurations of instruments can be used, some of which separate the consecutive mass analysis events spatially, while others carry out two or more analyses in the same compartment but separate them temporally. Tandem mass spectrometry (MS/MS or MS ) often involves two physically distinct mass analyzers separated by a collision cell to induce the fragmentation of precursor (primary or parent) ions. Higher-order analysis (MS and above) involves multiple rounds of collision and ion extraction, and is usually carried out in ion trap or ion cyclotron resonance instruments, which have ion storage and selection capability. Multidimensional MS is particularly useful where the analyte is very complex, where ionization produces relatively few structurally diagnostic ions, or where useful ions are obscured or suppressed by others... 

MS/MS has also become established in biochemistry and genetics, both as a discovery tool and a diagnostic technique. The high sensitivity of contemporary tandem and multidimensional mass spectrometers means they can be used to detect disease-specific molecules in tissue and blood samples down to the femtomole level. For example, MS/MS neutral loss scanning is used to detect increased levels of phenylalanine in the blood of newborn infants, to increase the detection rate and lower the false-positive rate associated with screening for phenylketonuria. Selected reaction monitoring is used widely to detect drug residues, such as steroids in athletes and domestic animals and in adulterated foods. 

Li, X.P., Guo, L., Casiano-Maldonado, M., Zhang, D.H., and Wesdemiotis, C. (2011) Top-down multidimensional mass spectrometry methods for synthetic polymer analysis. Macromolecules, 44, 4555 554. 

Yang, K., Jenkins, C.M., Dilthey, B. and Gross, R.W. (2015) Multidimensional mass spectrometry-based shotgun lipidomics analysis of vinyl ether diglyceiides. Anal. Bioanal. Chem. 407, 5199-5210. 

The connection of SRM/MRM mode to other MS/MS modes is briefly mentioned earlier. In fact, the other MS/MS techniques (i.e., product-ion analysis, NLS, and PIS) are also interrelated. This interrelationship provides a foundation to multidimensional mass spectrometry-based shotgun lipidomics (MDMS-SL) and can be schematically illustrated with a simplified model system that comprises three molecular ions (/ i, m2, and m ) of a lipid class (Figure 2.8). 

Multidimensional Mass Spectrometry-Based Shotgun Lipidomics... 

MDMS, SL, and HMR stand for multidimensional mass spectrometry, shotgun lipidomics, and high mass... 

MDMS-SL multidimensional mass spectrometry-based shotgun lipidomics... 

Sanders, S.L. Jennings, J. Canutescu, A. Link, A. J. Weil, P. A. Proteomics of the eukaryotic transcription machinery Identification of proteins associated with components of yeast tfiid by multidimensional mass spectrometry. Mol Cell Biol 2002, 22, 4723 738. 

Multidimensional or hyphenated instmments employ two or more analytical instmmental techniques, either sequentially, or in parallel. Hence, one can have multidimensional separations, eg, hplc/gc, identifications, ms/ms, or separations/identifications, such as gc/ms (see CHROMATOGRAPHY Mass spectrometry). The purpose of interfacing two or more analytical instmments is to increase the analytical information while reducing data acquisition time. For example, in tandem-mass spectrometry (ms/ms) (17,18), the first mass spectrometer appHes soft ionization to separate the mixture of choice into molecular ions the second mass spectrometer obtains the mass spectmm of each ion. 

The possibiHties for multidimensional iastmmental techniques are endless, and many other candidate components for iaclusion as hyphenated methods are expected to surface as the technology of interfacing is resolved. In addition, ternary systems, such as gas chromatography-mass spectrometry-iafrared spectrometry (gc/ms/ir), are also commercially available. 

Problem Solving Methods Most, if not aU, problems or applications that involve mass transfer can be approached by a systematic-course of action. In the simplest cases, the unknown quantities are obvious. In more complex (e.g., iTmlticomponent, multiphase, multidimensional, nonisothermal, and/or transient) systems, it is more subtle to resolve the known and unknown quantities. For example, in multicomponent systems, one must know the fluxes of the components before predicting their effective diffusivities and vice versa. More will be said about that dilemma later. Once the known and unknown quantities are resolved, however, a combination of conservation equations, definitions, empirical relations, and properties are apphed to arrive at an answer. Figure 5-24 is a flowchart that illustrates the primary types of information and their relationships, and it apphes to many mass-transfer problems. 

As discussed before, the mass renormalization is a reflection of the fact that the particle traces a distance longer than 2Qq in the total multidimensional coordinate space. 

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