Mass spectrometry basic equations

The basic principle behind TOP mass spectrometry [36] is tire equation for kinetic energy, ze V... 

Note Equation 4.14b has been known as the basic equation of mass spectrometry. Nowadays, there is no more justification for a single basic equation of mass spectrometry because of the various mass analyzers employed. 

The introductory chapter is brief but provides an ample introduction to mass spectrometry and leaves one comfortable as he/she moves on to the historical and instrumentation chapters that follow. A few of the basic equations are given as part of the review of basic concepts. In these few pages Dr Becker clearly introduces the concepts of atomic mass units relative to carbon, isotopes and isotope abundance. Figures 1.1 and 1.2 go hand in hand in providing the reader with the three major parts of a mass spectrometer (source, ion separation, detection) and show various alternatives for each of these. The subtle use of color in these and subsequent figures adds an attractive benefit for the reader. 

The relative binding strength of the adducts follows the qualitative trend of the gas-phase basicities of the donor base, i.e. f-BuOH > i-PrOH > EtOH > MeOH > H2O. The binding to alcohols can be sufficiently selective to the point where 1,2-cyclopentanediols isomers have been distinguished by their reactivity towards Me3Ge+ in tandem mass spectrometry ". The actual binding energy has been measured for H2O (equation 22) ... 

Modem mass spectrometry, photoionization techniques, and ion cyclotron resonance spectroscopy revolutionized gas-phase basidty determination. These techniques have permitted extremely accurate absolute gas-phase basidties to be obtained for a few molecules via thermodynamic cycles using electron affinity and ionization energy data. - Absolute gas-phase basicities for even a few molecules provide valuable references for determination of GB values for bases for which direct GB determination is problematic. The mathematical approach is conceptually straightforward. Consider the general GB equations for Bj and B2 ... 

UV-vis, fluorescence, and calorimetric titrations. It is probably safe to say that over 90% of all experimentally determined binding constants in snpramolecular chemistry are now determined nsing one of these four techniques. Other older or more speciahzed techniques such as solubility methods, potentiometric, and mass spectrometry have been discussed in earlier reviews and are not covered here. It should, however, be noted that the basic equations shown here can usually also be readily adapted to fit these older or more speciahzed techniques. 

The two key catalytic intermediates have been observed by electrospray mass spectrometry [394]. Although the exact role and influence of the base remains unclear [395], the transmetallation is thought to be facilitated by base-mediated formation of the tetracoordinate boronate anion [396], which is more electrophilic than the free boronic acid (Sections 1.5.1 and 1.5.2). A useful carbonylative variant has also been developed to access benzophenones (Equation 70) [397], which can also be produced from the coupling of acid chlorides [398] or anhydrides [399], A variant of this method allows the preparation of a, 3-unsaturated esters from alkenylboronic esters [243]. In all of these reactions, one dreaded limitation with some ortho-substituted and electron-poor arylboronic acids is the possible occurrence of a competitive protolytic de-boronation, which is exacerbated by the basic conditions and the use of a transition metal catalyst (Section 1.5.1). Methods to minimize this side reaction were developed in particular the use of milder alternative bases [400] such as fluoride salts [401], and... 

Equations 1.20 and 1.21 show that any negative ion impurities due to anions of strong acids, such as the phosphate or trifluoroacetate anions, which would have led to strongly bonded adducts to the ionized basic residue [see Eq. 1.20], would also have been prevented by the relatively much higher concentration of the acetate ion from the ammonium acetate used. An important example is the use of trifluoroacetic acid mobile phase in liquid chromatography-mass spectrometry. The presence of the TEA anion in the effluent leads to a large loss of sensitivity in ESIMS and addition of ammonium acetate to the solution... 

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