Applied High-Resolution Mass Spectrometry

Generally, high-resolution mass spectrometry (HR-MS) aims to achieve both high mass resolution and high mass accuracy. These quantities have been introduced without considering the means by which they can be measured. The key to this problem is mass calibration. Resolution alone can separate ions with m/z in close proximity, but it does not automatically reveal where on the m/z axis the respective signals are located. This section deals with the techniques for establishing accurate mass data and their analytical evaluation [32,33]. 

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This impressively indicates that A is a very difficult parameter to measure accurately. Recently, the situation was somewhat improved by applying high-resolution mass spectrometry for determining X, which allows a very precise measurement of end-groups originating from the two termination processes. This method arrived at a value for MMA at 85 °C of A = 0.63, which is very close to the average value X of all data obtained before, which is an indication of this method s accuracy. 

Advanced techniques like molecularly imprinted polymers (MIPs), infrared/near infrared spectroscopy (FT-IR/NIR), high resolution mass spectrometry, nuclear magnetic resonance (NMR), Raman spectroscopy, and biosensors will increasingly be applied for controlling food quality and safety. 

More recently, high-resolution chromatographic techniques (particularly reverse-phase and ion exchanged-based HPLC) have been applied in the separation of proteome proteins and high-resolution mass spectrometry is being employed to aid high-throughput sequence determination. 

Figure 3.14 Schematic representation of an ion cyclotron resonance cell (Penning trap) for high resolution mass spectrometry. The magnetic field is oriented and the ions are injected along the z axis. The ions are trapped along this axis by a trapping voltage (e.g., I V applied to the front and back plates 3 and 4). (Modified from C. Brunnee, Int. j. Mass Spectrom. 76, 125 (1987). Reproduced by permission from Elsevier.)...

High-resolution mass spectrometry (MS) is one of the analytical techniques that can furnish significant information on the heterocompounds in coal liquids. This technique has been widely applied to the analysis of coal-liquefaction products (1,2,3,4) and is essentially indispensable for the detailed analysis of heterocompounds (3,5,6). 

N.m.r. has been used for assignment of configuration to 5a-cholest-8(14)-ene-3/3,7a,15a-triol and related compounds with allylic hydroxy-groups/ and H n.m.r. studies have been applied to some C-19 substituted steroids and b/S-CHaX-substituted 19-nor-5(10)-enes, to evaluate a-, p, 7-, and 5-substi-tuent effects and obtain information on the rotameric populations of substituted methyl groups. Other authors report shift data for some 19-hydroxy-, 5,6-epoxy-, A -3-oxo-, and 24-ethyl steroids. The incorporation of and from labelled ethanol into cholic acid in rats has been studied by high-resolution mass spectrometry and n.m.r, ... 

The detection limits also depend to a great extent on the type of mass spectrometer used. The values for quadrupole mass spectrometers are by orders of magnitude higher than in the case of high-resolution mass spectrometry. This applies... 

An improved high-resolution mass spectrometry-based multiresidue method for veterinary drugs in various food matrices was reported by Kaufmann et al. (111). Their new method covers more than 100 different veterinary drugs. Validated matrices included muscle, kidney, liver, fish, and honey. A 15-cm-long Kinetex Cl8 column was applied in this study (111). 

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