Liquid chromatography—mass compositional analysis

S. M. Hayes, R. H. Liu, W. S. Tsang, M. G. Legendre, R. J. Berni, and M. H. Ho, Enantiomeric composition analysis of amphetamine and methamphetamine by chiral phase high-performance liquid chromatography-mass spectrometry, J. Chromatogr., 398 239 (1987). 

Xia YQ, Jemal M (2009) Phospholipids in liquid chromatography/mass spectrometry bio-analysis comparison of three tandem mass spectrometric techniques for monitoring plasma phospholipids, the effect of mobile phase composition on phospholipids elution and the association of phospholipids with matrix effects. Rapid Commun Mass Spectrom 23 2125-2138... 

Merkle RK, Poppe I (1993) Carbohydrate composition analysis of glycoconjugates by gas-liquid chromatography/mass spectrometry. In (ed) Methods enzmol, vol 230. Academic Press, NY, pi... 

Liquid chromatography-mass spectrometry (LC-MS) is an extremely power tool for the analysis of peptides, providing not only information on the purity of the product but also coMormation of structures. The s)rstem typically consists of a microbore HPLC system coupled to an electrospray mass spectrometer. Using such a system the composition of a crude peptide mixture can be quickly determined and by-products identified, enabling synthetic protocols to be rapidly optimized. 

To obtain a comprehensive analysis of carbohydrate mixtures from biological matrices that display a high degree of compositional and structural heterogeneity, a multidimensional approach is required. The combination into a so-called hyphenated system, of liquid chromatography (LC) or CE with MS provides the advantage of selective and efficient separation with the mass specificity, sensitivity, and structural information gained from MS. 

Advanced analytical techniques, particularly mass spectrometry (MS), often combined with liquid chromatography (LC) or gas chromatography (GC), are requisite for lipid analysis and they have played the crucial role in the emergence as well as the progresses of lipidomics. MS is the principal choice for the lipid analysis, particularly using electrospray ionization (ESI) and sometimes also atmospheric pressure chemical ionization or laser-based MS methods for surface analysis. The MS-based techniques are the best choice for lipidomics due to their superior sensitivity and molecular specificity, and because they provide the ability to resolve the extensive compositional and structural diversity of lipids in biological systems. 

Methyl Esters. These long-chain acyl esters are subjected to thin-layer chromatography, colorimetric analysis, and gas-liquid chromatography, coupled with mass spectrometry, as described in Chapter 4. These assays will provide information on the ester/P molar ratio (based on starting phosphate value it should be 2.0) and on the composition and relative distribution of fatty acyl residues. 

Analysis of the composition and purity of aromatherapy products relies on a number of well-established scientific techniques. The principles and application of those most commonly employed, such as GC (gas-liquid chromatography), MS (mass spectrometry) and optical rotation, are explained. The importance of the human senses in the physiological analysis and appreciation of essential oils is also outlined. 

Analyses of Pitch. Modern analytical facilities of high-pressure liquid chromatography, gel permeation chromatography, an(j 1 nuclear magnetic resonance and mass spectrometry, associated with 1R and UV spectroscopy enable a total molecular constituent analysis of pitch composition to be obtained. The use of such information could then possibly be the route to prediction of pitch quality on carbonization. It would appear that such an approach would not be successful (ignoring the cost factor for such detailed analysis). The pitch cannot be considered as an assembly of molecules which pyrolyse independently of each other. The pitch carbonizes as a multi-phase system and experience today would indicate the impossibility of predicting all interactions, physical and chemical. 

For the precise determination of the complex polymer composition including the chemical composition and MMD of the components in most cases a separation step is required. Only after obtaining fractions comprising the different polymer components, can an analysis with regard to chemical composition and MMD be conducted. The present section discusses different options which enable the use of liquid chromatography (SEC, HPLC, LC-CC) in conjunction with FTIR, mass spectrometry and NMR for the separation of complex polymers. 

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