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Unformatted text preview: David Grauer December 14, 2007 JP 3 Mixture Analysis Techniques in Present and Future Applications With a concentration on various host-gut microbial interactions 1.1 Introduction It is rare to find simple mixtures in natural systems. Solutions and fluids are inevitably complex and filled with an amalgam of various components. In years past, complex mixtures of chemicals were thought to be useless in the face of NMR spectroscopy, mass spectrometry and IR spectroscopy analyses due to the ‘forest’ of peaks that would result from a sample such as blood plasma. This assumption is generally true when looking at a single spectrum; there is no possible way to assign every peak, although some specific peaks may be assigned with relative confidence. This position changed with the advent of multivariate statistical analysis and techniques and pattern recognition technologies. These new technologies allow for the identification of individual peaks among the ‘forest’ and between many individual spectra. With such technology, it has thus become possible to both identify these individual peaks and assign them appropriately. With this degree of accuracy, it is then feasible to measure how different parameters can affect these various components of these complex mixtures giving rise to various new –omics notably metabonomics and metabolomics (Lindon, 2007). These new fields have applications as limited only by the imaginations of its developers. Currently, the field is beginning to see development in non-invasive medical testing, product quality control, fossil fuel testing among other fields both industrial and health related (Eide, 2005; Fragaki, 2005; Wang, 2004). 1.2 Data acquisition methods There are several methods now being employed in mixture analysis – NMR and mass spectrometry. One of the inherent advantages of mixture analyses employing these methods is the extremely simple sample preparation for a sample; there is essentially none. There are, however, several types of each technology mentioned above, and the following section will briefly describe the most important as they apply to mixture analysis. NMR has three different types of sample analyses available and generally used – 1D, 2D (COSY, TOCSY, and NOESY) and magic angle NMR. NMR technology can be applied to any NMR active atom that is readily prevalent within a sample. Thus, each of the previously mentioned technologies is typically applied to 1 H, 13 C, and 31 P. These types of NMR have been around for a while and are well established. A relatively newer type of NMR has made its presence felt in the mixture analysis field – magic angle NMR. This type of NMR sets the sample cell at 57 ° to the magnetic field and spun. This technique is used effectively on samples that are not inerently homogeneous, blood for example. This spinning, in effect, distributes the magnetic field evenly through the sample, despite a dearth of mixing in the sample (Lindon, 2007)....
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This essay was uploaded on 12/19/2007 for the course CHM 371 taught by Professor Andrewb.bocarsly,istvanpelczer,prasads.lakkaraju during the Fall '07 term at Princeton.
- Fall '07