Overlapping peaks application

A typical application can be found in chromatography. A group of components elute in a strongly overlapping peak cluster. We suspect that a particular chemical, for which we know the spectrum, might be in the unknown mixture, but due to overlap, its spectrum does not appear pure in the matrix Y. 

Fig. 15.5 Illustration of how two overlapping peaks S and ip emerging from the first colmnn (a) are resolved in GCxGC after passage to the second column (b) [31]. Reprinted from Marriott, R, Shellie, R., Principles and applications of comprehensive two-dimensional gas chromatography. Trends Anal. Chem. (2002), 21 573-583 with permission from Elsevier...

The application of AMDIS is triggered automatically by the end of the chromatographic run. It works in the background and the results of intermediate processes are not visible on the screen. The program detects peaks in the process of deconvolution, isolates their spectra from the background and overlapping peaks and compares the pure spectra of detected peaks with the spectra in the library currently used by AMDIS. 

In terms of organization, the text has two main parts. The first six chapters constitute generic background material applicable to a wide range of separation methods. This part includes the theoretical foundations of separations, which are rooted in transport, flow, and equilibrium phenomena. It incorporates concepts that are broadly relevant to separations diffusion, capillary and packed bed flow, viscous phenomena, Gaussian zone formation, random walk processes, criteria of band broadening and resolution, steady-state zones, the statistics of overlapping peaks, two-dimensional separations, and so on. 

The result of the application of the DDM decomposition formula Equation (14) is similar to that of Rietveld s approximation for /obs> except that it is DDM-oriented and thus does not require a background definition. In the DDM program the formula is also used for the Bragg R factor calculation. For single non-overlapped peaks or a set of peaks with the same position, the DDM decomposition directly gives the best estimate for /obs- For partly overlapped peaks it should be iterated to arrive at an optimized set of /obs similarly to the Le Bail method. The starting intensities f can either be calculated from an existing structure model or set arbitrarily when the model is absent. Notably, for fully overlapped peaks the DDM decomposition... 

Kiesswetter R, Brandi F, Kasmer-Pustet N, and Mann-schreck A (2003) Chiroptical detection during liquid chromatography deconvolution of overlapping peaks of enantiomers and its applications. Chirality 15 40-49. 

The application of surface-selective H Si cross polarization (CP) experiments for amorphous silica (Figure 1.9) gives three partially overlapping peaks Q2 for (=SiO)2Si(OH)2 sites at about -89 ppm (relative to a liquid tetramethylsilane [TMS], peak), Q3 for (=SiO)3SiOH... 

The application of evolutionary factor analysis (FA) methods to spectroscopic problems is reviewed by Malinowski. Evolutionary FA methods offer solutions to the problem of analyzing totally unknown complex mixtures. These are mixtures containing unknown quantities of an unknown number of unknown components. No model for peak shape is required for these methods to work, that is, they are self-modeling. Deconvolution of overlapped peaks in HPLC is the type of data analyzed. 

With its unique deconvolution algorithms, AMDIS has proven its capabilities for the efficient removal of overlapping interferences in many GC-MS applications (Mallard and Reed, 1997). The deconvolution process is independent from the type of analyser and scan rate used to resolve overlapping peaks for substance identification as well as multi component residue analysis (Dimandja, 2004 Mallard et al., 2005 Zhang, Wu and Li, 2006). Without time-consuming manual data evaluation, AMDIS provides sensitive compound information even with complex background present (Halket et al, 1999). 

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