Data analysis contour plots

With regard to comprehensive LC data elaboration, the acquired data is commonly elaborated with dedicated software that constructs a matrix with rows corresponding to the duration of the second-dimension analysis and data columns covering all successive second-dimension chromatograms. The result is a bidimensional contour plot, where each component is represented as an ellipse-shaped peak, defined by double-axis retention time coordinates. When creating a 3D chromatogram, a third axis by means of relative intensity is added. The colour and dimension of each peak is related to the quantity of each compound present in the sample. Figure 4.9 illustrates an example of data elaboration in comprehensive LC. 

Data analysis options include the preparation of isoenergy contour maps (CMAPS), linear energy vs. rotation angle plots (LINPLOT) and tables of local energy minima, statistical thermodynamic probabilities, and entropy terms to enable the reporting of "free" energies in addition to "conformational" energies. 

Once a solution is obtained, analysis of the data in the postprocessing step is similar to data analysis in a laboratory experiment program. Today, most packages provide contours, vectors, line plots, and alphanumeric reports for almost any quantity and on almost any surface desired. More-sophisticated features such as animation are also available. Flexible user interfaces also allow custom programming to extract additional quantities of interest. However, data exchange back to the geometry side or down to other analyses such as stress still requires significant effort. 

Early visualization in chemical three-way analysis was used in curve resolution methods, and especially GRAM. The extraction and visualization of unknown spectra (curve resolution) was considered very important. Tucker and PARAFAC analysis were used much in the exploratory sense and PARAFAC also for curve resolution. The first publication of Ho et al. [1978] has figures of eigenvalues expressed as a function of a parameter /S, see Figure 8.1. The second publication of Ho et al. [1980] also contains contour plots for the excitation-emission spectra of polyaromatic compounds (see Figures 8.2 and 8.3). They also show excitation and emission spectra as line plots (see Figures 8.4 and 8.5). The plots are only used to show the raw data and show no results after analysis. An early publication of de Ligny et al. [1984] has all the results shown as numbers in tables. 

Figure 34 Contour plot of a COSY experiment on ZSM-12 with projection in F,. The same conditions as those in Fig. 33 were used except that 80 scans were taken in each experiment. Four hundred and fifty real data points and power calculation were used in the data analysis. (From Ref. 75.)...

The combination of the two methods in the 2D setup dramatically increased the resolution of the separation system and gave a clear picture of the complex nature of the 16-component sample. Based on the composition of the sample, a contour map with the coordinates chemical composition and molar mass is expected to show 16 spots, equivalent to the 16 components. Each spot would represent a component which is ideally defmed by a single composition and molar mass. The experimental evidence of the improved resolution in the 2D analysis is given in Figure 9.23. This contour plot was calculated from experimental data based on 28 transfer injections. 

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