Principal Component Analysis of Polarity and Interaction Parameters in Inverse Gas Chromatography

Abstract

Inverse gas chromatography is used in the characterization of aliphatic-aromatic and aromatic ketones, their oximes, and ketone-oxime or oxime-oxime mixtures. All these organic materials are used as liquid stationary phases in gas chromatographic columns. A series of polarity and Flory-Huggins interaction parameters are determined and used to describe the physicochemical properties of examined materials, metal extractants, and products of their degradation. Principal component analysis (PCA) is performed on a data matrix consisting of polarity and interaction parameters for ketones, their oximes, and mixtures. The calculations are carried out on the correlation matrix. It is found that seven principal components account for more than 95% of the total variance in the data, indicating that the polarity (interaction) parameters are not correlating well. Physical meanings are attributed to the principal components, the most influential ones being that the first and the second principal components account for several Flory-Huggins interaction parameters, whereas the fifth is correlated with criterion "A". The plots of component loadings show characteristic groupings of polarity indicators, whereas that of component scores show several groupings of stationary phases. Cluster analysis provides mainly the same groupings. PCA allows for the grouping of polarity and solubility parameters based on the information carried within those parameters. There is no need to use more than one parameter from each cluster. McReynolds polarity and the partial molar excess Gibbs free energy of solution per methylene group carry the same information. The groups of ketones, oximes, and their mixtures can be distinguished with the use of PCA on the basis of the measured polarity, solubility parameters, or both.

Inverse Gas Chromatography

“…Subsequently, PCA became a popular technique in data analysis for pattern recognition and dimension reduction, as it can reveal several underlying components, and may also help to explain the vast majority of variance among the data [56,57]. PCA is particularly useful for classifying stationary phases [58,59], polarity [56], and interaction parameters [57]. Detailed descriptions of PCA are available in standard chemometric books and reviews [58,59].…”

Inverse Gas Chromatography in Characterization of Composites Interaction

“…It can reveal several underlying components, which explain the vast majority of variance in the data [Héberger, 1999;Malinowski, 1991;Héberger et al, 2001]. The principle is to characterize each object (rows in the input matrix) not by analyzing every variable (columns of the input matrix) but projecting the data in a much smaller subset of new variables (or principal component scores).…”

Determination of Hansen solubility parameters of solid materials by inverse gas-solid chromatography

“…Inverse gas chromatography (IGC) is one technique proposed for examination of the surface properties of solid materials under different conditions (temperature, humidity). IGC is an extension of conventional gas chromatography [2][3][4][5]. The word 'inverse' means that the examined material is placed in the chromatographic column and its properties are determined by study of the retention behavior of carefully selected test compounds.…”