TARGET AND RANK ANNIHILATION FACTOR ANALYSES IN ANALYTICAL CHEMISTRY.

摘要

Target factor analysis (TFA) error criteria are applied to Fourier transform infrared spectra in order to determine, without any prior knowledge of the experimental error, the number and identities of components in a series of related multicomponent mixtures. The TFA method is also used for quantitative analysis and is compared to regression analysis, which force-fits the data and does not compensate for an impurity of small but measurable quantity. In addition, it is shown how an impurity in a single mixture can be detected, identified, and quantified. An actual experimental example is presented, using solutions of o-xylene, m-xylene, p-xylene, and ethylbenzene in cyclohexane, with chloroform as an impurity.;In order to identify and quantify one or more components in a mixture without having to know the identities of the other components, one generally chromatographs the mixture so that each component of interest is characterized by a non-overlapping peak. Unfortunately, complete chromatographic separation is not always attainable. In such instances, the methods established here, using the ultraviolet (UV) absorbances of poorly resolved liquid chromatographic fractions, should prove to be useful. The methods use TFA to identify and rank annihilation factor analysis (RAFA) to quantify the component(s) of interest. A knowledge of the identifies or amounts of the other components is not required. Only partial chromatographic separation is needed and the component spectra may overlap severely.;TFA and RAFA programs in the APLSF language are developed. A liquid chromatograph, specially designed for RAFA, is described. Such a chromatograph is constructed by extensively modifying an existing model. The feasibility of using this chromatograph to identify and quantify individual components with overlapping spectra in mixtures yielding poorly resolved chromatograms is established. This is done by applying the TFA and RAFA methods to the UV absorbance values of the chromatographic fractions of solutions containing different amounts of o-xylene, ethylbenzene, and p-xylene.;An extra factor appears when the absorbances of the chromatographic fractions of one of the solutions are subjected to abstract factor analysis (AFA), the first step in TFA. The AFA results are used to indicate the fraction containing the UV-absorbing impurity(ies) giving rise to the extra factor.