Approaches to the Sample Preparation of Food Emulsions for Their Efficient Separation and Precipitation of Nonvolatile Polymer Components

Abstract

Gas chromatography is the main method for the analysis of volatile substances in food products, in particular, additives that improve their taste and appearance. However, food matrices are, usually, complex disperse systems (emulsions, gels, or foams), the direct gas chromatographic analysis of which is difficult. In addition, such matrices can damage chromatographic columns and contaminate evaporators and detectors, thereby leading not only to improper analytical data (unacceptable peak shapes or loss of sensitivity), but also to a decrease in the service life and the need for frequent maintenance of an entire system. Therefore, in order to obtain reliable results and protect expensive analytical equipment, it is necessary to use methods of preliminary preparation of samples with the purposed of purifying them from high-boiling natural compounds. In this work, we have compared two fundamentally different approaches to sample preparation of food emulsions, i.e., the liquid-liquid and solid-phase extraction in order to choose the most acceptable method both from the viewpoints of the accuracy and reliability of the results obtained and from the standpoints of economic advisability and time consumptions. The study was carried out by the example of determining the content of ethanol, as well as the qualitative analysis of impurity alcohols in an alcohol emulsion of shellac (E904).