Dispersive Liquid–Liquid Microextraction of Preservatives for Their Chromatographic Determination in Beverages.

A method of dispersive liquid–liquid microextraction, based on the dispersion of an extractant by the gas phase formed as a result of a phase transition, i.e., the evaporation of a highly volatile nonpolar organic solvent (dispersant) upon heating the extraction,—is developed. The analytical capabilities of the method are shown in the determination of preservatives (sorbic and benzoic acids) in soft drinks for baby food by high-performance liquid chromatography with photometric detection. The extractant and the dispersant for the microextraction of preservatives are chosen a terpenoid and a highly volatile organochlorine solvent, respectively, which excluded the use of polar organic solvents for dispersing phases, with which the distribution coefficients are reduced. The limits of detection (3σ) for sorbic and benzoic acids are 0.3 mg/L. The developed method does not require centrifugation for phase separation. [ABSTRACT FROM AUTHOR]