Analysis of four preservatives in beverages and instant noodle samples by high performance liquid chromatography-ultraviolet detection coupled with magnetic solid phase extraction based on metal-organic frameworks

Abstract

Magnetic amino functionalized metal-organic frameworks (MOFs) were prepared by a simple stirring and blending process. The obtained composites had good magnetic and thermal stability with a large specific surface area, and were used for the extraction of four preservatives with different polarities (benzoic acid, sorbic acid, propyl p-hydroxybenzoate and butyl p-hydroxybenzoate) in soda water, vitamin beverage and instant noodle cake samples. After optimizing the conditions for magnetic solid phase extraction (MSPE) and desorption, the four preservatives were analysed by a high performance liquid chromatography-ultraviolet detection (HPLC-UV) method. The analytes were separated on a Purospher® STAR LP C18 column (250 mm×4.6 mm, 5 μm). Methanol and 10 mmol/L ammonium acetate aqueous solution (50:50, v/v) were used as the mobile phases with gradient elution. The limits of detection of the four preservatives were 0.51-1.89 μg/L. The recoveries of the target preservatives were 72.2%-109% in the soda water, vitamin beverage and instant noodle cake samples. The method is simple, rapid, accurate and reliable, and is suitable for the analysis of preservatives with different polarities in beverages and foods. The method can provide an effective technology for food safety and quality control.