Steam-based solid-phase extraction method for benzoic and sorbic acids in food by HPLC

A steam-based solid-phase extraction (SPE) method was developed for the determination of benzoic acid and sorbic acid in food matrices. Samples were heated, and the generated steam was passed through an SPE cartridge in two successive cycles. Analytes were eluted with 0.1% (v/v) acetic acid in methanol and quantified by high-performance liquid chromatography (HPLC). Method validation demonstrated linearity over 1-100 μg mL^-1 for benzoic acid and 1-300 μg mL^-1 for sorbic acid (R² ≥ 0.999), and recoveries of 91.9-102.6% with repeatability of 0.7-3.8% RSD and intermediate precision of 1.9-5.0% RSD. Applicability was confirmed in 12 food products with recoveries of 85.2-103.1% and 0.1-4.9% RSD, indicating practical usage in food safety monitoring. By combining two techniques (steam-based extraction and SPE), the method provides a simplified and efficient purification strategy for the analysis of benzoic and sorbic acids in complex food matrices.