Benzoic and sorbic acid in soft drink, milk, ketchup sauce and bread by dispersive liquid–liquid microextraction coupled with HPLC

Benzoic acid and sorbic acid are widely used for food preservation. These preservatives are generally recognised as safe. The aim of this study was to determine the level of benzoic and sorbic acid in food samples that are usually consumed in Iran. Therefore, 54 samples, including 15 soft drinks, 15 ultra-high-temperature milk, 15 ketchup sauces and 9 bread samples, were analysed by high-performance liquid chromatography with UV detection. Benzoic acid was detected in 50 (92.5%) of the samples ranging from 3.5 to 1520 µg mL⁻¹, while sorbic acid was detected in 29 (50.3%) samples in a range of 0.8 and 2305 µg mL⁻¹. Limits of detection and limits of quantification for benzoate were found to be 0.1 and 0.5 µg mL⁻¹, respectively, and for sorbate 0.08 and 0.3 µg mL⁻¹, respectively. The results showed that benzoic acid and sorbic acid widely occur in food products in Iran.