Development of a Layered Double Hydroxides-Based Air-Assisted D-μSPE Method in Combination with HPLC for the Determination of Gallic Acid in Honey

Determining gallic acid in honey can provide information for assessing the nutritional value and tracing the source of honey. However, the complex matrix of honey and the low content of gallic acid may hamper the detection. Therefore, it is important to select an appropriate sample preparation method. This work established an air-assisted dispersive micro-solid phase extraction combined with a high-performance liquid chromatography method to determine gallic acid in honey. Zinc/nickel/aluminium layered double hydroxides were selected as the adsorbent to extract gallic acids in diluted honey samples. Under air-assisted extraction, the adsorbents adsorbed gallic acid in honey via anion exchange. Subsequently, the isolated adsorbents were dissolved in a 1% phosphoric acid solution. A high-performance liquid chromatography-UV-Vis detector was used for gallic acid detection. Under the optimised conditions, gallic acid showed good linearity over the concentration range of 0.005-10.0 mg.L-1 with a coefficient of determination greater than 0.999. The detection limit and quantification limit were 13.5 and 45 ng.g-1, respectively. The recoveries were 89.8-93.4%, with the intra-day and inter-day relative standard deviations in the range of 0.71-1.17% and 0.76-1.27%, respectively. The method possesses the advantages of simplicity, rapidity, economy and environmental friendliness and is suitable for detecting gallic acid in honey.