The present study is the first report in case of in-situ preparation and application of Zn-Al layered double hydroxide coated anodized aluminum stir bar for stir bar sorptive extraction approach. An anodized aluminum bar was electrochemically prepared and used as nanoporous substrate for in-situ growth of LDH without adding any aluminum precursor. The prepared anion exchange sorbent has been explored for the extraction of three organic acidic compounds including p-hydroxybenzoic acid, 3.4-dihydroxybenzoic, gallic acid from grape juice and nonalcoholic beer samples. In addition, the capability of the prepared bar for the extraction of quercetin was also investigated. After SBSE, phenolic acids were quantified through reversed-phase high-performance liquid chromatography-diode array detection. Plackett–Burman design was employed for screening the experimental factors. The effective factors were then optimized using Box Behnken design (BBD). Under optimum conditions, the linearity range of the method was between 0.2 and 200 μg L−1 and the coefficient of determination (r2) was higher than 0.9945. Relative standard deviations for intra- and inter-day precision of the analytes at 50 μg L−1 were 3.4–3.8% and 4.1–4.5%, respectively. Batch-to-batch reproducibility at the concentration level of 50 μg L−1 was 4.6–5.1% (n=3); the limits of detection were between 0.06 and 0.26 μg L−1 and so were the enrichment factors between 46 and 50. Different samples of juice such as commercial and natural white and red grape, cranberry and beer were satisfactorily analyzed in order to investigate the method capability in real sample analysis.
