Modification of garlic peel by nitric acid and its application as a novel adsorbent for solid-phase extraction of quinolone antibiotics

Abstract Garlic peel, an agriculture by-product, was modified by a simple method using HNO 3 , and the adsorption behaviors of garlic peel (GP) and HNO 3 modified garlic peel (HNO 3 -GP) for quinolone antibiotics were evaluated. Furthermore, HNO 3 -GP was used as a novel solid-phase extraction (SPE) sorbent for the detection of quinolone antibiotics for the first time. Comparisons of characterizations between GP and HNO 3 -GP revealed that the increase of surface acidic functional group of HNO 3 -GP led to a significant improvement of adsorption capacity (about 10 times of GP). In addition, the adsorption behaviors of GP and HNO 3 -GP for quinolone antibiotics including adsorption kinetic, isotherm and thermodynamic studies were discussed, and the results proved that HNO 3 -GP have higher affinity of quinolones. Moreover, key parameters influencing the relative recoveries of HNO 3 -GP based SPE, such as the content of eluent, the volume of eluent, the pH of water sample and the sorbent amount were investigated. Finally, an environmentally friendly, effective and economic HNO 3 -GP based SPE-HPLC method for the determination of four quinolone antibiotics was established, and successfully applied in the analysis of real sample. Under the optimized conditions, good liner relationships (>0.9996), limits of detections (LODs) from 0.65 to 0.85 μg L −1 , and relative recoveries from 86.3 to 95.1% with satisfactory analytical features (relative standard deviation, RSD,