Combination of in-situ electro synthesized Zn-Al-LDH@ pencil graphite fiber and three phase hollow fiber LPME for microextraction of some antibiotics in urine samples and quantification via HPLC-UV

In the present study, a combination of two useful extraction techniques including fiber solid phase micro -extraction based on the new synthesized sorbent and the porous hollow fiber liquid phase microextraction is reported. The selective anion-exchangeable Zn-Al-layered double hydroxide as a fiber was electrodeposited on the surface of pencil graphite substrate through simple and cost-effective method. The prepared fiber was characterized and put into the lumen of the porous hollow fiber, which was filled by alkaline solution. The obtained optimum condition for the method was as follows: donor phase HCl concentration of 0.10 mM, acceptor phase NaOH concentration of 7.60 mM and extraction time of 16 min. It is necessary to adjust the concentration of the donor phase in order to extract acidic analytes from an aqueous sample into an organic phase. The method was used for the quantification of three antibiotics including amoxicillin, ciprofloxacin and cefixime. The extracted antibiotics were analyzed by high performance liquid chromatography-ultraviolet detection (HPLC-UV). In the optimal conditions, the linearity of the proposed method was in the range of 0.50-500.00 mu g L-1 for selected analytes in water and urine matrices. All calibration curves showed determination of coefficient higher than 0.9958. The limits of detection and limits of quantification were calculated to be between 0.08 and 0.16 mu g L-1 and 0.28-0.56 mu g L-1, respectively. In order to define the precision of the method, the inter-day and intra-day relative standard deviations were determined between 3.25 and 5.73% in the three selected concentrations. The enrichment factors (EFs) were between 46.20 and 55.81 for selected drugs. Moreover, the calculated absolute recoveries were between 69.30 and 83.71%. The relative recoveries were obtained in the range of 93.00-105.00%. The proposed method was also employed for analysis of various urine samples containing the selected drugs. The obtained recoveries indicated that the method was useful and applicable in complicated biological samples.