Novel Solid Phase Extraction Technique Based On Functional Graphene And Its Applications In Antibiotic Residues

The abuse or the irrational use of antibiotics has done increasing potential harm to the ecological environment and human health, especially these existed in food, which can directly threaten the health and safety of people, should not be ignored.Sample pretreatment is an indispensable procedure before the analysis of antibiotics because of the low concentration levels and complex matrices. Solid phase extraction (SPE) is one of the most welcomed technologies due to its merits of simple operation and high performance. However, the SPE process is tedious, time-consuming and the use of cartridge in SPE is high-cost. What is more, the adsorbent used in SPE is of lowed selectivity, complicated preparation process and narrowed range application. Among them, the adsorbent is the key factor that determines the performance and development of SPE. In recent years, a new type of carbon materials, namely graphene and based its functional materials have become a research topic which used as the sorbents in SPE due to their large specific surface areas.Based on the above points, in this paper, it tries to synthesis novel functional graphene materials with excellent adsorption performance or design a new-type of solid-phase extraction device which is simple, economic and environmental for the detection of antibiotics in food.Based on the review of previous studies, the innovative works were carried out in this paper. (1) A graphene-based magnetic nanocomposite (CoFe2O4 - G) was successfully synthesized and used as an adsorbent for the magnetic solid phase extraction (MSPE) of SAs (SM1, SMTZ, SDX, SMZ, SIZ) for the first time. The surface morphologies and structures of the CoFe2O4-G was investigated by scanning electron microscopy (SEM), FT-IR, UV-vis spectroscopy, X-ray diffraction (XRD) and vibration sample magnetometer (VSM). Several parameters including sample pH, amount of sorbent, extraction time and desorption conditions were optimized in detail. Under the optimal experimental conditions, good linear relationships of five SAs were obtained in the linear ranges 0.02-50.00 mg L-1 with correlation coefficients (r)(?) 0.9982. The limits of detection (LODs) and the limits of quantification (LOQs) were less than 1.59 μg L-1 and 4.81 μg L-1. Besides, the relative standard deviations (RSDs) of intra- and inter-day analysis were less than 4.3 and 6.5%, respectively. The proposed method was successfully applied for the analysis of SAs in milk samples. The average recoveries determined for two milk samples spiked at levels were 62.0-97.6% and 68.8-104.0% with RSDs less than 14.0% and 10.4%, respectively. In addition, the CoFe2O4 - G could be reused after cleaning with acetone and ultrapure water, successively. The results demonstrated that the MSPE methodology is a convenient, reliable and promising extraction technology with merits of easy operation, sensitivity and efficiency. It could couple with suitable chromatographic detection techniques and used to detect SAs in complex matrix. (2) The miniaturization of self-assembled solid phase extraction (m-SASPE) based on graphene oxide/chitosan (GO/CS) coupled with liquid chromatography was developed for rapid screening of five SAs in eggs and honey. Parameters that affected extraction efficiency including sample pH, amount of the GO/CS, elution solvent and rotation speed were optimized in detail. Under the optimal conditions, good linear relationships of five SAs were obtained in the linear ranges 0.01 - 10.00 μg g-1 with correlation coefficients (r)(?) 0.9989. The limits of detections (LODs) were in the range of 0.71 - 0.98 ng g-1. The relative standard deviations (RSDs) of intra- and inter-day analysis were less than 3.5 and 7.1%, respectively. The proposed method was successfully applied for the analysis of SAs in eggs and honey. The average recoveries determined for two samples spiked at levels were in the range of 75.3 - 105.2% and 81.2-101.0% with RSDs less than 13.5% and 12.6%, respectively. The results indicated that the m-SASPE-HPLC methodology simple, fast and efficient. It could be used to quickly detect SAs in eggs and honey.