Studies Of Microwave-assisted Extraction Of Drug Residues In Food

As the continuous improving of people's quality of life, the demand for food is growing. However, due to the irrational use of various drugs, irreversible environmental pollution was caused and a number of food safety problems were triggered. So. it's necessary to develop a series of rapid and accurate detection methods of drug residues in food to ensure the safety of commercial foods. Microwave-assisted extraction (MAE) technology is rapid, less solvent consumption, high yield and pollution, so it has been widely used in drug analysis, food analysis and environmental analysis, etc.This paper focus on using several different methods of MAE combined with solid phase extraction (SPE) to extract tetracycline (TCs) in fish, sulfonamide (SAs) in feed and carbamate in apples.1. A MAE method was developed and optimized for the extraction of five TCs and the epimers of tetracycline and chlortracycline in fish muscle. The extract was cleaned-up in sequence with silica and Oasis hydrophilic-lipophilic balance (HLB) cartridge. Subsequently, the TCs trapped on the HLB cartridge were eluted with methanol and determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The good recoveries of TCs were achieved by MAE at 55℃for 10 min. The limits of detection (LODs) are in the range of 0.85-3.4 ng g-1 for all TCs. The relative standard deviations (RSD) of intra- and inter-day ranging from 2.6% to 9.1% and from 2.7%to 9.7% are obtained, respectively. In all three fortified levels (4,40 and 200 ng g-'), the recoveries of TCs are in the range of 74.5-92.8%. Compared to solvent extraction assisted by ultrasound or water bath heating, the proposed method was demonstrated to obtain higher recovery in a shorter time.2. A microwave assisted steam extraction (MASE) was developed to extract seven SAs in feed. The steam was selected as extraction solvent, combined with microwave-assisted, to extract the SAs in feed rapidly and effectively. The proposed method has avoided the use of organic solvents, reduced impurities in the extraction and the matrix effect. Then the carbon nanotubes were selected in the method as adsorbent for SPE and achieved high recoveries which were in the range of 46.9-92.6%. The LODs are in the range of 0.78-3.7 ng g-1 for all SAs. The RSD of intra- and inter-day ranging from 2.8-10.7% and from 3.3-11.2% are obtained, respectively.3. A dynamic microwave-assisted extraction (DMAE) combined with SPE was developed for the determination of carbamate residues in apples. In the proposed method, water was selected as the solvent to extract the carbamate from apples quickly and efficiently. And finally the extract was purified and enriched by HLB column. The LODs are in the range of 1.1-4.2 ng g-1 for all carbamate and the recoveries were 71.2-90.1%. Meanwhile, the extraction mechanism of carbamates has also been studied.