Studies On Microwave-assisted Steam Diffusion Of Drug Residues In Food

Microwave extraction, due to its advantages of short operation time, less organicsolvent, was commonly used for the extraction of organic contaminants from samples.In this paper, microwave-assisted steam diffusion combined with solid phaseextraction and the solidification of floating organic drop (SFO) method for drugresidues in food was studied. Liquid chromatography tandem mass spectrometry wasfor the detection of targets, the specific content as follows.1. An environmentally friendly method was proposed for determination ofsulfonamide antibiotic residues (SAs) in animal feed. The method was based onmicrowave-assisted steam extraction on-line coupled with solid-phase extraction andfollowing detection by high performance liquid chromatography-tandem massspectrometry (LC-MS/MS). Firstly the SAs residues in animal feed were extractedsuccessively with water steam under the action of microwave energy, and the extractobtained was directly introduced into a SPE column which was packed withcation-exchange resin. Subsequently, the SAs trapped on the resins were eluted withmethanol-ammonia (90:10, v/v) for detection. The limit of detection andquantification obtained were2.4-4.4ng g-1and8.2-14.7ng g-1for SAs, respectively.The recoveries of SAs at three fortified levels (25,100and1000ng g-1) in animalfeed were in the range of76-92%. Compared with the traditional methods, theproposed method was an environmentally friendly and effective alternative withrespect to less time, solvent and labor consumption for the analysis of SAs in complexsamples.2. A simple, rapid, and sensitive method based on microwave-assisted steamextraction (MASE) on-line coupled with clean-up which was followed by high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) wassuccessfully developed for the determination of six triazine herbicides in tea samples.Silica gel was used to remove chlorophyll in tea. C18solid phase extraction cartridgewas used for concentration of the targets. Water vapor under microwave irradiation isused to accelerate desorption of the analytes from the samples. The extraction andclean-up procedures were carried out simultaneously in one step. The limit ofdetection and quantification obtained were0.37-0.82ng g-1and1.23-2.72ng g-1forsix triazine herbicides, respectively. The recoveries of SAs at three fortified levels intea samples were in the range of80-97%. The proposed method is a more rapid andsimpler approach to analyse triazine herbicides in complex solid samples comparedwith the traditional extraction method.3. A rapid method of microwave-assisted steam extraction combined with SFOwas developed for determining triazines in corns. The method combines theadvantages of microwave-assisted steam extraction and SFO technique. Firstly,140μL of1-dodecanol was added to the sample in the extraction vessel, and then triazinswere extracted by water steam under microwave energy, after which2.0g sodiumchloride was added into the extract, then centrifuged and cooled. The1-dodecanolcontained the triazins was solidified and transferred for analysis. Limits of detectionof the triazines obtained were in the range of0.36–0.59ng g1. The method wassuccessfully applied to the analysis of four cereals and the recoveries of the triazinesfor the spiked samples were in the range of82-99%.