蜂蜜中氯霉素残留的检测及净化方法研究

Determination of honey chloramphenicol residue by monolithic column liquid chromatography-mass spectrometry and QuEChERS purifying method

建立了反相高效液相色谱-离子阱质谱法检测蜂蜜中氯霉素残留的方法。前处理采用改良的QuEChERS方法进行快速提取和净化。采用初级次级胺进行固相分散净化,可有效吸附蜂蜜中的糖类及有机色素等杂质。提取物在流动相甲醇∶水(0.2%乙酸胺)=45∶55(体积比)中,用整体色谱柱进行快速分离和质谱检测。并对MS检测中2种离子化方式(电喷雾ESI及大气压化学APCI)、各种离子化方式下正负离子模式及离子检测方法(总离子检测TIC和选择性离子监测MRM)进行了综合比较,最终确定采用电喷雾电离法(ESI)负离子模式、多反应离子监测(MRM)对氯霉素进行定性定量分析。在0.2～200μg/kg添加浓度下,添加回收率水平在78%～93%间,变异系数在3.9%以下。该方法的检出限为0.1μg/kg,在0.1～100μg/L浓度范围内,线性方程为y=58.753x+34867,相关系数R2=0.9995。

This paper aims to present a liquid chromatographic method with mass spectrometric detection and identification （LC-MS） for determining chloramphenicol residue in honey. In the paper honey samples were collected and analyzed with modified QuEChERS method. The procedure of our research can be shown as follows： first of all, mixing 5 g sample honey with 5 mL water and adding 20 mL acetonitrile ; then letting the sample mixture vortex for 2 min to form a uniformed liquid; afterwards taking 2 g NaCl to be ultrasonicated for 2 min and making it centrifugal, at a rate of 4 000 r/min for 5 min. And, finally, the acetonitrile phase is removed with another 20 mL acetonitrile added. In this stage, the mixture can be further vortexed and uhra-sonicated and centrifuged as is done before. Then, the acetonitrile phase is evaporated to be dried, dissolved in 1 mL acetonitrile, and, next, 25 mg PSA and 150 mg MgSO4 is added, vortexed, centrifuged in a 1.5mL tube. Last of all, 500 μL cleaned solution is transferred to the LC vial, The column used was a Merk Monolithic with a mixture of methanol-water with 0.5 % ammonium acetate （45 ： 55） as mobile phase, In our research, we have also tested the ESI and APCI method in positive and negative ionization mode and detected the ESI in negative ionization. As a result, it was more reproducible and sensitive than the others. At the 0.2 - 200 mg/kg residue level, the average recoveries prove to be between 78% - 93% and the coefficient variation ranged from 3.7% to 3.9%. 0.1 μg/L standard solution gave a signal equal 3 times the noise. The signal seems linear in the 0.1 - 100 μg/L concentration, whose linear equation is y = 58.753x ＋ 34867, correlating coefficient R^2 = 0. 999 5.