基于UPLC-QTOF MS的食品接触用回收PET中非挥发性有机物的非靶向筛查

Untargeted Screening of Nonvolatile Organic Compounds in Recycled PET Flakes for Food Contact Applications by Ultra-performance Liquid Chromatography-Quadrupole Time-of-flight Mass Spectrometry

采用超高效液相色谱-串联四极杆飞行时间质谱技术(UPLC-QTOF MS)对经初步清洗后的回收聚对苯二甲酸乙二醇酯(rPET)瓶片中潜在的非挥发性有机物进行非靶向筛查,并考察了不同沉淀溶剂、去除溶剂方式、测试样品量等前处理方法,以及不同测试方法、流动相及洗脱剂梯度等条件对rPET瓶片中非挥发性有机物测定的影响。研究结果显示:以0.2 g的rPET瓶片溶于10 mL六氟异丙醇中,20 mL甲醇作为沉淀溶剂、氮吹去除溶剂的前处理方式,以甲醇-0.1%甲酸水体系作为流动相梯度洗脱,采用数据依赖型采集(DDA)模式进行测试。此时获得方法的回收率为66.0%~80.4%,相对标准偏差(RSD)均不高于5.1%,表现出较好的稳定性和可重复性。采用质谱数据库和二级谱图定性,通过结构类似的化合物进行半定量,rPET瓶片中共检出30种非挥发性有机化合物,含量范围为0.038~4.92 mg/kg。检出物质包括环状和线型寡聚物、助剂副产物或降解产物和污染物等非有意添加物27种,其余3种可能是有意添加物。利用建立的非靶向筛查方法以及主成分分析(PCA)对两个不同地域厂家的24种rPET瓶片(rPETC和rPETN)进行检测,结果显示两组样品在正离子模式下有明显差异,检出差异物质15种;负离子模式下差异不明显。表明同类型但不同来源的rPET瓶片具有不同的差异物质。研究表明,所建立的UPLC-QTOF MS筛查方法具有准确可靠、简单、快速等优点,可有效用于食品接触rPET中非挥发性有机物的分析及安全评价工作。

An ultra-performance liquid chromatography coupled to quadrupole time of flight mass spectrometry(UPLC-QTOF MS)was established and employed for the untargeted screening of non-volatile organic compounds in washed recycled polyethylene terephthalate(rPET)flakes.Influences of pretreatment methods including choice of precipitation solvent,method of solvent removal,amount of test sample,and the chromatographic conditions including different mobile phases and elu⁃ent gradients on the determination of non-volatile organic compounds in rPET bottle flakes were inves⁃tigated.A satisfied results could be obtained by using the following optimized condition or method:0.2 g rPET flakes was dissolved in 10 mL hexafluoro-isopropanol,20 mL methanol was used as pre⁃cipitation solvent,the solvent was removed by nitrogen-assisted evaporation,methanol-0.1%for⁃mic acid water system was used as the mobile phase by gradient elution,and the data-dependent ac⁃quisition(DDA)mode was employed as data acquisition method.The qualitative analysis on the ana⁃lyte was carried out by using MS database and secondary spectroscopy,while the semi-quantitative analysis was performed using compounds with similar structures.A total of 30 non-volatile organic compounds were detected in the rPET flakes,with amount of 0.038-4.92 mg/kg.The detected compounds included 27 types of non-intentionally added substances such as cyclic and linear oligo⁃mers,by-products of additives,degradation and contaminants,and the remaining 3 compounds might be associated with intentionally added additives.The recoveries ranged fron 66.0%to 80.4%,with relative standard deviations(RSD)not higher than 5.1%,indicating that this method has good stability and repeatability.24 types of rPET bottle flakes(rPET C and rPET N)from two different geographic manufacturers were detected by the established non-targeted screening methods with prin⁃cipal component analysis(PCA).The(PCA)results showed that there were significant differences observed between rPET group C and group N,while 15 different types of compounds were detected.These results indicated that the recycled PET bottle flakes with the same type but having different sources may have different compositions.The UPLC-QTOF MS method was demonstrated to be ac⁃curate,reliable,simple and rapid,which could be effectively used for the analysis and safety as⁃sessment of non-volatile organic compounds in rPET intended for food contact applications.