应用超高效液相色谱-四极杆-飞行时间质谱建立茶叶中农药残留的筛查与确证方法

基于超高效液相色谱-四极杆-飞行时间质谱(UPLC-QTOF-MS),使用UNIFI软件建立91种农药残留的筛查与确证方法,进行定性方法验证并应用于流通市场中茶叶的筛查检测。通过对收集的农药认证标准物质(CRM)分析,构建91种农药化合物的质谱数据库。样品经乙腈提取,固相萃取柱净化,Acquity BEH C18色谱柱分离,在MS^E模式下进行全信息采集(ESI+), UNIFI软件对数据进行匹配分析。设置保留时间最大偏差为±0.1 min,精确质量偏差阈值为±5×10^-6,可识别加合物形式包括M+H]⁺、M+Na]⁺、M+K]⁺、M+NH₄]⁺。参照SANTE/11813/2017指南进行定性方法学验证。在21份茶叶样品中添加混合标准溶液至4个水平(0.01、0.05、0.10、0.20 mg/kg),确定每种农药在茶叶样品中的筛查检出限(SDL),共评估了1911种农药/样品组合。发现有66种农药的SDL为0.01 mg/kg, 8种农药的SDL为0.05 mg/kg, 1种农药的SDL为0.10 mg/kg, 3种农药的SDL为0.20 mg/kg,共有13种农药的SDL大于0.20 mg/kg。一种农药在筛查检测中存在基质抑制效应。最后,应用建立的方法分析了流通市场中22份茶叶样品的农药残留情况,从6份茶叶样品中筛查检测出6种农药化合物,经人工鉴定均为阳性。该法为茶叶中农药残留的高通量筛查检测提供了参考。

Establishment of screening and confirmation method for the analysis of pesticide residues in tea by ultra-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry

Based on ultra-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry (UPLC-QTOF-MS), UNIFI 1.7.0 software was used to establish a screening and confirmation method for the analysis of 91 pesticide residues, which was qualitatively validated and applied to tea screening in the circulation market. By analyzing the collected pesticide certified reference materials (CRM), a mass spectral database of 91 pesticides was constructed. The database contains multiple types of information, including formulas, theoretical exact masses, retention times, characteristic fragment ions, and adduct types. The samples were extracted with acetonitrile, purified on a solid-phase extraction column, and separated on an Acquity BEH C18 column. All the data (ESI+) were acquired in MS^E mode and analyzed using the UNIFI information system. Analyte detection was based on the retention time deviation ±0.1 min, accurate mass deviation ±5×10^-6, and major adduct forms including M+H]⁺, M+Na]⁺, M+K]⁺, and M+NH₄]⁺. Screening was performed by the software in an automated fashion. Compound identification was accomplished with retention time matching and accurate mass measurements of the primary diagnostic ions for each analyte. To ensure accuracy of the identification results, information from the MS/MS profiles must be compared with online mass spectral libraries such as PubChem and MassBank. The SANTE/11813/2017 protocol for the validation of the screening method was followed. A mixed standard solution was spiked to 21 tea samples at four levels (0.01 mg/kg, 0.05 mg/kg, 0.10 mg/kg, and 0.20 mg/kg) to determine the screening detection limit (SDL) of each pesticide, and a total of 1911 pesticide/sample combinations were evaluated. The results revealed 66 pesticides with an SDL of 0.01 mg/kg, eight pesticides with an SDL of 0.05 mg/kg, one pesticide with an SDL of 0.10 mg/kg, three pesticides with an SDL of 0.20 mg/kg, and 13 pesticides with an SDL greater than 0.20 mg/kg. One pesticide showed matrix-inhibitory effects in the screening tests. Finally, the established method was used to analyze the pesticide residues in 22 tea samples available on the market. Six pesticide compounds were found in the tea samples, all of which were confirmed to be positive after artificial identification. This method provides a reference for the high-throughput screening and detection of pesticide residues in tea as well as a research approach for the analysis of various chemical contaminants in other matrices.