应用超高效液相色谱-四极杆-飞行时间质谱法建立谷物中18种真菌毒素非靶向筛查数据库及确证方法

建立了基于超高效液相色谱-四极杆-飞行时间质谱(UPLC-Q-TOF/MS)的18种真菌毒素非靶向筛查方法。真菌毒素标准物质用HSS T3色谱柱进行色谱分离后在UPLC-Q-TOF/MS MS^E模式下分别用正、负离子模式采集,获取MS和MS/MS的信息,记录对应保留时间、加合物离子、碎片离子精确质量数等信息,设置保留时间偏移为0.3 min,加合物离子和碎片离子的精确质量匹配容差为5×10^-6,在UNIFI中建立18种真菌毒素的数据库。在稻谷、小麦基质中,以筛查检出限(SDL)作为主要参数对筛查方法进行了验证。18种真菌毒素分为有最大限量和无最大限量两种类型,结果有最大限量的真菌毒素均能在其限量水平被准确筛查,无最大限量的真菌毒素其SDL的范围为2~800μg/kg。基质效应考察表明,稻谷中有14种真菌毒素有中等基质效应,小麦中有11种真菌毒素有中等基质效应。样品经乙腈提取后用QuEChERS萃取盐包和HLB净化柱净化,用建立的方法对25批稻谷、小麦进行筛查,结果2批稻谷中检出4种真菌毒素,2批小麦中检出2种真菌毒素。该方法能准确筛查SDL水平以上的真菌毒素,具有高通量、简便、快捷、准确等特点,可实现无标准品情况下对稻谷、小麦中多种真菌毒素的定性筛查。

Establishment of non-targeted screening database and confirmation method for 18 mycotoxins in grains using ultra performance liquid chromatography-quadrupole-time of flight mass spectrometry

A mass spectral library of 18 mycotoxins was developed based on ultra performance liquid chromatography-quadrupole-time of flight mass spectrometry (UPLC-Q-TOF/MS), which was used to establish a non-targeted screening method for mycotoxins in rice and wheat matrices. Eighteen mycotoxin standards were separated on an HSS T3 column, and data were collected for both positive and negative ionization under the MS^E mode of the UPLC-Q-TOF/MS. Details including formulas, retention times, theoretical exact masses, measured exact masses of the adduct and fragment ions, and ion abundance ratios were recorded to establish the mass spectral library of the 18 mycotoxins in UNIFI Software. Analyte detection was based on a retention time deviation of 0.3 min, and the exact mass deviation of the adduct ions and fragment ions was set to 5×10^-6. The screening detection limit (SDL) was used as the main threshold for verifying the screening method. In the validation process, 18 mycotoxins were classified into two types: with maximum levels (MLs) and without MLs. The results showed that the mycotoxins with MLs could be accurately screened at their limited level, and the mycotoxins without MLs had a range of SDL concentration from 2 to 800 μg/kg. The matrix effect results showed that 14 mycotoxins in rice and 11 in wheat had moderate matrix effects. Finally, 25 batches of rice and wheat were purified using QuEChERS and HLB columns after acetonitrile extraction and screening were performed by employing the established method. The results revealed that aflatoxin G₁ (AFG₁), aflatoxin G₂ (AFG₂), fumonisins B₁ (FB₁), and sterigmatocystin (ST) were detected in one batch of rice, FB₁ and ST were detected in another batch of rice, FB₁ and ochratoxin A (OTA) were detected in two batches of wheat, and no other mycotoxins were detected. This method is characterized by high throughput, simplicity, rapidity, accuracy, and can be applied to accurately screen mycotoxins with concentrations higher than the SDLs and qualitatively screen various mycotoxins in rice and wheat without standards.