A novel method was developed for the simultaneous determination of eight cannabinoids in six types of food matrices, including chocolate, fondant, biscuit, beverage, cookie and baijiu, using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The sample extraction and cleanup steps were optimized, and various purification methods were investigated to remove the oil matrix and glue in chocolate and fudge, respectively. Enhanced matrix removal-lipid adsorbent (EMR-Lipid) provided efficient, selective cleanup of the evaluated matrices. The sample was extracted using acetonitrile, followed by EMR-Lipid cleanup, and then dried using anhydrous sodium sulfate. The acetonitrile layer was concentrated by nitrogen to near-dry after 100 μL 10% glycerol in methanol was added to improve the recovery by reducing loss during concentration under the stream of nitrogen gas. Eight cannabinoids were separated using a Waters ACQUITY UPLC BEH Shield RP18 column (100 mm×3.0 mm, 1.7 μm). The responses of the cannabinoids in the positive and negative ionization modes were investigated and optimized, and the responses were superior in the negative ion mode compared to those in the positive ion mode. MS detection was performed in the multi-reaction monitoring (MRM) mode using an electrospray source in the negative ion mode. The cannabinoids were quantified using an external standard with matrix calibration curves to reduce the influences of the matrix effects on the quantitative results. The developed method was verified, and the conditions of sample pretreatment were also optimized. The calibration curves of tetrahydrocannabinol, cannabidivarin, tetrahydrocannabivarin, and cannabigerol and those of cannabidiol, cannabinol, cannabidiolic acid, and tetrahydrocannabinolic acid exhibited good linearities, with r>0.995, in the ranges of 2-200 and 0.4-40 ng/mL, respectively. The respective limits of detection (LODs, S/N=3) and quantification (LOQs, S/N=10) of tetrahydrocannabinol, cannabidivarin, tetrahydrocannabivarin, and cannabigerol were 4 and 10 μg/kg, and those of cannabidiol, cannabinol, cannabidiolic acid, and tetrahydrocannabinolic acid were 0.8 and 2 μg/kg. The average recoveries of the cannabinoids were 82.0%-114.9% under three spiked levels with corresponding relative standard deviations (RSDs) of <15% (n=6). EMR-Lipid provided efficient, selective cleanups of food matrices with good accuracy. The method is sensitive, rapid, accurate, simple to execute, and it is suitable for the determination of cannabinol compounds in typical food matrices.
研究在优化前处理条件及色谱分离的基础上,建立了同时测定巧克力、软糖、糕点、饼干、饮料、白酒等6种典型食品基质中8种大麻素类化合物的超高效液相色谱-串联质谱(UPLC-MS/MS)的测定方法。前处理方法中考察了不同的净化方式,采用增强型脂质去除净化剂(EMR-Lipid)解决了巧克力中复杂油脂及软糖中胶质难以去除的问题;同时净化溶液在氮吹前加入10%丙三醇甲醇溶液,解决了目前文献方法中直接氮吹对回收率影响很大的关键问题。样品以乙腈为提取溶剂,EMR-Lipid为净化剂进行净化,无水硫酸钠除水后,乙腈层加入10%丙三醇甲醇溶液100 μL,氮吹至近干;采用Waters ACQUITY UPLC BEH Shield RP18色谱柱进行分离,电喷雾负离子扫描,多反应监测(MRM)模式检测,基质匹配外标法定量。方法学研究表明,四氢大麻酚、次大麻二酚、四氢大麻素、大麻萜酚在2~200 ng/mL范围内线性关系良好;大麻酚、大麻二酚、大麻二酚酸、四氢大麻酚酸A在0.4~40 ng/mL范围内线性关系良好,相关系数(r)均大于0.995;检出限和定量限分别为0.8~4 μg/kg和2~10 μg/kg。在不同加标水平下的平均回收率为82.0%~114.9%,相对标准偏差(RSD)均小于15%(n=6)。研究结果表明,采用EMR-Lipid净化剂净化食品基质时,净化效果明显,准确度较好。该方法灵敏、快速,准确度高,前处理简单,适用于食品基质中大麻素类化合物的准确定性定量检测。
Keywords: cannabinoids; enhanced matrix removal-lipid cleaning adsorbent (EMR-Lipid); foods; ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS).