在线固相萃取-高效液相色谱-高分辨质谱法测定植物中11种水溶性有机酸

采用在线固相萃取-高效液相色谱-四极杆-静电场轨道阱高分辨质谱建立植物中11种水溶性有机酸(乳酸、富马酸、琥珀酸、苹果酸、酒石酸、香豆酸、没食子酸、柠檬酸、香草酸、阿魏酸、新绿原酸)的分析方法。样品经匀浆、超声、过滤、稀释后，经在线Oasis MAX柱(20 mm×2.1 mm,30 μm)富集净化，采用BEH C₁₈ AX色谱柱(100 mm×2.1 mm,1.7 μm)分离，以含10 mmol/L甲酸铵的0.9%甲酸和0.9%甲酸-乙腈为流动相，梯度洗脱。在负离子扫描模式下，以Full MS/dd-MS²模式进行分析，内标法定量。结果表明，11种有机酸可在9 min内完成分离分析，各组分的精确质量数偏差小于5.00×10^-6，在1～100 μg/L质量浓度范围内线性关系良好，相关系数(R²)大于0.999，方法检出限为0.1～3.2μg/kg，定量限为0.3～9.6μg/kg。以芡实和小白菜为基质样品，在2个不同加标水平下，11种有机酸的平均添加回收率分别为92.2%～111%和94.2%～11...

Determination of 11 Water-Soluble Organic Acids in Plants by Online Solid-Phase Extraction Coupled with High Performance Liquid Chromatography-High Resolution Mass Spectrometry

An analytical method for the determination of 11 water-soluble organic acids (lactic acid, fumaric acid, malic acid, tartaric acid, coumaric acid, gallic acid, citric acid, vanillic acid, ferulic acid, and neochlorogenic acid) in plants by online solid-phase extraction (SPE) coupled with high performance liquid chromatography-quadrupole orbitrap high resolution mass spectrometry (HPLC-Q-Orbitrap-HRMS) was developed. Samples were homogenized, ultrasonically extracted, filtrated, diluted, and purified on an Oasis MAX column (20 mm × 2.1 mm, 30 μm). The analytes were separated on separated on a BEH C18 AX column (100 mm × 2.1 mm, 1.7 μm) by gradient elution using a mobile phase consisting of 0.9% formic acid solution containing 10 mmol/L ammonium formate and 0.9% formic acid in acetonitrile. The MS analysis was performed by full MS/dd-MS2 scanning in the negative ion mode. Quantitation was performed using the internal standard method. Under the optimum conditions, the 11 organic acids were well separated within 9 minutes, and the accurate mass deviation for each compound was less than 5.00 × 10-6. The developed method showed good linearity in the range of 1–100 μg/L with correlation coefficients (R2) greater than 0.999. The limits of detection (LOD) and quantification (LOQ) ranged from 0.1 to 3.2 μg/kg and from 0.3 to 9.6 μg/kg, respectively. The average recoveries of the 11 organic acids in Euryale ferox seeds and pakchoi spiked at two concentration levels were 92.2%–111% and 94.2%–110% with intraday relative standard deviations (RSDs) of 1.4%–4.9% and 0.8%–5.6%, respectively. The method was successfully applied to the analysis of organic acids in white radish, carrot, potato, pakchoi, banana, pear, grape, and E. ferox seeds. This method is simple, fast, accurate, and reliable, and can be used as a new approach for the rapid analysis of water-soluble organic acids in plants.