固相萃取-高效液相色谱串联质谱法测定油菜薹中反式维生素K1含量

为准确测定反式维生素K1的含量，建立了基于固相萃取-高效液相色谱串联质谱的甘蓝型油菜（Brassica napus L.）菜薹反式维生素K1高灵敏检测技术。样品经正己烷提取、中性氧化铝柱净化后，用C30反相色谱柱，以甲醇 （含0.025%甲酸+2.5 mmol/L甲酸铵）为流动相，采用选择反应监测（selected reaction monitoring, SRM）模式进行定量分析，20 min内可实现顺反异构体色谱分离。方法学考察结果显示，反式维生素K1在范围内线性关系良好，相关系数为0.9985。该方法检出限为0.29 μg/kg，定量限为0.95 μg/kg。回收率为87.5%～117.6%，精密度（RSD）在0.72% ～9.59%之间。利用该方法对油菜薹和反式维生素K1含量高的3种蔬菜进行分析，发现油菜薹中反式维生素K1含量为340.08 μg/100g，高于小白菜（B. rapa spp. chinensis，260.93 μg/100g）、西兰花（B. oleracea var. Italic Planch， 167.65 μg/100g）和结球甘蓝（B. oleracea var. capitata，151.11 μg/100g）。本文建立的蔬菜中反式维生素K1准确定量分析方法操作简单、灵敏度高、结果准确。同时比较发现油菜薹是一种富含维生素K1的蔬菜。 

Extraction and determination of trans-vitamin K1 in Brassica napus bolt by SPE-HPLC-MS/MS

 To accurately determine the content of trans-vitamin K1, extraction and determination of trans-vita?min K1 in vegetables was developed by using solid phase extraction high performance liquid chromatography-tan?dem mass spectrometry (SPE-HPLC-MS/MS). The target was extracted by n-hexane and purified by neutral alumi?na SPE column, and then separated on aC30 liquid chromatography column with methanol containing 0.025% formic acid and 2.5 mmol/L ammonium formate, and quantified by mass spectrometry in selected reaction monitoring (SRM) mode. The cis- and trans-vitamin K1 were separated within 20 min. The validation results showed that a good relationship in linear ranges was obtained with correlation coefficients of 0.9985. Meanwhile, limit of detection (LOD) and limit of quantification (LOQ) of trans-vitamin K1 were 0.29 μg/kg and 0.95 μg/kg, respectively. The re? covery rates ranged from 87.5% to 117.6%, the relative standard deviations (RSDs) of intra-day and inter-day var? ied from 0.72% to 9.59%. Then, the proposed method was used to analyze bolt of rapeseed (Brassica napus L.）and three other vegetables（B. rapa spp. chinensis, B. oleracea var. Italic Planch, B. oleracea var. capitata）with high content of trans-vitamin K1. The content of trans-vitamin K1 in B. napus was 340.08 μg/100g and higher than those in Chinese cabbage (260.93 μg/100g), broccoli (167.65 μg/100g) and kohlrabi (151.11 μg/100g). The proposed method has high sensitivity and selectivity, and could be successfully employed to detect vitamin K1 in vegetables. The comparison between Brassica napus with other vegetables indicated that Brassica napus is a vegetable with high vitamin K1 content.