泡腾和石墨化的多壁碳纳米管通过超高效液相色谱法辅助天然抗氧化剂的微萃取，电化学检测和四极杆飞行时间串联质谱外文翻译资料

评价项目 校准曲线 R 精密度(RSD%) LODs

日内 日间 重复性

重复性 重复性 样品间

(n = 6) (n = 3) (RSD%)n = 5

保留时间 峰面积 保留时间 峰面积 保留时间 峰面积 (ng/mL)^a (ng/mL)^b

原儿茶酸y = 3.8849x 0.4762 0.9993 0.07 1.56 0.45 3.21 0.10 3.79 2.56 0.17

儿茶素 y = 71.429x minus; 51.382 0.9989 0.10 0.48 0.70 2.59 0.09 4.13 6.83 0.01

绿原酸 y = 44.031x 7.5244 0.9991 0.10 0.67 0.78 2.11 0.11 3.46 7.30 0.02

咖啡酸 y = 34.101x minus; 29.867 0.9998 0.09 0.79 0.69 2.96 0.12 3.98 3.21 0.03

表儿茶素y = 73.879x 5.3933 0.9997 0.12 0.51 1.01 3.63 0.21 4.96 9.46 0.02

阿魏酸 y = 13.577x minus; 4.9145 0.9987 0.02 1.41 0.23 2.84 0.06 4.33 17.20 0.07

金丝桃苷y = 7.8268x 1.8277 0.9986 0.05 0.76 0.32 2.13 0.04 5.13 15.10 0.13

异槲皮苷y = 5.1873x 0.4836 0.9996 0.06 1.71 0.39 3.66 0.10 4.05 15.10 0.18

评价项目 含量（ng／ml） 绝对的提取

回收率%

山楂 山楂卷 山楂鳞片 三明治山楂 alpha;-山楂饮料 宜信山楂饮料 味之王山楂饮料

原儿茶酸2.30 0.75 1.06 0.57 1.

剩余内容已隐藏，支付完成后下载完整资料

Effervescence and graphitized multi-walled carbon nanotubes

assisted microextraction for natural antioxidants by ultra high

performance liquid chromatography with electrochemical detection

and quadrupole time-of-flight tandem mass spectrometry

Shu-Ling Wang, Xiao-Qing Pang, Jun Cao, Wan Cao, Jing-Jing Xu, Qiong-Yao Zhu,Qian-Yun Zhang, Li-Qing PengCollege of Material Chemistry and Chemical Engineering, Hangzhou Normal University, Hangzhou 310036, China

Abstact: In this article, effervescence and graphitized multi-walled carbon nanotubes assisted microextraction was first developed for the extraction of antioxidants in hawthorn samples. The use of an effervescent tablet composed of sodium dihydrogen phosphate, sodium carbonate and micro-scale carboxyl graphitized multi-walled carbon nanotubes (extraction sorbent) was the core of the method. In this study, ultra high performance liquid chromatography coupled with electrochemical detection and quadrupole timeof-flight tandem mass spectrometry was performed for qualitative and quantitative analyses of target analytes in hawthorn foodstuffs. Several experimental factors, such as amount of effervescent salts, the sorbent, elution time and elution solvent, were systematically assessed. Under the optimized conditions, a good linearity with R values better than 0.9980 was obtained. The detection limits estimated at a signalto-noise ratio of 3:1 were ranging from 0.01 to 0.18 ng/mL. These results suggested that the proposed method could be an alternative and promising sample preparation tool in future food analysis.

Keywords: Antioxidants Graphitized multi-walled carbon nanotubes Effervescence assisted microextraction Hawthorn Quadrupole time-of-flight tandem massspectrometry Ultra high performance liquid chromatography with electrochemicaldetection

3.3. Effect of elution time

In order to determine the elution time and improve desorption efficiency of antioxidants. The nylon membrane with target analytes was sonicated in an ultrasonic bath for 1–10 min with other parameters kept constant. The results (Fig. 3B) indicate that desorption efficiency increases with the increasing elution time up to 7.5 min. To the best of our knowledge, the dynamic equilibrium process was driven by both molecular diffusion and convective mass transfer. With the elution time increasing, ultrasonication could obviously promote mass transfer of target compounds from solid phase into the elution solvent. However, a slight decrease in the peak area response is observed for all of the tested analytes when ultrasonication time exceeds 7.5 min. This may be caused by small vacuum bubbles or void produced by ultrasonication. When these small vacuum bubbles or void violently collapsed, the temperature of sample solution rose rapidly, which influenced desorption quantity of the proposed method [23]. Therefore, 7.5 min was employed as the optimum elution time.

3.4. Amount of carboxyl graphitized multi-walled carbon nanotubes

The large specific surface area and unique structure of the GMWCNTs-COOH provided them with extraordinary absorption capability during the procedure of sample microextraction. The amount of dispersive sorbent may have a significant influence on extraction efficiency of the target antioxidants. To evaluate the effect of this parameter, different amounts of GMWCNTs-COOH (5–20 mg) were investigated in each tablet when the weight of mixed effervescent salts was 300 mg. As shown in Fig. 3C, as the concentration of sorbent increases from 5 to 10 mg, extraction performances of the model analytes are remarkably improved. This aspect could be attributed to the fact that higher amounts of the solid support presented a stronger interaction with the tested compounds as well as enhanced the kinetics of the extraction process, thus, improved extraction yields. However, the peak areas slightly decrease when the addition of sorbents is increased to 15 and 20 mg. A possible reason was that agglomeration would happen

if excessive amounts of GMWCNTs-COOH were used in the preparation. In addition, the increasing interaction between the analytes and sorbents may result in a disadvantage in the elution process. Furthermore, it should be emphasized that higher dose of nanoparticles could reduce the cohesion between the tablet components and affected the physical stability of effervescent tablets. Consequently, in order to obtain the best results using the least amount of sorbent, 10 mg of GMWCNTs-COOH were used for the present study.

3.5. Selection of elution solvent

The elution solvent is an important factor controlling the desorption efficiency of microextraction process. In this study, five kinds of elution solvent having different physicochemical properties were used, namely, ethyl acetate, ethanol, acetonitrile, acetone and methanol. A series of experiments was investigated to find out the best eluting solvent among them. It is found in Fig. 3D that lower peak areas are achieved after eluting with ethyl acetate, acetonitrile and acetone, which demonstrate they were not suitable as elution solvent due to the lack of active hydrogen

剩余内容已隐藏，支付完成后下载完整资料

资料编号：[280319]，资料为PDF文档或Word文档，PDF文档可免费转换为Word