| Desorption electrospray ionization-mass spectrometry imaging（DESI-MSI）is a commonly used mass spectrometry imaging method.It can be used to detect the samples to be introduced under mass pressure and to construct the ionized image of the detected substance by imaging software.In recent years,DESI-MSI has been widely used in medicine,industry,food,biology and other fields due to its advantages of atmospheric pressure operation,less fragment ions and high throughput.Although this technology has made some progress in the field of botany,there is still much room for progress.Coriander（Coriander sativum L.）is a kind of common plant,which is rich in nutrients and has powerful medicinal functions besides traditional edible functions.It has pharmacological activities like antibacterial,anti-inflammatory,antioxidant,anti anxiety and others.The traditional methods of GC-MS and LC-MS are usually used to analyze the components of coriander,which cannot determine the specific distribution of the internal components of coriander.Non destructive method is a potential method to study the spatial distribution of specific metabolites in plant tissues,and localization analysis of coriander components plays an important role in understanding the synthesis and metabolism of its internal components.Based on the DESI-MSI technology,the material composition distribution of coriander samples was obtained by indirect method.The visualization of the internal composition distribution of coriander was realized,and the changes of coriander under different storage time were studied.We explore the sample pretreatment method,and systematically optimize the detection conditions,and obtain the best imaging conditions as follows:the bending angle of the ion transfer tube is30°.The spray solvent system is acetonitrile+0.1%formic acid.Liquid flow rate5μL/min,and the N2pressure is 0.4 MPa.ESI-MS technology was used for full scan analysis of coriander extract.Thin layer chromatography tandem desorption electrospray ionization mass spectrometry was used to separate coriander extract and draw the sequence diagram.The specific spatial distribution pattern of different substances in coriander was observed by mass spectrometry imaging analysis of coriander root,stem and leaf.Coriander samples were stored at 4℃for 1,3,6 and9 days respectively for regular monitoring.The results showed that the internal components of coriander were lost with the extension of storage time.The experimental results show that MSI technology can observe the spatial distribution of the key components of plants from the overall level,which provides a new method for the analysis of plants at different levels.The mass spectrometry imaging technique was used to study the distribution and variation of the key components in coriander.This method has simple pretreatment and high spatial resolution.The study can provide a new perspective for the analysis and detection of coriander components.The experimental results can provide guidance for the storage,food safety and efficient utilization of medicinal ingredients in coriander. |
