Optimization Design Andapplication of Extracting Methods of Maize (Zea Mays L.) Volatile Compounds
|School||Henan Agricultural University|
|Course||Crop Cultivation and Farming System|
|Keywords||Maize Volatile Compounds Solid-phase Microextraction Steam Distillation Solvent Extraction Adsorption-Solvent Elution Liquid Nitrogen Condensation|
ABSTRACT : Maize volatile compounds are volatile organic compounds (VOCs) synthesized by plant secondary metabolism in plants, which play important ecological function in regulating the relation between plants and plants, microbial, insects and animals. However, the effective collection of maize volatile compounds is the basis of studying and using it. Currently the maize volatile compounds collection method is singleness. In order to collect and analysis maize volatile compounds accurately and rapidly, in this study, we used Zhengdan958, Xundan20 and Ludan981 as materials, comparative studied the five different collection methods, solid-phase microextraction, steam distillation, solvent extraction, gas adsorption and liquid nitrogen condensation, which were regularly used both at home and abroad to screen out one kind of reliable and accurate maize volatile compounds collection method. The main results were as follows:1. The condition of maize leaf volatile compounds collection by solid-phase microextraction was explored in this study. Volatile compounds of maize leaf were isolated and identified successfully by combined gas chromatography-mass spectrometry (GC/MS). The maize leaf volatile compounds can be effectively extracted by the fiber of 50/30um DVB/CAR/PDMS. 0.4g of maize leaf grinding sample was placed in a 4ml headspace flask. Optimum adsorption time was 30 min at 30℃. Analytic time was 2 min at 250℃.2. Volatiles from mechanical damaged fresh leaves of maize were collected by dynamic head-space sampling with adsorbents GDX-101, GDX-502, Porapak Q, Tenax-Ta and XAD-2, respectively. Components of the volatiles were analysis and identified by combined gas chromatography-mass spectrometry (GC/MS). The results showed that the adsorption efficiency of GDX-101, GDX-502, Porapak Q and Tenax-Ta were basically consistent. These four adsorbents could meet the requirement of adsorption and detection of the maize leaves volatile compounds. The adsorption capability of XAD-2 was poor to the lean content volatile compounds.3. The difference of the interaction force among different solvents, adsorbents and adsorbed compounds influenced the elution effects of the adsorbed compounds and limited the accuracy of quantitative analysis. In this study, the common green leaf volatile compounds of maize were adsorbed by Porapak Q and eluted with dichloromethane, methanol, ether and hexane, respectively, and were analyzed by gas chromatography. The results showed that ether and hexane are best for maize green leaf volatile compounds elution. The dichloromethane is following and methanol is the last choice. Meanwhile the elution effect of dichloromethane is obviously better than the other three solvents when amount of elution solvent was used.4. Compared different collection methods, the volatile compounds collected by steam distillation and solvent extraction could not really reflect the maize volatile compounds constituents under the natural state, but steam distillation and solvent extraction are suitable for extracted aromatic compounds and terpenoid compounds among maize volatile compounds. The volatile compounds collected by gas adsorption and liquid nitrogen condensation meet the maize volatile compounds constituents under the natural state. Compared the feasibility of gas adsorption and liquid nitrogen condensation, especially under the field conditions, gas adsorption should be first chosen.5. The optimized maize volatile compounds collection method is adsorption-solvent elution. Healthy and mechanical damaged maize leaf volatile compounds of different cultivars were adsorbed by Porapak Q and eluted with hexane. N-octane was added as internal standard. Qualitative and quantitative results showed that release patterns of maize volatile compounds were same between healthy and mechanical damaged maize of different cultivars, but there were some differences in the volatile types and contents. According to the results, the adsorption-solvent elution method adsorbed by Porapak Q and eluted with hexane could really reflect the maize volatile compounds constituents and suit for quantitative analysis of maize volatile compounds.