Study On The Volatiles Of Onion Plants Based On SERS

The researching on plant volatiles has a good prospect. And it has important theoretical and practical significance to applying modern spectrum technology for the researching of plant volatiles. In this article, Allium volatiles were extracted by headspace, analyzed with SERS using nano-silver colloid as the substrate.During testing volatiles SERS spectra of various Allium species with nano-silver colloid as the substrate, it is found that silver colloid silver colloid produced in different years have no effect on testing result. Volatiles SERS spectra of same species are essentially identical. SERS spectra of various Allium volatiles with nano-silver colloid as the substrate have well repeatability and stability.The analysis results of volatiles SERS spectra of 16 Allium species confirmed that the main categories of their volatile components include: allyl methyl sulfide, diallyl disulfide and 1-propanethiol. And different Allium species contain different kinds of volatile components. Some Allium species only contain one component, Some Allium species contain two components, some Allium species contain the three above components and relative content of various components which are contained in volatiles of different Allium species is different.The Raman spectra of 1-propanethiol-Ag had been calculated by Gaussian 09. The calculation corresponded well with experimental results of 1-propanethiol in silver colloid. It may be that 1-propanethiol in volatiles was adsorbed on the surface of silver nanoparticles and so produced the SERS effect. In order to study co-adsorption and competitive adsorption relationship of silver nanoparticles with diallyl disulfide and allyl methyl sulfide, we obtained the Synchronous Two-Dimensional Correlation Raman spectra while the perturbation t(t represents the test time interval) by two-dimensional spectrum analysis technology.The statistical analysis combined with allyl methyl sulfide, diallyl disulfide and 1-propanethiol adsorbed on the surface of silver nanoparticles was performed on the volatiles SERS spectra of 16 Allium species and results confirmed that the 16 species were divided into 7 categories according to volatile components and relative content.All of the above research results have revealed that SERS technology can be directly used to study Allium volatiles.