[Research on volatiles of rakkyo (Allium Chinense G. Don) and Chinese chive (Allium Tuberosum Rottl. ex Sprengel) based on headspace and the molecular recognition of SERS].

The head space and the molecular recognition of surface enhanced Raman scattering (SERS) were used to research volatiles of rakkyo and Chinese chive. Their volatiles SERS spectra were obtained using nano-silver colloid as the substrate. Then, volatiles SERS spectra of rakkyo and Chinese Chive were compared respectively with the volatiles SERS spectra of liquid allyl methyl sulfide, 1-propanethiol, diallyl disulfide and all possible pairings of the three compounds. The results showed that the repeatability of volatiles SERS spectra of rakkyo and Chinese Chive were all good. The volatiles SERS spectrum of rakkyo was basically consistent with the volatiles SERS spectrum of the mixture of liquid allyl methyl sulfide and 1-propanethiol. The volatiles SERS spectrum of rakkyo included both characteristic peaks at 626 and 674 cm(-1) in volatiles SERS spectrum of allyl methyl sulfide and characteristic peaks at 702, 893, 1024,1085, 1215 and 1320 cm(-1) in volatiles SERS spectrum of 1-Propanethiol. The volatiles SERS spectrum of Chinese chive was basically consistent with the volatiles SERS spectrum of the mixture of liquid allyl methyl sulfide and diallyl disulfide. The volatiles SERS spectrum of Chinese chive included both characteristic peak at 674 cm(-1) in volatiles SERS spectrum of allyl methyl sulfide and characteristic peaks at 407, 577, 716, 1189, 1291 and 1401 cm(-1) in volatiles SERS spectrum of diallyl disulfide. These illustrated that volatiles of rakkyo contained allyl methyl sulfide and 1-Propanethiol and volatiles of Chinese chive contained allyl methyl sulfide and diallyl disulfide. The volatiles of rakkyo and Chinese chive were different, but they all contained allyl methyl sulfide. All of the above have revealed that the headspace combined with molecular recognition of SERS can be directly used to study volatiles of rakkyo and Chinese chive. The technology under room temperature, can guarantee the volatiles obtained were the primitive constituents in plant volatiles. By comparison with the standard sample, the constituents in plant volatiles can be determined.