1. Laboratory of Mass Spectrometry, College of Chemistry, Key Laboratory of Pesticides and Chemical Biology, Central China Normal University, Ministry of Education, Wuhan, Hubei 430079, P. R. China
2. Department of Chemistry, Stanford University, Stanford, California 94305, United States
3. State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Science and Technology, Guangxi University, Nanning, Guangxi 530004, P. R. China