1. College of Public Health; Zhengzhou University; Zhengzhou 450001 China
2. Zhengzhou Tobacco Research Institute of China National Tobacco Corporation; Zhengzhou 450001 China
3. School of Chemistry and Chemical Engineering; Henan University of Technology; Zhengzhou 450001 China
4. Department of Chemistry and Biochemistry, Center for Intelligent Chemical Instrumentation; Ohio University; Athens OH 45701-2979 USA