1. Department of Gastrointestinal Surgery, Shengli Clinical Medical College of Fujian Medical University, Fujian Provincial Hospital, No. 134 Dongjie, Fuzhou 350001, P. R. China
2. Clinical Medical Center for Digestive Diseases of Fujian Provincial Hospital, No. 134 Dongjie, Fuzhou 350001, P. R. China
3. Key Laboratory for Analytical Science of Food Safety and Biology (MOE & Fujian Province), Department of Chemistry, Fuzhou University, Fuzhou 350108, P. R. China