Simultaneous determination of 15 pyrrolizidine alkaloids and their N-oxides in weeds, soil, fresh tea leaves, and tea: Exploring the pollution source of pyrrolizidine alkaloids in tea

Weiting Jiao, Lei Zhu, Tingting Shen, Luyao Wang, Qing X. Li, Chen Wang, Xiangwei Wu, Hongping Chen, Rimao Hua