Simultaneous determination and pharmacokinetic study of P-hydroxybenzaldehyde, 2,3,5,4′-tetrahydroxystilbene-2-O-β-glucoside, emodin-8-O-β-d-glucopyranoside, and emodin in rat plasma by liquid chromatography tandem mass spectrometry after oral administration of Polygonum multiflorum - Lin, L F; Ni, B R; Lin, H M; Cao, S; Yang, C; Zhao, Y; Xue, D; Ni, J (Anal Methods, 2015)