A modified 1H-NMR quantification method of ephedrine alkaloids in Ephedrae Herba samples - Li, Y C; Wu, C H; Le, T H; Yuan, Q; Huang, L; Chen, G F; Yang, M L; Lam, S H; Hung, H Y; Sun, H; Wu, Y H; Kuo, P C; Wu, T S (Int J Mol Sci, 2023)