Standardization of LWDH-WE was done using HPLC fingerprinting with chemical standards including 5hydroxymethyl-2- furaldehyde
(Sigma-Aldrich, USA), morroniside (Must, China), loganin (Scientific Pharmaceutical Elite Company, Taiwan), paeoniflorin (Nacalai Tesgue, Japan), verbascoside (Scientific Pharmaceutical Elite Company, Taiwan), and paeonol (Nacalai Tesgue, Japan).
Following standards were used: Hexadecane, 3-octanol, hexanal, pentadecane, 3-hexene-1-ol, 2-undecanone, 2- heptanone, butanal, 2-nonanone, 1-heptanal, furaldehyde
, 3methyl-1-butanol, trans-3-hexene-1-ol, octanal and decanal.
With the aforementioned precluded, we tested several other aldehydes, including 2-hexanal, cinnamic aldehyde, glyceraldehyde, furaldehyde
, and 5-hydroxymethyl-2-furaldehyde
, together with several compounds such as glycine-MDA, methionine-MDA, and dianil-MDA, which contain the MDA moiety .