2.1. Chemicals and Materials. Some reference standards (pyroglutamic acid, 5-(hydroxymethyl)furoic acid, and parishin B) for Gastrodia rhizoma were isolated and purified in our laboratory, and other standards (uridine, gastrodin A, and neocnilide) were purchased from the National Institutes for Food and Drug Control (Beijing, China). Purities of the standards were above 98% by HPLC analysis.