Objective: To compare content differences of main components in volatile oil from Zhizhu pills extracted in light and dark conditions. Method: Volatile oil in Zhizhu pills was obtained by steam distillation

one extracting volatile oil device was not wrapped to get oil exposed to the sun light oil(light condition oil) and the another device was wrapped with black cloth to get oil keeping out of the sun light(dark condition oil)

these two devices were used to extract volatile oil for the same time.Comparison of contents of atractylone

atractylenolide Ⅰ

Ⅱ

Ⅲ in these two kinds of volatile oil from Zhizhu pills were determined by HPLC

mobile phase consisted of water(A)-acetonitrile(B) for gradient elution of (0-22 min

55%-64%B;22-28 min

64%B;28-48 min

64%-100%B)

detection wavelength were 220 nm and 275 nm. Result: Yields of volatile oils extracted in dark and light conditions were 1.05% and 1.03%

respectively.The content of atractylone in light condition oil was significantly lower than that in dark condition oil

which were 73.01 mg·g-1 and 100.3 mg·g-1

respectively.The content of atractylenolide Ⅰ in light condition oil was much higher than that in dark condition oil

which were 0.757 2 mg·g-1 and 0.354 1 mg·g-1

respectively.There was no significant difference in the content of atractylenolide Ⅱ between these two kinds of oils

which were 2.026 mg·g-1 and 2.158 mg·g-1

respectively.The content of atractylenolide Ⅲ in light condition oil was obviously higher than that in dark condition oil

which were 0.412 4 mg·g-1 and 0.321 9 mg·g-1

respectively. Conclusion: No significant differences of yields of volatile oil are existed in these two extracted methods

but main ingredients are markedly different.It is suggested that inherent compounds change caused by experimental process should be avoided in constituent studies of Chinese prescription.