In this study, we chose to employ the HPLC method with an addition of a small β-cyclodextrin amount to the mobile phase with an UV detector at 205 and 210 nm for the analysis of all samples because of its straightforward application and excellent resolution between the three triterpenoids of interest (Fig. and). C. asiatica (Fig. and Tab. 3a). The variation of the biomass yields is due to the different climate conditions (sunlight, rainfall, temperature, etc.) between the harvest periods. The ratios of dry mass to fresh mass are a little higher in the summer time (about 14 -15% from March to August) than in the spring (from January to February) and the winter time (in November -December) using the VIETGAP and ORGANIC C. asiatica production techniques. The reasons for these differences may be due to reduced sunshine and increased rainfall and flooding in the Quang Tho commune (average temperatures are 27 -29 o C). These climate conditions are not optimal for the growing of C. asiatica. In the winter time the air temperature is low, so that C. asiatica is growing slowly, and the distances between two harvests become longer than in Summer.