Before planting C. asiatica, it was important to measure the quality of the water and soil used. cadmium (Cd) were well below Vietnamese regulatory maximum limits. For the soil (Table ), the five toxic elements arsenic (As), cadmium (Cd), lead (Pb), chromium (Cr) and copper (Cu) were analyzed and also determined to be comfortably under the Vietnamese maximum limits. The percentage yields of the extracts from the dry mass of C. asiatica for VIETGAP and ORGANIC samples for the same harvests as for a).