Study On The Removal Of Pesticide And Heavy-Metal Residues From Chinese Herbal Medicines

Virtually all of the Chinese Herbal Medicine (CHM) nowadays have been cultivated with the application of pesticides to reduce pest damage and promote the production.The application of pesticides not only pollutes the cultivating soil and ground water, i.e. the environment, but leads to the accumulation of them in plants, animals and human beings eating them. The risk of the consumers' health due to incidental intake of the remaining contaminants in CHM thus cultivated is highly possible. The organochlorine pesticides (OCPs) and heavy metals are the first ones to be considered, because they possess the characteristics of harmful biological effects and high accumulation.The cultivation of Green CHM has been promoted to reduce the pollution of OCPs and heavy metals. However, as many kinds of pesticides and fertilizers, which usually contain heavy metals, have been used for a long time, to say nothing of the soil and ground water, the proposal can hardly be put into practice. The need for an efficient method of reducing OCPs and heavy-metals in the cultivated CHMs is obvious. In the study, a method of CO₂ supercritical fluid extraction(SFE) has been developed for the removal of pesticide and heavy metal residues from CHMs, such as Radix Codoposis, Angelicae Sinenisis, Herba Epimedii, Radix Astragali and Radix Rehmanniae Preparata.1. An efficient and rapid method of CO₂ supercritical fluid extraction has been designed successfully for the removal of 12 remaining OCPs from the five CHMs mentioned above. In the study, L₉(3⁴), an orthogonal array of 3 levels, 4 factors and 9 trials, was used to optimize the conditions with the result of more than 85% removal of the pesticide and less...