Subcritical Butane Extraction for Effective Removalof Abamectin in Fresh Tea Leaves / 分析化学

ABSTRACT

Subcritical butane technology was employed for the separation of abamectin on the fresh tea leaves surface.Under the conditions of solid-liquid ratio of 1∶10 (m/V), the experiment was designed via the response surface methodology and conducted at different temperature, various separation time and discrepant cycle number.Besides, the activity of the polyphenol oxidase (PPO) relating to the quality of the tea was determined and compared.At the same time, scanning electron microscopy (SEM) was used to observe the surface structure of fresh tea leaves before and after treatment, and the effect on physiological characteristics of the leaves by subcritical butane treatment was analyzed.The experimental results showed that the subcritical butane extraction could effectively isolate the abamectin, making the physical structure basically remained and the polyphenol oxidase activity preserved as well.Through the analysis by Design Expert software, the optimal processing parameters of separating abamectin were as follows 45℃, 30 min, 1 cycle, and solid-liquid ratio of 1∶10 (m/V).Under the optimal conditions, the separation efficiency was over 91% and the relative PPO activity was 25.73%.The structure of fresh tea leaves changed insignificantly before and after the butane processing.This study suggested that the subcritical butane extraction technology could effectively remove pesticide residues in tea, thus provided a certain scientific basis for application of subcritical fluid removal of pesticide residue in natural plants.