Residue And Degradation Of Matrine And Total Alkaloids From Sophapra Alopecuroides L. In Pakchoi And Soil

Total alkaloids are the generic terms of alkaloids which are extracted from Sophora alopecuroides L. including sophoridine, matrine, sophocarpine, oxymatrine and other single alkaloids, that have excellent insecticidal and antifungal activities, especially matrine is most widely used for application. At present, there are nearly hundred kinds of preparations of matrine in the market, but few studies for its residue analysis. The study for their residual properties could promote rational use of matrine in crops and provided a theoretical basis the criterion of its maximum residue limit(MRL). In this study, high performance liquid chromatography(HPLC) analysis method and indirect competitive ELISA were established to detect matrine and total alkaloids in pakchoi and soil. The results The main results are as follow:1. High performance liquid chromatography(HPLC) analysis method for matrine and total alkaloids was set up respectively. In the concentration ranging from 0.1 to 12.5 mg/L for matrine,and 0.5~25.0 mg/L for total alkaloids, the standard working concentrations in blank solution of pakchoi and soil represented liner correlation with peak areas, LOD of method was 0.05 mg/L and 0.15 mg/L, respectively; the recoveries of two insecticides were75%~100% with relative standard deviations(RSD, n=5) under 15%. The results of matrine and total alkaloids conform to the requirements of pesticide residue detection.2. The IC-ELISA for matrine was established. Under the optimum conditions, the inhibition rate presented linearly relative to the logarithm of concentration correlation, the results showed that IC50 was 3.87 mg/L, the detection range(IC20 ~ IC80) was 0.20~75.41mg/L, and the detection limit(IC10) was 0.074 mg/L. The cross reactivity of sophocarpine,sophoridine and total alkaloids exceeded 50%. The range of adding recoveries were between60% and 130%, which could be capable of detection for a variety of alkaloids.3. The degradation results indicated the dissipation dynamics of matrine and totalalkaloids in pakchoi and soil accorded with the first-order kinetic equations. The samples were determined by HPLC and IC-ELISA, it showed that the half- lives of matrine were 2.49d(pakchoi) and 1.63 d(soil) and total alkaloids were 7.79 d(pakchoi) and 5.13 d(soil) by HPLC. The half- lives of determination by IC-ELISA show that matrine were 2.91 d(pakchoi)and 2.01 d(soil), total alkaloids were 9.00 d(pakchoi) and 4.59 d(soil).4. The final resdues samples of pakchoi and soil were detected by HPLC and IC-ELISA.The concentrations of matrine and total alkaloids all degraded original half above after the last spraying 7 d. The concentration of matrine was lower than total alkaloids, and the final residues in soil were significantly lower than pakchoi.In summary, matrine and total alkaloids which can be easily dissipated in pakchoi and soil, are kinds of easily degradable pesticides. The results of IC-ELISA were in accordance with HPLC, and the two methods both can be used for residue detection of matrine and total alkaloids.