Residue And Degradation Of Eugenol In Tomato-soil System

Eugenol, a broad-spectrum fungicide, is a new pesticide invented by China. At present there is no effective analytical method and reasonable application criterion. It is wholly essential to know the degradation behavior of eugenol for assessing its bio-environmental safety and its scientific application before it is applied. In order to extend eugemol use, an analytical method was established for determining residue of eugenol by HPLC at optimized conditions, and a set of application criterion in tomato was recommended for 0.3% eugenol AS according to the field experiment.The residue of eugenol in samples (soil and tomato) was extracted with methanol and the extract was re-extracted with dichloromethane. The final residue can be detected by HPLC with high sensitivity. The average recoveries from untreated control samples fortified with eugenol at rates of 0.05, 0.5 and 5mg/kg ranged from 82.58% to 105.35%, and the coefficient of variation was from1.65% to 8.00%. The lowest detectable quantity was 8×10~-10g and the lowest detectable concentrations of various samples were 0.010mg/kg and 0.008mg/kg in soil and tomato, respectively. The accuracy, sensitivity and precision for the method were good to satisfy the essential rules of pesticide residue determination.In 2002 and 2003, the degradation of eugenol in soil and tomato samples could be described by first-order kinetics equation C_t=C0e~-kt in natural environment in Changsha. The degradation velocity of eugenol in soil is quicker than that in tomato. The half-life of eugenol in soil wasl.30d and 1.38d, in tomato was 3.14d and 2.85d, respectively.The results also indicated that after application 0.3% eugenol AS according to the recommended dosage(diluted 600 times by water) and the high dosage(diluted 400 times by water), applying from once to four times, the sampling interval apart from last application was 1d, 3d and 5d, the final residue in soil and tomato was LOD-0.157mg/kg and LOD-0.278mg/kg, respectively. As a general rule, the residue in tomato was slightly higher...