Residue Analysis Methods and Degradation Regularity of Metalaxyl-M in Tobacco Leaves and Soils

Metalaxyl-M residues in tobacco leaves and soil were analyzed by high performance liquid chromatography. In this method residues were extracted with acetone and methyl alcohol, cleaned up on a column of florisil and activated carbon mixtures, and determined with an ultraviolet (UV) detector. Recoveries were 92.14%~97.12% for fresh leaves and 93.36%~96.46% for soisl respectively, and relative standard deviations (RSDs) were 3.2%~4.8% and 2.2%~2.9% respectively. The degradation rates of metalaxyl-M were faster in tobacco leaves than in soils, and the degradation half-life times were 1.2~1.5 days in tobacco leaves and 6.39~12.77 days in soils.