DETERMINATION OF CORN HERBICIDES BY GC-MS AND GC-NPD IN ENVIRONMENTAL-SAMPLES

Several herbicides widely used to control weeds in corn, alachlor, metolachlor, and pendimethalin, have been determined in soil and water. Analysis of herbicides was performed by GC-NPD and GC-MS. soil was extracted with ethyl acetate on a mechanical shaker, and water was extracted with dichloromethane in a separatory funnel. The average recoveries through the method were higher than 90% in soil and 85% in water. The detection limit was lower than 0.01 ppm in soil and 0.1 ppb in water for GC-MS and GC-NPD, respectively. Soil samples from corn fields, after harvest, were taken form the surface (0-10 cm) of several fields located in Albacete and Guadalajara, Spain, and water was taken from wells located in the fields. These samples were analyzed according to the proposed GC methods, and statistically similar values between the two methods were obtained. the identities of the detected herbicides were confirmed by GC-MS.