ABSTRACT
Use of agro-chemicals in forage crops is restricted due to the fear of direct toxicity to livestock and risk of pesticide residue accumulation in the food chain. Wheat and barley can be used as green fodder and silage, and herbicide residue estimation in green fodder and silage is important for ensuring the safety of dairy cattle. A field experiment was conducted for two years to study pendimethalin residues in the green fodder and silage of wheat and barley. In both cereal crops, pendimethalin (1.125 kg a.i./ha) was applied as pre-emergence along with an unsprayed control. Pendimethalin residues in fodder, silage, and soil were estimated using gas chromatography-tandem mass spectrometry (GC-MS/MS). At harvest, pendimethalin residues in fodder and silage of wheat and barley were below the limit of quantification (<0.01 mg/kg) during both crop seasons. Pendimethalin can be safely used for weed control in winter cereals grown for fodder and silage.
ABSTRACT
The purpose of this analysis was to develop an efficient analysis for the estimation of residues of propanil in rice grain, husk, straw and soil samples. A liquid-liquid partitioning method was used for the extraction of propanil residues from the rice grains and its contents. For this, representative 10 g samples of blended rice grain, husk, straw and soil were soaked in acetone for 24 h, and the contents then partitioned two times into 100 and 50 mL dichloromethane and one time with 100 mL hexane. The combined organic layers were collected and were concentrated to 10 mL acetone using a rotary vacuum evaporator at 40°C. The extract was then subjected to cleanup by dispersive solid phase extraction. The final extract was injected onto a GLC column, where the propanil residues were determined by electron capture detector. The percentage recoveries were ranged from 84.9 % to 98.3 % when samples were spiked at the levels of 0.05, 0.25 and 0.50 mg/kg. The limits of quantification and detection were 0.05 and 0.017 mg/kg, respectively.
