SPE_(C18) with GC-FID for the determination of 2,4-D residues in citrus

In this work,a GC-FID method for the determination of 2,4-D residues in citrus was established.The samples were extracted with ethyl acetate by the aid of ultrasonic extraction,then methyl esterification using sulfuric acid.Sample was enriched on C 18 column,and methanol was employed as elutent.The resulting esters were determined by gas chromatography equipped with flame ionization detector.Under the optimized conditions,the linear range was 1.00-20.00 mg·kg-1with a correlation coefficient of 0.9987.The 2,4-D residues in citrus were 1.04 mg·kg-1in correct use.The 2,4-D residues in five batches detected were between 0 to 0.90 mg·kg-1.The relative standard deviation in results were 4.8%-10.0%,with the recoveries ranging from 82% to 89%.