Reversed-phased silica gel column chromatography cleanup

4 Reversed-phased silica gel column chromatography cleanup 

Dissolve the crop residue samples from Section 6.3 in 0.5 mL of dichloromethane. Transfer this solution to the top of the reversed-phased silica gel column with 

5 mL of n-hexane-benzene-methanol (80 20 0.4, v/v/v) and elute with the same solvent. Discard the first 70-mL of the eluate and collect the second 100-mL of eluate in a 200-mL round-bottom flask. Evaporate the solvent under reduced pressure. 

Dissolve the residue in an appropriate volume of acetonitrile for HPLC analysis. 

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