HPLC-MS Determination of Residual Amounts of 30 Sulfonylurea Herbicides in Tea

HPLC in hyphenation with MS was applied to the determination of 30 sulfonylurea herbicide residues in tea.Sample of tea was soaked with small amount of water and then extracted with acetonitrile.The herbicides in the extract were purified by SPE through the Cleanert HXN column.Herbicides on the SPE column were eluted with a mixture of acetonitrile and 0.02 mol·L-1 H3PO4 (mixed in the ratio of 9 to 1 by volume).The eluate was evaporated to dryness by N2-blowing and 1 mL of the mobile phase solution was used to take up the residue.The solution was used for HPLC-MS analysis.External standard method was adopted in the determination.Linear relationships between values of response signal and concetration of the 30 sulfonylurea herbicides were found in the range within 100 μg·kg-1 with values of detection limit (2S/N) in the range from 2-10 μg·kg-1.Tests for recovery were made by standard addition method,giving results of recovery in the range from 74.5% to 115.5%,and values of RSD′s (n=6) in the range of 1.30%-9.36%.