Simultaneous GC Determination of Residual Amounts of 4 Diformylimide Bactericides in Spinach

A method for determination of residual amounts of 4 diformylimide bactericides, i.e. vinclozolin, chlorzolinate, procymidone and iprodione, in spinach by GC-MS was proposed. Samples were extracted with mixed solvent of ethyl acetate and n-hexane (1+4). The extract obtained was purified by gel permeation chromatography, and the eluates were taken for separation by GC and the contents of the 4 bactericides were determined by MS under select ion monitoring (SIM) mode. Values of detection limit (3S/N) found were 0.01 mg·kg-1 for vinclozolin, 0.01 mg·kg-1 for chlorzolinate, 0.01 mg·kg-1 for procymidone, and 0.02 mg·kg-1 for iprodione. Tests for recovery were made by addition of mixed standards to a blank spinach sample at 3 different concentration levels, values of recovery found were in the range of 78.1%-94.9%, with values of RSD′s (n=6) in the range of 4.9%-12%.