Pesticide Residue Methods

Category Others
Class Name Thiourea
Method Title Determination of 2-Imidazolidinethione in Fruits and Vegetables by GC/MSD
Method Date 2005/06/15
Method Type Confirmatory, Quantitative
Scope and Application For analysis of 2-Imidazolidinethione (Ethylene Thiourea) in fruits and vegetables at the reporting limit of 0.01 microgram per gram.
Method Summary A thawed sample (20.0 g) is homogenized in 500 mL of methanol, filtered and evaporated to 5-10 mL on a rotavap. The mixture is then boiled in water, methanol, boiling chips and benzyl chloride before adding conc. HCl followed by NaOH. Dichloromethane is used (and then discarded) to rinse sample from glass ware. The volume is reduced to 50 microliters by rotavap and N-Evap and derivatized using TFAA in toluene. Each sample is vortexed and pressed through a 0.45 micrometer filter. Sample is re-concentrated and toluene plus an internal standard Leptophos added prior to analysis by GCMSD. A HP Ultra 1 analytical column (25 m, 0.20 mm, 0.33 micrometer) is used.
Applicable Concentration Range 2-Imidazolidinethione may be detected in selected fruits and vegetables in the concentration range of 0.010 - 0.050 microgram per gram.
QC Requirements See SOP
Method Performance/Validation
Method Source Canadian Food Inspection Agency
Method SOP PDF icon SOP 
Citation Canadian Food Inspection Agency, SPR-008-V1.0