MT 162 - Determination of ethylenethiourea (ETU) (Imidazoldine-2-thione)
Content Handbook F
Outline of method
162.1 HPLC method (Referee method)
The ETU is extracted from the sample with methanol. An aliquot of the methanolic solution is evaporated to dryness and the residue is dissolved in water. The solution is filtered and diluted, if necessary, and injected on to a column of Nucleosil C18 or Spherisorb ODS. The ETU is eluted with water containing tetrahydrofuran and detected at 233 nm.
162.2 Paper chromatographic method
The ETU is extracted from the sample with methanol. Portions of the sample and standard solutions are spotted on to filter paper and developed with butan-1-ol + ethanol + water. The chromatogram is sprayed with pentacyanoaminoferroate [PCAF] reagent which produces a blue spot with ETU. The ETU content of the sample is determined by comparing the spot with those from the standards.
The methods are suitable for determining ETU in technical and formulated products containing ethylene-bis-(dithiocarbamate) (mancozeb, maneb, zineb and metiram).