Determination of deltamethrin in cattle dipping baths by high-performance liquid chromatography

Deltamethrin (S)-alpha-cyano-3-phenoxybenzyl) (1R,3R)-3-(2,2-dibromovinyl)- 2,2-dimethylcyclopropane- 1-carboxylate is classified as a pyrethroid pesti cide that is largely used as an acaricide and scabicide. For bovines, espec ially, the treatment is done with the aid of dipping baths of the pyrethroi d solution. Analytical control of the concentration of deltamethrin in thes e baths must be done periodically in order to guarantee treatment efficacy. In the proposed procedure, the sample is prepared by centrifugation follow ed by filtration and measurement by high-performance liquid chromatography (HPLC) with spectrophotometric detection at 275 nm. Separation is done in a Nucleosil C-18 column with acetonitrile-water as the mobile phase. A calib ration curve was constructed with external standards, and a detection limit of 0.2 mg L-1 was obtained. In the samples analyzed, only ca. 20% of the t otal deltamethrin content was found in the solution. The results obtained d emonstrate the potential of the described procedure for the determination o f deltamethrin in animal baths.