DETERMINATION OF UNCHANGED RESIDUES OF A PYRETHROID INSECTICIDE, PYR-VU-TO2, IN SHEEP INTERNAL ORGAN-TISSUES

During subacute toxicological testing of PYR-VU-TO2, a novel cypermeth rin-like pyrethroid with a high (150:1) cis: trans ratio, its distribu tion in skeletal muscle and internal organ tissues of two groups of ex perimental sheep was investigated after oral administration of two dif ferent doses (1/10 and 1/20 of the LD50). Residual levels of PYR-VU-TO 2 were also observed in sheep blood after administration of a single d ose of the compound. Homogenized internal organ tissues and blood samp les were extracted in light petroleum distillate + acetone for 15 min. After filtration. the extract was cleaned up on a 'Florisil'(R) and s odium sulfate layer. The pyrethroid elution was processed with acetone -light petroleum distillate (2 + 98 by volume). Recoveries ranged from 80.7 to 93.5%. Unchanged PYR-VU-TO2 residues were determined on a 1.5 -m stainless steel packed column under isothermal conditions with an e lectron-capture detector. The results were evaluated by the calibratio n curve method. The coefficients of variation were generally lower tha n 5% and determination limit for PYR-VU-TO2 was 20 mug kg-1. Mean unch anged PYR-VU-TO2 residues lay within a wide range. After six weeks of treatment the following order of tissue residue levels could be stated : heart > lung > muscle > spleen > kidney > liver > brain, and spleen > muscle > lung > heart > liver > kidney > brain for experiment groups I and II, respectively Only small differences between the residues in the tissues of males and females were found in the first group (daily PYR-VU-TO2 dose of 50 mg kg-1 live weight). The experimental females of the second group (daily PYR-VU-TO2 dose of 200 mg kg-1 body weight) revealed higher levels (other than spleen) than did the males. Maximu m PYR-VU-TO2 residues in sheep blood were found 24 h after administrat ion of a single dose. Confirmation of the results was carried out by d etermination of -dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic aci d methyl ester by capillary GC.