Residues of the carbamate acaricide, 3-methyl-5-isopropylphenyl-N(n-butanoyl)-N-methylcarbamate (promacyl) and two metabolites in the tissues and milk of cattle

In order to assess some of the residue characteristics of the experimental carbamate acaricide, 3-methyl-5-isopropylphenyl-N-(n-butanoyl-)-N-methylcarbamate (promacyl) a 0.2 % aqueous emulsion was applied to cattle in a series of five trials and in a sixth, the technical product was added to the feed of stalled cattle. A method of analysis involving the formation of a derivative suitable for gas chromatographic analysis on electron capture detection mode was developed. Separate estimations of levels of the parent compound and the metabolites, 3-methyl-5-isopropylphenyl -N-methylcarbamate and 3-methyl-5- isopropylphenol, were carried out on fatty tissues and butterfat but for non-fatty tissues “total” levels, which were a combined estimate of 3-methyl-5-isopropylphenol itself and all substances hydrolysable to it, were estimated and quoted as Promacyl. The highest group average level of the parent compound was 0.9 part/million in fatty tissues 24 h after the last of 8 applications at 3 day intervals. In a single spray trial the maximum group average of 0.7 part/million in fatty tissues 24 h after treatment fell to 0.2 part/million after 5 days. Residues in butterfat, 7 h after a single dermal application showed a maximum level of 1.2 parts/million and this declined to 0.1 part/million on the seventh day after treatment. “Total” residues in non-fatty tissues were of the order of 1/10 those found in fatty tissues.