A spectrophotometric method for the micro-determination of piperonyl butoxide in the presence of pyrethrins

Abstract

A rapid spectrophotometric method has been developed for the microdetermination of piperonyl butoxide in the presence of a wide range of pyrethrins. A solution of the mixture of piperonyl butoxide and pyrethrins in a low-boiling fraction of light petroleum is evaporated on a water-bath until only a small portion of the solvent remains. The final traces of solvent are removed at 50 °C and, to the residue containing piperonyl butoxide and pyrethrins, 18 per cent. m/V nitric acid is added in order to convert the piperonyl butoxide content into a soluble yellow-coloured compound. The quantitative colour reaction has a maximum absorption at 370 nm, and the method is applicable to the residues in the range 4 to 40 µg ml^–1 of piperonyl butoxide. The method is also applicable to the residues of formulated products extracted from grains and paper coatings.