Determination of Pyrethrosin Levels in Refined Natural Pyrethrin Extracts

Refined natural pyrethrin extracts from pyrethrum (Tanacetum cinerariifolium) can contain variable amounts of pyrethrosin, a sesquiterpene lactone natural product. Pyrethrosin has very low solubility in isoparaffin and has been observed to slowly precipitate from isoparaffin solutions of refined extracts. The presence of precipitates is undesirable as they can lead to blockage of spray applicators and are visually unappealing to consumers. In order to reduce the amount of pyrethrosin in the final refined extract, an analytical method is required to determine the levels of pyrethrosin in the final product as well as in-process samples. Toward these ends, a UPLC method has been developed that allows sufficient separation of pyrethrosin from near-eluting components, to be used for analytical purposes. The calibration curves show a linear response over a wide range of concentrations of pyrethrosin. The method was used to determine the levels of pyrethrosin in a representative batch of refined natural pyrethrin extracts.