March 30th 2008Pyrethroids are synthetic chemical compounds similar to the natural chemical pyrethrins and commonly used as household insecticides and insect repellents. Typically, pyrethroids possess multiple stereogenic centers and individual stereoisomer can have widely differing biological activities. Rapid, reliable, and precise determination of the isomeric ratios of these chiral pesticides is of great importance not only for product formulation but also for the subsequent study on the pharmacokinetics and metabolism of the pesticides. High performance liquid chromatography with chiral stationary phases (CSPs) has been the predominant tool for separating chiral pesticides. However, the complexity of the pyrethroids resulting from the multiple stereogenic centers presents a special challenge for baseline resolution of all isomers. Numerous CSPs, many of which are not available commercially, have been created to separate synthetic pyrethroids with varying degree of success (1-7).