New Method for Analysis of Pyrethroid Insecticides: Esfenvalerate, cis-Permethrin, and trans- Permethrin, in Surface Waters Using Solid-Phase Extraction and Gas Chromatography

Synthetic pyrethroids are used widely to control many common pests, including Lepidoptera, Diptera, and Coleoptera, on crops such as almonds, corn, garlic, and tomatoes (Meister, 1996). During the last 15 years, the use of synthetic pyrethroid insecticides, such as esfenvalerate and permethrin, has increased substantially, because of their potent insecticidal properties and low mammalian and avian toxicity (Ecobichon, 1996). In California, two commonly used pyrethroid insecticides are esfenvalerate or Asana®, cis-permethrin, and trans-permethrin. From 1990 through 1994, over 330,000 and 1.3 million lb of esfenvalerate and permethrin, respectively, were applied on various crops throughout California (Pesticide Use Report, 1990-1994). Many aquatic organisms (fish, amphibians, macroinvertebrates, and microinvertebrates) are highly susceptible to pyrethroid intoxication, and applications typically occurring throughout the spring and summer months coincide with the spawning period of several fish species in California (Moyle, 1976). Esfenvalerate has exhibited detrimental effects to aquatic organisms, by reducin