Determination of ivermectin residues in swine tissues--an improved clean-up procedure using solid-phase extraction.

A rapid and sensitive HPLC method has been developed for the determination of ivermectin in swine tissues. The clean-up procedure is based on solid-phase extraction on a Bond-Elut C8 cartridge. The average recovery from spiked swine muscle tissue was 87% in the concentration range 2-20 micrograms/kg. The method has a limit of detection of 0.5-1 microgram/kg. A survey of the levels in muscle tissues from 35 sanitary slaughtered sows was made. Five samples were found to contain ivermectin at concentrations between 3.4 and 27.6 micrograms/kg. A good correlation (r = 0.9696) was found between these results and those obtained using another established method.