Simultaneous determination of eprinomectin, moxidectin, abamectin, doramectin, and ivermectin in beef liver by LC with fluorescence detection

Eprinomectin, moxidectin, abamectin, doramectin, and ivermectin are drugs u sed to control parasitic infections in both meat-producing and nonmeat-prod ucing animals, A number of analytical methods are available to analyze thes e anthelmintic drugs individually. A multiresidue screening method was deve loped for these drugs; however, the initial attempt to derivatize eprinomec tin following the method published by Merck scientists was unsuccessful bec ause the eprinomectin derivatization reaction was temperature- and time-dep endent. The optimum time and temperature for the completion of eprinomectin derivatization were 90 min and 65 degrees C, respectively, without appreci able effect on the remaining 4 drugs. Beef liver samples were fortified wit h 0, 25, 50, and 100 ppb mixed standards of eprinomectin, moxidectin, abame ctin, doramectin, and ivermectin, Each set of 4 levels of recoveries was re peated 10 times with all 5 compounds, The average of 10 recoveries of 5 com pounds at all 4 levels of fortification was > 70%; the coefficient of varia tion was < 20%.