A method using high-performance liquid chromatography (HPLC) and fluorescence detection is presented for the simultaneous determination of the antiparasitic agents avermectins (abamectin, ivermectin and doramectin) an...
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A method using high-performance liquid chromatography (HPLC) and fluorescence detection is presented for the simultaneous determination of the antiparasitic agents avermectins (abamectin, ivermectin and doramectin) and moxidectin in liver. Samples are extracted using acetonitrile and cleaned up using solid phase extraction on a C-18 column, followed by derivatization with trifluoroacetic anhydride. The samples are injected without further cleanup into the HPLC column and any avermectins or moxidectin present are detected using fluorescence detector set at 361 nm excitation and 465 nm emission wavelengths. The limits of quantification are below the stipulated EU Maximum Residue Limit for each of the avermectins and moxidectin. Mean recoveries in bovine liver ranged from 77.5 to 90.8%, with a RSD from 2.7 to 7.7%. The procedure provides a rapid, reliable and sensitive method for determinating avermectin and moxidectin residues in liver of different species (cattle, sheep, pigs). It is also applicable to muscle without modification.
A method was developed to quantitate emamectin benzoate in fish feed at levels between 5 and 15 ppm. The active ingredient is extracted from 20 g medicated feed into aqueous-methanolic solvent by overnight shaking. A ...
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A method was developed to quantitate emamectin benzoate in fish feed at levels between 5 and 15 ppm. The active ingredient is extracted from 20 g medicated feed into aqueous-methanolic solvent by overnight shaking. A solid-phase extraction procedure using a 2 g C(18) cartridge is then used to concentrate the active residue and remove interfering matrix components. The extracted drug and internal standard are eluted from the cartridge, evaporated to dryness, and reconstituted in methanol. A control feed sample and fortified control working standard are simultaneously prepared. Remaining interferences and sample analysis are further separated on a gradient liquid chromatographic system. Recovery of emamectin benzoate from fortified feeds ranged from 97 to 100%, with a coefficient of variation (CV) of 1.2%. Determination of emamectin benzoate in medicated feeds resulted in CVs ranging from 2.3 to 4.2% and recoveries of 88 to 98% of label claim.
Evaluation of a wide range of avermectin derivatives for flea activity in an in vitro feeding screen using the cat flea, Ctenocephalides felis, revealed a narrow structure-activity relationship (SAR) with activity sur...
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Evaluation of a wide range of avermectin derivatives for flea activity in an in vitro feeding screen using the cat flea, Ctenocephalides felis, revealed a narrow structure-activity relationship (SAR) with activity surprisingly associated with monosaccharides and especially their C-5-oximes. We discovered commercially exploitable flea activity in a single compound, selamectin 33, which also possessed the necessary antiparasitic spectrum and margin of safety for development as a broad-spectrum companion animal endectocide. (C) 2000 Elsevier Science Ltd. All rights reserved.
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