Ivermectin confirmation

For reliable identification of a residue, detailed information about the molecular structure of the analyte is essential. The total information about the molecular structure of the analyte is the sum of the information derived from each individual analytical step of tire method. Frequently used selective analytical steps based on chromatography or immunoaffinity, provide more or less general indirect information. For example, solid-phase extraction (SPE) cleanup followed by liquid chromatography/ultraviolet detection (LC/UV) has been suggested for screening and quantification of ivermectin residues in liver, but presumptive positive samples can be confirmed by derivatizing an aliquot of the SPE eluate and reanalyzing the fluorescent derivative of ivermectin in an LC-fluorescence system (17). 

A combination of hquid-liquid extraction and SPE was applied in the sample pretreatment of bovine milk and liver samples in the PBI LC-MS analysis of ivermectins [88]. ECNI with methane was performed to the intact molecular anion and some structure-informative fragments of two ivermectin components at m/z 874 and 860. The molecular anion and four fragment ions were used for regulatory confirmation. Signals were observed from on-colunm injections of 4 ng in extracts equivalent to 2 ml milk or 0.2 g liver. 

D.N. Heller, F.J. Schenck, PBI LC-MS with ECNI for the confirmation of ivermectin residue in bovine milk and liver, Biol. Mass Spectrom., 22 (1993) 184. 

Ivermectin is indicated for intestinal strongyloidiasis in France (1987) and the USA (1996). With a view to obtaining approval for treatment with ivermectin, we are proceeding with a clinical trial at 200 pg/kg. With administration by this method, a high rate of eradication and safety are being confirmed. Ivermectin is as effective as, and better tolerated than, thiabendazole for treating strongyloidiasis. 

LC-PB-MS has been investigated as a potential confirmatory method for the determination of malachite green in incurred catfish tissue, " and cephapirin, furo-semide, and methylene blue in milk, kidney, and muscle tissue, respectively. LC-PB-MS has also been investigated for the analysis of ivermectin residues in bovine hver and milk. The specificity required for regulatory confirmation was obtained by monitoring the molecular... 

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