Determination of avermectins in plasma at nanogram levels using high-performance liquid chromatography with flourescence detection

Direct Determination of Avermectins in Plasma at Nanogram Levels by High-Performance Liquid Chromatography

“…This was determined by supplementing several 5-ml samples of normal cattle plasma with 100 ng of I and 140 ng of 111, processing them through the entire procedure, and comparing the resultant chromatographic signals to those obtained for the same amounts of I and 111 chromatographed directly. These recovery values are essentially the same as that previously determined for I in the portion of the fluorescence procedure preceding the derivatization reaction(6).…”

“…Because of this, effective dosage levels are unusually low (typically 0.2 mg/kg), and the concentrations of this drug found in plasma samples from animals treated with such doses are correspondingly low ( 4 0 0 ng/ml). The analytical procedure originally reported for determining the avermectins in animal plasma (6) is based on conversion of these compounds to fluorescent derivatives followed by high-performance liquid chromatography (HPLC) with fluorometric detection. The derivatization reaction, which involves dehydration using acetic anhydride-pyridine to form a six-membered aromatic ring in conjugation with a butadiene unit, is time consuming and sensitive to minor experimental variations.…”

Positive and negative electrospray LC–MS–MS methods for quantitation of the antiparasitic endectocide drugs, abamectin, doramectin, emamectin, eprinomectin, ivermectin, moxidectin and selamectin in milk

“…Abamectin is the commercialised major pair of isomers of avermectin itself, and ivermectin is the cishydrogenated product of abamectin (at the 22,23 position). In both compounds, the major isomer, B1a, contains a 2-butyl group, and the minor isomer (B1b) an isopropyl group attached to the carbon at the 25 position [2]. Many new avermectins have been synthesised to improve both the anti-parasitic efficacy and to change their pharmacokinetic profiles.…”

Control of Residues of Five Macrocyclic Lactones in Cow Milk By Liquid Chromatography with Fluorescence Detection

“…At first, very long reaction time necessary to obtain stable derivatives and the process was highly susceptible to the content of even traces of water (19). The change of the catalyst significantly reduced the time of reaction but the method was still long and required SPE purification of the obtained derivatives (20).…”