High-performance liquid chromatographic assay for the determination of a semisynthetic avermectin analog (eprinomectin) in bovine milk at parts per billion levels--method development and validation.
A sensitive and automated method has been developed and validated to determine marker residue eprinomectin B(1a) in bovine milk. Extraction of eprinomectin B(1a) from milk is accomplished with acetonitrile after the addition of an internal standard. The extract containing the analytes is evaporated to dryness and reconstituted in a solution containing 30% 1-N-methylimidazole in acetonitrile. Online derivatization is carried out with trifluoroacetic anhydride. Determination of eprinomectin B(1a) and its internal standard is carried out by HPLC using a reversed-phase C(18) column with a mobile phase consisting of methanol, acetonitrile, water, triethylamine and phosphoric acid. The overall extraction recovery of eprinomectin B(1a) is 94% with milk supplemented between 2 and 50 ng/ml eprinomectin B(1a). Precision RSD averaged 3.0% in Laboratory 1 (n=25) compared to 4.3% in Laboratory 2 (n=35). The limit of quantitation is approximately 2 ng/ml eprinomectin B(1a), the limit of detection is approximately 0.25 ng/ml using this method.
Pollmeier
M
M
Merial GmbH, Kathrinenhof Research Center, Walchenseestrasse 8-12, D-83101, Rohrdorf, Germany. matthias.pollmeier@merial.com
Maier
S
S
Moriarty
K
K
DeMontigny
P
P
D000818:Animals; D000871:Anthelmintics / Q000032:analysis*; D002417:Cattle; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D005456:Fluorescent Dyes; D007559:Ivermectin / Q000031:analogs & derivatives* / Q000032:analysis*; D008892:Milk / Q000737:chemistry*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D000871:Anthelmintics; D005456:Fluorescent Dyes; D007559:Ivermectin; C101434:eprinomectin