Abstract:

A new multi-residue analytical method was developed for the simultaneous determination of residues of 4
parasiticides, i.e. praziquantel, ivermectin, abamectin and doramectin, in milk by ultra performance liquid chromatography
tandem mass spectrometry (UPLC-MS-MS). The samples were extracted with acetonitrile and then cleaned up with alkaline
alumina column. The target compounds were separated with UPLC ACQUITY BEH C18 column. The mobile phase A
(acetonitrile plus 0.1% formic acid) and the mobile phase B (0.1% formic acid plus 5 mmol/L ammonium acetate) were
used in a gradient elution program. The target drugs were detected by electrospray ionization mass spectrometry in positive
ion mode with multiple reaction monitoring. The results showed good linear relationships in the range of 5-100 ng/mL
and the correlation coefficients were all above 0.996. The average recoveries ranged from 76.4% to 113.3%, and the relative
standard deviations (RSDs) were in the range of 2.4%-10.6%. The limits of detection (LODs) for praziquantel, ivermectin,
abamectin and doramectin were 1.0, 2.5, 2.5, and 2.5 μg/kg, respectively. The method was simple, rapid, and accurate to measure
the residues of these four parasiticides praziquantel, ivermectin, abamectin and doramectin in milk.

Key words: UPLC-MS-MS, praziquantel, avermectins, residue, milk