Amperometric flow-injection determination of the anthelmintic drugs ivermectin and levamisole using electrochemically pretreated boron-doped diamond electrodes

Sensitive, simple, low-cost, and rapid amperometric flow-injection methods were developed for determination of ivermectin (IVM) and levamisole (LVM) in anthelmintic pharmaceutical drugs and urine samples. These determinations were carried out with a cathodically (for IVM) or anodically (for LVM) pretreated boron-doped diamond electrode using aqueous 0.5 mol L-1 H2SO4 (with and without addition of 30% V/V of ethanol) as supporting electrolyte. The amperometric detection was performed at an applied electrode potential of E = 1.40V, for IVM, and E = 1.90V, for LVM, vs. Ag/AgCl (3.0 mol L-1 KCl). The respective analytical curves presented good linearity in the investigated concentration ranges (0.60-50 mu mol L-1, for IVM, and 0.010-5.0 mu mol L-1; for LVM) and the detection limits were 0.30 mu mol L-1 for IVM, and 1 nmol L-1, for LVM. Investigation of possible interferents showed no significant interference with the here-proposed methods; thus, they were used to determine IVM and LVM in pharmaceutical formulations as well as in urine samples, with results that showed good agreement with comparative methods. Furthermore, a mechanism for LVM electrooxidation was proposed using exhaustive potentiostatic electrolysis and NMR measurements. (C) 2015 Elsevier B.V. All rights reserved. (AU)