The electrochemical behavior of the

The electrochemical behavior of the anthelmintic veterinary drug nitroxynil at the mercury electrode was studied in a series of Britton-Robinson
universal buffer of pH 1.9–11 containing 20% (v/v) ethanol using dc-polarography cyclic voltammetry and controlled-potential coulometry. The
voltammograms exhibited two irreversible cathodic steps over the pH range 1.9–10.2; the height of the first step is double that of the second one.
Controlled-potential coulometry in the B–R universal buffer of pH 1.9–10 at a mercury pool working electrode revealed the consumption of four and
two electrons via the first and second reduction steps, respectively, which attributed to reduction of the NO2 group to the hydroxylamine stage (first
step), and then to the amine stage (second step). Three voltammetric analytical procedures including dc-polarography, differential-pulse adsorptive
stripping voltammetry and square-wave adsorptive stripping voltammetry were optimized for the direct determination of bulk nitroxynil. The three
proposed procedures were applied for analysis of bulk nitroxynil with limits of detection of 3 × 10−5, 1.31 × 10−8 and 8.4 × 10−10 M and limits
of quantification of 1 × 10−5 , 4.36 × 10−8 and 2.80 × 10−9 M, respectively. The three procedures were successfully applied to the determination
of nitroxynil in formulation (Dovenix, 25% nitroxynil injection solution) without the necessity for sample pretreatment and/or time-consuming
extraction steps prior to the analysis.