Electrochemical determination of picoxystrobin on boron-doped diamond electrode: Square-wave voltammetry versus BIA-multiple pulse amperometry

This article reports and compares the performance of two new electrochemical methods for the determination of picoxystrobin (a strobilurin-class fungicide). The methods were square-wave voltammetry (SWV) and batch-injection analysis (BIA) with multiple-pulse amperometric detection, both employing boron-doped diamond (BDD) electrode, which was cathodically treated to enhance the electrochemical activity for picoxystrobin. The SWV method presented higher sensitivity with lower detection (LOD of 0.2 mu mol L-1 or 0.07 mg L-1) and quantification limits (LOQ of 0.7 mu mol L-1 or 0.25 mg L-1) in comparison with the BIA amperometric method CLOD of 1.6 mu mol L-1 or 0.6 mg L-1 and LOQ of 5.3 mu mol L-1 or 2.0 mg L-1). However, the BIA-amperometric method provided wider linear range (from 5.3 to 100.0 mu mol L-1) in comparison with the SWV method (from 0.7 to 20.0 mu mol L-1) and higher analytical frequency rate (108 measurements h(-1)). Interference of other strobilurin compounds was evaluated and the presence of trifluoxystrobin and fluoxystrobin (up to 3-fold excess) affected the SWV determination of picoxystrobin. The amperometric method undergoes interference from the all of the tested strobilurins but a simple approach, based on multiple-pulse amperometry, can indicate the presence of some of the potential interfering species. Hence, either SWV or BIA-multiple pulse amperometry can be applied for picoxystrobin depending on analyte concentration, presence of interfering species, and required analytical frequency. (C) 2015 Elsevier B.V. All rights reserved.