Determination of azoxystrobin and its impurity in pesticide formulations by liquid chromatography

A method was developed for the simultaneous qualitative and quantitative determination of azoxystrobin and its relevant impurity (Z)-azoxystrobin using high performance liquid chromatography with diode array detector (HPLC-DAD) in suspension concentrate (SC) pesticide formulations, with the aim of the product quality control. Method validation was realized according to SANCO/3030/99 rev. 5. The proposed method was characterized by acceptable accuracy and precision. The repeatability expressed as ratio standard deviation (%RSD) to relative standard deviation (%RSDr) was lower than 1, whereas individual recoveries were in the range of 97-103% and 90-110% for azoxystrobin and (Z)-azoxystrobin, respectively. The limit of quantification (LOQ) for the impurity ((Z)-azoxystrobin) amounted to 0.3 µg mL^-1 and was acceptable because it was lower than the maximum permitted level according to Commission Implementing Regulation (EU) No 703/2011 of 20 July 2011 for the active substance (azoxystrobin) being 25 g kg^-1 of the azoxystrobin content found. The method described in this paper is simple, precise, accurate and selective as well as represents a new and reliable way of simultaneous determination of azoxystrobin and its relevant impurity in formulated products.