In this study a high performance liquid chromatographic (HPLC-DAD) procedure has been developed for the simultaneous determination of
azoxystrobin and
difenoconazole in
suspension concentrate
pesticide formulations, with the aim of the product quality control.
Azoxystrobin,
strobilurin fungicide and
difenoconazole (cis,trans-3-chloro-4-[4-methyl-2-(1H-1,2,4-triazol-1-ylmethyl)-1,3-dioxolan-2-yl]phenyl 4-chlorophenyl
ether),
triazole fungicide, are used for the protection of plants from wide spectrum of
fungal diseases. For the analysis LC system an Agilent Technologies 1100 Series was used. Good separation was achieved on a Zorbax SB-C18 column (5 μm, 250 mm x 3 mm internal diameter) using a mobile phase consisting of
acetonitrile/ultrapure water (90:10, v/v), at a flow rate of 0.9 ml/minute and UV detection at 218 nm. Column temperature was 25 degrees C, injected volume was 1 μl. Retention times for
azoxystrobin and
difenoconazole were 2.504 min and 1.963 min, respectively. This method is validated according to the requirements for new methods, which include linearity, precision, accuracy and selectivity. The method demonstrates good linearity with r2 > 0.997. The repeatability of the method, expressed as relative standard deviation (RSD, %), was found to be 1.9% for
azoxystrobin and 0.5% for
difenoconazole. The precision of the method was also considered to be acceptable as the experimental repeatability relative standard deviation (RSD) was lower than the RSD calculated using the Horwitz equation of 1.7% and 1.4% for
azoxystrobin and
difenoconazole, respectively. The accuracy of the proposed method was determined from recovery experiments through standard addition procedure. The average recoveries of the three fortification levels were 101.9% for
azoxystrobin and 103.2% for
difenoconazole with RSDs of 1.1% and 1.2%. The method described in this paper is simple, precise, accurate and selective and represents a new and reliable way of simultaneous determination of
azoxystrobin and
difenoconazole in formulated products.