Improvement of analytical determination of cyproconazole and propiconazole in fruit crops

Abstract

Goal. Development and unification of the method of simultaneous determination of cyproconazole and propiconazole in fruits (apples, peaches, grapes) by gas-liquid chromatography (GC).
 Methods. The active substances were determined by gas-liquid chromatography (GC) using a gas chromatograph «Perkin Elmer 8410» with an NPD detector. Propiconazole and cyproconazole were identified by the retention time of the compounds, quantification by the calibration dependence of the chromatographic peak area of the analyte on its concentration in the calibration solution by correlation and regression analyzes.
 Results. The choice of the method of determination is limited by the physicochemical properties of the active substance and the characteristics of the object under study (matrix). The optimal conditions for determination were selected using a chemical-analytical monitoring algorithm and a system for multiquantitative determination of pesticides in matrices. According to them, the matrices are analyzed in stages: extraction, purification, qualitative and quantitative determination. Cyproconazole and propiconazole are low-polar compounds (µ of their cis- and trans-isomers are 4.43; 4.71 and 3.80; 4.20 D, respectively), so extraction was performed with chloroform (ε 5.1). Purification of extracts from coextractive substances of matrices was performed by TLC. Compounds were identified by retention time, and quantification (C, µg/ml) was performed on the areas of chromatographic peaks (S, mm2) in the range of linear detection (2—10 ng) according to the linear regression equations: Sc = 11.991 C — 6.096 (R2 = 0.998); Sp = 13.721 C – 4.221 (R2 = 0,994). The average value of measurement is 81.0—87.8%; standard deviation 2.21—5.38%; confidence interval (P 0.95; n = 15) 1.94—4.72%.
 Conclusions. Optimal selective conditions for the analysis of triazole derivatives by chromatographic methods provide simultaneous determination of test compounds and quality control of fruit crops on the content of residual amounts of cyproconazole and propiconazole at the level of hygienic standards (MAL 0.05—0.10 mg/kg).