Algorithm for assessing the completeness of seed treatment of wheat and barley

L. Chervyakova; T. Panchenko; O. Tsurkan; N. Adamenko

doi:10.36495/1606-9773.2019.65.212-224

L. Chervyakova Institute of Plant Protection of NAAS of Ukraine, Vasylkivska st., 33, Kyiv, Ukraine, 03022
T. Panchenko Institute of Plant Protection of NAAS of Ukraine, Vasylkivska st., 33, Kyiv, Ukraine, 03022
O. Tsurkan Institute of Plant Protection of NAAS of Ukraine, Vasylkivska st., 33, Kyiv, Ukraine, 03022
N. Adamenko Institute of Plant Protection of NAAS of Ukraine, Vasylkivska st., 33, Kyiv, Ukraine, 03022

DOI: https://doi.org/10.36495/1606-9773.2019.65.212-224

Keywords: protectant, treatment seeds, thin layer chromatography

Abstract

Goal. To develop a method for the determination of imidacloprid, clothianidin, prothioconazole and tebuconazole in the treatment seeds of wheat and barley.

Methods. Active substances were determined by thin layer chromatography (TLC). Mathematical-statistical method for evaluate the linear range of the dependence of the area of the chromatographic zone on the amount of active substance was used.

Results. The determination of pesticides includes a number of basic stage: characteristic the matrix by the ratio of the content of coextracting substances, that interfere with the determination, and the content of pesticides; classification of pesticides by polarity in according to the dipole moment (µ, D); extraction from the analyzed sample by organic solvent with corresponding of the dielectric constant, ε; purification; qualitative and quantitative determination. In the case of the analysis of treatment seeds, in which the amount of pesticides is much greater than coextracting compounds, the stages of classification and purification are excluded from the analysis. The extraction is carried out with ethanol. Qualitative determination of pesticides is carried out on plates with a thin layer of adsorbent (silicagel) in the mobile phase (mixture of hexane and ethanol, ε = 7.49) with using corresponding reagents. Silver ammonia (AgNO₃) solution and followed by UV irradiation of the chromatogram is used for identification halogen-containing pesticides (zones of localization of compounds are formed dark spots of reduced silver). Pesticides containing donor atoms of sulfur, nitrogen, oxygen, identify by bromphenol blue (BPB) and subsequent bleaching of the background with an solution of citric acid (zones of localization of compounds are formed blue spots form on a light background). The active substances are identified with the corresponding Rf of the zones localization. Quantitatively of active substances is determined by the calibration dependence of the area of compound’ chromatographic zone on its quantity. For all four compounds, this dependence is linear in the concentration range of 0.20 — 0.80 µg and is described by the regression equation for: imidacloprid y = 6.25x + 5.45; for clothianidine y = 11.65x + 6.70; for prothioconazole y = 28.7x + 2.05; for tebuconazole y = 13.00x + 7.00. In all cases, the correlation between the indicators is estimated as strong (r = 0.99).

Conclusions The algorithm for assessing the completeness of the treatment of wheat and barley seeds is an express control method and using the thin layer chromatography method allows to determine four active substances in one sample during one analysis with high accuracy (relative error of less than 5% at n = 5, P = 0.95) excluding laborious experiment.

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