Volatilização dos herbicidas 2,4-D e dicamba

Abstract

Auxinic herbicides are likely to volatilize and reach non-target crops adjacent to treated areas. This property is affected by the active ingredient formulation. Studying the behavior and dynamics of molecules and their interactions requires efficient extraction and sampling methods. Thus, the objective of this work was to develop and validate methods of analysis and extraction of 2,4-D and dicamba herbicides in air samples by HPLC-MS / MS (Chapter I); to evaluate the volatilization potential of auxinic herbicides affected by the presence of straw and in mixture with glyphosate (Chapter II); and validate a passive collector prototype developed for the monitoring of auxinic herbicides in the air (Chapter III). According to the results, it was possible to select the most efficient extraction method, using methanol acidified to pH 2 with formic acid, to elute the herbicides 2,4-D and dicamba. However, different chromatographic column elution conditions and source ionization temperature were required, so two HPLC-MS / MS analysis methods were used. The amount of volatilized 2.4-D Colex-D™ herbicide was lower compared to the 2.4-D DMA and dicamba DGA formulations when applied on the straw. When the volatilization of the choline salt formulation in a tank mix with glyphosate was tested, it showed an increase in the volatilization potential, related to changes in pH and solution solubility. The passive collector was validated and proved suitable for use in the monitoring of 2,4-D and dicamba herbicides in the field. In addition, Strata-X® sorbent was efficient in analyte sorption and indicated for use in air sampling as an alternative to XAD-2.