Evaluation of a Stable Isotope-Based Direct Quantification Method for Dicamba Analysis from Air and Water Using Single-Quadrupole LC–MS

Abstract

Dicamba is a moderately volatile herbicide used for post-emergent control of broadleaf weeds in corn, soybean, and a number of other crops. With increased use of dicamba due to the release of dicamba-resistant cotton and soybean varieties, growing controversy over the effects of spray drift and volatilization on non-target crops has increased the need for quantifying dicamba collected from water and air sampling. Therefore, this study was designed to evaluate stable isotope-based direct quantification of dicamba from air and water samples using single-quadrupole liquid chromatography–mass spectrometry (LC–MS). The sample preparation protocols developed in this study utilize a simple solid-phase extraction (SPE) protocol for water samples and a single-step concentration protocol for air samples. The LC–MS detection method achieves sensitive detection of dicamba based on selected ion monitoring (SIM) of precursor and fragment ions and relies on the use of an isotopically labeled internal standard (IS) (D3-dicamba), which allows for calculating recoveries and quantification using a relative response factor (RRF). Analyte recoveries of 106–128% from water and 88–124% from air were attained, with limits of detection (LODs) of 0.1 ng mL−1 and 1 ng mL−1, respectively. The LC–MS detection method does not require sample pretreatment such as ion-pairing or derivatization to achieve sensitivity. Moreover, this study reveals matrix effects associated with sorbent resin used in air sample collection and demonstrates how the use of an isotopically labeled IS with RRF-based analysis can account for ion suppression. The LC–MS method is easily transferrable and offers a robust alternative to methods relying on more expensive tandem LC–MS/MS-based options.

Differential responses of soybean genotypes to off‐target dicamba damage

“…The accurate quantification of dicamba concentration in the air is challenging and requires detailed sampling logistics and analytical chemistry (Riter et al., 2020). Multiple methodologies have been proposed to quantify the concentration of dicamba from both air and water samples based on high‐performance liquid chromatography (Riter et al., 2020; Xu & Armstrong, 2013), gas chromatography (Rodríguez et al., 2005), and stable isotope‐based direct quantification (Ghaste et al., 2020). A consequence of unknown prolonged exposure to off‐target dicamba includes variable dosages at multiple growth stages with fluctuating environmental factors.…”

Agriculture Development, Pesticide Application and Its Impact on the Environment

“…Spray drift is the airborne movement of spray droplets receding from a treatment site during pesticide application [76][77][78][79], thus causing environmental pollution and food contamination [31,72,[80][81][82][83][84]. For example, aquatic ecosystems are the recipients of various pesticide residues, such as chlorpyrifos (ChF), due to leaching spray drift and agricultural runoff and cause toxicity in aquatic organisms, thus the oxidative stress enzymes and histological alterations in the vital organs of tilapia due to ChF exposure were investigated; the result of the study shows that sub-lethal concentrations of ChF can induce oxidative stress and histological alterations in the tissues of tilapia [85].…”

Volatilization of Standalone Dicamba and Dicamba Plus Glyphosate as Function of Volatility Reducer and Different Surfaces

“…The glass surface used as reference was inert and smooth, which does not represent any surface that could be potentially sprayed with dicamba. In contrast, dicamba can interact with ions on other surfaces, such as soil, straw or a plant surface, and be absorbed or adsorbed [22]. Information on the effect of the treated surface on dicamba volatilization is rare in the literature, and data on the effect of straw are very important, especially in Brazil, where most dicamba applications will be performed in the no-tillage system.…”