Cationic polyelectrolyte/graphene oxide as an efficient sorbent for the extraction and analysis of trace acidic herbicides in vegetables

Hexagonal boron nitride nanosheets based magnetic solid phase extraction for the extraction of phenoxy carboxylic acid herbicides from water samples followed by high-performance liquid chromatography-tandem mass spectrometry

High-efficiency caption of pesticide residue is of vital significance for environmental safety monitoring. Herein, a hexagonal boron nitride nanosheets-based magnetic composite (Fe₃O₄@h-BNNSs) was synthesized and applied for the magnetic solid phase extraction (MSPE) of five phenoxy carboxylic acid (PCA) herbicides from water samples. Based on the π-π interaction, hydrogen bond and halogen bond, the Fe₃O₄@h-BNNSs composite showed excellent adsorption ability towards PCA herbicides. Several main variables that influenced the extraction efficiencies of PCA herbicides were investigated and optimized via single-factor experiment. Combining this Fe₃O₄@h-BNNSs composite-based MSPE with high-performance liquid chromatography-tandem mass spectrometry, a novel sensitive method for the analysis of PCA herbicides was developed. Under the most favorable conditions, the proposed method displayed good linear ranges (20.0-10000.0 ng L^-1), low limits of detection (5.6-10.3 ng L^-1), satisfactory precisions (1.1-6.8%) and recoveries (76.6-107.2%). Overall, the present work can be a versatile and worthy utility for the determination of PCA herbicides from different water samples.

The physio-chemical properties and applications of 2D nanomaterials in agricultural and environmental sustainability

Global hunger and nutritional deficiency demand the advancement of existing and conventional approaches to food production. The application of nanoenabled strategies in agriculture has opened up new avenues for enhancing crop yield and productivity. Recently, two-dimensional (2D) nanomaterials (NMs) have manifested new possibilities for increasing food production and nutrition. Graphene nanosheets, the 2D form of graphene has been exemplary in enhancing the loading capacity of agro-active ingredients, their target-specific delivery, bioavailability, and controlled release with slow degradation, resulting in the increased shelf-life/active time of the agro-active components. Also, the development of novel formulations/composites of MXenes and Transition Metal Dichalcogenides (TMDs) can foster plant growth, metabolism, crop production, protection and improvement of soil quality. Additionally, the 2D NM-based biosensors can monitor the nutrient levels and other parameters affecting agronomical traits in plants. This review provides an insight into the details of 2D NM synthesis and functionalization methods. Notably, the review highlights the broad-range of 2D NM applications and their suitability in the development of nanotechnology-based agriformulations. The 2D NM-based derivatives have shown immense potential in enhancing the pedologic parameters, crop productivity, pest-protection and nutritional value. Thus, assisting in achieving food and environmental sustainability goals.

ZrO2 Nanoparticles and Poly(diallyldimethylammonium chloride)-Doped Graphene Oxide Aerogel-Coated Stainless-Steel Mesh for the Effective Adsorption of Organophosphorus Pesticides

A novel sorbent based on the ZrO₂ nanoparticles and poly(diallyldimethylammonium chloride)-modified graphene oxide aerogel-grafted stainless steel mesh (ZrO₂/PDDA-GOA-SSM) was used for the extraction and detection of organophosphorus pesticides (OPPs). Firstly, the PDDA and GO composite was grafted onto the surface of SSM and then freeze-dried to obtain the aerogel, which efficiently reduced the accumulation of graphene nanosheets. It integrated the advanced properties of GOA with a thin coating and the three-dimensional structural geometry of SSM. The modification of ZrO₂ nanoparticles brought a selective adsorption for OPPs due to the combination of the phosphate group as a Lewis base and ZrO₂ nanoparticles with the Lewis acid site. The ZrO₂/PDDA-GOA-SSM was packed into the solid-phase extraction (SPE) cartridge to extract OPPs. According to the investigation of different factors, the extraction recovery was mainly affected by the hydrophilic-hydrophobic properties of analytes. Effective extraction and elution parameters such as sample volume, sample pH, rate of sample loading, eluent, and eluent volume, were also investigated and discussed. Under the optimal conditions, the linearity of phoxim and fenitrothion was in the range of 1.0-200 μg L^-1, and the linearity of temephos was in the range of 2.5-200 μg L^-1. The limits of detection were ranged from 0.2 to 1.0 μg L^-1. This established method was successfully applied to detect OPPs in two vegetables. There was no OPP detected in real samples, and results showed that the matrix effects were in the range of 46.5%-90.1%. This indicates that the ZrO₂/PDDA-GOA-SSM-SPE-HPLC method could effectively extract and detect OPPs in vegetables.

Zr-MOF modified cotton fiber for pipette tip solid-phase extraction of four phenoxy herbicides in complex samples

Phenoxy herbicides are widely applied in agricultural weeding. The determination of herbicides is important in environmental protection, agricultural production, food safety, and public health. In this study, a facile and efficient analytical method was proposed for the trace detection of phenoxy herbicides in soil, cucumber, and tap water samples by coupling pipette tip solid phase extraction (PT-SPE) with high performance liquid chromatography. UiO-66-funtionalized cotton (Cotton@UiO-66) was packed into pipette-tip as sorbent to fabricate extraction device. The modification of UiO-66 on cotton fiber was confirmed using scanning electron microscope, Fourier transform infrared spectroscopy, and X-ray diffraction. The main factors affecting the adsorption of Cotton@UiO-66 for four phenoxy herbicides were evaluated by response surface methodology in detail. Under optimized conditions, Cotton@UiO-66 displayed excellent properties in the extraction of phenoxy herbicides with good peak shape. Linear ranges of 4-chlorophenoxyacetic acid, dicamba, 2,4-dichlorophenoxyacetic acid, and 2-(2,4-dichlorophenoxy) propionic acid were 1.4-72 μg/L, 5.6-280 μg/L, 2.8-140 μg/L and 3.2-160 μg/L (RSDs < 6.3%), respectively. The recoveries were between 83.3 and 106.8% with RSDs <6.7%, with detection limits ranging from 0.1 μg/L to 0.3 μg/L. The results show that Cotton@UiO-66 in PT-SPE is an effective method for monitoring phenoxy herbicides in complex samples.