Simultaneous determination of neonicotinoid insecticides in sunflower-treated seeds (hull and kernel) by LC-MS/MS

Analytical Methods Based on Liquid Chromatography and Capillary Electrophoresis to Determine Neonicotinoid Residues in Complex Matrices. A Comprehensive Review

Neonicotinoids (NNIs) are neuro-active and systemic insecticides widely used to protect crops from pest attack. During the last decades, there has been an increase concern about their uses and toxic effects, especially to beneficial and non-target insects such as pollinators. To assess potential health hazards and the environmental impacts derived from NNIs uses, a great variety of analytical procedures for the determination of their residues and their metabolites at trace level in environmental, biological and food samples have been reported. Due to the complexity of the samples, efficient sample pretreatment methods have been developed, which include mostly clean-up and preconcentration steps. On the other hand, among the analytical techniques used for their determination, high-performance liquid chromatography (HPLC) coupled to ultraviolet (UV) or mass spectrometry (MS) detection is the most widely used, although capillary electrophoresis (CE) has also been employed in the last years, considering some improvements in sensitivity when coupling with new MS detectors. In this review, we present a critical overview of analytical methods based on HPLC and CE reported in the last decade, discussing relevant and innovative sample treatments for the analysis of environmental, food and biological samples.

Rapid determination of 134 pesticides in tea through multi-functional filter cleanup followed by UPLC-QTOF-MS

Ensuring the safety of tea requires effective methods for the simultaneous analysis of pesticide residues in the product. A sensitive and reliable method to scan for 134 pesticide residues in tea was developed that employs a novel Multi-Functional Filter (MFF) based on d-SPE extraction and ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry. The adsorption material was developed by porous polyvinylpolypyrrolidone (PVPP) for the removal of polyphenols. Acetonitrile extraction was passed through a syringe and then detected by UPLC-Q-TOF-MS. Method validation revealed satisfactory linearity with correlation coefficients higher than 0.985 for all pesticides. All limits of quantification were below 10 µg/kg. The matrix effects of 133 of the pesticides were nearly negligible (<20%), except for Sebutylazine (=22%). The recoveries at two spiked levels (50, 100 μg/kg) were 66.83-118.33%, and the Relative standard deviation (RSD) was lower than 20%, indicating accuracy and precision of the new method.

Validation of QuEChERS Method Coupled with LC-MS/MS for Determination of Thiamethoxam and its Metabolites in Wheat and Soil

BACKGROUND

Thiamethoxam, a neonicotinoid insecticide, has been widely accepted for the control of sucking and certain chewing pests. Through different routes, i.e., wind drift, leaching, and surface runoff, it can reach non-target areas, which include humans as well. Therefore the fate of thiamethoxam in food grains and soil is of prime importance, entailing a need for pesticide use to be subject to steady observation.

OBJECTIVE

The review aimed to validate the Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) method for the detection of thiamethoxam and its metabolites in wheat leaves, grain, straw, and soil using liquid chromatography-tandem mass spectrometry (LC-MS/MS).

METHOD

The QuEChERS method allows sample extraction by acetonitrile followed by cleanup with a primary secondary amine sorbent, magnesium sulphate, and graphitized carbon black. The method was validated in terms of selectivity, linearity, LOD, LOQ, matrix match, accuracy, and precision. The estimation of residues was done by LC-MS/MS.

RESULTS

The recovery of thiamethoxam and its metabolites in wheat and soil samples was in the range of 81.22-98.14%. The LOQ for thiamethoxam and its metabolites was 0.01 mg/kg. The matrix effect values were in the acceptable range of -20 to +20%.

CONCLUSIONS

The method allows a simple and fast extraction of thiamethoxam and its metabolites from wheat leaves, grain, straw, and soil. It could be helpful in the evaluation of regulatory and food safety decisions regarding the use of neonicotinoids.

HIGHLIGHTS

The method was validated according to the European Commission SANTE/12682/2019 guidelines. An accurate, simple, and sensitive analytical method was validated for thiamethoxam and its metabolites.

An update of the Worldwide Integrated Assessment (WIA) on systemic insecticides. Part 1: new molecules, metabolism, fate, and transport

With the exponential number of published data on neonicotinoids and fipronil during the last decade, an updated review of literature has been conducted in three parts. The present part focuses on gaps of knowledge that have been addressed after publication of the Worldwide Integrated Assessment (WIA) on systemic insecticides in 2015. More specifically, new data on the mode of action and metabolism of neonicotinoids and fipronil, and their toxicity to invertebrates and vertebrates, were obtained. We included the newly detected synergistic effects and/or interactions of these systemic insecticides with other insecticides, fungicides, herbicides, adjuvants, honeybee viruses, and parasites of honeybees. New studies have also investigated the contamination of all environmental compartments (air and dust, soil, water, sediments, and plants) as well as bees and apicultural products, food and beverages, and the exposure of invertebrates and vertebrates to such contaminants. Finally, we review new publications on remediation of neonicotinoids and fipronil, especially in water systems. Conclusions of the previous WIA in 2015 are reinforced; neonicotinoids and fipronil represent a major threat worldwide for biodiversity, ecosystems, and all the services the latter provide.

A photochemically induced fluorescence based flow-through optosensor for screening of nitenpyram residues in cruciferous vegetables

One of the most used agrochemicals in agricultural production, nitenpyram (NTP), has been determined by using a flow-through optosensing device based on Photochemically Induced Fluorescence detection. The combination of both methodologies allows, on one hand, a quick on-line photodegradation of NTP and, on the other hand, the preconcentration, quantification and desorption of the fluorescent photoproduct generated when retained on Sephadex QAE-A25 as solid support, which was monitored at 295 and 362 nm for excitation and emission, respectively. The proposed analytical method presents a detection limit of 500 pg mL^-1 by using Multicommutated Flow Injection Analysis. Recovery experiments were carried out in different kinds of cruciferous vegetables at or below the MRL established in Japan, demonstrating that this method combines advantages of simplicity, high sensibility and high selectivity, fulfilling the requirements for its application in quality control. Results obtained in the analysis of real samples were in good agreement with those provided by a reference HPLC method.