Study on the environmental fate of three insecticides in garlic by in vivo sampling rate calibrated-solid phase microextraction-gas chromatography-mass spectrometry

Sampling-rate calibration vs. equilibrium calibration for in vivo solid-phase microextraction: Analysis of neonicotinoids in bananas

In vivo solid-phase microextraction (in vivo SPME) is an emerging fascinating sample pretreatment technique, but its quantitative correction method is different from the traditional correction methods, which has become a bottleneck limiting its development. At present, the sampling-rate calibration and equilibrium calibration are mainly used, however, their characteristics and applicability are not clear. In this study, the sampling-rate calibration and equilibrium calibration were evaluated in the case of the determination of neonicotinoids in bananas by in vivo SPME. The factors that affect the sampling rate (Rs), such as the matrix states, sampling durations, and individual differences were studied, and they all had impacts on Rs. Conversely, the equilibrium distribution coefficient (Kfs) remained constant after extraction equilibrium and the individual differences were smaller. The highest accuracy and precision were achieved by equilibrium calibration, and the relative recoveries were in the range of 83.2 %-104.3 % with the relative standard deviations below 8.1 % compared to a standard QuEChERS-based method. The lower limits of quantification for 4 neonicotinoids in bananas were below 5 ng g-1, lower than the standard method and the maximum residue levels in China and the European Union. This work clarifies the characteristics, rules and performance of the sampling-rate calibration and equilibrium calibration, which is of crucial importance for the development and application of in vivo SPME. The developed method is convenient, sensitive, and accurate for the determination of pesticide residues, which is of great significance to guide the safe use of pesticides in the field and prevent products with excessive pesticide residues from entering the market.

In vivo tracing of cyromazine and three neonicotinoids in cowpea under field conditions by solid-phase microextraction combined with ultra-performance liquid chromatography-tandem mass spectrometry

BACKGROUND

Excessive pesticide residues in agricultural products could accumulate in organisms through the food chain, causing potential harm to human health. The investigation of dissipation kinetics and residues of pesticides in crops is crucial for the scientific application of pesticides and the mitigation of their adverse effects on human health. In vivo solid-phase microextraction (in vivo SPME) has unique advantages, but the research on field plants is still lacking and the quantitative correction methods need to be further developed.

RESULTS

A method combining in vivo solid-phase microextraction with ultra-performance liquid chromatography-tandem mass spectrometry (in vivo SPME-UPLC-MS/MS) was developed to monitor the presence of acetamiprid, cyromazine, thiamethoxam and imidacloprid in cowpea fruits grown in the field. The sampling rates (Rs) were determined using both in vitro SPME in homogenized cowpea samples and in vivo SPME in intact cowpea fruit samples. The in vivo-Rs values were significantly higher than the in vitro-Rs for the same analyte, which were used for in vivo SPME correction. The accuracy of this method was confirmed by comparison with a QuEChERS-based approach and subsequently applied to trace pesticide residues in field-grown cowpea fruits. The residual concentrations of each pesticide positively correlated with application doses. After 7 days of application at two different doses, all of the pesticides had residual concentrations below China's maximum residue limits. Both experimental data and predictions indicated that a safe preharvest interval for these pesticides is 7 days; however, if the European Union standards are to be met, a safe preharvest interval for cyromazine should be at least 13 days.

SIGNIFICANCE

This study highlights the advantages of in vivo SPME for simultaneous analysis and tracking of multiple pesticides in crops under field conditions. This technique is environmentally friendly, minimally invasive, highly sensitive, accurate, rapid, user-friendly, cost-effective, and capable of providing precise and timely data for long-term pesticide surveillance. Consequently, it furnishes valuable insights to guide the safe utilization of pesticides in agricultural production.

Imprinted covalent organic frameworks solid-phase microextraction fiber for in vivo monitoring of acidic per- and polyfluoroalkyl substances in live aloe

Per- and polyfluoroalkyl substances (PFASs) can lead to risks associated with animal and human health through the transfer along food chains. It is confirmed that PFASs can be transported to each part of plants after taken up by the roots. To better elucidate the underlying mechanisms for such exposure, it is highly valuable to develop analytical capabilities for in vivo monitoring of PFASs in live plants. In this work, a novel imprinted covalent organic frameworks (CMIP) solid-phase microextraction coupled with ultra-performance liquid chromatography-tandem mass spectrometry was developed with low limits of detection for six acidic PFASs (0.1-0.3 ng g-1) and used for in vivo monitoring in live aloe. The CMIP coating shows good precision (RSD of intra and inter ≤9.6 % and 10.2 %, respectively) and possesses much higher extraction efficiency than the commercial coatings. After cultivating aloe in soil spiked PFASs, the in vivo assays gave a wealth of information, including steady-state concentrations, translocation factors, elimination rate constants, and half-life of PFASs. The in vivo tracing method for live plants can provide much needed and unique information to evaluate the risk of PFASs, which are very important for the safety of agriculture production.