Determination of tebufenpyrad and oxadiazon by solid-phase microextraction and gas chromatography-mass spectrometry

Dissipation behavior, residue distribution, and exposure risk assessment of tebufenpyrad and milbemectin acaricides in strawberries under open field conditions

Strawberries are a favorite fruit for most people, but the residues of pesticides on strawberries might be risky to human health. Tebufenpyrad and milbemectin are broad-spectrum acaricides with insecticide properties authorized for use on strawberries in Egypt. As a result, it is crucial to investigate their residues in the final product to ensure customers' safety. Consequently, field trials were conducted following the Good Agricultural Practices (GAPs) to study the dissipation rate and terminal residues of tebufenpyrad and milbemectin on strawberries. Tebufenpyrad and milbemectin residues in strawberries declined due to first-order decay process, showing significant degradation (88.5% and 94.7%, respectively) after 14 days. Risk assessment study was carried out by comparing the national estimated daily intake (NEDI) to the acceptable daily intake (ADI). The results demonstrated that the dietary risk posed by the residues of tebufenpyrad and milbemectin in strawberry fruits was acceptable for consumers. It is envisaged that the current study's findings would support the safe application of tebufenpyrad and milbemectin to strawberries and perhaps other crops in Egypt and other countries with similar climatic conditions.

Tebufenpyrad induces cell cycle arrest and disruption of calcium homeostasis in porcine trophectoderm and luminal epithelial cells

Tebufenpyrad is classified as a pyrazole acaricide and insecticide. It is widely used for several crops, especially in greenhouses, in several countries. While its unfavorable effects on non-target organisms have already been established, relatively little is known about its reproductive toxicity. Therefore, we demonstrated the biochemical effects of tebufenpyrad using porcine trophectoderm and porcine luminal epithelial cells, which are involved in implantation. We found that tebufenpyrad had antiproliferative effects and reduced cell viability. Tebufenpyrad also triggered apoptosis and excessive reactive oxygen species production. Furthermore, it induced cell cycle arrest in the G1 phase and disrupted calcium homeostasis in the cytosol and mitochondria. MAPK signaling pathways and the crosstalk among them were altered following tebufenpyrad treatment. In addition, the migration ability of cells was reduced after treatment with tebufenpyrad. Lastly, tebufenpyrad influenced the expression of genes related to pregnancy. Collectively, these results reveal the mechanism of the biochemical and physiological effects of tebufenpyrad to both trophectoderm and uterine cells and suggest that tebufenpyrad reduces the potential of successful implantation.

Occurrence, fate and environmental risk assessment of the organic microcontaminants included in the Watch Lists set by EU Decisions 2015/495 and 2018/840 in the groundwater of Spain

This paper aims to review the existing occurrence data in Spanish groundwater (GW) for the emerging organic contaminants (EOCs) defined in the surface water Watch Lists of Decisions 2015/495/EU and 2018/840/EU since these contaminants are likely to reach GW bodies because surface waters show close interaction with GW. These two lists include 20 substances: 9 pesticides (5 neonicotinoids, 2 carbamates, 1 oxadiazole and 1 semicarbazone), 6 pharmaceuticals (diclofenac and 5 antibiotics), 3 estrogens, 1 UV filter (2-ethylhexyl-4-methoxycinnamate, EHMC) and 1 antioxidant (2,6-di-tert-butyl-4-methylphenol, BHT). Most of these substances are usually detected at low ng/L concentration range or not detected in the GW bodies of Spain. However, eventually they are reported at concentrations>100ng/L (e.g., imidacloprid, methiocarb, diclofenac, macrolide antibiotics, ciprofloxacin, EHMC and BHT). Consequently, it is required to set up drinking water standards, and/or GW threshold quality values because GW is a valuable water resource worldwide. Overall, GW is less contaminated than other water bodies, such as rivers, suggesting that aquifers possess a natural attenuation capacity and/or are less vulnerable than rivers to contamination. Nevertheless, the natural hydrogeochemical processes that control the fate and transformation of these substances during infiltration and in the aquifer have been barely investigated so far. The concentrations of the target EOCs are used to calculate hazard quotients (HQs) in the Spanish GW bodies as an estimation of their ecotoxicity and in order to compare somehow their chemical quality with respect to those of surface water. Due to the limited ecotoxicity data for most EOCs, HQs can only be calculated for few substances. The results pointed out the risk posed by the anti-inflammatory diclofenac towards Ceriodaphnia dubia (HQ=21) and the medium risk associated to the antibiotic erythromycin for Brachionus calyciflorus (HQ=0.46).

Determination and Method Validation of the New Sulfone Fungicide 2-(4-Fluorophenyl)-5-Methylsulfonyl-1,3,4-Oxadiazole in Tomato and Soil by UPLC in Field Trial Samples from Guizhou Province, China

A new method was developed and validated for the determination of 2-(4-fluorophenyl)-5-methylsulfonyl-1,3,4-oxadiazole (jiahuangxianjunzuo, JHXJZ) by ultra-performance liquid chromatography equipped with photo-diode array detector. JHXJZ from tomato and soil was extracted with ethyl acetate without further cleanup. The limits of detection and quantification of JHXJZ were 0.0083 and 0.025 mg kg(-1) in tomato, 0.0017 and 0.005 mg kg(-1) in soil, respectively. The average recoveries of tomato and soil were studied at three spiked levels and ranged from 84.51 % to 101.30 % and 85.30 % to 101.53 %, respectively, with relative standard deviations of 2.61 %-4.13 % and 1.21 %-4.80 %, respectively. The results indicated that the reported method could meet the requirement for the analysis of JHXJZ in trace amount in tomato and soil.

Application of solid phase microextraction for the determination of soil fumigants in water and soil samples

The potential of solid phase microextraction (SPME) for the determination of the soil fumigants 1,3-dichloropropene (1,3-DCP) and methyl isothiocyanate (MITC) in environmental samples such as soil and water samples has been investigated. Direct immersion SPME followed by GC/ECD/NPD analysis allowed the rapid determination of the two fumigants in water samples, with very little sample manipulation, giving an LOD of 0.5 microg L(-1). Precision, calculated as relative standard deviation (RSD) for six replicates at three concentration levels, was found to be lower than 20% at the concentration levels tested. For the analysis of soil samples, headspace (HS)-SPME combined with GC/ECD/NPD analysis has been applied. Quantification using matrix-matched calibration curves allowed determination of both analytes (MITC and 1-3-DCP) with a LOD of 0.1 microg kg(-1) (RSD < 10%) for the two concentration levels assayed (0.02 and 0.2 mg kg(-1)). The HS-SPME procedure developed in this paper was applied to soil samples from experimental green house plots treated with metham-Na, a soil disinfestation agent that decomposes in soil to MITC. The absence of sample manipulation as well as the low solvent consumption in SPME methodology are among the main advantages of this analytical approach.

Solid-phase microextraction for herbicide determination in environmental samples

Liquid-liquid extraction or solid-phase extraction followed by gas chromatography (GC) or high-performance liquid chromatography are traditional herbicide residue determination methods for environmental samples. Solid-phase microextraction (SPME) is a solventless, fast, and sensitive alternative herbicide residue extraction method that can be applied to numerous environmental matrices. The objective of this paper was to review SPME literature regarding extraction theory, extraction modes, fiber types, and method optimization in conjunction with present and future SPME applications for herbicide determination in environmental samples.

Determination of oxadiazon residues by headspace solid-phase microextraction and gas chromatography-mass spectrometry

A method for the determination of trace amounts of the herbicide oxadiazon was developed using headspace solid-phase microextraction (HS-SPME), gas chromatography-mass spectrometry (GC-MS) and selected ion monitoring. It was applied to determine oxadiazon in ground water, agricultural soil, must, wine and human urine samples. To determine oxadiazon in liquid samples, a response surface methodology generated with a Doehlert design was applied to optimize the HS-SPME conditions using a 100 microm polydimethylsiloxane fibre. For the analysis of soil samples, they were mixed with water and the SPME fibre suspended in the headspace above the slurry. Ground water, human urine and must show linear concentration range of application of 0.5-50 ng ml(-1)' with detection limits < or =0.02 ng ml(-1). HS-SPME-GC-MS analysis yielded good reproducibility (RSD values between 6.5 and 13.5%). The method validation was completed with spiked matrix samples. The developed analytical procedure is solvent free, cost effective and fast.