Determination of fipronil and its metabolites in edible oil by pollen based solid-phase extraction combined with gas chromatography-electron capture detection

Facial synthesis of fluorine-engineered magnetic covalent organic framework for selective and ultrasensitive determination of fipronil, its metabolites and analogs in food samples

To improve the adsorption affinity and selectivity of fipronils (FPNs), including fipronil, its metabolites and analogs, a magnetic covalent organic framework (Fe3O4@COF-F) with copious fluorine affinity sites was innovatively designed as an adsorbent of magnetic solid-phase extraction (MSPE). The enhanced surface area, pore size, crystallinity of Fe3O4@COF-F and its exponential adsorption capacities (187.3-231.5 mg g-1) towards fipronils were investigated. Combining MSPE with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), an analytical method was established for the selective determination of fipronils in milk and milk powder samples. This method achieved high sensitivity (LODs: 0.004-0.075 ng g-1), satisfactory repeatability and accuracy with spiked recoveries ranging from 89.9% to 100.3% (RSDs≤5.1%). Overall, the constructed Fe3O4@COF-F displayed great potential for the selective enrichment of fipronils, which could be ascribed to fluorine‑fluorine interaction. This method proposed a feasible and promising strategy for the development of functionalized COF and broadened its application in fluorine containing hazards detection.

Simultaneous Determination of Fipronil, Permethrin, and Their Key Related Substances in a Topical Drug Product by a Single Stability-Indicating High-Performance Liquid Chromatography Method

BACKGROUND

The topical veterinary drug product containing fipronil and permethrin provides an effective repellent protection and high insecticidal efficacy for dogs.

OBJECTIVE

The objective of this study was to develop a stability-indicating high-performance liquid chromatography (HPLC) method for simultaneous detection and quantification of fipronil, permethrin, their key degradation products, and butylated hydroxytoluene (BHT) in a topical drug product.

METHOD

The two active ingredients, their degradation products, and the antioxidant (BHT) were separated by a gradient elution on a Phenomenex Kinetex C18 column (150 × 3 mm, 2.6 µm particle size) maintained at 37°C with H2O acetonitrile isopropyl alcohol 85% H3PO4 (65.5 + 32.5 + 4/0.0053, v/v/v/v) as mobile phase A and acetonitrile (100%) as mobile phase B. The flow rate was 0.9 mL/min, and analytes were detected and quantified at 235 nm.

RESULTS

The specificity of the method was demonstrated by adequate separation of fipronil, permethrin, their degradation products, and BHT in the forced degraded finished product. The linearity of the method was demonstrated in the range of 0.2% to 150% of target analytical concentration of both active ingredients and 50% to 150% for BHT. Excellent recoveries of fipronil, permethrin, and BHT in placebo spiked active ingredient solutions in the linearity range showed sufficient accuracy of the method. The LOQ and LOD of the method were determined to be 0.2% and 0.07% of the analytical concentration. A robustness study did not identify any critical parameter that adversely affected the separation and quantification.

CONCLUSIONS

Here, we report the development and validation of a robust, stability-indicating HPLC method for identification and assay of fipronil, permethrin, and BHT, including estimation of fipronil's and permethrin's degradation products in a topical drug product for dogs.

HIGHLIGHTS

The new HPLC method permits the acquisition of data for all analytes of interest for a topical finished drug product containing fipronil, permethrin, and BHT.

Spherical fluorinated covalent organic polymer for highly efficient and selective extraction of fipronil and its metabolites in soil

Covalent organic polymers (COPs) have garnered considerable attention as promising adsorbents of online solid phase extraction (online SPE). Morphology modulation provides an appealing solution to enhance adsorption efficiency and reduce back-pressure in the absorbent. However, the synthesis of COPs with regular geometric shapes and specific adsorption selectivity remains challenging. In this study, a uniform spherical fluorinated COP (F-sCOP, average diameter: 2.14 μm) was successfully synthesized by Schiff base reaction of 1,3,5-triformylphoroglucinol (TP) and 2,2'-bis(trifluoromethyl)benzidine (TFMB). The F-sCOP had a large surface area (BET: 346.2 m2 g-1), remarkable enrichment capacity (enrichment factors: 186-782), high selectivity toward fipronil and its metabolites (adsorption efficiency >93.1%), and admirable service life (>60 times). Based on the adsorbent, a novel μ-matrix cartridge extraction-online-μ-solid phase extraction-high performance liquid chromatography-mass spectrometry (μ-MCE-online-μ-SPE-HPLC-MS) method was constructed and used to track trace fipronil and its metabolites in soil. The proposed method exhibited a wide linear range (0.05-1000 ng g-1), low quantitation limits (LOQs: 0.0027-0.011 ng g-1), high recoveries (90.1-119.6%) and good repeatability (RSD ≤10.5%, n = 3) for fipronil analysis. This study paves the way for pesticide analysis in soil risk assessment.

Conveniently monitoring aldehyde changes in heated edible oils using miniaturized kapok fiber-supported liquid-phase extraction/in-situ derivatization coupled with liquid chromatography-tandem mass spectrometry

Heating edible oils generates aldehydes, potentially leading to adverse health effects, making their analysis essential for quality control. This study presents a convenient miniaturized kapok fiber-supported liquid-phase extraction/in-situ derivatization method for the simultaneous extraction and derivatization of aldehydes in oils. The method involves placing 150 mg oil into a 1 mL pipette tip packed with 25 mg kapok fiber, adding 150 μL ACN with 1.5 mg mL-1 DNPH, and post 30-minute static extraction, retrieving the extractant with a pipettor for liquid chromatography-tandem mass spectrometry analysis. By optimizing critical parameters through a Box-Behnken design, the method exhibits good linearity (1-500 ng g-1, R2 ≥ 0.991), low detection limits (0.2-1.0 ng g-1), excellent accuracy (95.3-107.1%) and high precisions (relative standard deviation < 7.9%). This method simplifies sample preparation processes, cuts solvent use, and facilitates automation. It effectively identifies ten aldehyde variations in six heated oils, displaying distinct profiles consistent with prior research.

Comprehensive study of allergenic tree species: Palynological insights enhanced by HPLC and GC-MS profiling

Considering the limited data available on tree species in Uzbekistan, this research aimed to provide new insights. We gathered plant samples from different locations within Samarkand city and thoughtfully selected 15 tree species that represent the country's flora. Using scanning electron microscopy, we conducted comprehensive analyses of pollen morphology, revealing a diverse range of variations in the shapes, dimensions, and surface characteristics displayed by pollen grains. Distinct ornamentations such as micro-echinate, reticulate, rugulate, gemmate-verrucate, and verrucate-scabrate patterns facilitated the differentiation of species. These scanning electron microscopy findings enhance our comprehension of tree species diversity, adaptation, and ecological roles. In addition, leaf extracts were analyzed using HPLC and GC-MS, revealing a plethora of bioactive compounds, including catechins, chlorogenic acid, vanillic acid, and others. Furthermore, GC-MS analysis revealed the presence of seven key compounds, including 1-hexadecyne, 2-chloroethanol, 1,6-heptadiene, 2-methyl-, 5-bromoadamantan-2-one, ethyl 3-(3-pyridyl) propenoate, bis (2-ethylhexyl) phthalate, and quercetin. This study demonstrates the effectiveness of this method in assessing the quality of leaf extracts from tree species by examining both microscopic characteristics and chemical composition. This multifaceted approach has deepened our understanding of the characteristics and chemical compositions of these trees, thus contributing to a more profound appreciation of their ecological significance and potential applications.

Colorimetric and ratiometric supramolecular AIE fluorescent probe for the on-site monitoring of fipronil

The overuse of fipronil (FPN, a broad-spectrum insecticide) in agriculture has brought great concerns for environmental pollution and food safety. The development of a rapid, reliable, and portable analytical method for the on-site monitoring of FPN is therefore of great significance but is full of challenge. Herein, a novel supramolecular probe using human serum albumin (HSA) as the host and an aggregation-induced emission-active fluorescence probe LIQ-TPA-TZ as the guest was developed for the colorimetric and ratiometric detection of FPN, displaying fast response (30 s), high sensitivity (LOD ∼ 0.05 μM), and good selectivity and anti-interference performance. Moreover, portable paper-based test strips could be facilely obtained and utilized for the determination of FPN, showing colorimetric changes from yellow to orange. This supramolecular probe also demonstrated great potential in real applications for choosing the best cleaning method to reduce the residue rate of FPN on apples. This study provides a versatile tool for the fast and real-time analysis of FPN, which greatly benefits the on-site determination of pesticides with the use of simple testing apparatus.

Au@BN-enhanced laser desorption/ionization mass spectrometry and imaging for determination of fipronil and its metabolites in food and biological samples

Gold nanoparticles (AuNPs) represent an attractive inorganic matrix for laser desorption/ionization mass spectrometry (LDI-MS) detection of low-molecular-weight analytes; however, their direct use is hindered by severe aggregation. To limit AuNPs aggregation, hexagonal boron nitride nanosheets (h-BNNs) were employed as supports to improve their desorption/ionization efficiency. Thus, Au@BN was synthesized and systematically characterized. It showed low background noise and high sensitivity for LDI-MS of fipronil and its metabolites. Au@BN-assisted LDI-MS was validated using complex samples including blueberry juice, green tea beverage, and fish muscle, achieving low detection limits (0.05-0.20 µg·L^-1 for liquid media, 0.82-1.25 ng·g^-1 for fish muscle), wide linear ranges (0.2-100 µg·L^-1 for liquid media, 3.00-1000 ng·g^-1 for fish muscle), high reproducibility (7.55%-13.7%), and satisfactory recoveries (82.62%-109.1%). Furthermore, spatial distributions of analytes in strawberries and zebrafish were successfully imaged. This strategy allows for the quantitative analysis of other small molecules in complex substrates.

Targeted and non-targeted analysis for the investigation of pesticides influence on wheat cultivated under field conditions

A comprehensive approach was applied to evaluate the effects of pesticides on the metabolism of wheat (Triticum aestivum L). The application of commercially available pesticide formulations under field cultivation conditions provided a source of metabolic data unlimited by model conditions, representing a novel approach to study the effects of pesticides on edible plants. Gas and liquid chromatography coupled to tandem mass spectrometry were employed for targeted and non-targeted analysis of wheat roots and shoots sampled six times during the six-week experiment. The applied pesticides: prothioconazole, tebuconazole, fluoxastrobin, diflufenican, florasulam, and penoxulam were found at concentrations ranging 0.0070-25.20 mg/kg and 0.0020-2.2 mg/kg in the wheat roots and shoots, respectively. The following pesticide metabolites were identified in shoots: prothioconazole-desthio (prothioconazole metabolite), 5-(4-chlorophenyl)-2,2-dimethyl-3-(1,2,4-triazol-1-ylmethyl)pentane-1,3-diol (tebuconazole metabolite), and N-(5,8-dimethoxy[1,2,4]triazolo[1,5-c]pyrimidin-2-yl)-2,4-dihydroxy-6-(trifluoromethyl)benzene sulphonamide (penoxulam metabolite). The metabolic fingerprints and profiles changed during the experiment, reflecting the cumulative response of wheat to both its growth environment and pesticides, as well as their metabolites. Approximately 15 days after the herbicide treatment no further changes in the plant metabolic profiles were observed, despite the presence of pesticide and their metabolites in both roots and shoots. This is the first study to combine the determination of pesticides and their metabolites plant tissues with the evaluation of plant metabolic responses under field conditions. This exhaustive approach contributes to broadening the knowledge of pesticide effects on edible plants, relevant to food safety.

Effects of glycosylation on the accumulation and transport of fipronil in earthworm (Eisenia fetida)

In this study, the differences in the accumulation of fipronil (F) and the glycosylated product glucose-fipronil (GTF) in Eisenia fetida within 48 h were investigated, and the reason for these differences was discussed. The accumulation of F and GTF in E. fetida and soil was determined by high-performance liquid chromatography (HPLC) after simple, rapid pretreatment; the mean recoveries of F and GTF were 84.79 ~ 95.83%, and the relative standard deviations were 3.39 ~ 9.21%, indicating that the methods could accurately detect the accumulation of F and GTF in E. fetida and soil. Results showed that the accumulation concentrations of F and GTF in E. fetida increased with exposure time; the concentrations of F in E. fetida were 3.1 ~ 6.2 times higher than those of GTF. In addition, the half-lives of GTF in soil (16.90 ~ 18.24 days) were significantly lower than those of F (24.75 ~ 26.65 days). After the addition of phlorizin, a hexose transport inhibitor, the accumulation of F in E. fetida did not change significantly, but the accumulation of GTF in E. fetida was significantly inhibited. The concentrations of GTF in E. fetida after adding phlorizin were 32.71 ~ 59.07% of those without phlorizin. Overall, our results indicated that the uptake and transport of F and GTF in E. fetida were significantly different; the uptake and transport of GTF was related to monosaccharide transporters, and glycosylation could reduce the bioaccumulation of fipronil to E. fetida and shorten the half-life of fipronil in soil, providing an important reference for the application of glucose-fipronil.

Bifunctional Amine- and Thiol-Modified Ti3C2Tx MXene for Trace Detection of Heavy Metals

Surface functionalization of two-dimensional (2D) transition metal carbides, nitrides, and carbonitrides, also known as MXenes, is a powerful approach for modification of their physical and chemical properties for new applications. In this study, we demonstrate the synthesis of a bifunctional Ti₃C₂T_x MXene modified with amine and thiol groups through a facile condensation reaction. We successfully employed the resulting NH₂/SH-Ti₃C₂T_x MXene as a solid phase in the ultrasonic-assisted dispersive micro solid-phase extraction (d-μ-SPE) method for the analytical determination of heavy metals at trace levels in food and soil samples. The prepared NH₂/SH-Ti₃C₂T_x MXene showed remarkable performance in the ultrasonic-assisted d-μ-SPE method with limits of detection of 0.12 and 2.30 ng mL^-1, with linear dynamic ranges of 0.50-90 μg L^-1 and 10-120 μg L^-1 for cadmium (Cd²⁺) and lead (Pb²⁺) ions, respectively. Furthermore, the extraction efficiencies were greater than 97%, with a relative standard deviation of less than 3% for five separate batch experiments in the determination of 5.0 μg L^-1 of Cd²⁺ and Pb²⁺. This study shows that NH₂/SH-Ti₃C₂T_x can be used as a simple, rapid, reliable, selective, and sensitive material in the d-μ-SPE method for the trace determination of Cd²⁺ and Pb²⁺ in soil and agricultural products. This study demonstrates the utility of MXenes for analytical chemistry and suggests that further advances in methods for the functionalization of MXenes can open new applications for these already exciting materials.