Fipronil Desulfinyl Research Articles

Squaraine-Linked Magnetic Covalent Organic Framework as a Solid-Phase Extraction Absorbent to Determine Trace Phenylpyrazoles.

Phenylpyrazoles are widely used pesticides in the food industry. It is highly desirable to develop efficient pre-treatment and analysis methods to extract and detect phenylpyrazoles in complex food matrices. Herein, the study reports novel squaraine-linked zwitterionic core-shell magnetic covalent organic frameworks (MCOFs), which are found to be excellent pretreatment materials for the detection of trace phenylpyrazoles in samples. By coupling MCOFs to magnetic solid-phase extraction (MSPE) with Ultra Performance Liquid Chromatography-Tandem Mass Spectrometry (UPLC-MS/MS) analysis, the detection of phenylpyrazoles (fipronil, fipronil sulfone, fipronil sulfide, fipronil de-sulfoxide, fipronil desulfinyl, ethiprole, and flufiprole) is achieved and shows good linearity at concentrations of 1-800µg L-1 (R2 ≥ 0.9930). The limit of detection (LOD), limit of quantification (LOQ), and recovery rates are 0.01-0.50µg kg-1, 0.04-1.72µg kg-1, and 70.96-115.32%, respectively. More importantly, this method is successfully applied to determine the phenylpyrazoles in commercial egg, poultry, milk, jujube, cabbage, tea, and rice with a detection rate of ≈0.04%. Therefore, the developed method may contribute to a new strategy for the purification and multi-target extraction of complex food matrices.

Development and Validation of an Analytical Method for the Determination of Fipronil and its Degradation Products in 28 Organic and Regular Honey Samples by GC-ECD

Recently, there has been a worldwide problem of increased bee mortality (Colony Collapse Disorder) and the intensive use of pesticides is suspected as one of the causes. Honey samples are one of many indicators to assess bee exposure to pesticides. In this work, a method for the simultaneous analysis of the pesticide Fipronil and its degradation products in honey samples by gas chromatography with electron capture detector (GC-ECD) is presented and validated. The extraction procedure was investigated using C18-SPE with different solvents and methanol showed the best performance. The analytical quantification was performed by internal standard matrix-matched calibration, which resulted in analytical curves presenting correlation coefficients higher than 0.99. The proposed method was validated with good results, such as recoveries around 70 - 99%, limits of detection and quantification bellow 0.014 and 0.072 μg mL-1, respectively, and relative standard deviations below 7%. The method is simple, effective and was successfully applied to 28 commercial honey samples, regular and organic, from different floral sources. The results showed the presence of fipronil desulfinyl, the main degradation product of fipronil, in some samples, even among the organic ones.

Rapid and Sensitive On-Site Detection of Fipronil in Foods Using Evanescent Wave Fluorescent Immunosensor

Fipronil (FIP), a broad-spectrum phenylpyrazole insecticide, is highly toxic and threatens human health and ecological balance. Developing convenient, rapid, portable analytical technology for on-site and high-frequency testing of FIP is essential to reduce its damage. Herein, a monoclonal antibody (Clone F-3F6) against FIP, with high affinity and specificity, was produced using a novel immunogen, FIP-BSA, which was simply and directly synthesized by conjugating FIP with bovine serum albumin (BSA). Among the previously reported antibodies, F-3F6 acts more specifically against FIP. The FIP metabolites fipronil desulfinyl, fipronil sulfide, and fipronil sulfone showed lower cross-reactivity, and other pesticides were not recognized. To achieve high-frequency and on-site measurements of FIP, an evanescent wave fluorescence biosensor was built by integrating evanescent wave fluorescence technology, a functionalized fiber bioprobe, and a fluorescence-labeled F-3F6 antibody. The detection limit of FIP was 0.032 μg/L. The detection results of real milk and water samples showed that all the coefficients of variation were less than 10%, and the recovery ranged from 90 to 120%. The high reusability and stability of functionalized fiber bioprobe enables the accurate, cost-effective, high-frequency, and facile quantitative detection of FIP. This highly specific and reliable evanescent wave fluorescence biosensor will be well suited to the sensitive and high-frequency on-site analysis of only FIP in food.

Molecular dynamics simulation studies on uptake of fipronil sulfone by gut microbiome and its influence on risk for cause of Parkinson’s disease

ABSTRACT Biotransformation of Fipronil forms three metabolites: fipronil sulfone, fipronil sulfide and fipronil desulfinyl. Among the triad of metabolites, fipronil sulfone exhibits quantitatively predominant production. Research on Fipronil and its relationship with Parkinson's disease (PD) has exclusively focused on the parent compound (fipronil), with no consideration given to its metabolites. We aim to investigate the effect of fipronil sulfone, on gut bacterial proteins involved in metabolite production, adversely affect patients with Parkinson’s disease. The proteins Diaminopimelate epimerase (Q88V90) (DapF) from Lactobacillus sp., and. Tyrosine Decarboxylase (P0DTQ4) (TDC) from Enterococcus sp. are involved in cellular mechanisms help bacteria maintain a normal functional state & cell population to produce metabolites. The interaction of FS with DapF and TDC for each bacterial species was simulated. A concentration-based simulation was performed for 100 ns at 92 mg/L, half the LD50 value (184 mg/L) of Fipronil sulfone. The values of molecular simulation analysis of TDC and DapF respectively were: RMSD = 4.9846 nm & 2.0648 nm and RMSF = 1.788071 nm & 1.237829 nm. The aforementioned interaction studies indicate conformation change in the protein structures of DapF and TDC could potentially inhibit the functioning of the bacteria, thereby reducing amount of metabolites produced possibly influencing Parkinson’s Disease.

Determination of fipronil and its three degradates in water using stir bar sorptive extraction–thermal desorption–gas chromatography–tandem mass spectrometry

A method was developed for determination of fipronil (FIP) pesticide and its three major degradates (fipronil desulfinyl, fipronil sulfide, fipronil sulfone) in water at the levels required by the EU Commission in the Decision 2022/1307. The method combines solvent-free stir bar sorptive extraction (SBSE) with thermal desorption–gas chromatography–tandem mass spectrometry (TD–GC–MS/MS). Simple sample processing involves 16 h of stirring a 100 mL water sample with a polydimethylsiloxane-coated sorptive stir bar, followed by TD of the trapped analytes into the GC. The greenness assessment by analytical Eco-Scale approach resulted in classification of the entire analytical method as "an excellent green analysis". The obtained limits of quantification for all FIPs determined in tap, lake, MilliQ water and artificial seawater were in the range of 0.12–0.30 ng L–1. The recoveries ranged between 81.7 and 109% with relative standard deviations from 2.8 to 14%. The results show that the method is suitable for screening and monitoring the studied analytes in selected matrices.

Tracing the attenuation of fipronil and its transformation products from a rice paddy field to receiving rivers using polar organic chemical integrative samplers

Irrational use of fipronil for rice pest control often occurred, resulting in high concentrations of fipronil and its transformation products (TPs) (collectively termed fiproles) in aquatic sediment, calling for a better understanding of the migration and transformation of fipronil in surface water as well as efficient methods for source identification. Herein, the fate and transport of fiproles from a paddy field to receiving rivers were assessed in Poyang Lake basin, Jiangxi, China using polar organic chemical integrative samplers with mixed-mode adsorbents (POCIS-MMA). Average concentrations of fiproles in water were 6.16 ± 6.32 ng/L, with median, minimum, and maximum values being 2.99 ± 0.67, 0.40 ± 0.08, and 18.6 ± 3.1 ng/L, respectively. In all samples, over half of fiproles (55.9 %–90.8 %) presented in the form of TPs and fipronil desulfinyl was the dominant TP. Two approaches were applied for source identification, including the change of molar concentration ratios of fipronil to its TPs and the relative attenuation values of fiproles normalized to a reference compound (acetamiprid) that was stable in aquatic environment. While the paddy field upstream was the main source of waterborne fiproles, additional input sources in the downstream region were identified. The present study indicated that the combination of attenuation of molar concentration ratios of micro-pollutants to their respective TPs and relative attenuation values of micro-pollutants' concentrations normalized to a reference compound measured by POCIS is an effective means to study the migration and transformation of micro-pollutants in field.

Photodegradation of the insecticide fipronil in aquatic environments: photo-dechlorination processes and products.

Fipronil (FIP) is a phenylpyrazole insecticide that, along with neonicotinoid insecticides, is regularly used worldwide. Photodegradation of FIP in aqueous systems is thought mainly to involve the reaction of desulfinylation to give fipronil desulfinyl (FIP-desulfinyl); however, little is known about further degradation reactions. We investigated FIP photodegradation by analyzing photodegradation products by liquid chromatography and liquid chromatography high-resolution tandem mass spectrometry using an Orbitrap instrument. A wide range of products, including dechlorinated compounds, was detected, and the structures were identified. FIP-desulfinyl has previously been found to be an important and persistent FIP photodegradation product; however, we also found that FIP-desulfinyl was photochemically decomposed to a didechlorinated product via a monodechlorinated product. The main photodegradation pathway was probably similar to that of ethiprole, which has a similar skeleton. The photodegradation rate constant was 22.6 times lower for FIP-desulfinyl (0.00372 min-1) than FIP (0.0839 min-1). The photodegradation rate constant was lower for the newly found didechlorinated product (0.001 min-1 or below) than FIP-desulfinyl, suggesting that the product is persistent in aquatic environments and could be an important indicator of long-term FIP contamination.

Magnetic Solid-Phase Extraction of Fipronil from Aqueous Solution and Eggshells Using Amine-Coated Iron Oxide Nanoparticles.

Fipronil, as a broad use insecticide, is regulated under directives and standards in many countries since it is classed as Class II moderately hazardous pesticide and Group C possible human carcinogen. In this study, amine coated iron oxide (NH2 -Fe3 O4 ) is used as a new adsorbent with high adsorption capacity in the removal of fipronil from aqueous solution and eggshells.The adsorption performance was studied through batch adsorption under different concentrations of fipronil (10-200 μg/mL), different nanoparticles amount (0.1-1 mg) at different pH (4.5-6.0) and temperature (25-75 °C). Results showed that NH2 -Fe3 O4 nanoparticles (0.1 mg) have excellent adsorption efficiency (97.06 %) at 25 °C, and pH 5.5. It also showed higher adsorption capacity towards fipronil sulfide, fipronil sulfone and fipronil desulfinyl with removal efficiencies of 92.82 %, 86.35 % and 76.24 % from aqueous solution and 97.62 %, 76.97 % and 62.65 % from eggshells, respectively. Fipronil adsorption process on NH2 -Fe3 O4 nanoparticles showed best fitting to Langmuir adsorption isotherm indicating monolayer chemical adsorption by physicochemical interactions spontaneously on homogenous surfaces. Having higher adsorption capacity and reusability NH2 -Fe3 O4 nanoparticles were shown to be effective adsorbents for removal of fipronil from aqueous solution and eggshells.

Thyroid-Disrupting Effects of Exposure to Fipronil and Its Metabolites from Drinking Water Based on Human Thyroid Follicular Epithelial Nthy-ori 3-1 Cell Lines.

Fipronil is a broad-spectrum insecticide used for plants and poultry. Owing to its widespread use, fipronil and its metabolites (fipronil sulfone, fipronil desulfinyl, and fipronil sulfide), termed FPM, can be frequently detected in drinking water and food. Fipronil can affect the thyroid function of animals, but the effects of FPM on the human thyroid remain unclear. We employed human thyroid follicular epithelial Nthy-ori 3-1 cells to examine combined cytotoxic responses, thyroid-related functional proteins including the sodium-iodide symporter (NIS), thyroid peroxidase (TPO), deiodinases I-III (DIO I-III), and the nuclear factor erythroid-derived factor 2-related factor 2 (NRF2) pathway induced by FPM of 1-1000-fold concentrations detected in school drinking water collected from a heavily contaminated area of the Huai River Basin. Thyroid-disrupting effects of FPM were evaluated by examining biomarkers of oxidative stress and thyroid function and tetraiodothyronine (T4) levels secreted by Nthy-ori 3-1 cells after FPM treatment. FPM activated the expression of NRF2, HO-1 (heme oxygenase 1), TPO, DIO I, and DIO II but inhibited NIS expression and increased the T4 level of thyrocytes, indicating that FPM can disrupt the function of human thyrocytes through oxidative pathways. Given the adverse impact of low FPM concentrations on human thyrocytes, supportive evidence from rodent studies, and the critical importance of thyroid hormones on development, the effects of FPM on the neurodevelopment and growth of children warrant priority attention.

Occurrence, fate, and probabilistic risk assessment of fipronil residues in Chinese tea

The objective of this study was to determine the occurrence of fipronil and its three metabolites in tea samples collected from 2011 to 2018 in China, where the use of fipronil in agriculture had been banned since 2009. Among the 726 tea samples, the total fipronils (∑FIPs, non-detected (ND)− 140 µg/kg) were dominated by the parent compound fipronil (ND-80.6 µg/kg) and its major metabolites fipronil desulfinyl (ND-36.9 µg/kg) and fipronil sulfone (ND-24.2 µg/kg), while fipronil sulfide (ND-6.78 µg/kg) contributed little to the total. A total of 20.0 % and 30.7 % of the tea samples detected ∑FIPs residues exceeded the maximum residue limits of 0.005 and 0.002 mg/kg set by the European Union and Japan, respectively. The average concentration of ∑FIPs decreased by 22 times during the three survey periods. By the probabilistic model, the chronic exposure risk of Chinese tea consumers was less than 25 % of the acceptable daily intake of fipronil, and a ten-fold decrease was observed within eight years. The ∑FIPs residues in tea were within a low health risk for Chinese tea consumers. This was the first study to provide the basic information on the occurrence and the temporal variation of fipronil in tea samples from China.

Molting enhances internal concentrations of fipronil and thereby decreases survival of two estuarine resident marine crustaceans.

In aquatic arthropods, molting is a pivotal physiological process for normal development, but it may also expose them to higher risks from xenobiotics, because the organism may take up additional water during that time. This study aimed to assess the effects of molting on bioconcentration and survival after 96-h exposure to insecticide fipronil with or without oxygenase (CYP450s) inhibitor piperonyl butoxide (PBO) of two estuarine resident marine crustacean species: the sand shrimp Crangon uritai and the kuruma prawn Penaeus japonicus, with 96-h LC50 value of fipronil=2.0µg/L and 0.2µg/L, respectively. Two graded concentrations included group high (H) (equivalent to the 96-h LC50 values) and low (L) (one-tenth of the H group concentration). Molting and survival were individually checked, and internal concentrations of fipronil and its metabolites (fipronil desulfinyl, fipronil sulfide, fipronil sulfone) were measured. The results showed that, only fipronil and fipronil sulfone were detected from organism, and that internal concentrations of these insecticides in molted specimens were higher than those of unmolted ones but comparable with those of dead ones. Accordingly, mortality was more frequent in molted specimens than those that were unmolted. Furthermore, involvement of oxygenase and higher lethal body burden threshold may confer higher tolerance to fipronil in sand shrimp than in the kuruma prawn. This study is the first to demonstrate that the body-residue-based approach is useful for deciphering the causal factors underlying fipronil toxicity, but highlights the need to consider physiological factors in arthropods, which influence and lie beyond body burden, molting and drug metabolism.

Pesticide trends in a tailwater recovery system in the Mississippi Delta

AbstractTailwater recovery (TWR) systems are an important best management practice (BMP) used to address both water quality and quantity issues in the Mississippi Delta region. Tailwater recovery systems are surface water capture‐and‐irrigation reuse systems using a combination of ditches to capture surface water, an on‐farm storage (OFS) reservoir to store captured surface water, and pumps to move surface water from ditches to the reservoir and from the reservoir to irrigate nearby fields. It is anticipated that TWR systems improve water quality by allowing agricultural contaminants to settle out in ditches and reservoirs rather than being transported during irrigation to nearby fields and downstream aquatic systems. To determine if TWR systems are an effective way to reduce downstream pesticide transport, water samples from a ditch‐and‐reservoir TWR system in Sunflower County, MS, were routinely collected and analyzed for 5 yr. Objectives of this study were to assess seasonal pesticide and pesticide metabolite concentrations throughout the different components of the TWR system and identify any trends that may exist. Atrazine‐desethyl, atrazine‐desisopropyl, atrazine, clomazone, propanil, fipronil desulfinyl, metolachlor, fipronil, p,p'‐DDT, bifenthrin, beta‐cyfluthrin, and zeta‐cypermethrin were found in every season in both ditch and reservoir samples. Several pesticides that have not been used in the United States for decades were detected including DDT and its metabolites as well as dieldrin, heptachlor, lindane, and methyl parathion, demonstrating their environmental persistence. The reservoir featured more types and higher concentrations of pesticides, indicating a possible risk of cross‐crop injury from the recycling of the water from the reservoir for irrigation.

Fipronil and its metabolites in human seminal plasma from Shijiazhuang, north China

Fipronil (FP) is an emerging insecticide which could induce reproductive toxicity in male rats at very low dosage, but the occurrence of FP and its transformation products (FPs) in human seminal plasma and their impacts on human semen quality have not been documented. In this study, FPs including FP, fipronil desulfinyl (FP-DES), fipronil sulfone (FP-SFO), fipronil amide (FP-AM), and fipronil sulfide (FP-SFI), were measured in seminal plasma samples (n = 200), which were collected from Shijiazhuang, north China. The cumulative concentration of FPs (ΣFPs), in the seminal plasma samples ranged from 0.003 to 0.180 ng/mL (median: 0.043 ng/mL). FP-SFO was the major target analyte (median: 0.040 ng/mL), accounting for approximately 42.3–100.0% of the ΣFPs. Significantly higher exposure levels of FPs were found in the overweight or obese group (≥25 kg/m2) vs. the normal BMI group (18.5–25 kg/m2) (ΣFPs: 0.047 vs. 0.033 ng/mL), never smoking group vs. current smoking group (ΣFPs: 0.057 vs. 0.037 ng/mL), and low sexual frequency group (<1 time/week) vs. high sexual frequency group (≥3 times/week) (ΣFPs: 0.048 vs. 0.030 ng/mL). No significant association between FPs and impaired semen quality parameter was found in this study. This is the first time to report FPs' occurrence in human seminal plasma and variations in their concentrations among people with different demographic and behavioral characteristics. Further studies on adverse effects of exposure to FPs on reproductive function are needed.

Toxic effects of fipronil and its metabolites on PC12 cell metabolism

Fipronil and its metabolites (fipronil sulfone, fipronil sulfide and fipronil desulfinyl) adversely affect the environment and human health. Targeted metabolomics and lipidomics based on ultra-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was used to analyse the alterations of glycerophospholipids and amino acids after exposure to fipronil and its metabolites at dosages of 0.5, 12.5 and 50 μM for 72 h and to evaluate their different toxic effects. Results showed that fipronil sulfone and fipronil desulfinyl are more toxic than their parent compound, with fipronil desulfinyl as the most toxic and fipronil sulfide as the least toxic. Fipronil and its metabolites affected the metabolism of PC18:1/16:0, PI18:0/20:4, arginine, leucine and tyrosine and the “phenylalanine, tyrosine and tryptophan biosynthesis” pathway, indicating their possible inducing role in cellular macromolecule damage, nerve signal transmission disturbance and energy metabolism disruption caused by oxidative stress. Importantly, fipronil sulfone and fipronil desulfinyl more strongly influenced lipid and amino acid metabolism, mainly reflected in the number of changed glycerophospholipids and differential metabolites associated with oxidative stress, including PS18:0/20:4, glutamate, phenylalanine and histidine for fipronil sulfone and PS18:0/20:4, glutamate, phenylalanine, serine and aspartic acid for fipronil desulfinyl. Therefore, the higher toxicity of fipronil desulfinyl and fipronil sulfone may be also related to oxidative stress. This study provides implications for risk assessment and toxic mechanism research on fipronil and its metabolites.

Covalent Triazine Framework Sorbent for Solid Phase Extraction of Fipronil and its Metabolite in Eggs with Ultra-High Performance Liquid Chromatography-Tandem Mass Spectrometry

ABSTRACT A solid-phase extraction (SPE) method was established for fipronil and its metabolite residues (fipronil desulfinyl, fipronil sulphone and fipronil sulphide) in eggs with a covalent triazine framework (CTF) porous material as the adsorbent followed by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) detection. Multiple probes and quantum chemistry theory calculations were conducted to describe the versatile adsorption property directly and quantifiably. The conjugated structure of CTF and N-containing triazine generated π-π interactions and hydrogen bonds between the CTF and the targets, which led to high extraction efficiency and recoveries. The solid-phase extraction parameters, including amount of the adsorbent, type of eluent, amount of eluent and loading rate were investigated. Under the optimal experimental conditions, the recoveries of the analytes were between 85.5% and 103.2%, and the RSD (n = 5) was between 1.8% and 3.6%. The LODs and LOQs were 0.13–0.2 ng g−1 and 0.5–0.8 ng g−1, respectively. The sorbent can effectively reduce the interference of the matrix and meet the detection requirements of fipronil and its metabolites in eggs. These results imply that the CTF as adsorbents have great potential in the analysis of trace targets in samples with complex matrices.

Insecticide fipronil and its transformation products in human blood and urine: Assessment of human exposure in general population of China

Fipronil (FP) is widely used as a highly effective insecticide worldwide, thereby raising concern about environmental contamination and risk for human health. However, data on the occurrence of FP and its transformation products (FPs) in human blood and urine are limited. In this study, 39 pairs of serum, plasma, blood cells (BCs), and urine samples were collected from adults in Wuhan, central China (2020), in order to characterize the concentration profiles of FPs in different matrices. FPs were also determined in serum samples (n = 226, including 57, 56, 56, and 57 samples for Wuhan, Huangshi, Nanjing, and Zhenjiang, respectively) collected from four cities of China (2015) to characterize the exposure levels of FPs among the general population and potential spatial variations. Fipronil sulfone (FP-SFO) was 100% detectable in blood samples, and it was the predominant metabolite (accounting for 86–95% of the cumulative concentrations of FPs [ΣFPs]), with the median concentrations (ng/mL) of 0.17, 0.16, and 0.03 in serum (range: 0.07–1.53), plasma (range: 0.06–1.41), and BCs (range: 0.01–0.24), respectively. The compositional profiles of FPs in serum, plasma, and BCs were similar; very strong positive correlations were observed between different blood matrices for FP-SFO (r = 0.94–0.97, p < 0.01) but not between blood and urine. The median ΣFPs (ng/mL) in the serum (0.20; range: 0.09–1.56) and the plasma samples (0.19; range: 0.09–1.43) was higher than that in BCs samples (0.04; range: 0.01–0.24). In the urine samples, only the major metabolite FP-SFO was detectable in approximately 10% of the samples. Additionally, the highest median ΣFPs (ng/mL) in the serum samples was found in Nanjing (0.56; range: 0.13–1.88), followed by Wuhan (0.34; range: 0.06–1.02), Huangshi (0.10; range: 0.03–0.60), and Zhenjiang (0.08; range: 0.02–0.42). The level of ΣFPs seemed to increase with city sizes and urbanization scale, though further studies are needed to confirm the variations with larger sample size. The estimated daily intake of ΣFPs based on the median concentration of samples from Nanjing (18.5 ng/kg-bw/d) was higher than that of Wuhan (11.3), Huangshi (3.40), and Zhenjiang (2.80). Dietary intake should be the major exposure route for the general population, while water or indoor dust accounted for <1% of the ΣFPs intake. This pilot study provided the first data on the profiles of FPs in paired human serum, plasma, BCs, and urine samples, and potential spatial variations of ΣFPs in China. FP-SFO and FP desulfinyl should be considered among priority substances worthy to be bio-monitored in China due to its moderated persistence and ubiquitous occurrence in human blood.

Application of biochar: An approach to attenuate the pollution of the chiral pesticide fipronil and its metabolites in leachate from activated sludge

The present study investigated the bio-effects and fate of the chiral pesticide fipronil and its three primary metabolites, fipronil desulfinyl, fipronil sulfide and fipronil sulfone on Chlorella pyrenoidosa and Danio rerio in the absence and presence of biochar. The results revealed that fipronil and its metabolites exhibited high toxicity to algae and fish. Enantioselectivity was observed with regard to the toxicity and degradation of fipronil and its metabolites. For Chlorella pyrenoidosa, R-fipronil was more toxic than S-fipronil and degraded preferentially during the toxicity and degradation experiments. For Danio rerio, S-fipronil exhibited higher toxicity than R- and rac-fipronil. The toxicities of fipronil sulfide and sulfone were 3–6 and 5–6 times higher, respectively, than that of rac-fipronil, and the metabolites also exhibited longer persistence. The remediation capacity for water and leachate contaminated by fipronil with the application of biochar was investigated. Biochar significantly mitigated the toxicity of fipronil and its metabolites to nontarget organisms, and reduced residues by 90 % for fipronil, 72 % for sulfone, 65 % for sulfide and 60 % for desulfinyl, whereas mitigation of only 30 %-51 % was observed in the absence of biochar. This study demonstrates that biochar has strong potential as an ideal material for the removal of fipronil and its metabolites from contaminated aquatic environments.

Combination of Modified QuEChERS and Disposable Polyethylene Pipet Assisted DLLME Based on Low Density Solvent Extraction for Rapid and Sensitive Determination of Fipronil and Its Metabolites in Eggs by GC-MS

In the present study, a new method for separation and enrichment of fipronil and its metabolites in eggs was proposed by combining a modified QuEChERS procedure with a disposable polyethylene pipet assisted DLLME (DPP-DLLME). The DPP-DLLME employed low density solvent as extractant and was conducted in a cheap, disposable polyethylene pipet with an open and narrow tip upside. After phase separation, the extractant was floating on the aqueous solution and concentrated in the narrow neck of the pipet, which can be directly withdrawn by a microsyringe for instrument analysis. By coupling with GC-MS detection, a new method for analysis of fipronil and its metabolites in eggs was established. The linearity range was 0.5–200 ng/g with correlation coefficient R2 higher than 0.9967. The recoveries in spiked egg samples were in the range of 89.3–103.8% with the RSDs less than 13.6% (intra-day) and 17.5% (inter-day). The limits of quantification for the four target analytes (fipronil desulfinyl, fipronil sulfide, fipronil, fipronil sulfone) in eggs were in the range of 0.2–0.3 ng/g, which was comparable or better to the previously reported methods. Finally, the established QuEChERS-DPP-DLLME method was successfully applied to detect fipronil and its metabolites in several egg samples with different brands from local market.

Multi-Residue Analysis of Fipronil and Its Metabolites in Eggs by SinChERS-Based UHPLC-MS/MS.

A method for simultaneous detection of fipronil (F) and its metabolites fipronil desulfinyl (FD), fipronil sulfide (FS), fipronil sulfone (FSO) in chicken eggs was applied and validated. It includes single-step, cheap, effective, rugged, safe-based method (SinChERS) for sample preparation and ultra high performance liquid chromatography coupled with mass spectrometry (UHPLC-MS/MS) for chemical analysis. Results suggested that formic acid enhanced the recovery of 4 target residues and 1% supplementation to acetonitrile gained higher recoveries than that of 5%. SinChERS integrated extraction and clean-up steps into one, with shorter time (1.5 h) to operate and higher recoveries (97%–100%) than HLB, Envi-Carb-NH2 and quik-easy-cheap-effective-rugged-safe method (QuEChERS), and it consumed the smallest volume of extracting solvent (10 mL) as QuEChERS. Quantitative analyses using external standard method suggested the linear ranges of 4 target compounds were 1–20 μg/L with R2>0.9947. The limit of detection (S/N>3) and quantification (S/N>10) were 0.3 μg/kg and 1 μg/kg. Recoveries ranged from 89.0% to 104.4%, and the relative standard deviations (n=6) at 1, 10, and 20 μg/kg were lower than 6.03%. Thirty batches of domestic eggs (500 g each) were detected by the established SinChERS-based UHPLC-MS/MS and no target residues were detected in all samples. The method developed in this study is a rapid, sensitive, accurate and economic way for multi-residue analysis of fipronil and its metabolites in eggs.

Determination of Fipronil and Four Metabolites in Foodstuffs of Animal Origin Using a Modified QuEChERS Method and GC–NCI–MS/MS

A sensitive, effective, and reliable method for the accurate determination of fipronil and four metabolites (fipronil carboxamide, fipronil sulfone, fipronil sulfide, and fipronil desulfinyl) in foodstuffs of animal origin (egg, milk, beef kidney, beef liver, chicken, and chicken liver) was developed by isotope dilution–gas chromatography–negative chemical ionization–tandem mass spectrometry (GC–NCI–MS/MS). Samples were purified by a modified QuEChERS method. Four isotopically labeled internal standards were added in the sample extraction process to compensate for the matrix effect. The average recoveries were 78.2–107.1% with RSD ≤ 8.5%. The limits of quantification (LOQs) were 0.2 μg kg−1 for fipronil carboxamide and fipronil sulfone and 0.1 μg kg−1 for fipronil, fipronil sulfide, and fipronil desulfinyl. At the same time, the fragmentation mechanism of the five target compounds was analyzed via mass spectral data to help identify the compounds.