Determination of carbosulfan and its metabolites in oranges by liquid chromatography ion-trap triple-stage mass spectrometry

Hydrolysis enabled specific colorimetric assay of carbosulfan with sensitivity manipulation via metal-doped or metal-free carbon nanozyme

Precise determination of the carbamate pesticide carbosulfan is crucial for assessing the associated risks in food and environment. Due to the strong interaction between carbosulfan and target enzyme, current methods primarily depend on the acetylcholinesterase (AChE) inhibition strategy, which generally lacks selectivity. In this study, we propose a nanozyme colorimetric sensor for the specific carbosulfan detection, based on its distinctive hydrolysis property. In contrast to other pesticides, carbosulfan can be hydrolyzed to produce the reductive sulfide compound by the cleavage of N-S bond under acidic condition, thereby significantly hindering the nanozyme-mediated chromogenic reaction. Consequently, the absorbance is significantly correlated with carbosulfan concentration. Furthermore, the influence of nanozyme type is disclosed, and two oxidase-like carbon nanozymes were formulated, namely metal-free NC and metal-based CeO2@NC. However, the distinct active sites significantly impact the proposed sensor. For CeO2@NC-based sensor, the produced sulfide compounds not only poison Ce active site, but also consume the reactive oxygen species, thereby, exhibiting high sensitivity with low detection limit of 3.3 nM. By contrast, the metal-free nature of NC allows the assay to remain unaffected by coordination effects, exhibiting superior anti-interference capability. This work not only offers an efficient alternative to the conventional method for detecting carbosulfan specifically, but also shed light on the role of metal-based or metal-free nanozyme among analytical applications.

Absorption, metabolism and distribution of carbosulfan in maize plants (Zea mays L.)

BACKGROUND

The insecticide carbosulfan is usually applied as a soil treatment or seed-coating agent, and so may be absorbed by crops and pose dietary risks. Understanding the uptake, metabolism and translocation of carbosulfan in crops is conducive to its safe application. In this study, we investigated the distribution of carbosulfan and its toxic metabolites in maize plants at both the tissue and subcellular levels, and explored the uptake and translocation mechanism of carbosulfan.

RESULTS

Carbosulfan was mainly taken up by maize roots via the apoplast pathway, was preferentially distributed in cell walls (51.2%-57.0%) and most (85.0%) accumulated in roots with only weak upward translocation. Carbofuran, the main metabolite of carbosulfan in maize plants, was primarily stored in roots. However, carbofuran could be upwardly translocated to shoots and leaves because of its greater distribution in root-soluble components (24.4%-28.5%) compared with carbosulfan (9.7%-14.5%). This resulted from its greater solubility compared with its parent compound. The metabolite 3-hydroxycarbofuran was found in shoots and leaves.

CONCLUSION

Carbosulfan could be passively absorbed by maize roots, mainly via the apoplastic pathway, and transformed into carbofuran and 3-hydroxycarbofuran. Although carbosulfan mostly accumulated in roots, its toxic metabolites carbofuran and 3-hydroxycarbofuran could be detected in shoots and leaves. This implies that there is a risk in the use of carbosulfan as a soil treatment or seed coating. © 2023 Society of Chemical Industry.

Review of extraction and detection techniques for the analysis of pesticide residues in fruits to evaluate food safety and make legislative decisions: Challenges and anticipations

Fruits are vital parts of the human diet because they include necessary nutrients that the body needs. Pesticide use has increased dramatically in recent years to combat fruit pests across the world. Pesticide usage during production, on the other hand, frequently results in undesirable residues in fruits after harvest. Consumers are concerned about pesticide residues since most of the fruits are directly consumed and even recommended for the patients as dietary supplements. As a result of this worry, pesticide residues in fruits are being randomly monitored to re-assess the food safety situation and make informed legislative decisions. To assess the degree of pesticide residues in fruits, a simple and quick analytical procedure is usually required. As a result, pesticide residue detection (using various analytical techniques: GC, LC and Biosensors) becomes critical, and regulatory directives are formed to regulate their amounts via the Maximum Residue Limit (MRL). Over the previous two decades, a variety of extraction techniques and analytical methodologies for xenobiotic's efficient extraction, identification, confirmation and quantification have been developed, ranging from traditional to advanced. The goal of this review is to give readers an overview of the evolution of numerous extraction and detection methods for pesticide residue analysis in fruits. The objective is to assist analysts in better understanding how the ever-changing regulatory landscape might drive the need for new analytical methodologies to be developed in order to comply with current standards and safeguard consumers.

Assessment of the dissipation, pre-harvest interval and dietary risk of carbosulfan, dimethoate, and their relevant metabolites in greenhouse cucumber (Cucumis sativus L.)

BACKGROUND

The dissipation behavior, pre-harvest interval and dietary risk of carbosulfan, dimethoate, and their relevant metabolites were investigated in greenhouse cucumber in Tianjin, northern China, to ensure raw consumption safety.

RESULTS

Carbosulfan was metabolized to carbofuran, dibutylamine, 3-hydroxycarbofuran and 3-ketocarbofuran, and dimethoate was degraded to omethoate in cucumber fruits and leaves. The dissipation of carbosulfan, carbofuran, 3-hydroxycarbofuran and dimethoate fitted first-order kinetics well, with R² ranging from 0.912 to 0.992, and their half-lives were 2.6, 2.7, 2.4 and 5.2 days in cucumber fruits and 2.8, 3.0, 4.6 and 2.5 days in leaves, respectively. The estimated daily intakes of the active ingredients and their relevant metabolites were 0.1-4% of the corresponding acceptable daily intakes. Acute oral exposure to carbofuran (a metabolite of carbosulfan) represented 367% of the acute reference dose (ARfD) for 1-6-year-old Chinese children and 227% for the general Chinese population.

CONCLUSION

A minimum pre-harvest interval of 12 days for carbosulfan is proposed to ensure safe consumption of cucumber. The slow dissipation rate of omethoate in cucumber reveals that a longer pre-harvest interval (≥ 27 days) is necessary to prevent dietary risk when dimethoate is applied to cucumber. © 2018 Society of Chemical Industry.

Residues of carbosulfan and its metabolites carbofuran and 3-hydroxy carbofuran in rice field ecosystem in China

The fate of carbosulfan (seed treatment dry powder) was studied in rice field ecosystem, and a simple and reliable analytical method was developed for determination of carbosulfan, carbofuran, and 3-hydroxyl carbofuran in brown rice, rice straw, paddy water, and soil. The target compounds were extracted using acetonitrile or dichloromethane, cleaned up on acidic alumina or florisil solid phase extraction (SPE) cartridge, and analyzed by gas chromatography. The average recoveries of carbosulfan, carbofuran and 3-hydroxy carbofuran in brown rice, rice straw, paddy water, and soil ranged from 72.71% to 105.07%, with relative standard deviations of 2.00-8.80%. The limits of quantitation (LOQs) of carbosulfan, carbofuran and 3-hydroxy carbofuran in the samples (brown rice, rice straw, paddy water and soil) were 0.011, 0.0091, 0.014, 0.010 mg kg(-1), 0.016, 0.019, 0.025, 0.013 mg kg(-1), and 0.031, 0.039, 0.035, 0.036 mg kg(-1), respectively. The trials results showed that the half-lives of carbosulfan, carbofuran and 3-hydroxy carbofuran in rice straw were 4.0, 2.6 days, 3.9, 6.0 days, and 5.8, 7.0 days in Zhejiang and Hunan, respectively. Carbosulfan, carbofuran and 3-hydroxy carbofuran were detected in soils. Carbosulfan and 3-hydroxy carbofuran were almost undetectable in paddy water. Carbofuran was detected in paddy water. The final residues of carbosulfan, carbofuran and 3-hydroxy carbofuran in brown rice were lower than 0.05 mg kg(-1), which were lower than 0.5 mg kg(-1) (MRL of carbosulfan) or 0.1 mg kg(-1) (MRL of carbofuran). Therefore, a dosage of 420 g active ingredient per 100 kg seed was recommended, which could be considered as safe to human beings and animals. These would contribute to provide the scientific basis of using this insecticide.

The identification of vitamin E homologues in medicinal plant samples using ESI(+)-LC-MS3

The aim of this study was to elucidate the presence of vitamin E homologues in medicinal plants. To identify various homologues in the matrix of medicinal plant samples, a method for simultaneous determination was developed using ESI(+)-LC-MS3. A complete separation of each homologue was achieved within 20 min using a PFP column and an isocratic elution system of water/methanol (10:90, v/v) at a flow rate of 0.5 mL/min. The ESI-MS condition for each homologue was optimized, and the m/z value and the fragmentation pathway of each homologue were summarized. This LC-MS3 method made it possible to detect the homologues without the effect of matrix; therefore, high sensitive analysis was established, and then, the MS3 makes it possible to extract from plants with methanol only. The LC-MS3 method was applied to identify the eight vitamin E homologues in 11 medicinal plants.

Quantitation of polypeptides (glucagon and salmon calcitonin) in plasma samples by 'high resolution' on a triple quadrupole mass spectrometer

BACKGROUND

Bioanalysis of large molecules can be challenging on LC-MS/MS due to multiply charged and endogenous interferences. While high sensitivity triple quadrupole systems (QqQ) have been commercialized recently, high-resolution MS (HRMS) systems are also available. HRMS provides alternative analysis methods, but more costly and with sensitivity lower than MRM on QqQ.

RESULTS

QqQ is generally operated at unit resolution; however, newer systems are able to practically tune to 'high resolution'. Therefore, the advantages of both higher sensitivity of MRM on QqQ and better specificity on HRMS can possibly be combined on a QqQ to meet bioanalysis needs. Glucagon and salmon calcitonin were successfully quantified in high-resolution with fast cycle time on AB Sciex TripleQuad™ 5500. LLOQ (S/N) was increased and interferences reduced.

CONCLUSION

For large molecules, the bioanalysis methods developed using high resolution on the QqQ are validated and used in preclinical and clinical studies.

Current mass spectrometry strategies for the analysis of pesticides and their metabolites in food and water matrices

Analysis of pesticides and their metabolites in food and water matrices continues to be an active research area closely related to food safety and environmental issues. This review discusses the most widely applied mass spectrometric (MS) approaches to pesticide residues analysis over the last few years. The main techniques for sample preparation remain solvent extraction and solid-phase extraction. The QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) approach is being increasingly used for the development of multi-class pesticide residues methods in various sample matrices. MS detectors-triple quadrupole (QqQ), ion-trap (IT), quadrupole linear ion trap (QqLIT), time-of-flight (TOF), and quadrupole time-of-flight (QqTOF)-have been established as powerful analytical tools sharing a primary role in the detection/quantification and/or identification/confirmation of pesticides and their metabolites. Recent developments in analytical instrumentation have enabled coupling of ultra-performance liquid chromatography (UPLC) and fast gas chromatography (GC) with MS detectors, and faster analysis for a greater number of pesticides. The newly developed "ambient-ionization" MS techniques (e.g., desorption electrospray ionization, DESI, and direct analysis in real time, DART) hyphenated with high-resolution MS platforms without liquid chromatography separation, and sometimes with minimum pre-treatment, have shown potential for pesticide residue screening. The recently introduced Orbitrap mass spectrometers can provide high resolving power and mass accuracy, to tackle complex analytical problems involved in pesticide residue analysis.

Sensitive determination of herbicides in food samples by nonaqueous CE using pressurized liquid extraction

We have developed a method involving extraction with mixtures of solvents under pressure (pressurized liquid extraction (PLE)) for the determination of triazine herbicides in a series of samples from the food industry. The organic extracts obtained were subjected to a clean-up step with SPE, using Oasis MCX sorbents, after which they were analyzed by NACE. Potato was chosen as a representative matrix of horticultural products since it has a high water content. Spiked potato samples were used to optimize extraction conditions. In order to compare the results obtained with NACE, different studies were also conducted using HPLC. The detection limits in NACE were similar to those found with HPLC and were of the order of 10-15 microg/kg, depending on the analyte. Satisfactory results were obtained on applying the method proposed for the potato matrix (PLE with separation by electrophoresis) to other food matrices such as other tubercles, fruits, vegetables and cereals.

Development and validation of a multi-residue method for the determination of pesticides in processed fruits and vegetables using liquid chromatography–electrospray ionization tandem mass spectrometry

A sensitive multi-residue analytical method, utilizing ethyl acetate extraction and liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS-MS), has been developed and validated for simultaneous determination of 28 pesticides of different chemical classes (polar organophosphates, carbamates, strobilurines, neonicotinoids, amides, pyrimidines, benzimidazoles, imidazoles and triazoles), and their transformation products, in processed fruit and vegetables. Two precursor-product ion transitions were monitored for each pesticide in selected reaction monitoring (SRM) mode. Linearity (r (2) > or = 0.99) was good over the concentration range 0.5 to 100 microg L(-1) for all the pesticides, and instrumental detection limits ranged from 0.1 to 1 microg L(-1). Mean recovery for fruit and vegetables spiked at 0.010 mg kg(-1) ranged from 65 to 94.4%, and relative standard deviations ranged from 9.0 to 20.0%. When the amount spiked was 0.050 mg kg(-1) recoveries ranged from 72.5 to 90% and relative standard deviations were from 6.1 to 19.0%. Method detection limits were from 0.002 to 0.007 mg kg(-1) for the different food matrices studied. The method was used to monitor pesticide residues in a wide variety of fruits and vegetables.

Methods of sample preparation for determination of pesticide residues in food matrices by chromatography-mass spectrometry-based techniques: a review

Much progress has been made in pesticide analysis over the past decade, during which time hyphenated techniques involving highly efficient separation and sensitive detection have become the techniques of choice. Among these, methods based on chromatographic separation with mass spectrometric detection have resulted in greater likelihood of identification and are acknowledged to be extremely useful and authoritative methods for determination of pesticide residues. Even with such powerful instrumental techniques, however, the risk of interference increases with the complexity of the matrix studied, so sample preparation before instrumental analysis is still mandatory in many applications, for example food analysis. This article summarizes the analytical characteristics of the different methods of sample-preparation for determination of pesticide residues in a variety of food matrices, and surveys their recent applications in combination with chromatographic mass spectrometric analysis. We discuss the advantages and the disadvantages of the different methods, address instrumental aspects, and summarize conclusions and perspectives for the future.

Liquid Chromatography Quadrupole Time-of-Flight Mass Spectrometry Analysis of Carbosulfan, Carbofuran, 3-Hydroxycarbofuran, and Other Metabolites in Food

The potential of liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QqTOF-MS) to identify and confirm carbosulfan and seven of its main metabolites (carbofuran, 3-hydroxycarbofuran, 3-ketocarbofuran, 3-hydroxy-7-phenol carbofuran, 3-keto-7-phenolcarbofuran, 7-phenolcarbofuran, dibutylamine) at trace levels from food is explored for the first time. The analytical method developed consists of pressurized liquid extraction (PLE) and LC-QqTOF-MS in positive ion mode, which attains unequivocal identification and quantification of the studied compounds in food, at levels well below of those of concern (0.05 mg/kg for the sum of carbosulfan, carbofuran, and 3-hydroxycarbofuran). PLE recoveries ranged from 55 to 94% with limits of quantification from 10 (for carbosulfan, carbofuran, 3-hydroxycarbofuran, and dibutylamine) to 70 microg/kg (3-keto-7-phenolcarbofuran). The method is precise, with relative standard deviations varying between 5 and 11% for the repeatability (within-day) and 8-13% for the reproducibility (interday). This method was used to monitor the presence and fate of the target compounds in orange, potato, and rice crops treated with a commercial product containing carbosulfan. Field degradation studies show that carbofuran, 3-hydroxycarbofuran, and dibutylamine are the main degradation products formed in the environmental disappearance of carbosulfan.

Identification of Pesticide Transformation Products in Food by Liquid Chromatography/Time-of-Flight Mass Spectrometry via “Fragmentation−Degradation” Relationships

The identification of transformation products of pesticides in foodstuffs is a crucial task difficult to tackle, due to the lack of standards and scarce information available. In this work, we describe a methodology for the identification and structural elucidation of pesticide transformation products in food. The proposed strategy is based on the use of liquid chromatography electrospray time-of-flight mass spectrometry (LC/TOFMS): accurate mass measurements of (molecule and fragment) ions of interest are used in order to establish relationships between fragmentation of the parent pesticides in the instrument (in-source CID fragmentation) and possible degradation products of these pesticides in food. Examples of this strategy showing the potential of LC/TOFMS to determine unknown pesticides in food are described in two different real samples, suggesting that pesticides often are transformed into degradation products in the same fashion that they are fragmented in the instrument. Using the proposed approach and without using standards a priori, based solely on accurate mass measurements of ions and "fragmentation-degradation" relationships, we have identified two parent pesticides (amitraz and malathion) along with six degradation products, m/z 253 (N,N'-bisdimethylphenylformamidine), 163 (N-2,4-dimethylphenyl-N-methyl formamidine), 150 (2,4-dimethylformamidine), and 122 (2,4-dimethylaniline) from amitraz, and m/z 317 and 303, due to ether hydrolysis of methyl and ethyl groups from malathion. Structures for these species were proposed, and the potential of the proposed approach was critically discussed.

Current literature in mass spectrometry

In order to keep subscribers up‐to‐date with the latest developments in their field, John Wiley & Sons are providing a current awareness service in each issue of the journal. The bibliography contains newly published material in the field of mass spectrometry. Each bibliography is divided into 11 sections: 1 Books, Reviews & Symposia; 2 Instrumental Techniques & Methods; 3 Gas Phase Ion Chemistry; 4 Biology/Biochemistry: Amino Acids, Peptides & Proteins; Carbohydrates; Lipids; Nucleic Acids; 5 Pharmacology/Toxicology; 6 Natural Products; 7 Analysis of Organic Compounds; 8 Analysis of Inorganics/Organometallics; 9 Surface Analysis; 10 Environmental Analysis; 11 Elemental Analysis. Within each section, articles are listed in alphabetical order with respect to author (6 Weeks journals ‐ Search completed at 4th. Oct. 2006)

Pesticides analysis by liquid chromatography and capillary electrophoresis

Nowadays, a wide range of pesticides are used in agricultural production, and their monitoring in samples of environmental and alimentary interest is of extreme importance to ensure, among others, the safety of consumption of foods. The aim of this work is to provide updated information about the major developments in CE and HPLC in pesticide analysis, covering relevant publications between 2004 and early 2006. The use of different sample pretreatment steps to provide a suitable extraction of these compounds from the different matrices as well as to increase the sensitivity of the determination is also discussed.

Optimization of LC–MS/MS using triple quadrupole mass analyzer for the simultaneous analysis of carbosulfan and its main metabolites in oranges

This paper describes an analytical method involving a simple solvent extraction for the simultaneous liquid chromatography coupled to quadrupole tandem mass spectrometry (LC-MS/MS) determination of carbosulfan, its most toxic metabolite--carbofuran--, and its other main metabolites--3-hydroxycarbofuran, 3-ketocarbofuran, 3-hydroxy-7-phenolcarbofuran, 3-keto-7-phenolcarbofuran, 7-phenolcarbofuran and dibutylamine--in oranges. Chromatography was performed on a Zorbax Bonus-RP (150 mm x 2.1 mm, 5 microm). The mobile phase was a ternary gradient water-methanol-acetonitrile with 1.0 mM ammonium acetate at flow rate of 0.2 ml min(-1). The LC separation and MS/MS optimization were studied to select the most appropriate operating conditions. The method developed has also been validated. The limits of quantification (LOQs) were from 1 microg kg(-1) for carbofuran to 10 microg kg(-1) for 3-keto-7-phenolcarbofuran. Extracts spiked with carbosulfan and its metabolites, at LOQ level, yielded average recoveries in the range 60-94%, with relative standard deviations (R.S.D.s) less than 15%. Calibration curves for carbosulfan and its metabolites (range LOQ-1000LOQ) were linear, with coefficients of correlations better than 0.990. The method was successfully applied to establish the primary degradation products in oranges treated with carbosulfan. The LC-MS/MS method developed is simple, rapid, and suitable for the quantification and confirmation of carbosulfan and seven of its main metabolites in orange at levels lower than 10 microg kg(-1).

Comparison of four mass analyzers for determining carbosulfan and its metabolites in citrus by liquid chromatography/mass spectrometry

Four liquid chromatography/mass spectrometry (LC/MS) systems, equipped with single quadrupole, triple quadrupole (QqQ), quadrupole ion trap (QIT) and quadrupole time-of-flight (QqTOF) mass analyzers, were evaluated for the analysis of carbosulfan and its main transformation products. The comparison of quantitative aspects (sensitivity, precision and accuracy) was emphasized. Results showed that the triple quadrupole instrument reaches at least 20-fold higher sensitivity (LOD from 0.04 to 0.4 microg kg(-1)) compared to the single quadrupole (4-70 microg kg(-1)), the QIT (4-25 microg kg(-1)) and the QqTOF (4-23 microg kg(-1)) instruments. Recoveries were over 70% for all the analytes, except dibutylamine and 7-phenolcarbofuran. Repeatabilities (within-day) were slightly better by the single quadrupole (5-10%) and the QqQ (5-9%) than by the QIT (12-16%) and the QqTOF (9-16%). Both the QqTOF and QIT offer a linear dynamic range of two orders of magnitude whereas the single quadrupole and QqQ of, at least, three orders of magnitude. The method was applied to analyze carbosulfan field-treated orange samples, in which carbosulfan, carbofuran, 3-hydroxycarbofuran, and dibutylamine were found. As an example, the mean carbosulfan concentration was 20 +/- 0.6 microg kg(-1) measured by the QqQ, 22 +/- 1.2 microg kg(-1) by the single quadrupole, 25 +/- 2.8 microg kg(-1) by the QIT, and 20 +/- 1.8 microg kg(-1) by the QqTOF. Although the QqQ is more sensitive and precise, the mean values obtained by the four instruments are acceptable and comparable. The potential of each technique for the verification of the identity of residues detected in oranges is discussed using the concept of identification points.