Trace analysis of dithiocarbamate fungicide residues on fruits and vegetables by hydrophilic interaction liquid chromatography/tandem mass spectrometry

Pesticide contamination pattern from Morocco, insights into the surveillance situation and health risk assessment: a review

The widespread application of pesticides in Morocco's agriculture renders their monitoring in food and environmental samples very necessary. Recent years have witnessed a growing interest in reporting studies related to the monitoring of pesticide residues in food, water, groundwater, and soil as well as their quantitative health risk assessment. Most published studies have been done by university researchers. However, the lack of research reproducibility remains a problem that considerably limits the possibility of exploiting data from the literature. Our study involves an extensive literature review utilizing search engines with keywords like "pesticide residues," "monitoring," "vegetables and fruits," "water and soil," "risk assessment," and "Morocco" from 2009 to 2023. Analysis of pesticide residues in foodstuffs and environmental samples highlights concerns over compliance with EU regulations, the health risks associated with pesticide exposure, and the necessity for comprehensive monitoring and risk assessment strategies. This paper could help influence policies to develop a strategy and action plan for the sound management of pesticides, including measures to reduce their use, raise awareness, and monitor compliance. Also, this paper could be useful for scientists interested in understanding the current situation and challenges regarding pesticide residues in Morocco, as well as countries with which commercial links exist.

Trends in dithiocarbamates food research: A bibliometric vision

Dithiocarbamate Fungicides (DTFs) are widely analyzed and studied mainly due to the fact that they play an important role in the cultivation of fruits and vegetables. This manuscript aims to display the results of a bibliometric analysis based on the Web of Science© database, performed in the DTF and food research area. A total of 374 publications were examined. The most scientific production was concentrated between 2012 and 2021, showing a decrease of 32% over the last two years. The Journal of Agricultural and Food Chemistry, India, and Sardar Vallabhbhai National Institute of Technology were the most productive journal, country, and institution, respectively. Reference Publication Year Spectroscopy index showed a decrease of 95% in the last last years studied. Finally, current and future trends should focus on keywords such as individual DTF (Mancozeb, Thiram and Maneb), metabolites (Ethylenethiourea, Propilenthiourea) and a change in the analysis methodology: HPLC versus traditional GC.

Chromatographic analysis of dithiocarbamate residues and their metabolites in foods employed in dietary exposure studies-a review

Dithiocarbamates (DTCs) belong to a group of compounds used as fungicides in food production and can be divided into three major groups. Since DTCs easily oxidise and hydrolyse in alkaline and acidic medium respectively, precautions have to be implemented during preparation/homogenisation and extraction of samples. As such, test samples are commonly prepared individually by cutting into small pieces just before the digestion of DTCs with a hot acid to give carbon disulphide (CS₂) and the results are expressed as CS₂ without any differentiation of individual DTCs. However, individual DTCs have different toxicological potencies whilst their metabolites are more toxic than the parent compound. Apart from the hot digestion method, chromatographic separation of three major groups of DTCs has been developed by a number of different researchers. This review provides a comprehensive examination of sample preparation, extraction, clean-up and chromatographic methods for the determination of individual DTCs and their more toxic metabolites in foodstuffs. Moreover, this review also studies on how dietary exposure of DTCs can be efficiently and effectively estimated using different methods of analysis.

A simple derivatization RP-HPLC method for the simultaneous determination of zineb and hexaconazole in pesticide formulation using a PDA detector

A simple derivatization reverse-phase high performance liquid chromatographic method for the simultaneous analysis (separation and quantification) of zineb and hexaconazole has been optimized and validated. The method was carried out on an Agilent Eclipse plus C18 column (150 × 4.6 mm; 5 μm), with a mobile phase comprising acetonitrile + methanol (80 + 20 v/v): water (0.1% v/v trifluoroacetic acid) (60 : 40 v/v) at a flow rate of 1.0 mL minute^-1, and the quantification was achieved at 272 nm and 205 nm. The retention times of zineb and hexaconazole were found to be 6.4 min and 7.6 min, respectively. The performance of the method was validated according to the SANCO, CIPAC and ICH guidelines for specificity, selectivity, linearity, precision, accuracy, limit of detection, limit of quantification and robustness. The developed method was successfully applied for the estimation of zineb and hexaconazole in a pesticide dosage form.

Evaluation of the automated micro-solid phase extraction clean-up system for the analysis of pesticide residues in cereals by gas chromatography-Orbitrap mass spectrometry

Food analysis is a tremendously broad field that is constantly evolving. New methods have emerged to increase productivity, such as modern miniaturized and robotic analytical techniques. In this paper, a micro-solid-phase extraction system (µ-SPE) for clean-up was combined with a robotic autosampler to yield ready-to-analyze extracts. The system was evaluated for its applicability in routine laboratories. The new, automated, high-throughput µ-SPE clean-up method was applied to acetonitrile extracts and was developed for the analysis of pesticide residues in cereals by gas chromatography-Orbitrap mass spectrometry (GC-Orbitrap-MS). The µ-SPE clean-up efficiency was demonstrated in the removal of matrix-interfering components and in the recovery of pesticides. The sorbent bed mixture consisted of magnesium sulfate, primary-secondary amine, C₁₈, and CarbonX, and effectively retained matrix components without loss of target analytes. Analysis of five types of cereals (barley, oat, rice, rye, and wheat) by GC-Orbitrap-MS showed that the method removed more than 70% of matrix components. The clean-up method was validated for 170 pesticides in rye, 159 pesticides in wheat, 142 pesticides in barley, 130 pesticides in oat, and 127 pesticides in rice. Spike recovery values were 70-120% for all pesticides and the repeatability, calculated as the relative standard deviation, was less than 20%. The limits of quantitation achieved were 0.005 mg kg^-1 for almost all analytes, ensuring compliance with the maximum residue limits.

Advances in the Detection of Dithiocarbamate Fungicides: Opportunities for Biosensors

Dithiocarbamate fungicides (DTFs) are widely used to control various fungal diseases in crops and ornamental plants. Maximum residual limits in the order of ppb-ppm are currently imposed by legislation to prevent toxicity problems associated with excessive use of DTFs. The specific analytical determination of DTFs is complicated by their low solubility in water and organic solvents. This review summarizes the current analytical procedures used for the analysis of DTF, including chromatography, spectroscopy, and sensor-based methods and discusses the challenges related to selectivity, sensitivity, and sample preparation. Biosensors based on enzymatic inhibition demonstrated potential as analytical tools for DTFs and warrant further research, considering novel enzymes from extremophilic sources. Meanwhile, Raman spectroscopy and various sensors appear very promising, provided the selectivity issues are solved.

Stabilization of maneb group by ethylenediamine and direct-determination by liquid chromatography tandem mass spectrometry

A rapid, low-cost, and selective method for simultaneous and direct determination of maneb group residues (containing ethylenebis and propylenebis dithiocarbamates) in fruit by liquid chromatography coupled to tandem mass spectrometry was developed and validated in the current study. The results showed the maneb group could be melt and stabilized by 5 v% ethylenediamine for 60 days keeping in conventional refrigerators, in which a stable and ionizable pentadentate ligand complex was considered to be formed by the bidentate diamine and sulfhydryl followed by Density Functional Theory calculation. The validated method showed a sensitive quantification limits (0.03 mg/kg), a steady recovery (82.1%-91.0%) and an excellent precision (2.7%-4.3% RSD). This method is applied to analyze fruit samples and achieved satisfactory results. Therefore, this method can be proposed as a robust analytical method of maneb group in fruit, and can be adapted to detect other compounds with sulfhydryl group.

Determination of Mancozeb, a Pesticide Used Worldwide in Agriculture: Comparison among GC, LC, and CE

Background:

The determination of mancozeb, a fungicide extensively used in agriculture, is a challenge, due to the nature of the compound, a manganese and zinc complex of ethylenebis dithiocarbamate and because of the general instability of the dithiocarbamates.

Methods:

Mancozeb was analyzed in a GC-EI-MS system after derivatization by CE-UV with detection at 280 nm and in LC-ESI-MS-MS in MRM mode.

Results:

A comparative study of the performance of three different techniques for the detection of mancozeb was explored, highlighting the advantages and drawbacks of them. The limits of detection and quantification of the techniques were determined; the repeatability was assessed, showing values of relative standard deviation. Gas chromatography, although very sensitive, was not reproducible enough due to fast degradation of the derivatization product, whereas capillary electrophoresis-UV showed problems in run-to-run reproducibility which had the worst limit of detection. LC coupled with tandem mass spectrometry was the most reliable and precise technique and was able to determine the main degradation product of Mancozeb, at the same time. The proposed LC procedure was verified by applying it to a commercial formulation, a fungicide of known concentration, and to Italian white grapes treated with the formulation sprayed during cultivation.

Conclusion:

Thanks to the simplified sample handling, the proposed method resulted to be simple, fast, green, economic, and suitable for residue analysis in grapes and other fruits. Finally, the method was compared with other similar investigations.

Review of pesticide residue analysis in fruits and vegetables. Pre-treatment, extraction and detection techniques

A wide variety of pesticides have been used in agriculture to increase the yield, quality and extend the storage life of crops. However, the use of pesticide has been increased now a day due to the ever-increasing population and rapid urbanization. The continuous uses of these pesticides have resulted in contamination of the environment, crops and also caused potential risk to human health. For this reason, strict regulations are developed and regulated to monitor these compounds. To date, several techniques have been developed for the extraction and detection of pesticides, from traditional to advanced detection techniques. The present study delineates a comprehensive up to date overview of the available traditional methods (gas chromatography and high-performance liquid chromatography coupled with various detector) to advanced pre-treatment (polystyrene-coated magnetic nanoparticle) and detection (sensor development and nanotechnology) techniques used in the analysis of pesticides residue in various fruits and vegetables. Also, categorization of pesticides and its toxicity have been discussed.

Determination of propineb and its metabolites propylenethiourea and propylenediamine in banana and soil using gas chromatography with flame photometric detection and LC-MS/MS analysis

A sensitive and specific method for the determination of propineb and its metabolites, propylenethiourea (PTU) and propylenediamine (PDA), using gas chromatography with flame photometric detection (GC-FPD) and LC-MS/MS was developed and validated. Propineb and its metabolite residue dynamics in supervised field trials under Good Agricultural Practice (GAP) conditions in banana and soil were studied. Recovery of propineb (as CS₂), PDA and PTU ranged from 75.3 to 115.4% with RSD (n = 5) of 1.3-11.1%. The limit of quantification (LOQ) of CS₂, PDA and PTU ranged from 0.005 to 0.01 mg kg^-1, and the limit of detection (LOD) ranged from 0.0015 to 0.0033 mg kg^-1. Dissipation experiments showed that the half-life of propineb in banana and soil ranged from 4.4 to 13.3 days. PTU was found in banana with a half-life of 31.5-69.3 days, while levels of PDA were less than 0.01 mg kg^-1 in banana and soil. It has been suggested that PTU is the major metabolite of propineb in banana. The method was demonstrated to be reliable and sensitive for the routine monitoring of propineb and its metabolites in banana and soil. It also serves as a reference for the detection and monitoring of dithiocarbamates (DTCs) residues and the evaluation of their metabolic pathway.

Combined determination and confirmation of ethylenethiourea and propylenethiourea residues in fruits at low levels of detection

In this work, a new method for the determination of ethylenethiourea (ETU) and propylenethiourea (PTU) in fruits and vegetables is presented. Different extraction and purification techniques, including matrix solid phase dispersion (MSPD) and solid-liquid extraction (SLE), followed by a clean-up step by solid phase extraction (SPE), were compared. The determination of ETU and PTU was performed by high performance liquid chromatography with diode array detection (HPLC/DAD) or by gas chromatography with mass spectrometry detection (GC/MS). The effect of several parameters on the extraction, separation and detection was studied. The proposed method based on solid-liquid extraction with acetonitrile, clean-up with Envicarb II/PSA cartridges and subsequent analysis by HPLC/DAD was characterised and applied to the analysis of fruits and vegetables from different countries. Analytes recoveries were between 71% and 94% with relative standard deviations (RSDs) ranging from 8% to 9.5%. Quantification limits obtained for ETU and PTU with the HPLC/DAD method were 7 and 16 μg kg⁻¹ in strawberries (fresh weight), respectively. For apples, they were 11 and 25 μg kg⁻¹, respectively.

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.

Determination of dithiocarbamates and milneb residues in foods by gas chromatography-mass spectrometry

A highly sensitive gas chromatographic-mass spectrometric (GC-MS) method was developed for dithiocarbamates (DTCs) and milneb in foods. DTCs and milneb were extracted from foods with cysteine-EDTA solution as sodium salts, and methylated with methyl iodide. Methyl derivatives of DTCs and milneb were cleaned up on a neutral alumina mini column and determined by GC-MS. The mean recoveries of DTCs and milneb were in the range of 72-120%, except for methiram. The quantification limits were 0.01 mg/kg (as CS(2)) in foods except tea (0.1 mg/kg as CS(2)). The developed method was applied to 10 compounds (4 dimethyldithiocarbamates, 3 ethylenebisdithiocarbamates, polycarbamates, propineb and milneb).

Bioanalytical hydrophilic interaction chromatography: recent challenges, solutions and applications

Hydrophilic interaction chromatography (HILIC) has, in recent years, been shown to be an important supplement to reversed-phase liquid chromatography for polar analytes. HILIC, in conjunction with tandem mass spectrometry (MS/MS), has been steadily gaining acceptance in the analysis of polar compounds from complex biological matrices. This hyphenated technique offers the advantages of improved sensitivity by employing high organic content in the mobile phase, shortened sample preparation time with direct injection of the organic-solvent extracts of biological samples and the potential for ultra-fast analysis because of low-column backpressure. This article reviews recent challenges presented by HILIC, advancements in the better understanding of retention characteristics of analytes with different mobile- and stationary-phase compositions and solutions to ion suppression and interference problems encountered in HILIC–MS/MS assays. Applications of HILIC–MS/MS are summarized, including those for pharmacokinetic studies, metabolic studies, therapeutic drug monitoring and clinical diagnostics.