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

Sample Preparation Methods for Metal Containing Pesticides in Food and Environmental Samples

Metal-containing pesticides are used in many areas for purposes such as harvest efficiency and keeping pests away from the vegetable environment. Metal-containing pesticides are in the form of dithiocarbamate complexes and are named differently according to the type of metal they contain and are used for different purposes. Since the presence of these pesticides even at residue level threatens human and environmental health, their determination at trace level is important. In this review, studies on the determination of metal-containing dithiocarbamate pesticides in different matrices are discussed. This review on the analysis of dithiocarbamate pesticides with different techniques will shed light on the studies to be carried out for the determination of these pesticides one by one in different matrices.

Dithiocarbamates: Properties, Methodological Approaches and Challenges to Their Control

Dithiocarbamates (DTCs) are a group of chemicals used primarily as fungicides, although they are exploited for various other applications. DTCs represent one of the oldest classes of broad-spectrum fungicides employed worldwide to control fungal diseases on many crops. Due to their ease of synthesis, low production costs (cheap and readily available starting materials) and a fungicidal activity with a multi-site mode of action, they are still among modern agriculture's most extensively used pesticides. Although the environmental degradation in air, water, and soil is relatively rapid due to photolysis and/or hydrolysis, they are among the most frequently detected pesticides in the European Union (EU), also with a high frequency of maximum residue level (MRL) exceedances. The current review aims to comprehensively survey all aspects of DTCs, including the environmental fate, toxicity and analytical methods for determining parental compounds and degradation products in environmental and food samples. Furthermore, the accumulation of carbamate and dithiocarbamate pesticides in vegetables, fruits, bioindicator organisms and human biological samples, as well as their health effects on humans, are also considered in this study.

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.

Analytical and toxicological aspects of dithiocarbamates: an overview of the last 10 years

Compilation studies related to toxicological aspects and also biological monitoring and analysis methods for specific fungicides and, mainly, those that belong to the class of the dithiocarbamates (DTCs) have not been carried out at least in the last ten years. DTCs - dimethyldithiocarbamates, ethylenebisditiocarbamates, propylenebisditiocarbamates - are organosulfur compounds that form complexes due to the presence of different chemical elements, which bind strongly and inhibit enzymes that are essential to the functioning of the organism, causing a serious proven adverse effect on biological systems, such as alteration of thyroid hormones, teratogenesis and neurotoxicity. It is still evident, as shown by world data, that the growing consumption of fungicides has increasingly exposed the population in general and, in particular, workers who deal with these substances. There is a scarcity of studies in the literature discussing the toxicological and analytical aspects that are important for understanding the real effects of DTCs and monitoring human exposure to them. Therefore, the aim of this work was to expose, in a comprehensive way and through a narrative review, the negligence of research related to the fungicides of the DTCs class, their metabolites, as well as the toxicological and analytical aspects involved. The review is divided into two parts: (1) Toxicological aspects, including toxicokinetics, toxicodynamics and toxidromes; and (2) Analytical Toxicology, which comprises biomarkers, sample preparation and identification/quantification methods.

Luminescent determination of propineb fungicide by using a carbon quantum dots-europium ions system

We propose a modification of lanthanide-sensitized luminescence (LSL) to increase the selectivity and sensitivity of analytical methods based on this detection. LSL consists in the formation of complexes of lanthanide ions and organic compounds. Then, an intramolecular energy transfer occurs from the excited state of the ligand (organic analyte) to the emitting level of the lanthanide. The utilization of luminescent nanoparticles (carbon quantum dots, CQDs) in LSL systems can enhance their sensitivity and selectivity. CQDs can react with lanthanide ions through their carboxylic groups. These systems can thus be used as time-resolved luminescent probes. Propineb (PPN), a well-known dithiocarbamate fungicide, has been selected as the target analyte to show the advantages of using CQDs in LSL systems. The method proposed is based on the quenching produced by PPN in europium-CQDs luminescence, obtaining a detection limit of 0.03 μg mL^-1 PPN and a method detection limit of 3 mg kg^-1 in capers (bud and fruit), fulfilling the maximum residue limit in these samples (25 mg kg^-1). The results showed that the use of nanoparticles in LSL systems may provide novel and simple analytical methods for the screening of contaminants in the agri-food sector.

Hydrolysis and photolysis of bentazone in aqueous abiotic solutions and identification of its degradation products using quadrupole time-of-flight mass spectrometry

Hydrolysis and photolysis of bentazone in abiotic aqueous solutions were examined under laboratory conditions. Hydrolysis was studied in different buffer solutions (pH 4.0 ± 0.1, 7.0 ± 0.1, and 9.0 ± 0.1), at different temperatures (15 °C ± 2 °C, 25 °C ± 2 °C, 35 °C ± 2 °C, and 45 °C ± 2 °C), and at different Fe³⁺ concentrations (1, 5, and 10 mg/L). Photolysis was assessed in different buffer solutions and at different solvent (methanol and ethyl acetate) concentrations (10%, 20%, and 30%) or Fe³⁺ (1, 5, and 10 mg/L) concentrations and under mercury or xenon light irradiation. Hydrolysis half-lives ranged 46-99 days at three different conditions. Photolysis half-lives ranged 2.3-7.5 h in three different conditions under mercury and xenon irradiation. Hydrolysis and photolysis of bentazone were accelerated by both alkaline conditions and elevated temperatures, and solvents and Fe³⁺ strongly enhanced bentazone degradation. Photodecomposition was much faster under a mercury lamp than under a xenon lamp. N-methyl bentazone and 6-OH bentazone/8-OH bentazone were identified as degradation products using UPLC-Q-TOF-MS. The data generated from this study could be useful for risk assessment of pesticides in the environment.

Simultaneous determination of neonicotinoid insecticides and insect growth regulators residues in honey using LC-MS/MS with anion exchanger-disposable pipette extraction

In this study, we developed an anion exchanger-disposable pipette extraction (DPX) method to detect the residual concentrations of eight neonicotinoid insecticides (dinotefuran, acetamiprid, clothianidin, thiacloprid, imidachloprid, imidaclothiz, nitenpyram, and thiamethoxam) and eight insect growth regulators (IGRs; triflumuron, cyromazine, buprofezin, methoxyfenozide, tebufenozide, chromafenozide, fenoxycarb, and RH 5849) in Chinese honey samples collected from different floral sources and different geographical regions using liquid chromatography tandem mass spectrometry (LC-MS/MS). QAE Sephadex A-25 was used as the anion exchanger in the DPX column for the purification and cleanup of honey samples. Analytes were eluted with a mixture of acetonitrile and 0.1 M HCl, and the elution was subjected to LC analysis. This method was thoroughly validated for its reproducibility, linearity, trueness, and recovery. Satisfactory recovery of pesticides was obtained ranging from 72% to 111% with intraday RSDs (n = 5) of 1%-10%. High linearity (R² ≥ 0.9987) was observed for all 16 pesticides. Limits of detection and quantification for all 16 compounds ranged from 0.3 to 3 μg/kg and from 1 to 10 μg/kg, respectively. Pesticide residues (9-113 μg/kg) were found in Chinese honey samples. The anion exchanger-DPX method was effective for removing sugars and retaining target analytes. Moreover, this method was highly reliable and sensitive for detecting neonicotinoids and IGRs in different floral sources of honey and will be applicable to matrixes with high sugar content.