Application of magnetic carbon nano-onions in dispersive solid-phase extraction combined with DLLME for extraction of pesticide residues from water and vegetable samples

Deep eutectic solvent-based iron nanoparticles coated by N, S-doped amorphous carbon and its application in magnetic Dµ-SPE combined with DLLME for the extraction of PAHs in eyeliner

This work presents a preparation of new magnetic nanoparticles coated with amorphous carbon and their application in dispersive solid-phase extraction in simultaneous extraction of sixteen polycyclic aromatic hydrocarbons from eyeliner. The extraction procedure was hyphenated with a lower density than water dispersive liquid-liquid microextraction (DLLME) for further preconcentration of the analytes to sensitive determination of them with gas chromatography-flame ionization detection. The magnetic adsorbent was prepared sonically from iron pentacarbonyl and then the nanoparticles were coated by N, S-doped amorphous carbon and the deep eutectic solvent prepared from tetrabutyl ammonium chloride and decanoic acid. The magnetic properties of the nanoparticles were studied by vibrating sample magnetometer. Also, scanning electron microscopy was used to investigate the nanoparticles morphology. The extraction procedure was done by migration of the analytes from eyeliner into a proper aqueous solution and their adsorption onto the nanoparticles. Then, the analytes were eluted and more concentrated by the DLLME approach. After validating the method, acceptable limit of detection and broad linear range were accessed in the ranges of 0.25-0.54 and 1.8-250 ng/g, respectively. Relative standard deviation values were ≤ 7.1% for the repeated analyses in the same day (n = 6) and different days (n = 6). Extraction recovery of the method was in the range of 79-96%. The introduced method was successfully used for the analysis of the PAHs in five eyeliner samples and only two of them were identified in all samples at ng/g level.

Modified matrix solid phase dispersion-HPLC method for determination of pesticide residue in vegetables and their impact on human health: A risk assessment

The use of pesticides is unavoidable in agricultural practices. This class of chemicals is highly toxic for the environment as well as for humans. The present work was carried out to assess the presence of some pesticides (diafenthiuron, lufenuron, azoxystrobin, difenoconazole, and chlorothalonil) residues in five of the very commonly used vegetables (eggplant, capsicum, apple gourd, cauliflower, and sponge gourd). Matrix solid phase dispersion (MSPD) technique was used to extract the pesticides and subsequently their quantification was performed through high performance liquid chromatography (HPLC) coupled to ultraviolet-visible (UV-Vis) detector. The elution was accomplished at wavelength of 254 nm by injecting 20 µL of standards or samples into chromatographic system. The mobile phase consisted of acetonitrile and water (80:20 v/v), where the flow rate was adjusted at 1.0 ml/min. The linearity was good (R ² ≥ 0.994) over a concentration range from 20 to 100 μg/ml for the investigated pesticides. The low detection limits showed a quite appreciable potential of the method to detect (1.12-1.61 μg/L) and quantify (3.73-5.36 μg/ml) the pesticides under study. The accuracy was demonstrated in terms of percent recovery which ranged between 88.5% and 116.9% for all the pesticides under investigation. These results justify the suitability of the technique for the intended purpose. The concentration of difenoconazole in apple gourd (20.97 mg/kg), cauliflower (10.28 mg/kg), and sponge gourd (40.32 mg/kg) whereas diafenthiuron in cauliflower (0.66 mg/kg) exceeded the maximum residue level (MRLs) as defined by Food and Agriculture Organization of the United Nations and the World Health Organization (FAO/WHO). Target hazard quotient (THQ) values of difenoconazole and diafenthiuron (except for adults) were more than one which indicates the significant effect on human health on consumption of apple gourd, cauliflower, and sponge gourd.

Ag-EDTA-Zr and Au-EDTA-Zr Nanocomposites for the Quantitative Determination of Some Organophosphate Pesticides in Water and Tomatoes

Background

Organophosphate pesticides (OP) pose risks to health and the environment, and monitoring them is an urgent task.

Objective

Development of a method for their determination in water and food.

Method

A simple photometric method for the determination of some OPs was demonstrated. Ag-EDTA-Zr and Au-EDTA-Zr nanoparticles were synthesized and were applied for the determination of some OPs (dimethoate, chlorpyrifos, and diazinon).

Results

It was demonstrated that silver nanoparticles provide more sensitivity in comparison to gold nanoparticles. As a result, Ag-EDTA-Zr nanoparticles were further applied for the determination of these pesticides in tomatoes.

Conclusions

The lowest detectable concentrations for dimethoate, diazinon, and chlorpyrifos in water reached 0.1 (SD 0.082), 0.4 (SD 0.075), and 0.4 mg/L (SD 0.088), respectively, whereas in tomato the lowest detectable concentrations for these pesticides were 0.5 (SD 0.789), 2 (SD 0.085), and 0.5 mg/L (SD 0.088). The sensitivity of detection in tomatoes is lower than in water; however, these concentrations are comparable with allowable concentrations of OP pesticides.

Highlights

A novel approach for quantitative detection of OPs was developed. Ag-EDTA-Zr and Au-EDTA-Zr nanocomposites interact with these pesticides, and, as a result, optical changes of these nanoparticles take place. These changes correlate with the concentration of pesticides.

Simultaneous determination of nereistoxin insecticides in foods of animal origins by combining pH-dependent reversible partitioning with hydrophilic interaction chromatography-mass spectrometry

Although nereistoxin insecticides (NIs) are banned for animal husbandry operations, they are still used because of their high insecticidal activities. Therefore, a reliable residue analysis method for the simultaneous detection of cartap, bensultap, thiocyclam, and nereistoxin in foods of animal origins, including beef, pork, chicken, milk, and eggs, was developed using hydrophilic interaction liquid chromatography-mass spectrometry (HILIC-LC-MS/MS). The NIs were extracted with an acidic cysteine and formate buffer solution and hydrolyzed to nereistoxin. The molarity and pH of the buffer were optimized at 20 mM and 3, respectively, to keep the pH of the extracts at 4-5. pH-dependent acid-base partitioning coupled with salting-out-assisted liquid-liquid extraction using acetonitrile was performed for purification and for the direct introduction of the extracts to LC. The optimal pH values were 5 and 9 for the acid-base partitioning. Nereistoxin quantitation was achieved with consistent column retention (RSD < 0.6%) and a high degree of separation (N > 10⁶). The matrix-dependent method limit of quantitation was 2 μg nereistoxin/kg, and the calibration curve showed good linearity (R² > 0.998). The recovery efficiencies were in the range of 89.2-109.9% with relative standard deviations less than 10%, and matrix effects did not exceed ± 10%, which satisfied the criteria outlined in the European SANTE/12682/2019 guidelines.

Efficiency of the removal of tetraethyl pyrophosphate (TEPP) pesticide in water: use of cork granules as a natural adsorbent on acetylcholinesterase activity in neuronal PC12 cell

Tetraethyl pyrophosphate (TEPP) is an organophosphate pesticide that irreversibly inhibits acetylcholinesterase (AChE). Cork powder or granules have been recommended as a sustainable sorbent to remove pesticides from water. In the present study, we evaluated the effectiveness of removing TEPP from water using wine corks to obtain cork granules as natural adsorbent, analyzing the TEPP effects on AChE activity in commercial enzyme from Electrophorus electricus and secreted by neuronal PC12 cells. TEPP inhibited AChE activity in a concentration-dependent manner. For the first time, we showed that different concentrations of TEPP diluted in water after adsorption experiments using cork granules decreased TEPP's inhibitory effects on AChE activity in commercial enzyme and neuronal PC12 cell culture medium. Our results suggest that the optimum removal of TEPP from water by corks was 91.4 ± 4.0%. Overall, the findings support the hypothesis that cork granules can be used to remediate pesticide-contaminated environments, such as those contaminated by organophosphate pesticides, and demonstrate a new application of a biochemical assay on AChE activity using a commercial enzyme or secreted by neuronal PC12 cells in culture as a possible methodologic strategy for evaluating the success of TEPP removal from water.

Development of poly(vinyl alcohol)/chitosan/aloe vera gel electrospun composite nanofibers as a novel sorbent for thin-film micro-extraction of pesticides in water and food samples followed by HPLC-UV analysis

Schematic presentation of applying PVA/CA/CS/AV composite nanofibers as the extraction phase in thin-film micro-extraction (TFME) of six pesticide compounds prior to HPLC-UV analysis.

Ultrasound-assisted dispersive liquid-phase microextraction by solidifying L-menthol-decanoic acid hydrophobic deep eutectic solvents for detection of five fungicides in fruit juices and tea drinks

An ecofriendly and efficient ultrasound-assisted deep eutectic solvents dispersive liquid-phase microextraction by solidifying the deep eutectic solvents-rich phase was developed to determine azoxystrobin, fludioxonil, epoxiconazole, cyprodinil, and prochloraz in fruit juices and tea drinks by high-performance liquid chromatography. A varieties of environmental hydrophobic deep eutectic solvents serving as extraction agents were prepared using L-menthol and decanoic acid as hydrogen-bond acceptor and hydrogen-bond donor, respectively. The deep eutectic solvents were ultrasonically dispersed in sample solutions, solidified in a freezer and easily harvested. The main variables were optimized by one-factor-at-a-time and response surface test. The new method performs well with relative recovery of 71.75-109.40%, linear range of 2.5-5000 μg/L (r ≥ 0.9968), detection limit of 0.75-8.45 μg/L, quantification limit of 2.5-25 μg/L,_, and inter- and intraday relative standard deviations below 13.53 and 14.84%, respectively. As for the extraction mechanism, deep eutectic solvents were disposed into many fine particles in the solution and captured the analytes based on the changes of particle size and quantity in deep eutectic solvents droplets after extraction. The environmental method can successfully detect fungicide residues in real fruit juices and tea drinks.