Determination Of Organophosphorus Pesticides Research Articles

Facile extraction and determination of organophosphorus pesticides using poly (8-hydroxyquinoline) functionalized magnetic multi-walled carbon nanotubes nanocomposite in water, fruits, and vegetables samples

This study presents a dispersive micro-solid phase extraction (D-μ-SPE) approach for extracting and determining of two organophosphorus pesticides (OPPs), including diazinon and chlorpyrifos as model analytes in various samples. For this purpose, we synthesized, characterized, and utilized magnetic multi-walled carbon nanotubes coated with poly 8-hydroxyquinoline (MWCNTs/Fe3O4@PHQ) as a novel sorbent. The impact of various parameters, including sorbent type, sample pH, sample volume, sorbent amount, desorption solvent (type and volume), extraction time, and ionic strength on the extraction efficiency was investigated and optimized. Following the extraction, the desorbed pesticides in acetone were analyzed using gas chromatography with an FID detector. Under the optimized experimental conditions, the proposed method showed excellent linearity in the range of 3–1000 µg/L, low detection limit (0.9–1.5 µg/L), good relative recoveries (86–101.5 %), and high precision (RSD < 6.5 %). Finally, the applicability of this method was evaluated by analyzing the target OPPs in a variety of real samples, and obtained satisfactory results.

Smartphone-assisted colorimetric biosensor for the determination of organophosphorus pesticides on the peel of fruits

Nowadays, the widespread use of organophosphorus pesticides (OPs) in agricultural production leads to varying degrees of residues in crops, which pose a potential threat to human health. Conventional methods used in national standard for the detection of OPs in fruits and vegetables require expensive instruments or cumbersome sample pretreatment steps for the analysis. To address these challenges, in this work, we took advantage of the peroxidase-like activity of PtCu3 alloy nanocrystals (NCs) for a colorimetric and smartphone assisted sensitive detection of OPs. With the assist of a smartphone, the concentration of OPs on the peel of fruits could be obtained by comparing the B/RG value (the brightness value of blue divided by those of red and green) of a test strip with a calibration curve. This work not only provides a facile and cost-effective method to detect pesticides but also makes a positive contribution to food safety warning.

Molecularly imprinted polymer-coated paper for the selective extraction of organophosphorus pesticides from fruits, vegetables, and cereal grains

Biodegradable molecularly imprinted polymer-coated paper (MIP@paper) was effectively produced by polymerization using azinphos-methyl as a template molecule, terephthalic acid as a functional monomer, ethylene glycol dimethacrylate as a cross-linker, and aqueous ethanol as a green porogenic solvent. The material was subsequently composited onto cellulose paper, which served as the natural substrate, by dip coating with the aid of chitosan and citric acid natural adhesive. The properties, such as static and dynamic adsorption, selectivity, and reusability, were assessed. At rapid adsorption equilibrium (10 min), the MIP@paper had a high adsorption capacity in the range of 2.5–3.7 mg g−1 and good recognition with imprinting factors up to 2.1. In addition, the proposed MIP@paper was utilized efficiently as a sorbent for dispersive solid phase extraction (d-SPE) of eight organophosphorus pesticides (OPPs) prior to high-performance liquid chromatography (HPLC) analysis. The d-SPE-HPLC method displayed low detection limits of 1.2–4.5 μg kg−1 and significant enrichment factors (up to 320-fold). The proposed method was effectively applied for the determination of OPP residues in agricultural products, including fruits, vegetables, and cereal grains, with satisfactory spiked recoveries (80.1–119.1 %). Thus, the MIP@paper material provided a selective and environmentally favorable method for extracting and determining organophosphorus pesticides.

A Laser-Induced Graphene-Based Sensor Modified with CeO2 for Determination of Organophosphorus Pesticides with Improved Performance

In this work, a flexible electrochemical sensor was developed for the detection of organophosphorus pesticides (OPs). To fabricate the sensor, graphene was generated in situ by laser-induced graphene (LIG) technology on a flexible substrate of polyimide (PI) film to form a three-electrode array, and pralidoxime (PAM) chloride was used as the probe molecule. CeO2 was used to modify the working electrode to improve the sensitivity of the sensor because of its electrocatalytic effect on the oxidation of PAM, and the Ag/AgCl reference electrode was prepared by the drop coating method. The effects of the laser power, laser scanning speed, and CeO2 modification on the electrochemical properties of the sensor were studied in detail. The results prove that the sensor has good repeatability, stability, and anti-interference ability, and it shows an excellent linear response in the chlorpyrifos concentration range from 1.4 × 10−8 M to 1.12 × 10−7 M with the detection limit of 7.01 × 10−10 M.

GSH-AuNCs/Cu2+ as selective fluorescent sensing probe for sensitive determination of glyphosate in the environment

The sensitive and selective detection of glyphosate (Gly) in the environment is urgently need because it has significant implications for human health and environmental safety. In this work, a GSH-AuNCs/Cu2+ sensing probe was fabricated via the coordination between Cu2+ and GSH-AuNCs, which resulted in the suppression of the fluorescence of GSH-AuNCs. Glyphosate can competitively grasp Cu2+ from GSH-AuNCs/Cu2+, leading to fluorescence recovery. Thereby, a simple and sensitive “turn-on” fluorescence strategy was developed for the quantitative detection of glyphosate. The linear range of glyphosate detection is 0.25 ∼ 1.25 μM, with a detection limit of 92.16 ng/mL. This method was demonstrated selectivity, fast response, and sensitivity, making it suitable for the quantitative determination of glyphosate in real water samples. Furthermore, a paper-based test strip was constructed using the sensing probe, which enabled on-site visual and semiquantitative detection of Gly. Overall, our strategy provides new opportunities for determination of organophosphorus pesticides in the environment.

A convenient and effective method for determining organophosphorus pesticides in citrus fruits based on a novel dispersive solid phase extraction using UiO-66/Alg bead as the sorbent

This work presents a novel, convenient and effective method for assaying organophosphorus pesticides (OPPs) in the pulp and peel of citrus fruits. In this method, shaped UiO-66/alginate (UiO-66/Alg) beads were employed to replace the powder sorbents used in traditional dispersive solid phase extraction (d-SPE) methods. The UiO-66/Alg beads can be easily separated by only using a tweezer within 1 min, which effectively simplifies the sample pretreatment and overcomes the shortages brought by the incomplete separation of powder sorbents. Moreover, the matrix compounds can be effectively excluded by UiO-66/Alg beads, and the UiO-66/Alg beads can be reused at least 8 times. The d-SPE conditions were optimized by a single factor test. The method shows satisfactory sensitivity, accuracy and precision. Furthermore, ATR-FTIR and UV–Vis-DRS were employed to investigate the adsorption mechanism. Finally, the developed method was applied to monitor the OPPs in ten different citrus fruits.

Electrochemical biosensors based on multifunctional double-enriched MOFs@MOFs derivatives for the detection of malathion

Multifunctional nanocomposites derived from metallic-organic frameworks @ metallic-organic frameworks (MOFs@MOFs) based on nanoarchitectonics may provide an innovative approach for the design of promising biosensors. A novel electrochemical biosensor based on tribulus-shaped ZrO2@Fe2O3-C nanocomposites for ultra-sensitive determination of organophosphorus pesticides (OPs) was prepared the pyrolysis of UiO-66@MIL-88B. ZrO2 from the inner UiO-66 displayed an ultrahigh adsorption capability for OPs, and the interface electronic interaction of ZrO2@Fe2O3 made Fe2O3 positive, which can fix and enrich acetylcholinesterase (AChE) in the outer layer, since AChE was a negatively-charged enzyme. The dual enrichment property and synergistic effect of ZrO2@Fe2O3-C were responsible for enhanced detection performances toward OPs, including a wide linear range (3.07 × 10−14 M−3.07 × 10−8 M) and a low limit of detection (3.9 × 10−15 M) (S/N = 3). The emergence of the multifunctional nanocomposites, through calcining MOFs@MOFs, opens a new chapter for the construction of biosensors for OPs determination.

A new solid phase extraction sorbent developed based on cyanopropyl functionalized silica nanoparticles for organophosphorus pesticides determination

In this work, a simple sol-gel approach was used for the preparation of cyanopropyl (CNPr) functionalized silica nanoparticles (SiO2-CNPr) that tetraethoxysilane (TEOS) and cyanopropyltriethoxysilane (CNPrTEOS) used as precursors. This as-prepared SiO2-CNPr nanoparticle sorbent was first characterized using FESEM, EDX, FTIR, TGA, and BET techniques. Then, the SiO2-CNPr nanoparticle was applied as a new SPE sorbent for determining trace levels of OPPs in environmental water samples. To enhance the simultaneous extraction of non-polar or/and polar OPPs and to obtain the most efficient sorbent, several sol-gel synthesis parameters were studied. In addition, the effect of several effective parameters on SPE performance was investigated toward simultaneous extraction of non-polar or/and polar OPPs. Moreover, the figures of merit such as precision, linearity, LOQ, LOD, and recovery were evaluated for the sorbent. Finally, the designed SiO2-CNPr SPE was used to determine OPPs in real water samples, and its extraction performance was compared to commercial cartridges based on cyanopropyl.

Eco-friendly thermosensitive magnetic-molecularly-imprinted polymer adsorbent in dispersive solid-phase microextraction for gas chromatographic determination of organophosphorus pesticides in fruit samples

A thermosensitive magnetic-molecularly-imprinted polymer (TMMIP) was successfully prepared in an aqueous medium. The TMMIP was applied as an effective adsorbent in dispersive solid-phase microextraction for the selective enrichment of five organophosphorus pesticides (OPPs; diazinon, fenitrothion, fenthion, parathion-ethyl, and ethion) before analysis by gas chromatography. The polymerization was performed using mixed-valence iron hydroxide nanoparticles as the magnetic support, N-isopropyl acrylamide as the thermosensitive monomer, ethion as the template, and methacrylic acid as the functional monomer. The adsorption and desorption mechanisms of OPPs depend on their interactions with the adsorbents and solution temperature. Our methodology provides good linearity (0.50–2000 µgL-1), with a correlation determination of R2 > 0.9980, low limit of detection (0.25–0.50 µgL-1), low limit of quantitation (0.50–1.50 μg L−1), and high precision (%RSD < 7%). The developed method demonstrates excellent applicability for accurately and efficiently determining OPP residuals in fruit and vegetable samples with good recoveries (93–117%).

A dual-emission ratiometric fluorescence strategy with enzyme-based inhibition for organophosphorus pesticides determination.

A fast, eco-friendly and accurate ratiometric fluorescent strategy is presentedfor the determination of organophosphorus pesticides (OPs) using intrinsic dual-emission silica nanoparticles modified with Rhodamine 6G (SiNPs-Rho6G). SiNPs-Rho6G had intrinsic dual-emission at 410 and 550 nm. The substrate acetylcholine was catalyzed by acetylcholinesterase (AChE) to produce thiocholine (TCh). TCh triggered the specific reaction of Ellman's reagent 5, 5-dithiobis (2-nitrobenzoic acid) to obtain 5-thio-2-nitrobenzoic acid, which caused the decrease in fluorescence intensity of SiNPs-Rho6G at 410 nm by the inner filter effect, while the fluorescence intensity of SiNPs-Rho6G at 550 nm was not significantly changed. OPs caused the recovery of the fluorescence at 410 nm by inhibiting the activity of AChE. Thus, the quantitative detection of OPs could be achieved through utilizing the catalytic characteristic of AChE. The linear curve from 0.010 to 0.250 μg mL-1 with a detection limit of 7 ng mL-1 was obtained for the determination of chlorpyrifos (Cpf). The ratiometric probe was used to detect the spiked Cpf in environmental and food sampleswith good recoveries. Therefore, combined with the dual emission characteristics of SiNPs-Rho6G and the specificity of theenzyme, the ratio fluorescence sensing platform has potential application prospects in OPs determinations.

Comparative evaluation of solid-phase extraction and in-tube liquid-liquid extraction for the determination of Organophosphorus pesticides in the surface water from Medjerda River, Tunisia

In the present work, we develop, validate, and compare two extraction procedures (in-tube liquid-liquid extraction (ITLLE) and solid-phase extraction (SPE)). The parameters that influence extraction efficiency, the nature and volume of the extraction solvent, as well as the pH nature, were improved and a standard solution of Organophosphorus pesticides (OPPs) was used. Results indicated that SPE is clearly more successful than ITLLE extraction under optimum conditions. The validated method showed that this approach had good linearity, with correlation coefficients ranging from 0.991 to 0.998 and low detection and quantification limits of 0.01–0.03 ng L−1 and 0.03–0.9 ng L−1, respectively. Relative standard deviations were in the range of 0.2 and 1.2%, while extraction recoveries varied from 79 to 97%. The SPE was selected and, optimum recoveries for OPPs were obtained at pH 7, with 10 mL of ethyl acetate. The suggested approach was effectively applied to the analysis of water samples collected from the Medjerda River in two seasons. The average OPPs concentrations ranged from not detected (ND) to 17.5 ng L−1 during the dry season and from not detected ND to 13.1 ng L−1 during the wet season. The results demonstrate that none of the OPPs concentrations measured exceeded the regulatory limits.

Rapid and simple determination of organophosphorus pesticides in urine using polydopamine-modified monolithic spin column extraction combined with liquid chromatography–mass spectrometry

The determination of organophosphorus pesticides in urine is useful for evaluating human exposure. In this study, a simple micro-solid-phase extraction method based on a polydopamine-modified monolithic spin column combined with liquid chromatography–mass spectrometry (LC-MS) was developed for the determination of six organophosphorus pesticides (dimethoate, dichlorvos, carbofuran, methidathion, phosalone, and chlorpyrifos) in urine samples. A methacrylate polymer monolithic support was prepared in situ in the spin column, and dopamine solution was repeatedly passed through the monolith matrix via centrifugation to generate a polydopamine layer in the polymeric network. All extraction steps were performed via centrifugation. The monolith exhibited good permeability, which enabled high-flow-rate sample loading and significantly reduced the sample pre-treatment time. The addition of polydopamine significantly improved the extraction efficiency of the monolithic spin column owing to the catechol and amine groups in dopamine, which can enhance hydrogen bonding and π–π stacking. Factors affecting the extraction, including the solution pH, centrifugation speed, and desorption solvent, were investigated to determine the optimal extraction conditions. Under the optimal conditions, the OPP detection limits were 0.02–1.32 µg/L. The relative standard deviations of the single column (n = 5) and column-to-column (n = 3) precision for the extraction method were <11%. The monolithic spin column exhibited high stability and could be used for more than 40 extraction cycles. The recoveries for spiked urine samples were 72.1–109.3% (RSDs: 1.6–7.9%). The developed method was successfully applied to the simple and rapid analysis of organophosphorus pesticides in urine samples.

Development of a Zeolite H-ZSM-5-Based D-μSPE Method for the Determination of Organophosphorus Pesticides in Tea Beverages

In this study, a novel dispersive micro-solid phase extraction (D-μSPE) technique with H-ZSM-5 zeolite as an adsorbent was developed for the determination of 21 trace pesticides in tea beverages. The adsorption and desorption of H-ZSM-5 zeolites were investigated based on structural characteristics and adsorption properties similar to those of H-beta zeolites. In combination with the properties of the adsorbates, it was explained that the adsorption reaction occurred on the microporous surface and mesopores of H-ZSM-5. Based on optimal parameters, the beverage samples were extracted by 50 mg of zeolite within 1 min. The zeolite was eluted with 2 mL of an acetonitrile-water mixture after separation, and the eluent was filtered prior to HPLC-MS/MS analysis. The D-μSPE protocol demonstrated acceptable accuracy and precision, with recoveries between 62.1% and 106.6% and relative standard deviations of 1.4% to 12.6%, as validated by analytical reliability. The correlation coefficient in the linear range of 0.2–50 ng·mL−1 was greater than 0.98, with limits of detection of 0.05–0.1 ng·mL−1 and limits of quantification of 0.1–0.2 ng·mL−1. The matrix effects ranged from 76.2% to 112.7%. The results indicate that the novel D-μSPE technique based on H-ZSM-5 is a rapid, simple, green and economical method for the determination of pesticide residues in tea beverages. The proposed method achieved simultaneously low adsorbent dosage, 20-fold enrichment factor, rapid pre-concentration in 12 min, minimal organic wastes, and effective reduction of matrix interference.

New di-(2-Ethylhexyl)Phosphoric Acid-Based Supramolecular Solvent (DEHPA-SUPRAS) Microextraction Coupled to High Performance Liquid Chromatography (HPLC) for the Determination of Organophosphorus Pesticides in Tea Drinks

A new supramolecular solvent (SUPRAS) made up of di-(2-ethylhexyl)phosphoric acid (DEHPA) surfactant its introduced and its application was assessed through the microextraction of organophosphorus pesticides (OPPs) including fenitrothion, phosalone, and chlorpyrifos from tea drinks before being determined by high performance liquid chromatography with ultraviolet detection (HPLC-UV). The method was based upon the extraction of the analytes into the SUPRAS phase spontaneously formed in the ternary mixture of DEHPA, tetrahydrofuran (THF), and the aqueous sample. A phase diagram delimiting the SUPRAS region was constructed and the microstructure of supramolecular aggregates constituting SUPRAS was examined under the optical microscope. After optimizing the main variables in the procedure, the method provided extraction recoveries and preconcentration factors from 77 to 98% and 15 to 19, respectively. The limits of detection (LODs) for the studied pesticides were from 6 to 10 µg L−1. The intra- and inter-day relative standard deviation (RSD) values were from 4.4 to 8.9 and 9.0 to 9.5%, respectively. The developed method has been successfully applied to the several tea drinks and acceptable recoveries for spiked samples were obtained between 82 and 106% with relative standard deviations of less than 9.3%.

Organophosphorus Residues in Fish in Rural Areas

A total 45 fish samples (Tilapia, Claris) were collected from EL-Bagoria, EL-Menofi drainage and Bahr Shibin for detection and determination of organophosphorus pesticides (diazinon, Malathion and chlorpyrifos).

Deep Learning-Based Multicapturer SERS Platform on Plasmonic Nanocube Metasurfaces for Multiplex Detection of Organophosphorus Pesticides in Environmental Water.

In situ rapid detection of contaminants in environmental water is crucial for protecting the ecological environment and human health; however, it is always hindered by the complexity of sample matrices, trace content, and unknown species. Herein, we demonstrate a deep learning-based multicapturer surface-enhanced Raman scattering (SERS) platform on plasmonic nanocube metasurfaces for multiplex determination of organophosphorus pesticides (OPPs) residues. Poly(vinylpyrrolidone), 4-mercaptobenzoic acid, and l-cysteine are assembled on Ag nanocubes (AgNCs) and act as capturers to chemically define OPPs. Meanwhile, the OPPs-captured AgNCs efficiently close the interparticle distance and generate plasmonic metasurfaces, guaranteeing ultrasensitive and reproducible SERS analysis. Furthermore, by strategically combining all capturer-OPP SERS spectra, comprehensive "combined-SERS spectra" are reconstructed to enhance spectral variations of each OPP. Based on the combined-SERS spectra, a deep learning model is trained to predict OPPs, which significantly improve the qualitative and quantitative analysis accuracy. We successfully identified multiple OPPs in farmland, river, and fishpond water using this strategy. The whole detection procedure requires only 30 min, including sampling, SERS measurements, and deep learning analyses. This combination of a multicapturer SERS platform with the deep learning algorithm creates a rapid and reliable analytical strategy for multiplex detection of target molecules, providing a potential paradigm shift for environment-related research.

Organophosphorus Residues in Fish in Rural Areas

A total 45 fish samples (Tilapia, Claris) were collected from EL-Bagoria, EL-Menofi drainage and Bahr Shibin for detection and determination of organophosphorus pesticides (diazinon, Malathion and chlorpyrifos). Organophosphorus pesticides could not be detected in Bahr Shibin. No diazinon in Tilapia from EL-Bagoria but mean value of of Malathion 5.50±2.0, chlorpyrifos 5.0±1.66 but from EL-Menofi drainage mean level of diazinon 3.33±0.65, Malathion 4.98±1.22 and chlorpyrifos3.0±0.71 but in Claris samples, there were no diazinon, no Malathion, no chlorpyrifos from EL-Bagoria canal but from EL-Menofi drainage, mean value of diazinon 6.8±1.42, Malathion 4.64±0.81 and chlorpyrifos4.0±0.96. Pesticides are one the main contaminant of water sources which are considered the natural environment of fish. on the other hand, fish could be contaminated by pesticides either directly by gills breathing or indirectly through contamination of feeding items, so it is very important to analyze fish samples to detect to what extent the rate of accumulation of pesticides residues in fish flesh and organs.

A luminescent probe based on terbium-based metal-organic frameworks for organophosphorus pesticides detection.

Terbium-based metal-organic frameworks (Tb-MOF) prepared under mild conditions was utilized to construct a fluorescence probe for determination oforganophosphorus pesticides (OPs) coupled with acetylcholinesterase (AChE), acetylcholine chloride (Ach), and choline oxidase (CHO). Since OPs have obvious inhibition on the activity of AChE in the Tb-MOF/ACh/CHO/AChE system, the detection of OPs was accomplished by restoring the fluorescence of Tb-MOF resulting from reduced production of H2O2. By taking chlorpyrifos (CPF) as a pesticide model, the method exhibits high sensitivity in the linear range 0.1-4.0μg·L-1 with the limit of detection (LOD) of 0.04μg·L-1 under optimum conditions (λex = 280nm, λem = 544nm). The Tb-MOF/ACh/CHO/AChE fluorescence system has high selectivity for CPF. Themethod was successfully applied to the detection of CPF in tap water and strawberry samples (recovery of 87.36-115.60% for tap water and 95.04-103.20% for strawberry). Free from complicated fabrication operation, the Tb-MOF-based system is rapid, simple, and stable, which provides a reference and new way for the design of OPs fluorescent probes in the future.

Designing Hierarchically Porous Single Atoms of Fe-N5 Catalytic Sites with High Oxidase-like Activity for Sensitive Detection of Organophosphorus Pesticides.

Recently, single-atom catalysts (SACs) have been used to construct biosensors for the determination of organophosphorus pesticides (OPs). However, most nanozymes including SACs are peroxidase-like enzymes and require highly toxic and unstable hydrogen peroxide (H2O2) as a co-reactant to generate reactive oxygen species. Inspired by the heme site of cytochrome c oxidases (Ccos), the construction of Fe-N5-coordinated SACs by introducing axial N ligands is expected to bind O2 to generate active metal-oxygen intermediates. Herein, a SAC with an Fe-N5 active center confined by hierarchically porous carbon nanoframes (Fe SAs/N5-pC-4) was prepared by a polymerization-pyrolysis-evaporation-etching strategy, and its underlying enzyme-like mechanism was uncovered through experiments and density functional theory calculations. The 100% metal atom utilization, increased accessible active sites, accelerated mass transfer, excellent hydrophilicity, and an electron-driven mechanism of axial N endow the SAC with enhanced oxidase-like activity. Notably, its catalytic rate constant (0.398 s-1) is 569 times greater than that of the commercial Pt/C catalyst. Similar to the catalytic mechanism of Ccos, O2 can be converted into reactive oxygen species, avoiding the use of co-reactant H2O2 effectively. In addition, based on the inhibitory effect of thiols on the active site of Fe SAs/N5-pC-4, a biosensor was constructed and applied to the colorimetric analysis of OPs. This provides a facile, cost-effective method for efficient OP screening at sites to help control their contamination.

Microextraction of organophosphorus pesticides on a screw coated with PAN/calcined ZnMgAl-LDH electrospun nanofibers.

The present research is an attempt to expand the recently reported microextraction on screw method. For this purpose, polyacrylonitrile/calcined ZnMgAl-LDH nanofiber was fabricated by the electrospinning technique on the surface of a screw. It was applied tothe extraction of organophosphorus pesticides (OPP)from agricultural samples. The separation and determination of OPPs were carried out by gas chromatography-mass spectrometry. The characterization of the fabricated nanofiber was performed utilizing Fourier transform infrared spectroscopy, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction instruments. Effective parameters on the extraction efficiency of the analytes including sample pH, ionic strength, sample flow rate and number of cycles, type, volume, and flow rate of desorption solvent were optimized by one-variable-at-a-time method. Under optimized conditions, the limits of detection were 0.03 and 0.07μg L-1 for diazinon and chlorpyrifos, respectively. This method showed wide linearity in the range 0.10-1000μg L-1 for diazinon and 0.25-1000μg L-1 for chlorpyrifos with R2 > 0.996. The intra- and inter-day precisions (RSD%, n = 3) were ≤ 6.4% and ≤ 7.7%, respectively. Also, RSD% values less than 11.1% were obtained for screw-to-screw reproducibility. The applicability of the method for the extraction and determination of the analytes in complex agricultural environments such as cabbage, potato, tomato, cucumber, and beetroot was investigated. The results led to acceptable relative recoveries in the range 81.0-108.2%.