Trace determination of triazine herbicides in fruit and vegetables using novel hydrophobic deep eutectic solvent-based dispersive liquid-liquid microextraction followed by high-performance liquid chromatography-ultraviolet.

In the present research, a novel hydrophobic deep eutectic solvent-based dispersive liquid-liquid microextraction technique was established and combined with high-performance liquid chromatography-ultraviolet for the determination of triazine herbicides in fruit and vegetable samples. A deep eutectic solvent was synthesized using l-menthol as a hydrogen bond acceptor and ethylene glycol as a hydrogen bond donor and used as a green extractant. The characterization of deep eutectic solvent was investigated by Fourier-transform infrared, nuclear magnetic resonance, and thermogravimetric analysis. Under the optimum conditions, relative standard deviation values for intra-day and inter-day of the method based on seven replicate measurements of 50.0 µg/kg of triazines were in the range of 2.8%-5.5% and 3.7%-7.2%, respectively. The calibration graphs were linear in the range of 3.0-500 µg/kg and the limits of detection were in the range of 1.0-2.0 µg/kg. The relative recoveries of different fruit and vegetable samples that have been spiked with two levels of target compounds were 91.5%-109.8%. The method has good linearity, sensitivity, accuracy, and precision. It is also environmentally friendly and was successfully used to determine the concentrations of triazines in fruit and vegetable samples.

Extraction and determination of heavy metals in soil and vegetables irrigated with treated municipal wastewater using new mode of dispersive liquid-liquid microextraction based on the solidified deep eutectic solvent followed by GFAAS.

BACKGROUND: In this research, a new extraction method based on dispersive liquid-liquid microextraction and the solidification of deep eutectic solvent has been developed for the determination of heavy metals in soil and vegetables prior to their analysis by graphite furnace atomic absorption spectrometry (GFAAS). In this method, a green solvent consisting of 1-decyl-3-methylimidazolium chloride and 1-undecanol was used as an extraction solvent, yielding the advantages of material stability, low density and a suitable freezing point near room temperature. RESULTS: Under optimal conditions, enrichment factors are in the range of 114-172. The calibration graphs are linear in the range of 0.02-200 µg kg-1 and limits of detection are in the range of 0.01-0.03 µg kg-1 . Repeatability and reproducibility of the method based on seven replicate measurements of 0.80 µg kg-1 of Hg and 0.20 µg kg-1 of Pb and Cd in analyzed samples were in the range of 2.3-4.1% and 3.7-6.6%, respectively. CONCLUSION: A new deep eutectic solvent consists of two parts: 1-decyl-3-methylimidazolium chloride and 1-undecanol in a molar ratio of 1:2. The accuracy of the proposed procedure was also assessed by determining the concentration of the studied metal ions in a polluted farmland soil standard reference material. © 2018 Society of Chemical Industry.

Persistent sample circulation microextraction combined with graphite furnace atomic absorption spectroscopy for trace determination of heavy metals in fish species marketed in Kermanshah, Iran, and human health risk assessment.

BACKGROUND: Persistent sample circulation microextraction (PSCME) combined with graphite furnace atomic absorption spectrometry (GFAAS) was developed as a high pre-concentration technique for the determination of heavy metals in fish species. In this method, a few microliters of organic solvent (40.0 µL carbon tetrachloride) was transferred to the bottom of a conical sample cup. Then 10.0 mL of aqueous solution was transformed to fine droplets while passing through the organic solvent. At this stage, metal-ligand hydrophobic complex was extracted into the organic solvent. After extraction, 20 µL of extraction solvent was injected into the graphite tube using an auto-sampler. RESULTS: Under optimal conditions, enrichment factors and enhancement factor were in the range of 180-240 and 155-214, respectively. The calibration curves were linear in the range of 0.03-200 µg kg-1 and the limits of detection (LODs) were in the range of 0.01-0.05 µg kg-1 . Repeatability (intra-day) and reproducibility (inter-day) for 0.50 µg L-1 Hg and 0.10 µg L-1 Cd and Pb were in the range of 3.1-4.2% (n = 7) and 4.3-6.1% (n = 7), respectively. CONCLUSION: Potential human health risk assessment was conducted by calculating estimated weekly intake (EWI) of the metals from eating fish and comparison of these values with provisional tolerable weekly intake (PTWI) values. EWI data for the studied metals through fish consumption were lower than the PTWI values. © 2017 Society of Chemical Industry.

Optimization of a methodology for the simultaneous determination of deltamethrin, permethrin and malathion in stored wheat samples using dispersive liquid-liquid microextraction with solidification of floating organic drop and HPLC-UV.

The purpose of this study was to investigate common pesticides in stored wheat at Kermanshah province's silos in Iran. A simple, inexpensive, reliable and environmentally friendly method based on dispersive liquid-liquid microextraction with solidification of floating organic drop was developed. The analytical characteristics of the method were determined. Also, various parameters such as the materials of the silos, types of ownerships of the silos, geographic orientation of silo locations and climatic conditions of silo locations on pesticide residues in studied wheat samples were investigated. Among all the studied parameters, the climatic conditions of silo locations showed the highest influence on pesticide residues in wheat samples. Generally, 61.2% of the samples had pesticide levels below the method detection limits and 38.8% of the total samples had at least one of the understudied pesticides. Also, 13.9% of the samples had deltamethrin residues, 16.7% of the samples had permethrin, 22.2% of the samples had malathion, 11.1% of the samples had both permethrin and malathion and 2.8% of the samples had both deltamethrin and malathion. The results revealed that the residues of deltamethrin and malathion were lower than the standard level announced by European Union regulation and only three samples contained permethrin higher than Europe standard level.

Sensitive determination of methadone in human serum and urine by dispersive liquid-liquid microextraction based on the solidification of a floating organic droplet followed by HPLC-UV.

Dispersive liquid-liquid microextraction based on solidification of floating organic droplet was developed for the extraction of methadone and determination by high-performance liquid chromatography with UV detection. In this method, no microsyringe or fiber is required to support the organic microdrop due to the usage of an organic solvent with a low density and appropriate melting point. Furthermore, the extractant droplet can be collected easily by solidifying it at low temperature. 1-Undecanol and methanol were chosen as extraction and disperser solvents, respectively. Parameters that influence extraction efficiency, i.e. volumes of extracting and dispersing solvents, pH, and salt effect, were optimized by using response surface methodology. Under optimal conditions, enrichment factor for methadone was 134 and 160 in serum and urine samples, respectively. The limit of detection was 3.34 ng/mmL in serum and 1.67 ng/mL in urine samples. Compared with the traditional dispersive liquid-liquid microextraction, the proposed method obtained lower limit of detection. Moreover, the solidification of floating organic solvent facilitated the phase transfer. And most importantly, it avoided using high-density and toxic solvents of traditional dispersive liquid-liquid microextraction method. The proposed method was successfully applied to the determination of methadone in serum and urine samples of an addicted individual under methadone therapy.

Sensitive determination of atorvastatin in human plasma by dispersive liquid-liquid microextraction and solidification of floating organic drop followed by high-performance liquid chromatography.

A novel and sensitive dispersive liquid-liquid microextraction method based on the solidification of the floating organic drop combined with high-performance liquid chromatography and ultraviolet detection was used for the determination of atorvastatine in blood serum samples. The chromatographic separation of atorvastatin was carried out using methanol as the mobile phase organic modifier. Various parameters affecting the extraction efficiency were optimized, such as the kind and volume of extraction solvent (1-undecanol) and disperser solvent (acetonitrile), pH, and the extraction time. The calibration curve was linear in the range of 0.2-6000 µg/L of atorvastatin (r(2) = 0.995) with a limit of detection of 0.07 µg/L. The relative standard deviation for 100 µg/L of atorvastatin in human plasma was 8.4% (n = 4). The recoveries of plasma samples spiked with atorvastatin were in the range of 98.8-113.8%. The obtained results showed that the proposed method is fast, simple, and reliable for the determination of very low concentrations of atorvastatin in human plasma samples.

Trace analysis of some organophosphorus pesticides in rice samples using ultrasound-assisted dispersive liquid-liquid microextraction and high-performance liquid chromatography.

An ultrasound-assisted dispersive liquid-liquid microextraction based on solidification of a floating organic drop method followed by high-performance liquid chromatography was developed for the extraction, preconcentration, and determination of trace amounts of organophosphorus pesticides in rice samples. Variables affecting the performance of both steps were thoroughly investigated. Some effective parameters on extraction were studied and optimized. Under the optimum conditions, recoveries for rice sample are in the range of 58.0-66.0%. The calibration graphs are linear in the range of 4-800 µg/kg and, limits of detection and limits of quantification are in the range of 1.5-3 and 4.2-8.5 µg/kg, respectively. The relative standard deviation for 50.0 µg/kg of organophosphorus pesticides in rice sample are in the range of 4.4-5.1% (n = 5). The obtained results show that proposed method is a fast and simple method for the determination of pesticides in cereals.

Acrylamide in potato chips in Iran, health risk assessment and mitigation.

This study aimed to determine the acrylamide content in potato chips sold in Kermanshah, Iran and assess the potential health concerns associated with acrylamide exposure. HPLC-DAD was used to analyse 120 samples across 40 brands. The possible non-carcinogenic risk index for adults was below 1 for all 40 brands (100%), but for children it was only below 1 for 9 brands (22.5%) and above 1 for 31 brands (77.5%). Regarding the possible carcinogenic risk index, for adults only 1 out of 40 brands rated > 10-4, whereas for children all brands rated > 10-4. This shows that children's exposure to acrylamide through potato chips consumption in Kermanshah can be considered a risk on cancer and exposure of adults requires attention and monitoring. The best way to reduce acrylamide in potato chips and associated health risks is to improve the production process, especially temperature and time.

Acid-based deep eutectic solvents followed by GFAAS for the speciation of As(III), As(V), total inorganic arsenic and total arsenic in rice samples.

In the present study, an efficacious, safe, inexpensive and eco-friendly microextraction was provided by deep eutectic solvents based on dispersive liquid-liquid microextraction (DLLME - DES) followed by GFAAS. A series of DESs were synthesised using l-menthol as hydrogen bond acceptor (HBA) and carboxylic acids with 4, 6, 8 and 10 carbon atoms as hydrogen bond donors (HBD). The synthesised DESs were used as extractants of arsenic ions. Under optimised conditions, good linearity with coefficient of determination (r2) 0.992 and an acceptable linear range of 0.3-100 µg kg-1 was obtained. The limit of detection was 0.1 µg kg-1 (S/N = 3) for arsenite (As(III)) ions, and a high enrichment factor (EF = 200) was obtained. The enhancement factor and extraction recovery (ER%) of the method were 340 and 60%, respectively. RSDs including inter- and intra-day ranged from 3.2% to 5.8% in three examined concentrations. After a specific digestion, the capability of the synthesised DES in the extraction of As(III) from rice was tested. Total inorganic arsenic was separated similarly after reduction of arsenate (As(V)) to As(III), and As(V) concentration was calculated by difference. Using a second digestion method, total arsenic concentration (sum of organic and inorganic arsenic) in the samples was determined.

Sensitive determination of daunorubicin in plasma of children with leukemia using pH-switchable deep eutectic solvents and HPLC-UV analysis.

An environmental friendly, fast, easy and inexpensive liquid-liquid microextraction (LLME) in combination with pH-switchable deep eutectic solvent (DES) method followed by HPLC was investigated for the separation and determination of daunorubicin (DNR) in human plasma samples. For this purpose, first, 9 DESs were prepared based on previous studies and their switchability in aqueous solution was evaluated by changing the pH. Non-switchable DESs were discarded and switchable DESs were used to extract DNR. The parameters affecting the extraction efficiency were optimized (DES type, volume of DES, concentration of KOH, volume of HCl, salt addition and extraction time). After optimizing the conditions and drawing the calibration curve, figures of merit were calculated. Relative standard deviations (%RSDs) based on 7 replicate with 50 µg L-1 of DNR in plasma were 2.7 for intra-day and 4.8 % for inter-day. A wide linear range from 0.15 to 200 µg L-1 was obtained. The detection limit of the method based on signal-to-noise 3 and the quantification limit of the method based on signal-to-noise 10 were 0.05 and 0.15, respectively. After spiking plasma samples with different concentrations of DNR, relative recoveries were obtained in the range of 91.0-107.8 %.

Application of magnetic dispersive solid phase extraction combined with solidification of floating organic droplet-based dispersive liquid-liquid microextraction and GC-MS in the extraction and determination of polycyclic aromatic hydrocarbons in honey.

A magnetic dispersive solid phase extraction method combined with solidification of floating organic droplet-based dispersive liquid-liquid microextraction has been validated for the extraction of polycyclic aromatic hydrocarbons from honey samples. For this purpose, a carbonised cellulose-ferromagnetic nanocomposite was used as a sorbent through the magnetic dispersive solid phase extraction. For preparation of the sorbent, first, carbonised cellulose nanoparticles were created by treating cellulose filter paper with concentrated solution of sulfuric acid. Then, the prepared nanoparticles were loaded onto Fe3O4 nanoparticles through coprecipitation. In the extraction process, first, a few mg of the sorbent was added to the diluted honey solution and dispersed in it using vortex agitation. The particles were then separated and the adsorbed analytes were eluted with an organic solvent. The eluent was taken and after mixing with a water-immiscible extraction solvent was used in the following solidification of floating organic droplet-based dispersive liquid-liquid microextraction procedure. By performing the extraction process under the obtained optimum conditions, low limits of detection (0.08-0.17 ng g-1) and quantification (0.27-0.57 ng g-1), satisfactory precision (relative standard deviations ≤ 5.0%), and wide linear range (0.57-500 ng g-1) with great coefficients of determination (r2≥ 0.9986) were obtained.

Application of dispersive liquid-liquid microextraction based on solidification of floating organic drop for simultaneous determination of alachlor and atrazine in aqueous samples.

Dispersive liquid-liquid microextraction based on solidification of floating organic drop coupled with HPLC-UV detection as a fast and inexpensive technique was applied to the simultaneous extraction and determination of traces of two common herbicides, alachlor and atrazine, in aqueous samples. The critical experimental parameters, including type of the extraction and disperser solvents as well as their volumes, sample pH, salt addition, and extraction time were investigated and optimized. Under the optimum conditions, the calibration graphs found to be linear in the range of 0.1-200 µg/L with LOD in the range of 0.02-0.05 µg/L. The RSDs were in the range of 4.2-5.3% (n = 5). The relative recoveries of well, tap, and river water samples which have been spiked with different levels of herbicides were 94.0-106.0, 99.0-105.0, and 88.5-97.0%, respectively.

Determination of abamectin in citrus fruits using SPE combined with dispersive liquid-liquid microextraction and HPLC-UV detection.

A new pretreatment method, SPE combined with dispersive liquid-liquid microextraction, was proposed for the determination of abamectin in citrus fruit samples for the first time. In this method, fruit samples were extracted by ultrasound-assisted extraction followed by SPE. Then, the SPE was used as a disperser solvent in the next dispersive liquid-liquid microextraction step for further purification and enrichment of abamectin. The effects of various parameters on the extraction efficiency of the proposed method were investigated and optimized. Good linearity of abamectin was obtained from 0.005 to 10.0 mg/kg for B1a and from 0.05 to 10.0 mg/kg for B1b with correlation coefficient (r(2)) of 0.998 for B1a and 0.991 for B1b, respectively. The LODs were 0.001 and 0.008 mg/kg (S/N = 3) for B1a and B1b, respectively. The relative recoveries at three spiked levels were ranged from 87 to 96% with the RSD less than 11% (n = 3). The method has been successfully applied to the determination of abamectin in citrus fruit samples.

Evaluation of blood lead levels in opium addicts and healthy control group using novel deep eutectic solvent based dispersive liquid-liquid microextraction followed by GFAAS.

Today, drug dealers and sellers add lead compounds to these substances to get more profit. As a result, drug users are heavily exposed to lead, and lead poisoning is clearly seen in most of them. Therefore, it is especially important to check the blood lead levels in these people. In this research, an efficient and eco-friendly pretreatment method was established by deep eutectic solvent for dispersive liquid-liquid microextraction (DES - DLLME) followed by graphite furnace atomic absorption spectrometry (GFAAS) analysis. The selected hydrophilic deep eutectic solvent consists of l-menthol and (1S)-( +)-camphor-10-sulfonic acid (CSA) at a 5:1 molar ratio as a green solvent instead of traditional toxic organic solvents. Under the optimal extraction conditions, the introduced method exhibited good linearity with coefficient of determination (r2) 0.9975 and an acceptable linear range of 0.3-80 µg L-1. Accordingly, the detection limit was 0.1 µg L-1 (S/N = 3) for lead ions, and the high enrichment factor (240) was obtained. The proposed method was successfully applied to analysis lead ions in real blood samples, which is a promising technique for biological samples. The case samples were classified and analyzed based on age, duration of consumption, and type of substance. The results showed that there was no significant difference between blood lead levels in different age groups and different duration of use, while blood lead levels were higher in opium residue (shireh) users than in opium users.

Chalcopyrite as an oxidants activator for organic pollutant remediation: A review of mechanisms, parameters, and future perspectives.

Advanced oxidation processes (AOPs) based on oxidants have attracted attention for the degradation of organic pollutants. The combination of chalcopyrite with oxidants such as persulfate, peroxide, percarbonate, and others shows promise as a system due to its ability to activate through various pathways, leading to the formation of numerous radical and non-radical species. In this review, the generation of sulfate radical (SR) and hydroxyl radical (HR) in AOPs were summarized. The significance of chalcopyrite in various approaches including Fenton, photo-Fenton, and photo/Fenton-like methods, as well as its involvement in electrochemical Fenton-based processes was discussed. The stability and reusability, toxicity, catalyst mechanism, and effects of operational parameters (pH, catalyst dosage, and oxidant concentration) are evaluated in detail. The review also discusses the role of Fe2+/3+, Cu1+/2+, S2- and Sn2- present in CuFeS2 in the generation of free radicals. Finally, guidelines for future research are presented in terms of future perspectives.

Determination of vanillin in different food samples by using SMM/Au@ZIF-67 electrochemical sensor.

Vanillin is a popular flavoring agent in many food products. Simple, fast, and reliable quantification of this compound is crucial for the food industry. In this work, we have developed a new electrochemical sensor for accurate detection of vanillin in various real samples. The composite electrode was made of sodium montmorillonite nanoclay (SMM) and gold nanoparticles modified ZIF-67 (Au@ZIF-67), in which SMM contributes to the large adsorption capacity of the analyte, ZIF-67 and SMM supply more sensing active sites, and gold nanoparticles provide high electrical conductivity. The sensing electrode was comprehensively characterized using Brunauer-Emmett-Teller, EDS, XRD, SEM, FTIR, and TEM, and its electrochemical behavior for determination of vanillin including the electrooxidation mechanism of vanillin and different parameters such as scan rate and pH value was investigated. The result revealed that a two electron-two proton process was involved in the electrooxidation of vanillin, which takes place more readily due to the lower potential on the surface of SMM/Au@ZIF-67/carbon paste electrode. The new composite electrode was also more sensitive to vanillin detection with an anodic peak current almost 2.6 times more than that of the bare electrode. A linear sensing concentration range was established between 1 and 1200 nM with a detection limit of 0. 3 nM and a limit of quantitation of 1 nM. For real samples, the sensor demonstrated excellent recovery rates and reliability that was comparable to the standard high-performance liquid chromatography method.

A national systematic literature review for aflatoxin M1 in commonly consumed cheese brands in Iran: Human health risk assessment by Monte Carlo simulation.

Cheese is popular in Iran because of its high nutritional value; therefore, it is necessary to control this product regarding health risk factors, particularly aflatoxin M1 (AFM1). This research reviewed AFM1 in various varieties of cheese in Iran to assess the potential health risks associated with consuming these products for different age groups. In this regard, all accessible papers from different databases were screened between June 27, 2000 and October 10, 2022 b y systematic research and then considering the selection criteria of the studies; finally, 22 articles were selected for the current review. The amount and prevalence of AFM1 were calculated and separated based on the cheese variety, and the sampling location; health risk assessment (HRA), statistical, uncertainty, and sensitivity analysis for AFM1 of cheese for different age groups were performed. The study results for 2143 samples showed that the overall average AFM1 for cheese is 160 ± 175 ng/kg, below the European Commission (EC) regulation (250 ng/kg). AFM1 contaminated 72.42% of all cheese samples, and 13% of these contaminated samples had a higher AFM1 than the EC regulation. Cheese varieties were ranked based on average levels of AFM1 as white pasteurized > traditional > creamy > probiotic > Lighvan, and this ranking was obtained based on sampling locations as market > dairy factories > livestock farms. Based on the HRAs, from the perspective of the liver cancer risk (LCR), the margin of exposure (MOE), and the hazard index (HI) approach, it can be concluded that cheese produced in Iran, in terms of AFM1, particularly for children, poses serious health risks. Accordingly, it is imperative to carefully consider implementing suitable management methods to inhibit the growth of aflatoxin B1 (AFB1) in livestock fodder, and training in sanitary production and processing of dairy products according to world standards is suggested for industrial and traditional cheese producers across Iran.

Simultaneous preconcentration and determination of 2,4-D, alachlor and atrazine in aqueous samples using dispersive liquid-liquid microextraction followed by high-performance liquid chromatography ultraviolet detection.

Dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography-ultraviolet detection as a fast and inexpensive technique was applied to the simultaneous extraction and determination of traces of three common herbicides, 2,4-D, alachlor and atrazine, in aqueous samples. The critical experimental parameters, including type of the extraction and disperser solvents as well as their volumes, sample pH, salt addition, extraction time and centrifuging time, and speed were investigated and optimized. Under the optimum conditions, the calibration graphs found to be linear in the range of 0.3-200 µg/L with limits of detection in the range of 0.05-0.1 µg/L. The relative standard deviations were in the range of 4.5-6.2% (n = 7). The relative recoveries of well, tap, and river water samples which have been spiked with different levels of herbicides were 92.0-107.0, 82.0-104.0, and 82.0-86.0%, respectively.

Countercurrent Salting-out Homogenous Liquid-Liquid Extraction and Dispersive Liquid-Liquid Microextraction Based on the Solidification of Floating Organic Drop Followed by High-Performance Liquid Chromatography for the Isolation and Preconcentration of Pesticides from Fruit Samples.

BACKGROUND: Pesticides are widely used to control pests and prevent diseases in crops, including cereals, vegetables, and fruits. Due to factors such as the persistence of pesticides, bioaccumulation, and potential toxicity, pesticide residue monitoring in foodstuffs is very important. OBJECTIVE: In the current research, we proposed a novel approach using countercurrent salting-out homogenous liquid-liquid extraction combined with dispersive liquid-liquid microextraction based on the solidification of floating organic droplets (DLLME-SFO) for isolation and preconcentration of pesticides from aqueous samples for analysis by high-performance liquid chromatography-ultraviolet detection (HPLC-UV). METHODS: In brief, sodium chloride was used as a separation reagent, in a small glass column, through which was passed a mixture of an aqueous solution of, for example, fruit juice and acetonitrile. In this process, the droplets rose through the column and a separated layer would be formed on the remained an aqueous phase. Following that, acetonitrile as the organic phase was mixed with 50.0 µL of 1-undecanol (extraction solvent). To further enrich the analytes, the mixture was injected into 5 mL of a 4% w/v sodium chloride solution and placed in a tube for the DLLME-SFO. RESULTS: Under optimal conditions, a dynamic linear range of 0.5-500 µg/L, extraction recovery of 65-85%, enrichment factors of 108-142, and limit of detection of 0.2-0.4 µg/L were obtained for the organophosphorus pesticides analysed. In addition, the repeatability and reproducibility from five replicate measurements of the pesticides (100 µg/L) were within the ranges of 3.5-5.1% and 4.5-6.3%, respectively . CONCLUSION: In this research, a new extraction method based on countercurrent salting out homogeneous liquid-liquid extraction combined with DLLME-SFO has been applied for the determination of pesticide residues in fruits, juice and environmental samples before using HPLC-UV analysis. The combined method not only leads to high enrichment factors, but can also be used in complex matrices (such as fruits, juices and high-salt solutions) without pre-treatment or dilution. Compared with other sample preparation methods, this analysis procedure has many advantages, including simplicity, ease of operation, high pre-enrichment factor, low detection limit and relatively short analysis time. HIGHLIGHTS: Combination of CCSHLLE and DLLME-SFO was applied for the analysis of organophosphorous pesticide residues in fruit, fruit juices and environmental samples. The DLLME-SFO method avoided using high density and toxic extraction solvents. LODs are achievable at ng L-1 using CCSLLE-DLLME-SFO-HPLC-UV.

Extraction and determination of strobilurin fungicides residues in apple samples using ultrasound-assisted dispersive liquid-liquid microextraction based on a novel hydrophobic deep eutectic solvent followed by H.P.L.C-U.V.

In this study, several novel and natural hydrophobic deep eutectic solvents (D.E.Ss) were prepared using methyl trioctylammonium chloride (M.T.O.A.C) as H.B.A and different types of straight chain alcohols as H.B.Ds. One of the D.E.Ss composed of M.T.O.A.C and n-butanol was advantageously used to develop an ultrasound-assisted dispersive liquid-liquid microextraction (U.A-D.L.L.M.E) method combined with high-performance liquid chromatography-ultraviolet detection (H.P.L.C-U.V) for the determination of some strobilurin fungicides in apple samples. Several important parameters influencing extraction efficiency were investigated and optimised, including the type and volume of extractant in ultrasound stage, sonication time, the type and volume of D.E.S, sample solution pH and effect of salt addition. Under optimal experimental conditions, the method showed good linearity with correlation coefficients (R2) of 0.9985 - 0.9991 in the linear range of 4-1500 µg kg-1, low limits of detection of 1.5-2 µg kg-1 and acceptable extraction recoveries in the range of 76-92%. Enrichment factor was in the range of 95-115. The proposed method was successfully applied for the extraction and preconcentration of trace fungicides in apple samples, and the results demonstrated the potential of the synthesised D.E.S for the extraction and determination of contaminants in aqueous samples.