Ultrasound-assisted Dispersive Liquid-liquid Microextraction Research Articles

Alcohol-based hydrophobic deep eutectic solvents and ultrasound-assisted liquid phase microextraction followed by GC-MS for the extraction and analysis of organophosphorus pesticides in the blood of farmers.

Organophosphorus pesticides (OPPs) are a group of pesticides that are most widely used in the agricultural sector, and farmers are exposed to these chemicals more than other members of society. In this work, an environmentally friendly, simple, and safe ultrasound-assisted dispersive liquid-liquid microextraction (USA-DLLME) method using alcohol-based hydrophobic deep eutectic solvents (HDESs) followed by gas chromatography-mass spectroscopy (GC-MS) was developed for the extraction and determination of OPPs in the blood of farmers studied in Ravansar cohort. DESs synthesized from thymol as hydrogen bond donor (HBD) and aliphatic alcohols as hydrogen bond acceptor (HBA) have been used as extractants. Under optimal experimental conditions, the reproducibility of the method based on 7 replicate measurements of 10 µg L-1 of OPPs in blood samples was in the range of 1.4-3.8%. The method showed a linearity in the range of 0.01-150 µg L-1. The limits of detection and limits of quantification were between 0.003 and 0.02 µg L-1 and 0.01-0.05 µg L-1, respectively. The matrix effect and accuracy of the method were confirmed by spiking different amounts of OPPs in real blood samples and obtaining relative recoveries in the range of 91-112%. The results showed that the concentration of OPPs in the case group was significantly higher than in the control group, which is because the case group was exposed to OPPs during the spraying of agricultural products.

Solvent-Focused Gas Chromatographic Determination of Thymol and Carvacrol Using Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction through Solidifying Floating Organic Droplets (USA-DLLME-SFO).

An ultrasound-assisted dispersive liquid-liquid microextraction by solidifying floating organic droplets, coupled to a form of temperature-programmed gas chromatography flame ionization detection, has been developed for the extraction and determination of thymol and carvacrol. This method utilizes undecanol as the extraction solvent, offering advantages such as facilitating phase transfer through solidification and enhancing solvent-focusing efficiency. The optimal gas chromatography conditions include a sample injection volume of 0.2 µL, a split ratio of 1:10, and a flow rate of 0.7 mL min-1. The extraction conditions entail an extraction solvent volume of 20 µL, a disperser solvent (acetone) volume of 500 µL, pH 7.0, 7.0% NaCl (3.5 M), a sample volume of 5.0 mL, an ultrasound duration of 10 min, and a centrifuge time of 7.5 min (800 rpm). These conditions enable the achievement of a high and reasonable linear range of 3.5 to 70. 0 μg mL-1 for both thymol and carvacrol. The detection limits are found to be 0.95 and 0.89 μg mL-1, respectively, for thymol and carvacrol. The obtained relative standard deviations, 2.7% for thymol and 2.6% for carvacrol, demonstrate acceptable precision for the purpose of quantitative analysis.

Investigating the capability of UA-DLLME and DART-HRMS in the analysis of benzodiazepines in whole human blood

Benzodiazepine (BZD) misuse has increased in the last decade, making its occurrence in criminal cases more commonplace. The detection of BZD in complex biological samples is challenging since they are usually found in small concentrations, requiring the development of sensitive and fast-to-execute methods. In this study, the application of direct analysis in real time – high-resolution mass spectrometry (DART-HRMS) was evaluated in the detection of 10 benzodiazepines (diazepam, oxazepam, chlordiazepoxide, temazepam, alprazolam, flunitrazepam, bromazepam, clonazepam, lorazepam, and midazolam) in ante and postmortem blood samples. Moreover, an ultrasound-assisted dispersive liquid–liquid microextraction (UA-DLLME) approach was developed by full factorial design as a clean-up step before the DART-HRMS analysis. DART-HRMS was capable of qualitative detection of all evaluated BZD in raw antemortem blood samples at concentrations as low as 10 µg mL−1. The UA-DLLME DART-HRMS approach was linear for the 10 BZD in the range of 1 to 10 µg mL−1, with recoveries ranging from 78.5 to 119.5 %, a precision lower than 36 % at 1 µg mL−1, and limits of detection varying between 0.25 and 0.50 µg mL−1. Moreover, the UA-DLLME DART-HRMS method was efficiently applied to postmortem blood samples from criminal cases, enabling the detection of BZD. The developed method facilitated the analysis of 10 BZD in ante and postmortem blood samples, offering a quick sample extraction that linked to the DART-HRMS can be used as a fast and reliable triage method for regulatory screening purposes and could be readily integrated into routine forensic analysis workflows in a high throughput manner.

Evaluate the aluminum concentrations in whey milk samples of cows from different areas using deep eutectic solvent-based ultrasound-assisted dispersive liquid-liquid microextraction method

This study investigates the contamination of cow milk with aluminum (Al) and its potential health implications, particularly for children. Cow milk samples were collected from both nonexposed and exposed areas in Sindh, based on the source of livestock drinking water (fresh canals and groundwater). An environmental friendly deep eutectic solvent (DES) was used with ultrasonic-assisted dispersive liquid-liquid microextraction (UDLLμE) to enrich trace amounts of Al in whey milk and water samples. The enriched samples were then analyzed using inductively coupled plasma optical emission spectrometry. Certified reference materials were employed to validate the methodology, and the experimental results exhibited acceptable conformity. The DES-based dispersive liquid-liquid microextraction method was environmental friendly, devoid of acids and oxidizing agents, and used safe and inexpensive components for routine trace metal analysis in diverse samples. The resulting data revealed that Al in whey milk samples was observed in the range of 31–45 %, corresponding to (160–270) μg L−1 and (700–1035) μg L−1 in nonexposed and exposed whole cow milk samples, respectively. Additionally, it was observed that milk boiling in Al utensil for 10–20 min enhanced the Al levels from 3 to 8% of its total contents in milk samples.

An optimized methodology for the determination of multiclass organic ultraviolet sunscreens and metabolites in human milk through chromatographic and chemometric resolution

Organic UV filters (UVFS) are used to mitigate the dermal effects associated with health risks from UV radiation, making them essential in personal care products. UVFS are frequently identified in environmental samples due to their high lipophilicity and persistence, underscoring the urgency of comprehensive assessments and regulatory measures aimed at safeguarding ecosystems and human health. The present study reports a multiclass analytical method for determining 16 UV sunscreens and metabolites in breast milk based on an ultrasound-assisted-dispersive liquid-liquid micro-extraction (UA-DLLME) with further chromatographic and chemometric resolution. The experimental conditions of the UA-DLLME were optimized through the implementation of the Design of Experiment tools. To model the responses, least-squares and artificial neural network methodologies were implemented. The optimal conditions were found by employing the desirability function. The samples were analyzed through reverse-phase liquid chromatographic separation, UV diode array, and fast-scanning fluorescence detection. The chromatographic analysis enabled the resolution of 16 analytes in a total time of 13.0 min. Multivariate curve resolution-alternating least-square (MCR-ALS) modelling was implemented to resolve analytes that were not fully resolved and to determine analytes that coeluted with endogenous components of the breast milk samples. An enrichment factor of 5-fold concentration was obtained with this methodology, reaching recoveries between 65 % and 105 % for 13 multiclass UV sunscreens and metabolites in breast milk samples with RSD % and REP % lower than 12 %.

A novel deep eutectic solvent-based ultrasound-assisted dispersive liquid–liquid microextraction coupled with high-performance liquid chromatography for the determination of quinolones in environmental water samples

In this work, a novel deep eutectic solvent composed of thymol and octanol was synthesized and employed as a green extractant for ultrasound-assisted dispersive liquid–liquid microextraction (UA-DLLME) of three quinolones in environmental water followed by HPLC-UV analysis. Parameters affecting UA-DLLME were investigated and optimized. The optimal DES ratio was 2:1, the volume was 150 μL, ultrasonic time was 5 min, and the NaCl concentration was 0.68 mol·L-1. Good linearity was obtained over the concentration range of 1–100 ng·mL−1 with R2 ≥ 0.9986. The limits of detection (LOD) were 0.1–0.3 ng·mL−1 and the limits of quantification (LOQ) were 0.4–1.0 ng·mL−1 with RSD less than 4.8%. The method was fast, sensitive and eco-friendly, which offered a new way to monitor quinolone levels in environmental water.

Development of a generic approach for monitoring leachable compounds in hospital pharmacy-prepared prefilled plastic packaging by ultrahigh-performance liquid chromatography coupled to high-resolution mass spectrometry with postcolumn infusion

Prefilled plastic packaging is time- and cost-effective in hospital pharmacy because it prevents waste, preparation errors, dosage errors, microbial contamination and accidents. This packaging mostly includes prefilled syringes (PFS), intravenous (IV) bags and vials intended for long-term storage that can be used for immediate treatment. There is a rising availability in the market for prefilled drug products due to their practical approach. Leachable compounds could be evaluated in hospital pharmacy-prepared prefilled drug solutions. The Pharmacy Department at the Lausanne University Hospital has developed an innovative, highly sensitive, and generic method by postcolumn infusion based on ultrahigh-performance liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) for the analysis of plastic additives in hospital pharmacies. The postcolumn infusion solution was developed with 2% ammonium hydroxide in methanol on a representative set of 30 candidate compounds with different physical-chemical properties, such as log P and molecular structure, to represent the most important categories of additives. The LODs obtained for all compounds ranged from 0.03 to 7.91 ng/mL with linearity up to 250 ng/mL. Through this screening method, plastic additives can be rapidly identified due to the combined use of retention time, exact mass (including isotopic pattern) and MS/MS spectra. In addition, the users can screen for vast categories of plastic additives, including plasticizers, epoxy monomers, antioxidants, UV stabilizers, and others. The screening is facilitated by assessments of a complex in-house-built database for extractable and leachable trace assessment (DELTA), containing 205 compounds for unambiguous identification. Relative response factors were established for all analytes to obtain a semiquantitation of compounds. Moreover, the database also contains valuable estimative toxicology information, which was obtained through calculating their permissible dose exposure threshold; thus, estimative toxicology assessment can be performed for identified compounds in prefilled drug products. This method and the database were applied to a hospital pharmacy-prepared prefilled vancomycin syringe for paediatric use. Ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) was used to prepare the samples for leachable analysis. As a result, 17 plastic additives were formally identified, and their concentrations were estimated. A toxicology assessment was performed by comparing their concentrations with their theoretical PDE thresholds. In conclusion, the prefilled drug solution released a negligible amount of known leachables that appeared to be safe for use in neonates and children.

Development of microextraction methods for the determination of sulfamethoxazole in water and biological samples: modelling, optimization and verification by central composite design

This study aimed to preconcentration of sulfamethoxazole (SMX) in water and biological samples. Ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) and ultrasound-assisted dispersive solid-phase microextraction (UA-DSPME) methods paired with spectrophotometry were applied to extraction and preconcentration of SMX. ZnFe2O4 nanoparticles were prepared as adsorbent in UA-DSPME method by hydrothermal method. The scanning electron microscopy (SEM) technique showed that the adsorbent had symmetrical, bullet-shaped particles with uniform size. The results of the X-ray diffraction (XRD) showed the successful synthesis of the ZnFe2O4 nanoparticles. Effective parameters in extraction, including ultrasonication time, disperser solvent volume, adsorbent amount, extraction solvent volume, eluent volume, and pH were investigated and optimized. The practical and optimal conditions of the process were determined by the central composite design (CCD). The optimal conditions were 0.024 g of adsorbent, 535 µL of disperser solvent volume, 7.5 min of ultrasonication time, 235 µL of eluent volume, pH of 5, and 185 µL of extraction solvent volume. Linear ranges and detection limits were 20–1,200 μg L−1 and 6 μg L−1 for UA-DSPME and 10–800 μg L−1 and 3 μg L−1 for UA-DLLME. Relative standard deviation (RSD) of less than 4% were obtained for UA-DSPME and UA-DLLME methods. The reusability showed that the ZnFe2O4 adsorbent could extract SMX up to five cycles of adsorption/desorption without significant reduction in its efficiency. Also, interference studies showed that the presence of different cations and anions did not significantly interfere in the extraction of SMX. The outcomes of real-time samples analysis showed that the extraction of SMX for both methods was in the range of 92.44%–99.12%. The results showed the developed methods are simple, sensitive, and suitable for SMX preconcentration in environmental water and biological samples.

Ultrasound-assisted dispersive liquid-liquid microextraction based on solidification of floating organic drop for analiysis of propineb in water and food samples: Experimental modeling

Here, a fast and simple ultrasound-assisted dispersive liquid-liquid microextraction based on solidification of floating organic drop using deep eutectic solvent (UA-DLLME–SFO–DES) procedure was optimized for the extraction of propineb from water and food samples prior to analysis by UV-VIS spectrophotometer. In this research, the extraction step was carried out by using DESs as the extraction solvent. The optimization of the significant variables of the UA-DLLME–SFO–DES procedure was carried out by multivariate statistical method. After multivariate optimization, linearity range was observed from 20 to 450 ng mL−1. The detection limit, preconcentration factor, and enhancement factor were estimated as 6.1 ng mL−1, 120, and 93, respectively. The calibration curve of the UA-DLLME–SFO–DES procedure was estimated at A = 0.0074–0.015 [propineb, ng mL−1]. Intra- and inter-day precisions were ≤1.9% and ≤2.8%, respectively. Recoveries between 90.4% and 98.6% indicated the absence of matrix effects, indicating that the UA-DLLME–SFO–DES procedure was suitable for the extraction and determination of propineb in water and food samples. The UA-DLLME–SFO–DES procedure was an efficient, simple, and cheap alternative to other extraction and determination techniques, and can be used for routine monitoring of propineb in complex matrices.

Ultrasound-assisted dispersive liquid-liquid microextraction approach for preconcentration of acyclovir as antiviral drug in dosage forms prior to spectrophotometric determination

ABSTRACT. For acyclovir (ACV) determination in bulk and dosage forms, quick, sensitive, straightforward, and eco-friendly ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME)-based spectrophotometric method has been created and validated. ACV with 1,2-naphthoquine-4-sulfonate (NQS) react in alkaline medium to produce a yellow-colored product, which is the basis of the newly created method. Investigation and optimization were done on the crucial experimental variables influencing ACV's extraction effectiveness. At λmax = 495 nm, the minuscule organic droplets were detected. The linearity was present from 0.1 to 3.0 μg/mL under ideal circumstances, with a linear correlation coefficient of 0.9995. The detection limit was 0.03 μg/mL and quantification limit was 0.1 μg/mL. 22.50 was the enrichment factor. Relative standard deviation (RSD%) as accuracy at 2.0 μg/mL of ACV was 1.0%, with good recovery (99.30%). The developed UA-DLLME method was effectively used to determine the ACV in dosage forms, and the validation was evaluated. Results from the suggested technique for dosage forms and pure ACV were in excellent agreement with the results from the official method.
 
 KEY WORDS: Ultrasound-assissted, Dispersive liquid–liquid microextraction, Acyclovir, Spectrophotometry, Dosage forms
 Bull. Chem. Soc. Ethiop. 2023, 37(5), 1081-1092. 
 DOI: https://dx.doi.org/10.4314/bcse.v37i5.2

Profiling Docetaxel in Plasma and Urine Samples from a Pediatric Cancer Patient Using Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction Combined with LC-MS/MS.

In recent years, therapeutic drug monitoring (TDM) has been applied in docetaxel (DOC)-based anticancer therapy to precisely control various pharmacokinetic parameters, including the concentration of DOC in biofluids (e.g., plasma or urine), its clearance, and its area under the curve (AUC). The ability to determine these values and to monitor DOC levels in biological samples depends on the availability of precise and accurate analytical methods that both enable fast and sensitive analysis and can be implemented in routine clinical practice. This paper presents a new method for isolating DOC from plasma and urine samples based on the coupling of microextraction and advanced liquid chromatography with tandem mass spectrometry (LC-MS/MS). In the proposed method, biological samples are prepared via ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) using ethanol (EtOH) and chloroform (Chl) as the desorption and extraction solvents, respectively. The proposed protocol was fully validated according to the Food and Drug Administration (FDA) and the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH) requirements. The developed method was then applied to monitor the DOC profile in plasma and urine samples collected from a pediatric patient suffering from cardiac angiosarcoma (AS) with metastasis to lungs and mediastinal lymph nodes, who was receiving treatment with DOC at a dose of 30 mg/m2 body surface area. Due to the rarity of this disease, TDM was carried out to determine the exact levels of DOC at particular time points to ascertain which levels were conducive to maximizing the treatment's effectiveness while minimizing the drug's toxicity. To this end, the concentration-time profiles of DOC in the plasma and urine samples were determined, and the levels of DOC at specific time intervals up to 3 days after administration were measured. The results showed that DOC was present at higher concentrations in the plasma than in the urine samples, which is due to the fact that this drug is primarily metabolized in the liver and then eliminated with the bile. The obtained data provided information about the pharmacokinetic profile of DOC in pediatric patients with cardiac AS, which enabled the dose to be adjusted to achieve the optimal therapeutic regimen. The findings of this work demonstrate that the optimized method can be applied for the routine monitoring of DOC levels in plasma and urine samples as a part of pharmacotherapy in oncological patients.

Thymol-Based Hydrophobic Deep Eutectic Solvents as a Green Approach for Screening Polar Nitrosamines in Sartans Pharmaceutical Products by Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction Combined with HPLC-DAD

Nitrosamines are carcinogens substances firstly detected in sartans drugs in 2018, leading to new regulations and monitoring programmes that raised the costs and challenges to the pharmaceutical industry. Therefore, reliable and cost-effective methods for screening nitrosamines in medicines are highly desirable. Hydrophobic deep eutectic solvents (HDES), a novel “eco-friendly” alternative to solvents commonly used in microextraction techniques, can meet these requirements. In this study, a simple and rapid method of ultrasound-assisted dispersive liquid-liquid microextraction using thymol-based HDES followed by HPLC-DAD detection was developed for the determination of n-nitrosodimethylamine (NDMA) and n-nitroso-n-methylamino butyric acid (NMBA) from candesartan, irbesartan, losartan, olmesartan, telmisartan and valsartan drug substances, and from losartan tablets. Various influencing factors (such as HDES type, HDES:sample ratio, salt addition and sample pH) were investigated. Best extraction efficiencies were achieved with thymol:benzyl alcohol HDES. Under optimal conditions, the linearities ranged from 15 to 1000 ng mL−1 for both NDMA and NMBA (R² > 0.99), with recoveries between 81.8–104.2% and precision from 0.2 to 14.6%. The limits of detection were 17.3 – 220.0 ng g−1 and 16.3 – 290.0 ng g−1 for NDMA and NMBA, consecutively. Finally, the proposed method was successfully applied in spiked sartans drug substances and in losartan potassium tablets collected in the market.

Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction Using Deep Eutectic Solvents (DESs) for Neutral Red Dye Spectrophotometric Determination.

Deep eutectic solvents (DES), which have low toxicity and are low cost, biodegradable, and easily synthesized, were used for the extraction of neutral red (NR) dye before its spectrophotometric analysis. DES, containing choline chloride as a hydrogen bond acceptor and phenol as a hydrogen bond donor with a molar ratio of 1:2, was used for the extraction of NR dye from aqueous media. The possible interaction of different DESs with NR was studied using density functional theory (DFT) calculations. Experimentally, a UV-visible spectrophotometer was used for the quantitative analysis. The most important parameters affecting method performance, such as pH, extraction temperature, DES type, its volume, THF volume, sonication time, and centrifugation time, were optimized. The developed method provides exceptional sensitivity in terms of LOD and LOQ, which were 2.2 and 7.3 µg/L respectively. The relative standard deviation was 1.35–1.5% (n = 10), and the pre-concentration factor was 40. The method was found to be linear in the range of 2–300 µg/L (R2 = 0.9967). The method was successfully used for the determination of NR in wastewater samples. Finally, the DES-based method presents operational simplicity, high sensitivity, and rapid determination (<5 min) compared with other analytical procedures.

Experimental design of magnetic ionic liquid ultrasound-assisted dispersive liquid-liquid microextraction for the determination of 5-HMF in honey samples

A green, sensitive, and accurate ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) procedure using a magnetic ionic liquid (magnetic-IL) was optimized for the preconcentration and extraction of 5-hydroxymethylfurfural (5-HMF) in honey samples collected from different regions of Turkey prior to analysis by UV–VIS spectrophotometer. A multivariate optimization strategy was employed to optimize microextraction factors (pH, [C8mim]FeCl4 magnetic-IL amount, ultrasound time, dispersing agent volume) affecting the magnetic-IL UA-DLLME. Since the separation of the phases was achieved with a neodymium magnet, centrifugation step was not necessary. Under optimal experimental conditions, linear range of 3–600 µg L−1, limit detection of 1.0 µg L−1 and an enrichment factor of 175 were obtained. The magnetic-IL UA-DLLME procedure was successfully applied for the analysis of 5-HMF in the honey samples, and the extraction recovery were in the range of 92–103%. To evaluate the precision of the magnetic-IL UA-DLLME procedure, relative standard deviations from the inter-day assay and intra-day assay ranged from 3.9% to 5.1% and 3.3–4.2%, respectively. This study reports the first application of magnetic-IL with the UA-DLLME technique based on multivariate optimization for the determination of 5-HMF in different honey samples.

GC–MS determination of malondialdehyde, acrolein, and 4-hydroxy-2-nonenal by ultrasound-assisted dispersive liquid-liquid microextraction in beverages

A new, fast, simple, and effective ultrasound-assisted dispersive liquid-liquid microextraction procedure (UA-DLLME) for the gas chromatography-mass spectrometry (GC–MS) determination of malondialdehyde, acrolein, and 4-hydroxy-2-nonenal in beverages was successfully developed. 2,4-Dinitrophenylhydrazine derivatization was performed during extraction. An asymmetrical 3541//18 screening design and a central composite surface response design were used to investigate the influence of the most critical factors during the extraction process (ultrasound time and temperature, extraction and disperser solvents volumes, salt addition, and derivatization reagent concentration). According to FDA guidelines, the method was validated, achieving good linearities with r2 ≥ 0.9982, recoveries between 94.0 and 102.4%, and reproducibility with RSD lower than 4.5%. The method was applied to simultaneously determine the compounds in 60 different beverage samples, including beer, coffee, black tea, and fruit juices. The presence of secondary lipid oxidation products is demonstrated in beverages with a strong roasting process or oxidation.

Comparison Studies on Several Ligands Used in Determination of Cd(II) in Rice by Flame Atomic Absorption Spectrometry after Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction.

Ligands plays an important role in the extraction procedures for the determination of cadmium in rice samples by using flame atomic absorption spectrometry (FAAS). In the present study, comparative evaluation of 10 commercially available ligands for formation of Cd(II)-ligand complex and determination of cadmium in rice samples by ultrasound-assisted dispersive liquid–liquid microextraction (UADLLME) combined with FAAS was developed. Sodium diethyldithiocarbamate (DDTC) provided a high distribution coefficient as well as a good absorbance signal, therefore DDTC was used as a ligand in UADLLME. A low density and less toxic solvent, 1-heptanol, was used as the extraction solvent and ethanol was used as the disperser solvent. In addition, the experimental conditions of UADLLME were optimized in standard solution first and then applied in rice, such as the type and volume of extractant and dispersant, pH, extraction time, and temperature. Under the optimal experimental conditions, the detection limit (3σ) was 0.69 μg/L for Cd(II). The proposed method was applied for the determination of Cd(II) in three different rice samples (polished rice, brown rice, and glutinous rice), the recovery test was carried out, and the results ranged between 96.7 to 113.6%. The proposed method has the advantages of simplicity, low cost, and accurate and was successfully applied to analyze Cd(II) in rice.

New low viscous hydrophobic deep eutectic solvents for the ultrasound-assisted dispersive liquid-liquid microextraction of endocrine-disrupting phenols in water, milk and beverage

In the present work, several new hydrophobic deep eutectic solvents (HDESs) were prepared with quaternary ammonium salts as hydrogen bond acceptors (HBAs) and salicylate esters as hydrogen bond donors (HBDs). Then, the obtained HDESs were used as extraction solvents to establish an ultrasound-assisted dispersive liquid-liquid microextraction method combined with high-performance liquid chromatography-ultraviolet detection technique for the determination of four endocrine-disrupting phenols (EDPs) compounds. One of the obtained HDESs composed of tetrabutylammonium chloride (N4444Cl) and methyl salicylate possessed a viscosity of 89.28 mPa•s lower than most reported ionic HDESs (>200 mPa•s), and the low viscous HDES was selected as the optimal extraction solvent. Several key parameters affecting the extraction efficiency were investigated, including the type and volume of HDES, ultrasound time, sample solution pH and salt addition. Under the optimized experimental conditions, the proposed method had good coefficients of determination (R2 > 0.9976) in the linear range of 0.5–400 µg•L−1, the limits of quantification and limits of detection respectively were 0.5–2.5 µg•L−1 and 0.25–1 µg•L−1, and the recoveries were in the range of 81.79–109.82%. Finally, the method was used for the preconcentration and determination of EDPs in different samples, including bottled water, tea beverage and milk.

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

ABSTRACT 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 (R 2) 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.

Novel hydrophobic deep eutectic solvents for ultrasound-assisted dispersive liquid-liquid microextraction of trace non-steroidal anti-inflammatory drugs in water and milk samples

In the present study, several novel and natural hydrophobic deep eutectic solvents (HDESs) were prepared, and one of the HDESs composed of guanidinium chloride and thymol was advantageously used to develop an ultrasound-assisted dispersive liquid–liquid microextraction (UA-DLLME) method combined with high-performance liquid chromatography for the determination of four non-steroidal anti-inflammatory drugs (NSAIDs). Several important parameters influencing extraction efficiency were investigated and optimized, including the type and volume of HDES, ultrasound time, solution pH and the amount of salt addition. Under optimal experimental conditions, the method showed good linearity with the determination coefficients (R2) of 0.994–0.999 in the linear range of 5–2000 μg/L, low limits of detection of 0.5–1 μg/L and acceptable recoveries in the range of 79.42%–107.52%. The proposed method was successfully applied for the pretreatment of trace NSAIDs in real water and milk samples, and the results demonstrated the potential of the synthesized HDES for the extraction and determination of contaminants in aqueous samples.

Ultrasensitive determination of underivatized adamantane analogs in biological fluids by capillary electrophoresis with contactless conductivity detection

Separation techniques are promising for the detection of adamantane analogs with various functional groups. The derivatization of adamantane analogs with chromophores or fluorophores should be conducted using a separation technique combined with a common ultraviolet–visible or fluorescence detector. However, limited research has been conducted on underivatized adamantane analogs. Therefore, we present a highly rapid and sensitive method for detecting underivatized adamantane analogs by integrating ultrasound-assisted dispersive liquid–liquid microextraction (UADLLME), field-amplified sample stacking (FASS)-related capillary electrophoresis (CE), and capacitively coupled contactless conductivity detection (C4D). In the proposed system, UADLLME is used for sample clean up and analyte enrichment, whereas FASS-related CE provides on-line concentration of underivatized adamantane analogs during CE separation. A mixture of memantine (MT), amantadine (AT), and rimantadine (RT) was separated at baseline within 8 min through the application of optimized UADLLME (mixing extraction solvent, 50 μL of 1,1,2,2-tetrachloroethane (C2H2Cl4) and dispersive solvent, 200 μL of acetonitrile; mixing solution was injected into 1 mL of the sample solution at pH 12.5), FASS (buffer, 1.5 M acetic acid; additive, 0.05 mM β-cyclodextrin; pH 2.5), and C4D (amplitude, 2 Vpp; frequency, 500 kHz). The calibration curve exhibited acceptable linearity, with a coefficient of determination higher than 0.99. The limits of detection (signal-to-noise ratio of 3) were estimated to be 0.9, 1.0, and 1.2 nM for MT, AT, and RT, respectively. The relative standard deviations of peak areas varied from 8.9% to 9.3% (n = 5), whereas the sensitivity improvement of three underivatized adamantane analogs ranged from 1342 to 1766. The feasibility and accuracy of the present method for the determination of MT, AT, and RT in human serum and urine was satisfactorily confirmed by the excellent recovery and relative error. The proposed method exhibited high enrichment factors and offers excellent precision, high accuracy, and a short analysis time.