Dispersive Liquid-liquid Microextraction Method Research Articles

Digital colorimetric detection of ammonium in water samples after microextraction procedure using deep eutectic solvent, based on DLLME method

In this study, we have presented a simple, cost-effective, and efficient method for quantifying ammonium ions based on digital colorimetry using a smartphone. Firstly, ammonium ions are converted into a yellow-colored derivative in an alkaline medium in the presence of acetylacetone and formaldehyde. Then, the colored compound is extracted using the dispersive liquid–liquid microextraction (DLLME) technique and its color intensity was measured using a smartphone as RGB Color Detector. For this purpose, a novel deep green eutectic solvent including tetrapropylammonium bromide (TPABr) and 3-methyl-1-butanol (isoamyl alcohol) was employed, with a molar ratio of 1:6. The impact of key variables on the derivatization and microextraction processes, including solution pH, concentration of acetylacetone and formaldehyde, temperature, reaction time, and extraction solvent volume, was thoroughly investigated and optimized. In the optimized conditions, the method was found to be linear in the range of 0.15–5.00 µg mL−1 with a limit of detection of 0.05 µg mL−1 (S/N = 3). Moreover, the proposed method was successfully applied for the determination of ammonium ions in environmental water samples, fish pond, and aquarium water samples, with recoveries ranging from 94.7 to 106.7 %.

The determination of mycotoxins using isotope-coded labeling and dispersive liquid–liquid microextraction by high throughput flow injection analysis coupled with tandem mass spectrometry

A novel and rapid method for the determination of ochratoxin A (OTA), funmonisin B1 (FB1) and zearalenone (ZEN) in legumes samples by high throughput flow injection analysis-tandem mass spectrometry (FIA-MS/MS) in conjunction with isotope-coded labeling (ICD) coupled with dispersive liquid–liquid microextraction (DLLME) was developed. The samples were extracted by a known QuEChERS method (Quick, Easy, Cheap, Effective, Rugged, Safe). The extracted components and mycotoxin standards were, respectively, labeled by d0-10-methyl-acridone-2-sulfonyl chloride and its deuterated counter part (d3-MASC). Subsequently, the mixed light-/heavy-labeled solutions were enriched and purified by DLLME method and corresponding extracts were directly used for FIA-MS/MS analysis. The FIA-MS/MS method coupled with ICD-coded labeling technique for the determination of mycotoxins in legume samples could be achieved within 2 min, which was much suitable for high throughput screening analysis. Meanwhile, the labeled mycotoxins with d3-MASC as internal standards could effectively eliminate matrix interference and ensure the accuracy and precision of mass spectrometry analysis. The limits of detection (LODs) and the limits of quantification (LOQs) ranged from 0.29 to 0.42 μg/L and 0.85 to 1.30 μg/L, respectively. The recoveries were 66.9 %–85.2 %, and the daily and inter day RSDs were within the range of 2.0 %–4.9 % and 2.4 %–5.0 %, respectively. The established method could be feasibility applied to the determination of mycotoxins in legume samples with satisfactory results.

Development of a dispersive liquid-liquid microextraction method for the evaluation of maternal-fetal exposure to cocaine employing human umbilical cord tissue.

Illicit drug use is a serious and complex public health problem, not only due to the severity of the health damage but also to the social implications, such as marginalization and drug trafficking. Currently, cocaine (COC) is among the most abused drugs worldwide with about 22 million users. Drug abuse has also been found in women during the pregnancy period, which has shed light on a new group for epidemiology. The diagnosis of COC use in these cases usually depends largely on the mother's reports, which in several cases omit or deny consumption. Therefore, considering physical-chemical methods of sample preparation and exposure biomarkers, the development of analytic toxicological methods can help to confirm drug use during pregnancy. Thus, the objective of the present work was to develop an analytical method based on dispersive liquid-liquid microextraction (DLLME) for the determination of COC analytes, using umbilical cord tissue as an alternative biological matrix, and detection by gas chromatography coupled to mass spectrometry (GC-MS). Therefore, after optimization, the DLLME method was fully validated for quantification of COC, benzoylecgonine (BZE), cocaethylene (CE), ecgonine (ECG), ecgonine methyl ester (EME) and norcocaine (NorCOC). The limits of detection were between 15 and 25 ng/g, the limits of quantification (LOQ) were 30 ng/g for ECG, and 25 ng/g for the other analytes. Linearity ranged from the LOQ to 1,000 ng/g. Coefficients of variation for intra-assay precision were <18.5%, inter-assay was <8.75%, and bias was <16.4% for all controls. The developed method was applied in 10 suspected positive samples, based on the mother's report and maternal urine screening and confirmation. COC, BZE, ECG, and EME were quantified in 4 umbilical cords with concentrations that ranged from 39.6 to 420.5 ng/g.

Investigation of different solvents for selective, safe and rapid extraction of curcumin from various food and herbal supplement products: Multivariate strategy and assessment of green profile

In the paper, different extraction solvents including magnetic ionic liquids (MILs), deep eutectic solvents, SUPRAS and surfactant were investigated for the fast, reliable and simple extraction of curcumin in the dispersive liquid–liquid microextraction (DLLME) method prior to UV–Vis spectrophotometric analysis. As a result of preliminary studies, the [Co(C8IM)42+]2[Cl−] MIL was selected as the extraction solvent for the extraction of curcumin from various matrix samples. Optimization of essential factors in the DLLME method was carried out with central composite design (CCD). Effective dispersion of the [Co(C8IM)42+]2[Cl−] MIL in the sample solution was achieved by orbital shaking (OS). After the CCD modelling, the OS-MIL-DLLME method provided linearity in the range of 0.5–225 ng mL−1 with a detection limit of 0.15 ng mL−1 for the model solution. The OS-MIL-DLLME method showed a matrix effect of 7.6 % with an enrichment factor of 135. Validation parameters of the OS-MIL-DLLME method such as selectivity, robustness, intraday/interday precision and recovery test were investigated in detail. The green analytical scale of the method was determined using the analytical greenness calculator tool. The OS-MIL-DLLME method was applied to the foods and herbal supplement products together with the reference method, and quantitative recoveries and statistically reliable results were obtained.

Determination of triazole fungicides in soybeans with cobalt-enhanced lanthanide metal chloride anion magnetic deep eutectic solvents in-situ dispersion extraction

In this work, we synthesized a series of magnetic deep eutectic solvents (MDESs) with lanthanide metal chlorides as paramagnetic metal centers and developed a reversed-phase dispersive liquid–liquid microextraction method (DLLME) based on the in-situ dispersion of MDESs for the extraction and preconcentration of triazole fungicides (TFs) from bean samples. Different MDESs were synthesized by combining quaternary ammonium salts, short-chain carboxylic acids, and lanthanide metal chlorides. The dissolution of short-chain carboxylic acids in n-hexane led to the in-situ dispersion of MDESs to replace the toxic dispersant of traditional DLLME species and shorten extraction time. Cobalt powder was added to encapsulate MDESs to enhance the magnetic properties after the extraction and achieve the purpose of easy phase separation. Notably, the highest extraction efficiency of TFs was observed in the MDES formed by tetrabutylammonium bromide, propionic acid, and gadolinium chloride in a ratio of 1:10:0.06. We optimized various parameters that affected the extraction efficiency of the method, including volume of MDES, extraction time, amount of cobalt powder, and volume of elution solvent. Under the optimal conditions, the detection limits (LODs) and quantification limits (LOQs) of the technique varied between 0.097–0.13 ng·g−1 and 0.32–0.43 ng·g−1, respectively. To assess the accuracy, the method was tested with samples spiking at three concentration levels, and the obtained results revealed that the recovery rates varied from 88.97–113.7%. To summarize, this study represents the initial application of in-situ dispersed lanthanide metal chloride anion-MDESs for analyzing bean samples and the proposed DLLME technique is rapid, straightforward, and efficient.

Terpenes based hydrophobic deep eutectic solvents for dispersive liquid-liquid microextraction of aliphatic aldehydes in drinking water and alcoholic beverages

Aliphatic aldehydes are a class of organic compounds containing aldehyde groups, which are widespread, and closely related to people's daily life and health. In this work, a series of terpenes based hydrophobic deep eutectic solvents were designed and synthesized using hexafluoroisopropanol as hydrogen bond donor and menthol/thymol as hydrogen bond acceptor. Then they are used as extraction solvent in dispersive liquid-liquid microextraction for extracting and determining seven aliphatic aldehydes from drinking water and alcoholic beverage combined with high performance liquid chromatography-ultraviolet. Due to the fact that these hydrophobic deep eutectic solvents are liquid at the room temperature, a density greater than that of water, a lower viscosity (≤26.10 mPa s, 25 °C), after extraction and centrifugation, the microvolume DES-rich phase in the bottom is convenient for collection and direct analysis without further dissolution or dilution with organic solvents. Some factors affecting the extraction recovery were optimized by one-variable-at-a-time and response surface methodology. Under the optimal conditions, the enrichment factors for the seven aliphatic aldehydes were 48–56. The method had good performance: linear ranges of 1.0–200, 0.5–200, 0.2–200, 0.4–400, 1.0–400, 0.4–400 and 0.4–400 μg L−1 for seven aliphatic aldehydes (r2 ≥ 0.9949), limits of detection of 0.1–0.5 μg L−1, intra-day and inter-day precisions <4.9%. The recoveries of seven aliphatic aldehydes ranged from 76.0 to 119.0%. The proposed dispersive liquid-liquid microextraction method is simple, rapid, highly efficient, and green, which effectively reduces the amount of toxic chemical reagents used and their impact on the environment. Rapid and efficient detection of aliphatic aldehydes helps ensure a healthy diet and has great application prospects in food safety analysis.

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.

Trace element levels: How Substance Use Disorder (SUD) contributes to the alteration of urinary essential and toxic element levels.

Increasing illicit drug use is one of the main problems in most countries or societies. Monitoring heavy metals and trace elements in this vulnerable group seems to be necessary. Therefore, we assessed the urinary trace element and toxic metals/metalloids concentrations (Zinc (Zn), Iron (Fe), Copper (Cu), Chromium (Cr), Lead (Pb), Cadmium (Cd), Arsenic (As), Nickel (Ni), and Mercury (Hg)) in opium, tramadol, and cannabis users compared to healthy subjects. In this cross-sectional study, patients with substance use disorder (SUD) (n = 74) were divided into four groups: cannabis, tramadol, opium, and mixed (simultaneous use of more than one of the three studied substances), along with a healthy group (n = 60). Urine samples were prepared by dispersive liquid-liquid microextraction method so that heavy metals/metalloids could be measured by ICP-MS. The mean urinary concentration of Cu (48.15 vs. 25.45; 89.2%, p<0.001), Hg (1.3 vs. 0.10; 1200%, p < 0.001), and Zn (301.95 vs. 210; 43.8%, p < 0.001) was markedly lower among patients with SUD. The mean urinary concentration of other elements including As (1.9 vs. 4.1; 115.8%), Cd (0.1 vs. 1.10; 1000%), Cr (6.80 vs. 11.65; 71.3%), Ni (2.95 vs. 4.95; 67.8%), and Pb (1.5 vs. 7.9; 426.6%) were significantly higher among patients with SUD compared to healthy subjects. When sub-groups were compared, no significant differences were observed between their trace element levels (Kruskal-Wallis test, p > 0.05). This can be an indication that regardless of the type of drug, the levels of trace elements are changed with respect to healthy individuals. Our results showed that illicit drug use causes changes in urinary trace element/heavy metal/metalloid levels and highlights the need for monitoring heavy metals and trace elements in individuals with substance use disorder. Assessment of different elements in biological samples of drug dependents may be useful for implementing new prevention and treatment protocols. In case of changes in their levels, complementary recommendations, attention to diet, and periodic assessment of toxic metal levels within treatment programs will be needed.

Development of a dispersive liquid-liquid microextraction method for the determination of plastic additives in seawater.

A method using dispersive liquid-liquid microextraction (DLLME) prior to high performance liquid chromatography-diode array detection (HPLC-DAD) was developed to determine seven additives from the plastics industry (butylated hydroxytoluene, diisodecyl phthalate, irgafos 168, lawsone, quercetin, triclosan and vitamin E) in seawater samples. These compounds can reach seawater due to direct discharge from wastewater treatment plants and leaching from plastics and microplastics. The extraction was performed using 25 mL of seawater, 500 μL of 1-octanol (extraction solvent) and a stirring step instead of dispersive solvent. Additive concentrations were determined by LC-DAD on a C18 column with a mobile phase of acetonitrile and phosphoric acid aqueous solution (pH 3.5) by gradient elution. The analytical recoveries ranged from 82 to 93% for all compounds, except for lawsone (60%). Repeatability and intermediate precision were adequate with RSD < calculated values following the Horwitz equation at the concentration levels evaluated (0.06 and 0.24 mg L-1). All additives exhibited linear matrix calibration curves (R2 > 0.99). Detection limits ranged from 0.009 to 0.028 mg L-1 and quantification limits ranged from 0.027 to 0.084 mg L-1. Finally, the application of the method to real samples verified the method as accurate and applicable to seawater.

Dispersive liquid-liquid microextraction as a novel enrichment approach for compound-specific carbon isotope analysis of chlorinated phenols.

Compound-specific isotope analysis (CSIA) via gas chromatography-isotope ratio mass spectrometry (GC-IRMS) is a potent tool to elucidate the fate of (semi-)volatile organic contaminants in technical and environmental systems. Yet, due to the comparatively low sensitivity of IRMS, an enrichment step prior to analysis often is inevitable. A promising approach for fast as well as economic analyte extraction and preconcentration prior to CSIA is dispersive liquid-liquid microextraction (DLLME) - a well-established technique in concentration analysis of contaminants from aqueous samples. Here, we present and evaluate the first DLLME method for GC-IRMS exemplified by the analysis of chlorinated phenols (4-chlorophenol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol) as model compounds. The analytes were simultaneously acetylated with acetic anhydride and extracted from the aqueous phase using a binary solvent mixture of acetone and tetrachloroethylene. With this method, reproducible δ13C values were achieved with errors ≤ 0.6‰ (n = 3) for aqueous concentrations down to 100 μg L-1. With preconcentration factors between 130 and 220, the method outperformed conventional liquid-liquid extraction in terms of sample preparation time and resource consumption with comparable reproducibility. Furthermore, we have demonstrated the suitability of the method (i) for the extraction of the analytes from a spiked river water sample and (ii) to quantify kinetic carbon isotope effect for 2,4,6-trichlorophenol during reduction with zero-valent zinc in a laboratory batch experiment. The presented work shows for the first time the potential of DLLME for analyte enrichment prior to CSIA and paves the way for further developments, such as the extraction of other compounds or scaling up to larger sample volumes.

Development and evaluation of a gas chromatography-mass spectrometry method for biogenic amines to assess decomposition in seafood

Biogenic amines (BAs) are low molecular mass compounds formed by the microbial-induced decarboxylation of specific amino acids. These molecules are markers of quality index and can indicate potential spoilage of a product. Currently, the FDA relies on sensory analysis as well as indole and histamine levels to evaluate the degree of seafood decomposition. However, there is a need for alternative analytical methods to corroborate those analyses. An optimized dispersive liquid-liquid microextraction (DLLME) method was developed for the extraction of four BAs (putrescine, cadaverine, histamine and tyramine) from various decomposition stages of nine seafood species previously tested by the FDA Seafood Sensory Experts. The BAs depicted very different concentration patterns between species and were able to distinguish within-species decomposition stages classified by the organoleptic analysis as “borderline increments”. The results suggest that all four analyzed BAs can be potentially used as biomarkers of seafood decomposition, but the choice of biomarker is species dependent. Some of the prominent associations were putrescine in shrimp, cadaverine in weakfish, histamine in canned tuna, and tyramine in scallops. The differentiation between “borderline” stages of decomposition also demonstrates the suitability of the method to support the FDA sensory analyses of seafood, ultimately leading to improved consumer protection.

Development of an Air-assisted Dispersive Liquid-Liquid Microextraction Method as a Valuable Biomonitoring Tool for Exposure Assessment of Phthalates

In recent years, the number of epidemiological studies on phthalates that can inform and help update health risk assessments has grown rapidly. Developing reliable and rapid analytical methods for determining phthalate monoesters (m-PAEs) is an important biomonitoring tool for assessing exposure. In this study, a fast and sensitive method was developed to determine 15 m-PAEs in human urine samples as effective biomarkers for exposure assessment. Air-assisted dispersive liquid-liquid microextraction and liquid chromatography coupled to mass spectrometry were used. In order to determine the optimal conditions and model the variables influencing the extraction efficiency, a central composite rotatable design coupled with response surface methodology was used. Under the optimized conditions, the method achieved good linearities (R &gt; 0.99), satisfactory intra- and inter-day accuracies (97–111%), and intra- and inter-day precision (RSD &lt; 14%). The proposed procedure allowed the detection of the m-PAEs with limit of detection values between 0.02 and 0.10 ng mL-1, which makes the method sensitive and appropriate for assessing internal exposure to phthalates. The applicability of the proposed procedure was evaluated by screening fifty children’s urine from Brazil. High detection frequencies and urinary concentrations of several m-PAEs associated with using personal care products and diet were found.

Phthalates in marine sediment, water and the cockle Anadara antiquata on the coast of Tanzania

Phthalates are a group of chemicals used as plasticisers, and are easily released into the environment, where they degrade over time. We investigated the concentrations of phthalates in sediments, seawater, and the cockle Anadara antiquata from beaches at Dar es Salaam, Mtwara, Tanga and Zanzibar in Tanzania. A dispersive liquid-liquid microextraction method was used to extract analytes from samples, whereafter they were analysed with a gas chromatograph coupled to a mass spectrophotometer. Concentrations of diisobutyl phthalate (DiBP), dibutyl phthalate (DBP) and Bis(2-ethylhexyl) phthalate (DEHP) were determined. DiBP concentrations were highest at Dar es Salaam (11.5 - 12.4 ng/mL in seawater; 11.5 - 13.6 ng/g dry weight in sediments), compared to the other three sites, where minimum and maximum concentrations in sediments were 3.5 ng/g dw (Mtwara) and 10.7 ng/g dw (Tanga). DBP concentrations were also highest at Dar es Salaam (12.4 - 20.6 ng/mL in seawater; 12.1 - 18.7 ng/g dw in sediments) compared to 2.7 (minimum, Mtwara) and 11.2 ng/g dw (maximum, Tanga). DEHP at Dar es Salaam ranged from un-detected to 12.6 ng/mL in seawater and to 12.6 ng/g dw in sediments. It was further revealed that A. antiquata from Kawe Beach (Dar es Salaam) had higher concentrations of DiBP, DBP, and DEHP compared to other sites. Monitoring of phthalate concentrations will indicate pollution hotspots and trends in the region.

A selective dispersive liquid-liquid micro-extraction technique for trace level pollutants enrichment of pharmaceutical residues from hospital wastewaters followed by liquid chromatographic analysis

In this study a dispersive liquid-liquid micro-extraction (DLLME) method was utilized for extraction of trace pharmaceuticals in wastewater samples. Factors influencing the extraction performances were tested and accordingly 900 µL dichloroethane as the extraction solvent, 1400 µL acetonitirle as dispersive solvent, 10 min extraction time at 4000 rpm centrifugation, and pH 5 were found optimum. Acetonitrile and 0.2% formic acid in water were used as eluent. The column temperature was maintained at 25 °C and the optimum detection wavelengths of 273 nm for sulfamethoxazole and 280 nm for ciprofloxacin were used. For both the analytes, the coefficients of determinations (r2) were found to vary from 0.9989 to 0.9997, confirming good linearity in the concentration range of 0.005-100 µg mL-1 for sulfamethoxazole and 0.01-100 µg mL-1 for ciprofloxacin. The LOD and LOQ were in the range of 0.78-1.58 ng mL-1 and 2.24-5.28 ng mL-1, respectively; the RSDs were 0.41-3.21% for intra-day precision and 0.37-6.44% for inter-day precision. The concentrations of the three pharmaceuticals determined ranged from 0.76-1.53 μg mL-1 in the wastewater samples collected from Black Lion Hospital. However, ciprofloxacin and doxycycline were not detected and only low concentration of sulfamethoxazole was detected in the wastewater samples collected from Menelik II Hospital.&#x0D; KEY WORDS: Antibiotics, DLLME, Dispersive solvent, Hospital wastewater&#x0D; Bull. Chem. Soc. Ethiop. 2024, 38(1), 27-42. DOI: https://dx.doi.org/10.4314/bcse.v38i1.3&#x0D;

Development of an analytical method for the determination of pesticides in tropical fruits by LC-QTOF-MS/MS after QuEChERS extraction sample cleanup and DLLME preconcentration

In this study, QuEChERS extraction was combined with dispersive liquid–liquid microextraction (DLLME) to extract pesticides from tropical fruits for determination by a highly accurate and sensitive liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QTOF-MS/MS) system. The QuEChERS method served as a matrix clean-up tool and the DLLME method preconcentrated the analytes for their determination at trace levels. All parameter variables of the DLLME method were optimized to improve the extraction output and lower the limits of detection and quantification (LOD and LOQ) for all the analytes. Under the optimum experimental conditions, the LOD and LOQ values were found in the range of 0.004–0.013 and 0.27–0.61 μg l−1, respectively. The detection limits achieved by direct LC-QTOF-MS/MS analysis were increased by about 10–260 folds using the optimized DLLME method. To assess the accuracy and applicability of the developed method, spike recovery experiments on tropical fruits were carried out. The matrix matching calibration method was used to enhance the quantification accuracy of the analytes in kiwi, pineapple, and mango matrices, with percent recoveries ranging between 89 and 117%.

Magnetic hydrophobic deep eutectic solvents for orbital shaker-assisted dispersive liquid-liquid microextraction (MAGDES-OS-DLLME) - Determination of nickel and copper in food and water samples by FAAS

In this work, a cheap and widely applicable dispersive liquid-liquid microextraction (DLLME) method was developed for the extraction of Ni(II) and Cu(II) from water and food samples and analysis using flame atomic absorption spectrometry. DLLME was assisted by orbital shaker, while ferrofluid as an extractant was based on deep eutectic solvent (DES). This ferrofluid was made of hydrophobic DES (hDES), composed of lauric acid and menthol (molar ratio 1:2), and toner powder@aliquat 336 magnetic particles. The extraction procedure does not require any heating or centrifugation. The method limits of detection value were 0.15 µg L−1 and 0.03 µg L−1 for Ni(II) and Cu(II) respectively along with wide linearity range (0.4–250 µg L−1). The validation of the method was performed using certified reference materials (CRMs). The studies revealed excellent accuracy between results obtained by the developed method and expected values for all CRMs. The relative recoveries of Ni(II) and Cu(II) ions ranged from 92.8% to 98.6%. The developed method was further used for the determination of Ni(II) and Cu(II) in real water and food samples and provided quantitative recoveries.

Dispersive liquid-liquid microextraction coupled with gas chromatography-mass spectrometry (GC-MS) for the determination of soy sauce aroma compounds

In the present work, a dispersive liquid-liquid microextraction (DLLME) method combined with gas chromatography-mass spectrometry (GC-MS) was successfully developed for accurate determination of aroma-active components in soy sauce. Several key experimental parameters were optimized, including the type of dispersant, vortex time and the volume ratio of extractant and dispersant. The optimal conditions were 1200 μL acetone as dispersant, 800 μL dichloromethane as extractant and 3 min of vortex mixing. The proposed method was validated, achieving good linearities with R2 ≥ 0.9941, recoveries between 82 and 129% with 4-hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF) and 4-hydroxy-2 (or 5)-ethly-5 (or 2)-methyl-3(2H)-furanone (HEMF) within 84–103%, relative standard deviations ranging from 0.02 to 8.60% with HDMF and HEMF between 0.26 and 1.44%, and limits of detection and limits of quantification in the range of 0.08–35.95 μg/L and 0.25–119.83 μg/L, respectively. The entire sample processing with DLLME was completed in roughly 15 min with a total consumption of 2 mL of organic solvent, and 93 volatiles identified in the obtained extracts, with 87.1% (81 volatiles) showing relative standard deviations lower than 10%. Compared to conventional liquid-liquid extraction (LLE), DLLME exhibited obvious advantages of simplicity, rapidity, stability and low solvent consumption, favouring the extraction of acids and ketones. This is the first application of the DLLME technique for the analysis of aroma compounds in soy sauce and is suitable for rapid determination of key aroma compounds like HDMF and HEMF, especially for routine detection and large batch analysis of soy sauce, which can provide reliable information for soy sauce flavour analysis.

Application of chemometric modeling for ionic liquid-based ultrasonic-assisted dispersive liquid-liquid microextraction: Analysis of fosetyl-aluminum in fruit and vegetable samples

This manuscript presents a new method for selective extraction and determination of fosetyl-aluminum in fruits and vegetable samples based on ultrasonic-assisted dispersive liquid-liquid microextraction method using ionic liquids (IL-UA-DLLME). A UV-Visible spectrophotometer was used for detection and quantification. Plants used for sample collection were grown under controlled conditions in a greenhouse. Central composite design (CCD)-response surface methodology (RSM) analysis was used for the optimization of significant factors (volume of IL, pH, ultrasonication time, and THF volume). Under optimal conditions, the limit of detection and limit of quantification of the IL-UA-DLLME procedure were 1.5 ng mL−1 and 5.0 ng mL−1 respectively with relative standard deviation 1.9–3.3%. The developed IL-UA-DLLME procedure demonstrated linearity within the concentration range of 5–600 ng mL−1 with an R2 value of 0.9914. The enrichment factor was 114 with a recovery% of 94.2–98.6% (n = 3) at optimal conditions. The IL-UA-DLLME assay was used for the analysis of fosetyl-aluminum in a variety of food samples and was found highly selective and efficient.

Distance-based thread analytical devices coupled with dispersive liquid-liquid microextraction for melatonin detection

This article reports the first distance-based thread analytical devices (dTADs) coupled with a dispersive liquid-liquid microextraction (DLLME) method for quantitative monitoring of trace melatonin levels in human samples and dietary supplements. Detection is based on colorimetric reaction between melatonin and 2,3-naphthalenedialdehyde (2,3-Nda) carried out on a thread substrate. Herein, melatonin is preconcentrated and extracted to the organic phase of an extraction solvent utilizing the DLLME method. A little droplet of the extraction solvent was then introduced into the dTAD. The yellow-orange colored length is measured, which is proportional to the amount of melatonin level. We obtained a linear range from 15.0 to 45.0 pg mL−1 (R2 = 0.9949) and a detection limit (LOD) of 2.50 pg mL−1, resulting in the clinically relevant ranges for melatonin monitoring in human samples. This technique also exhibited remarkable reproducibility and selectivity. The proposed method is simple, inexpensive, and exhibits more sensitivity than other methods that request expensive reagents and instrumentation. Additionally, this assay constituted an accurate and precise device for concentration quantification in human control samples with recovery percentage ranging from 98.42% to 102.52%. Likewise, there was no significant difference in measured melatonin levels obtained from our method against the nutrition label obtained from melatonin dietary supplements by t-test validation. The combination of an economical dTAD with a simple microextraction method, the proposed device therefore has the advantage of simplicity, instrument-free convenience, and affordability for trace melatonin detection, making it suitable for point-of-care medical diagnostics and food analysis.

A new method based on dispersive liquid-liquid microextraction for fat-soluble vitamin determination in serum by LC-MS/MS.

A green and inexpensive pretreatment known as dispersive liquid-liquid microextraction (DLLME) was developed in this assay coupled with the LC-MS/MS method for routine analysis of fat soluble vitamins (FSVs). The technique was performed with methanol as the dispersive solvent and dichloromethane as the extraction solvent. The extraction phase containing FSVs was evaporated to dryness and reconstituted in a mixture of acetonitrile and water. The influence variables concerning the DLLME procedure were optimized. After that, the method was investigated for its applicability in LC-MS/MS analysis. As a result, the parameters were settled for the optimal conditions during the DLLME process. A cheap and lipid-free substance was found as an alternative to serum to eliminate the matrix effect while preparing the calibrators. The method validation indicated that it was suitable for determining FSVs in serum. Moreover, this method was applied successfully to determine serum samples, which was consistent with the literature. In summary, the DLLME method developed in this report was reliable and more cost-effective than the traditional LC-MS/MS method, and could be applied in the future.