Single-drop Microextraction Research Articles

Determination of Rhodamine 6G with direct immersion single-drop microextraction combined with an optical probe.

The combination of an optical probe and single-drop direct immersion microextraction (DI-SDME-OP) was used for the preconcentration and subsequent spectrophotometric determination of rhodamine 6G (Rh6G). The developed method is based on the formation of an ionic associate between Rh6G and picric acid at pH 3.0 and its extraction with amyl acetate. A microdrop of the organic phase was stably placed in the hole of an optical probe immersed in the sample solution. The absorbance of the extraction phase was monitored at 534 nm. The proposed method combines in a single step several stages of the analytical procedure, such as pre-concentration, phase separation, transfer of the extraction phase to the instrument and online measurement. The sensitivity of the proposed approach is not inferior to existing microextraction methods involving the combination of liquid-phase or solid-phase extraction with spectrophotometry or HPLC with a UV-Vis detector. The evaluation of the greenness of the developed method carried out by the AGREE method (0.58 points) showed that it outperforms other similar existing techniques using this parameter. The calibration plot for the determination of Rh6G by the DI-SDME-OP method was linear over the range of 10-500 nM with a correlation coefficient of 0.9956. The limit of detection was 3.4 nM. The accuracy and applicability of the method were evaluated by the determination of Rh6G in natural waters and lipstick.

Water as a green solvent for sustainable sample preparation: single drop microextraction of N-nitrosamines from losartan tablets.

Water, renowned for its sustainability and minimal toxicity, is an ideal candidate for environmentally friendly solvent-based microextraction. However, its potential as an extractant solvent in miniaturized sample preparation remains largely unexplored. This paper pioneers using water as the extraction solvent in headspace single-drop microextraction (HS-SDME) for N-nitrosamines from losartan tablets. Autonomous HS-SDME is executed by an Arduino-controlled, lab-made Cartesian robot, using water for the online preconcentration of enriched extracts through direct injection into a column-switching system. Critical experimental parameters influencing HS-SDME performance are systematically explored through univariate and multivariate experiments. While most previously reported methods for determining N-nitrosamines in pharmaceutical formulations rely on highly selective mass spectrometry detection techniques to handle the strong matrix effects typical of pharmaceutical samples, the water-based HS-SDME method efficiently eliminates the interfering effects of a large amount of the pharmaceutical active ingredient and tablet excipients, allowing straightforward analysis using high-performance liquid chromatography with ultraviolet detection (HPLC-UV-Vis). Under optimized conditions, the developed method exhibits linear responses from 100 to 2400ngg-1, demonstrating appropriate detectability, precision, and accuracy for the proposed application. Additionally, the environmental sustainability of the method is assessed using the AGREEprep methodology, positioning it as an outstanding green alternative for determining hazardous contaminants in pharmaceutical products.

A configuration for cooling assisted organic solvent coated thin film microextraction after dispersive liquid-liquid microextraction method: A microextraction method for ultra-trace analyzing of volatile sample

A combination of the dispersive liquid-liquid microextraction (DLLME) method based on the total vaporization procedure and cooling-assisted organic solvent-coated thin film microextraction (TFME) was applied for extracting chlorpyrifos (as the model compound). Based on the high thermal conductivity, a nickel foam thin film with the dimensions of 5.0 mm × 5.0 mm was used as a substrate for holding the organic solvent. Supporting thin film by organic solvent increases the thickness and contact area of the film relative to TFME or single drop microextraction (SDME) alone, resulting in a dramatic increase in the extraction efficiency. To protect the organic solvent and enhance the analyte distribution coefficient between the film and the vapor phase, a cooling system was applied. The proposed design was effective due to condensing the target analyte only on the uniform cooled thin film and not on the other regions in the extraction chamber. A corona discharge ionization source-ion mobility spectrometer was employed to identify the analyte. After optimizing the effective parameters, the limits of quantification (S/N = 10) and detection (S/N = 3) were calculated 0.1 and 0.03 μg L−1, respectively, and the dynamic range was measured between 0.1 and 7.0 μg L−1, with a determination coefficient of 0.9997. For three concentration levels of 0.1, 3.0, and 7.0 μg L−1, the relative standard deviations (n = 3) as the repeatability index were to be 6 %, 5 %, and 4 % for intra-day and 9 %, 6 %, and 5 % for inter-day, respectively. The enrichment factor was also calculated to be 3630 for the analyte concentration of 1.0 μg L−1. Well water, potato, and agricultural wastewater were analyzed as the real samples and the relative recovery values were measured between 92 % and 99 %. The accuracy of the proposed technique was validated by the European Standards EN 12393 method. In this approach, two steps of analyte extraction (DLLME and TFME) were used consecutively, resulting in better preconcentration and reduced matrix interference during cleaning-up.

A dual-mode fluorometric and colorimetric sensor based on N-doped carbon dots for selective and sensitive detection of nitrite in food samples

A highly sensitive and selective nitrite sensing platform based on nitrogen-doped carbon quantum dots (N-CDs), by means of a headspace single drop microextraction process, was constructed for dual-mode fluorometric and visual colorimetric determination of nitrite. In this system, the two-channel selective sensing of nitrite was achieved at the same time, with color ranging from colorless to red and N-CDs fluorescence quenching gradually. Meanwhile, gaseous NO was generated from the redox chemical vapor generation process and further extracted into a single drop, which effectively improving the analytical sensitivity and alleviating the matrix interference. By fluorescence and colorimetry, the limits of detection were calculated to be 0.03 and 0.08 μg mL−1, respectively, while 0.8 μg mL−1 nitrite was discernable by the naked eye. This method was utilized to analysis of diversified real food samples (vegetables, milk and ham), and the results were proved to be nearly consistent with a standard method. Furthermore, the storage conditions of vegetable juice have also been explored.

Advancements in solvent microextraction: Recent developments and diverse applications in the modern era

AbstractSolvent microextraction (SME) is designed to selectively isolate desired analytes while minimizing the presence of interfering substances in the extracted sample. There are different approaches from which single‐drop microextraction (SDME) can be amalgamated with various analytical methods to enhance its functionalities and improve the analysis of extracted compounds like gas chromatography, and liquid chromatography amplify sensitivity, selectivity, and the capacity to detect trace amounts of analytes in complex matrices. The review focuses on the intricacies of solid‐phase microextraction and elucidates its operational principles. Additionally, it explores various types of SDMEs, detailing their respective benefits, drawbacks, and potential applications in the future. A typical explanation of the construction and working of hollow fiber‐liquid phase microextraction as well as its types has been discussed. The applications of SMEs in the medical and biomedical fields from food analysis to environmental analysis like analysis and purification of water, organic pollutants, drug analysis, and screening of new drugs have been discussed and also illustrated in tabular form. The pros and cons of both analytical techniques are given in a tabular manner as well a broad comparison between different types of advanced SME techniques provides a new direction for environmental monitoring, food safety, and refining of impurities from water samples. The review provides a comprehensive overview of the current progress, recent obstacles, and future possibilities of SMEs in an appropriate manner. Despite numerous promising advancements, the utilization of SMEs remains a challenging field.

Head space single-drop microextraction of pyridine from nargile smoke and determination by high-performance liquid chromatography

Head space single-drop microextraction of pyridine from nargile smoke and determination by high-performance liquid chromatography

Head Space Single Drop Micro Extraction Gas Chromatography Flame Ionization Detection (HS-SDME-GC-FID) Method for the Analysis of Common Fatty Acids.

Post-marketing/surveillance studies show that most of the many vegetable oils that are sold with health-promoting claims or statements with high nutritional values and are beneficial against diseases are off-limits of related monographs/criteria. Defining the oil with a fast, cheap, and efficient analytical method is needed to express fatty acids in any herbal product to authenticate, trace, specify, and classify the content.The majority of the after marketing/surveillance studies shows that most of the many vegetable oils that are sold with health-promoting claims or statements with high nutritional values and are beneficial against diseases are off-limits of related monographs/criteria. Defining the oil with fast, cheap and efficient analytical method to express fatty acids in any herbal product, to authenticate, trace, specify and classify the content is needed. Here, we define a new simple tool with a headspace single drop microextraction (HS-SDME) method coupled with a gas chromatography-flame ionization detector (GC-FID) for the analysis of common fatty acids (FAs) in oils. Linolenic acid, γ-linolenic acid, and linoleic acid in olive oil, thyme oil, and fish oil were determined. Derivatization was performed with 0.2 mL of 2 mol/L KOH in methanol to transfer the FAs of oils into their methyl esters (FAMEs). Then, FAMEs were extracted using a head space single drop, which is 2.0 μL of sodium dodecyl sulfate:1-butanol (1:3, v/v) mixture. The most suitable extraction condition was that 360 μL of the FAMEs, 2.0 mL vial, 0.07 g NaCl as a salting-out effect, 45 °C extraction temperature, and 35 min extraction time. The precision of the method was below 12%, with accuracy validated by the GC-FID reference method.The most suitable extraction condition was that 360 μL of the fatty acid methyl esters (FAMEs), 2.0 mL vial, 0.07 g NaCl as a salting-out effect, 45 °C extraction temperature, and 35 min extraction time. The precision of the method was below 12% with an accuracy validated by the GC-FID reference method. The HS-SDME can be used effectively for extracting FAs from oils for improved analysis of other FAs. The method is of direct importance and relevance for the herbal, pharmaceutical, and cosmetics industries.The HS-SDME can be used for effectively for extracting fatty acids from oils for improved analysis of other fatty acids while the method is direct importance and relevance for herbal, pharmaceutical, cosmetics industry.

Combination of headspace single-drop microextraction with smartphone-based on-drop colorimetric detection for determination of ammonia and total nitrogen in environmental and food samples

In the present study, a simple, environmentally friendly and inexpensive analytical method was proposed based on the combination of headspace single-drop microextraction with smartphone-based on-drop colorimetric detection for determination of ammonia (free ammonia and ammonium ion) in environmental and food samples. This method was also coupled with micro Kjeldahl digestion for determining total nitrogen content (or protein) in foods. Ammonia was extracted into an aqueous microdrop containing o-phthalaldehyde (OPA)-Na2SO3 reagent, and simultaneously converted to a colored derivative (1-sulfonatoisoindole). The colored microdrop was directly imaged by smartphone camera as a detector, and the captured image was processed with a color recognition app for ammonia quantification. The influence of experimental variables on the sensitivity of this method was studied. The linear range of the method was achieved from 0.25 to 10 mg L−1 for ammonium with the detection limit of 0.07 mg L−1. The intraday and interday relative standard deviations were between 2.5 and 5.5 % at the concentration levels of 0.5 and 5 mg L−1. This method was satisfactorily applied to determining ammonia and total nitrogen in environmental and food samples with ammonia and total nitrogen recoveries in the range of 90–109 %. In comparison with the Berthelot and classical Kjeldahl methods, there was no considerable difference in accuracy between these methods and the present method.

Single-drop microextraction application for the rapid and sensitive determination of endosulfan and its metabolites in water samples

This study aims to investigate the practical application of Single Drop Micro Extraction (SDME) as an efficient and sustainable technique for determining endosulfan and its metabolites in water. Experiments were performed with samples collected from different areas in the Loukkos region, Morocco, using a Finnigan MAT GCQ Model, equipped with a 30-m x 0.32-mm ID, ZB-5 (0.25-μm film thickness) fused-silica capillary column, Helium was used as a carrier gas (at 30 kPa), The ion trap mass spectrometer was operated in the electron ionization mode. The research highlights SDME's sensitivity in detecting and quantifying endosulfan and its metabolites in environmental samples, with achieved detection limits ranging from 0.3 to 0.5 μg/L. Furthermore, this study underscores the innovative potential of SDME by showcasing its compatibility with advanced detection techniques. These approaches have the potential to enhance sensitivity even further, potentially lowering detection limits to more stringent levels. Another notable aspect of SDME is its substantial reduction in solvent consumption, effectively minimizing costs and diminishing the ecological footprint associated with pesticide analysis. SDME may be considered a promising method due to its simplicity, cost-effectiveness, and eco-friendliness

Enhancing peroxidase-like activity of AuNPs through headspace reaction: A signal amplification strategy for colorimetric and fluorescent sensing of trace Hg2+

BackgroundRecently, headspace single-drop microextraction (HS-SDME) has attracted some attention for developing sensitive and selective colorimetric assays due to its excellent capability to reduce matrix interference and enrich analytes. However, the single droplet limits direct visual observation of color change and its quantitative measurement suffers from reduced optical path length. Therefore, amplifying the detection signals in both volume and intensity is an important and challenging task for improving the sensitivity, stability, and accuracy of such colorimetric analysis. ResultsIn this study, a "headspace-nanoenzyme" (HS-NE) strategy was proposed that successfully addressed these challenges and enabled the colorimetric and fluorescent dual-mode detection of trace Hg2+. Atomic Hg0, generated via chemical vapor generation (CVG), underwent headspace reaction with AuNPs droplet to form Au@HgNPs, thus catalyzing the oxidation of o-phenylenediamine (OPD) in the presence of H2O2. The absorbance and fluorescence intensity of oxidized OPD were proportion to the concentration of Hg2+ in the sample solution. Due to the greatly enhanced peroxidase-like activity by Au@HgNPs, the limit of detection was as low as 0.98 nM and 0.21 nM for the colorimetric and fluorescent modes, respectively. The applicability of this assay was further demonstrated with determination of Hg2+ in real environmental and biological samples. Moreover, a convenient and cost-effective paper-based sensing platform was fabricated for rapid on-site detection of Hg2+. Significance and noveltyThis novel HS-NE strategy combines HS-SDME and nanoenzyme-based sensing to achieve dual effects of eliminating matrix interference and amplifying the measurement signal, resulting in improved accuracy, enhanced stability, high sensitivity, and exceptional selectivity, with great potential for on-site determination of trace Hg2+.

Direct immersion single-drop microextraction combined with fluorescence detection using an optical probe. Application for highly sensitive determination of rhodamine 6G

The use of an optical probe for fluorescence detection combined with direct immersion single-drop microextraction has been demonstrated as an innovative approach. The optical probe served both as a drop holder for extractant and as a measuring device which made it possible to eliminate the use of cuvettes. A laser and a light emitting diode (LED) were tested as possible light sources. Both of them showed comparable results. However, given the much smaller half-band width of the laser radiation, its use has proven to be preferable since background correction can be eliminated. Direct immersion single-drop microextraction of an ionic association complex of rhodamine 6G with picric acid with subsequent fluorescent detection (λex was 532 nm and 525 nm for laser and LED, respectively; λem was 560 nm for both laser and LED) was used a model system to evaluate the new approach. The extractant phase was a 55 μL amyl acetate microdrop fixed in the optical part of the probe. LOD, LOQ and linear calibration range were found as 0.14, 0.48 and 0.5–10 nmol L−1, and 0.15, 0.50 and 0.5–5 nmol L−1 for laser and LED light sources, respectively. The accuracy of the method was assessed by analyzing real water samples.

Development of a Green Single Drop Microextraction Based on Deep Eutectic Solvent and HPLC-UV for Trace Residue Analysis of Three Frequent-Used Pesticides.

A green sample preparation method named deep eutectic solvent-based single drop microextraction (DES-SDME) was developed and optimized for determining trace metribuzin, dichlorvos, and fenthion. Two hundred seventy experimental runs were performed, and the optimal values of the five influential factors in the DES-SDME method were determined. The design of the study was based on one factor at a time and the peak area of high-performance liquid chromatography was used as a benchmark for comparing analysis results. After optimizing the effective factors, the linearity range, detection limit and quantification limit of the method were determined by drawing calibration curves for the studied analytes. The results indicated the success of the developed method in obtaining acceptable figures of merit as a green preparation method with accuracy and precision.

Headspace single drop microextraction based visual colorimetry for highly sensitive, selective and matrix interference-resistant determination of sulfur dioxide in food samples.

Excessive intake of SO2, a widely-used food additive, is able to cause respiratory, cardiovascular and neurological disease. For effectively monitoring SO2 level, we have developed a headspace single drop microextraction based visual colorimetry for highly sensitive and selective sensing of SO2 with TMB (3,3',5,5'-tetramethylbenzidine) as a classic chromogenic reagent. A combination of single drop and headspace microextraction integrated merits of high extraction efficiency, low consumption of reagents and excellent matrix interference-resistant ability. The colorimetric principle was based on oxidation of TMB, and SO2 could compete with TMB to preferentially react with ·OH, resulting in the fading of color blue that could be easily read out by naked eye. LOD was calculated to be 0.53μM and 5μM by UV-vis and naked eye, respectively. The method was successfully utilized to analysis of food samples, and the experimental device was miniaturized and easy to construct, thus showing a promising potential in field analysis.

Combination of headspace single-drop microextraction (HS-SDME) with a nickel-embedded paper-based analytical device for cyanide quantification

BackgroundCyanide anion can be found in foodstuffs, tobacco smoke and a variety of types of waters, mainly originating from anthropogenic activities. Due to its highly toxic nature, several agencies have established limits for cyanide levels in water. Additionally, monitoring cyanide levels in biological samples, such as blood and urine, is crucial for obtaining clinical information about the health condition of patients. Therefore, there is a pressing need for the development of simple, cost-effective, and reliable analytical methods capable of quantifying cyanide at low concentrations. ResultsThis study presents a novel analytical method for the selective and sensitive determination of cyanide based on analyte volatilization, pre-concentration via single-drop microextraction (SDME) using a selective reagent, and colorimetric quantification using a paper-based analytical device. For this, 10 mL of a liquid sample was acidified with phosphoric acid and the generated HCN was collected using a single drop of 3 μL of a palladium dimethylglyoximate solution (Pd (DMG)22−) positioned in the flask headspace using a syringe. The reaction of Pd (DMG)22− leads to the formation of Pd(CN)42− and the demasking of the organic ligand. After 15 min of extraction time, the reagent drop was added to a paper-based analytical device that has been previously impregnated with 3 μL of nickel chloride, resulting in the formation of a red precipitate of nickel (II) dimethylglyoximate. Digital images of the paper-based device were captured and the red channel (R) was used for quantification purposes. Under optimized conditions, the method demonstrates a suitable linear relation (r2 > 0.99) ranging from 26 to 286 μg L−1 and a limit of detection of 5 μg L−1. SignificanceAs a proof of concept, cyanide levels were quantified in water and urine samples using this method. The proposed approach offers high sensitivity and selectivity while requiring only a small volume of reagents. Furthermore, it exhibits a high degree of portability for in-situ applications.

Comparing π-complexation capabilities of ionic liquids containing silver(I) and copper(I) ions by headspace single drop microextraction in combination with high-performance liquid chromatography.

Selective π-complexation capabilities of silver(I) and copper(I) ions can be effectively facilitated in ionic liquids. To understand the effects of environmental factors that influence the π-complexation of these metal ions with analytes, techniques that employ small volumes of ionic liquid that can be readily analyzed are desired. In this study, headspace single drop microextraction coupled with HPLCis used to investigate a diverse set of environmental factors on the metal ion-mediated complexation with aromatic compounds in ionic liquid media. Silver(I) and copper(I) bis[(trifluoromethyl)sulfonyl]imide salts were both studied by dissolving them in the 1-decyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ionic liquid and employing the mixture as extraction media for aromatic compounds. Water and acetonitrile within the sample solution were observed to interfere with the complexation of silver(I) ions and aromatic compounds, while ethylene glycol and triethylene glycol did not. The temperature and extraction times were optimized to fully facilitate the π-complexation capabilities of metal ions in ionic liquid media. Partition coefficients between the sample headspace and metal ion were determined using a three-phase equilibria model. Although no discernable difference in analyte partitioning between the headspace and ionic liquid solvent was observed, analyte partition coefficients to silver(I) ion tended to be greater compared to copper(I) ion.

Deep eutectic solvents in sample preparation and determination methods of pesticides: Recent advances and future prospects

This review summarizes recent advances of deep eutectic solvents (DESs) in sample preparation and determination methods of pesticides in food, environmental, and biological matrices since 2019. Emphasis is placed on new DES categories and emerging microextraction techniques. The former incorporate hydrophobic deep eutectic solvents, magnetic deep eutectic solvents, and responsive switchable deep eutectic solvents, while the latter mainly include dispersive liquid-liquid microextraction, liquid-liquid microextraction based on in-situ formation/decomposition of DESs, single drop microextraction, hollow fiber-liquid phase microextraction, and solid-phase microextraction. The principles, applications, advantages, and limitations of these microextraction techniques are presented. Besides, the use of DESs in chromatographic separation, electrochemical biosensors, fluorescent sensors, and surface-enhanced Raman spectroscopy are discussed. This review is expected to provide a valuable reference for extracting and detecting pesticides or other hazardous contaminants in the future.

Magnetic three-phase single-drop microextraction for highly sensitive detection of aflatoxin B1 in agricultural product samples based on peroxidase-like spatial network structure.

In this work, a highly sensitive method for aflatoxin B1 (AFB1) detection was developed based on a peroxidase-like spatial network structure. The specific antibody and antigen of AFB1 were coated on a histidine-modified Fe3O4 nanozyme to form the capture/detection probes. Based on the competition/affinity effect, the spatial network structure was constructed by the probes, which could be rapidly (8s) separated by a magnetic three-phase single-drop microextraction process. In this single-drop microreactor, the network structure was applied to catalyze a colorimetric 3,3',5,5'-tetramethylbenzidine oxidation reaction for AFB1 detection. The signal was amplified significantly due to the strong peroxidase-like ability of the spatial network structure and the enrichment effect of the microextraction. Thus, a low detection limit (0.034pg/mL) was achieved. The matrix effect of real sample can be eliminated by the extraction approach, and the practicability of this method was proved by agricultural product samples analysis.

Quantitative Time-Resolved Visualization of Catalytic Degradation Reactions of Environmental Pollutants by Integrating Single-Drop Microextraction and Fluorescence Sensing.

Current methods for evaluating catalytic degradation reactions of environmental pollutants primarily rely on chromatography that often suffers from intermittent analysis, a long turnaround period, and complex sample pretreatment. Herein, we propose a quantitative time-resolved visualization method to evaluate the progress of catalytic degradation reactions by integrating sample pretreatment [single-drop microextraction, (SDME)], fluorescence sensing, and a smartphone detection platform. The dechlorination reaction of chlorobenzene derivatives was first investigated to validate the feasibility of this approach, in which SDME plays a critical role in direct sample pretreatment, and inorganic CsPbBr3 perovskite encapsulated in a metal-organic framework (MOF-5) was utilized as the fluorescent chromogenic agent (FLCA) in SDME to realize fast in situ colorimetric detection via the color switching from green (CsPbBr3) to blue (chlorine lead bromide, inorganic CsPbCl3 perovskite). The smartphone, which can calculate the B/G value of FLCA, serves as a data output window for quantitative time-resolved visualization. Further, a [Eu(PMA)]n (PMA= pyromellitic acid) fluorescent probe was constructed to use as an FLCA for the in situ evaluation of cinnamaldehyde and p-nitrophenol catalytic reduction. This approach not only minimizes the utilization of organic solvents and achieves quantitively efficient time-resolved visualization but also provides a feasible method for in situ monitoring of the progress of catalytic degradation reactions.

Headspace single-drop microextraction combined with nanodrop spectrophotometry for ultra-trace detection of ethanethiol using a suspended drop of AuNPs as a plasmonic sensor

It is challenging to achieve ethanethiol extraction, enrichment in a single-drop microextraction system, and an assay with good sensitivity and selectivity for analyzing food analytes in complex matrices. In this study, we combined headspace single-drop microextraction (HS-SDME) with nanodrop array spectrophotometry applied for ultra-trace determination of ethanethiol. A suspended drop of gold nanoparticles (AuNPs) solution was utilized for sensing ethanethiol as an acceptor phase. The thiol portion of ethanethiol molecules binds to the negatively charged AuNPs. Thus, the aim of target enrichment was attained, while matrix effects interference was also minimized. The approach can be used for the direct detection of ethanethiol in food without any sample pretreatment. The obtained range of linearity was 1–1000 µM and 100–1000 nM. The detection limits were 66.62 nM, comparable with those of previously reported methods. The method successfully determined ethanethiol in food (beverage, non-alcoholic beer, and cheese).

Determination of iron species in food samples with dual direct immersion single-drop microextraction followed by graphite furnace atomic absorption spectrometry

Determination of iron species in food samples with dual direct immersion single-drop microextraction followed by graphite furnace atomic absorption spectrometry