Two-phase hollow fiber liquid-phase microextraction

Streamlined Water-Leaching Preconcentration Method As a Novel Analytical Approach and Its Coupling to Dispersive Micro-Solid-Phase Extraction Based on Synthetically Modified (Fe/Co) Bimetallic MOFs

The streamlined water-leaching preconcentration method is introduced as a novel preconcentration method in this study. The approach has many benefits including low consumption of organic solvent and deionized water and operation time, energy-saving, no need for dispersion or evaporation, and implementation of more efficient preconcentration. Also, a methodological study was done on the synthesis of (Fe/Co) bimetallic-organic framework that eased the synthesis procedure, decreased its time, and enhanced its analytical performance by increasing its surface area, total pore volume, and average pore diameter parameters. To perform the extraction, bi-MOF particles were added into the solution of interest enriched with sodium sulfate. After vortexing to adsorb the analytes, centrifugation isolated the sorbent particles. A microliter-volume of acetonitrile and 1,2-dibromoethane mixture was used for desorption aim via vortexing. After the separation of the organic phase and transferring it into a conical bottom glass test tube, a milliliter volume of sodium chloride solution was applied to leach the organic phase. A gas chromatograph equipped with a flame ionization detector was applied for the injection of the extracted phase. The method was applied for the extraction and preconcentration of some pesticides from juice samples. Wide linear ranges (5.44-1600 μg L-1), low relative standard deviations (3.1-4.5% for intra- (n = 6) and 3.5-5.2% for interday (n = 4) precisions), high extraction recoveries (61-95%), enrichment factors (305-475), and low limits of detection (0.67-1.65 μg L-1) and quantification (2.21-5.44 μg L-1) were obtained for the developed method.

Modern automated microextraction procedures for bioanalytical, environmental, and food analyses

Sample preparation frequently is considered the most critical stage of the analytical workflow. It affects the analytical throughput and costs; moreover, it is the primary source of error and possible sample contamination. To increase efficiency, productivity, and reliability, while minimizing costs and environmental impacts, miniaturization and automation of sample preparation are necessary. Nowadays, several types of liquid-phase and solid-phase microextractions are available, as well as different automatization strategies. Thus, this review summarizes recent developments in automated microextractions coupled with liquid chromatography, from 2016 to 2022. Therefore, outstanding technologies and their main outcomes, as well as miniaturization and automation of sample preparation, are critically analyzed. Focus is given to main microextraction automation strategies, such as flow techniques, robotic systems, and column-switching approaches, reviewing their applications to the determination of small organic molecules in biological, environmental, and food/beverage samples.

An all-embracing analytical method comprising modified QuEChERS-dispersive micro-solid-phase extraction-dispersive liquid-liquid microextraction using FeGA MOF for the extraction and preconcentration of pesticides simultaneously from juice and flesh of watermelon

For the first time, a comprehensive analytical method based on a one-dimensional metal-organic framework comprising "quick, easy, cheap, effective, rugged, and safe-dispersive micro solid phase extraction-dispersive liquid-liquid microextraction" was introduced in this research. Moreover, the first-ever attempt was accomplished to apply the iron-gallic acid metal-organic framework in analytical method development. The goal of the research was to analyze the pesticide content of watermelon comprehensively in its flesh and juice. Based on this, comprehensive and reliable food safety monitoring can be done. Initially, pesticides of the watermelon flesh were extracted using an mL volume of acetonitrile by vortexing. At the same time, the pesticides of watermelon juice were extracted from the juice matrix onto the sorbent particles facilitated by vortexing. The obtained acetonitrile phase was also used to desorb the analytes from the sorbent surface by vortexing. As a result, the pesticide content of both juice and flesh was extracted into the acetonitrile. The pesticide-enriched acetonitrile was then used as the disperser solvent by being merged with µL level of 1,2-dibromoethane and injection into deionized water. A cloudy solution was created as the result. Centrifugation triggered extractant at the bottom of the conical glass test tube and an aliquot of it was injected into a gas chromatograph equipped with a flame ionization detector. High enrichment factors (210-400), appreciable extraction recoveries (42-80%), wide linear ranges (3.20-1000 µg kg^-1), relative standard deviations in the ranges of 3.6-4.4% for intra- (n = 6) and 4.4-5.3% for inter-day (n = 3) precisions, and low limits of detection (0.43-0.97 µg kg^-1), and quantification (1.42-3.20 µg kg^-1) were obtained by the application of the developed method.

Extraction of Organochlorine Pesticides from Porous Membrane Packed Dried Fish Samples: Method Development and Greenness Evaluation

In this work, ultrasound-assisted solvent extraction was utilized for extraction of organochlorine pesticides from membrane-protected dried fish samples. The dried fish samples were packed inside a porous membrane bag which was immersed in a solvent and subjected to ultrasonication. After the extraction process, the sample-containing bag was separated from the extract. Since samples were packed inside the membrane, their separation did not require centrifugation or filtration. Moreover, the complex components of the biota matrix may also retain inside the porous membrane bag, alleviating the requirement of extract cleanup before analysis. The parameters that can affect the ultrasound-assisted solvent extraction of membrane-protected dried fish samples were suitably optimized. These parameters include the extraction solvent and its volume, the sample amount, ultrasound intensity and extraction time. Under the optimum extraction conditions, good linearity was achieved for all the tested organochlorine pesticides, with the coefficients of determination (R2) higher than 0.9922 for the linear ranges from 5–1000, 10–1000 and 20–1000 ng/g. The values of intra-day and inter-day relative standard deviations were ≤13.8%. The limit of detection ranged from 1.5 to 6.8 ng/g. The spiked relative recoveries were in the range of 87.3–104.2%. This method demonstrated excellent figures of merit and could find potential applications in routine analytical laboratories. Finally, the greenness of this method was evaluated using the green analytical procedure index and analytical greenness calculator metrics.

A critical review of selected preconcentration techniques used for selenium determination in analytical samples

Selenium (Se) is considered to be an essential trace element needed for all living organisms. The importance, deficiency, and toxic effects of Se mainly depend on its quantity and chemical nature. It has been observed that the inorganic versions of Se are more hazardous than the organic versions. This review is mainly focused on the application of different extraction methods used for Se extraction and determination such as microextraction, solid-phase extraction (SPE), and their modified modes in the last 12 years. The use of different dispersive medium (magnetic field, ultrasonic radiation, and vortex agitator) to enhance Se separation is also part of this review. The usage of environmentally friendly solvents such as supramolecular solvents, hydrophobic deep eutectic solvents (DESs), and ionic liquids (ILs) are also the focus of attention in this review. This review is also emphasized the application of advanced microextraction methods, particularly liquid-phase microextraction (LPME). The most recent advances in LPME extraction techniques for Se in various environmental samples, as well as their prospects, are reviewed. Additionally, a summary of cheap, simple, and accurate techniques that have not yet been used to determine small amounts of Se has been provided.

Research Advances in the Analysis of Estrogenic Endocrine Disrupting Compounds in Milk and Dairy Products

Milk and dairy products are sources of exposure to estrogenic endocrine disrupting compounds (e-EDCs). Estrogenic disruptors can accumulate in organisms through the food chain and may negatively affect ecosystems and organisms even at low concentrations. Therefore, the analysis of e-EDCs in dairy products is of practical significance. Continuous efforts have been made to establish effective methods to detect e-EDCs, using convenient sample pretreatments and simple steps. This review aims to summarize the recently reported pretreatment methods for estrogenic disruptors, such as solid-phase extraction (SPE) and liquid phase microextraction (LPME), determination methods including gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry (LC-MS), Raman spectroscopy, and biosensors, to provide a reliable theoretical basis and operational method for e-EDC analysis in the future.

Trends in hollow fibre liquid phase microextraction for the preconcentration of pharmaceutically active compounds in aqueous solution: A case for polymer inclusion membrane

Low concentrations of pharmaceutically active compounds have been reported in samples from highly complex aqueous environments. Due to their low concentrations, efficient sample pretreatment methods are needed to clean samples and concentrate the compounds of interest prior to instrumental analysis. Hollow fibre liquid-phase microextraction (HF-LPME) is an effective alternative to conventional techniques such as liquid-liquid extraction (LLE) and solid phase extraction (SPE) because it consumes less organic solvent and is less labour intensive with a short extraction time. HF-LPME involves the preconcentration and mass transfer of target analytes from an aqueous sample into an acceptor solution in the lumen of the fibre using a supported liquid membrane (SLM) impregnated in the hollow fibre pores. However, despite the high contaminant selectivity, reproducibility, and enrichment that HF-LPME offers, this technique is limited by membrane instability. Although several advances have been made to address membrane instability, they are either too costly or not feasible for industrial application. Hence, hollow fibre polymer inclusion membrane liquid-phase microextraction (HF-PIM-LPME) was introduced to ameliorate membrane instability. This new approach uses ionic liquids (ILs) as a green solvent, and has demonstrated high membrane stability, good contaminant enrichment, and similar selectivity and reproducibility to HF-SLM-LPME. Hence, this review aims to raise awareness of HF-PIM-LPME as a viable alternative for the selectivity and preconcentration of pharmaceuticals and other contaminants in aquatic environments.

Liquid-Phase Microextraction Approaches for Preconcentration and Analysis of Chiral Compounds: A Review on Current Advances

Chirality is a critical issue in pharmaceutics, forensic chemistry, therapeutic drug monitoring, doping control, toxicology, or environmental investigations as enantiomers of a chiral compound can exhibit different activities, i.e., one enantiomer can have the desired effect while the other one can be inactive or even toxic. To monitor enantioselective metabolism or toxicokinetic/toxicodynamic mechanisms in extremely low content in biological or environmental matrices, sample preparation is vital. The present review describes current status of development of liquid-phase microextraction approaches such as hollow fiber liquid-phase microextraction (HF-LPME), electromembrane extraction (EME), dispersive liquid-liquid microextraction (DLLME), and supramolecular solvent-based microextraction (SSME), used for sample preparation of enantiomers/chiral compounds. The advantages and limitations of the above techniques are discussed. Attention is also focused on chiral separation approaches commonly applied to study the stereo-selective metabolism or toxicokinetic/toxicodynamic mechanisms of enantiomers in the biological and environmental samples.

Recent sample pretreatment methods for determination of selective serotonin reuptake inhibitors (SSRIs) in biological samples

Selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine (FLU), sertraline (SER), paroxetine (PAR), fluvoxamine (FLV) and citalopram (CIT) have been the first treatment drugs for pregnant and breastfeeding women. Quantitative analysis of SSRIs in biological samples is extremely needed in public health and clinical practice. During the analysis, sample pretreatment is an important step that can obtain an accurate quantitative analysis of SSRIs in the complex samples. The present paper discussed the recent development of sample preparation methods for SSRI analysis. Traditional sample preparation techniques such as liquid liquid extraction (LLE) and solid phase extraction (SPE), which have been widely used in the separation of SSRIs in biological samples, were extensively presented. Moreover, the new sample preparation techniques including liquid phase microextraction (LPME), solid phase microextraction (SPME), electromembrane extraction (EME) and other miniaturized extraction techniques, which are becoming highly popular in SSRI analysis, were also critically reviewed. In this review, both the advantages and disadvantages of these sample pretreatment methods were addressed. As a summary, we prospected the challenges and promising directions for the future of sample pretreatment methods in SSRI analysis.

Current overview and perspectives in environmentally friendly microextractions of carbamates and dithiocarbamates

Carbamates and dithiocarbamates are two classes of pesticides widely employed in the agriculture practice to control and avoid pests and weeds, hence, the monitoring of the residue of those pesticides in different foodstuff samples is important. Thus, this review presents the classification, chemical structure, use, and toxicology of them. Moreover, it was shown the evolution of liquid- and solid-phase microextractions employed in the extraction of carbamates and dithiocarbamates in water and foodstuff samples. The classification, operation mode, and application of the microextractions of liquid-phase and solid-phase used in their extraction were discussed and related to the analytical parameters and guidelines of green analytical chemistry.

Latest Insights on Novel Deep Eutectic Solvents (DES) for Sustainable Extraction of Phenolic Compounds from Natural Sources

Phenolic compounds have long been of great importance in the pharmaceutical, food, and cosmetic industries. Unfortunately, conventional extraction procedures have a high cost and are time consuming, and the solvents used can represent a safety risk for operators, consumers, and the environment. Deep eutectic solvents (DESs) are green alternatives for extraction processes, given their low or non-toxicity, biodegradability, and reusability. This review discusses the latest research (in the last two years) employing DESs for phenolic extraction, solvent components, extraction yields, extraction method characteristics, and reviewing the phenolic sources (natural products, by-products, wastes, etc.). This work also analyzes and discusses the most relevant DES-based studies for phenolic extraction from natural sources, their extraction strategies using DESs, their molecular mechanisms, and potential applications.

A computational simulation of electromembrane extraction based on Poisson - Nernst - Planck equations

Electromembrane extraction (EME) has attracted a great deal of interest in researchers because of its advantages. For analysis, design and optimization purposes, understanding the ion transport mechanisms in the organic supported liquid membrane (SLM) is of prominent importance, where the interplay between the passive diffusion and electric-driven mass transport across SLM affects the mass transfer. In present work, a 2D numerical simulation is developed to examine the mass transfer behavior and the analyte recovery in EME devices. The presented model is capable of describing the effect of different parameters on the recovery of the EME setup. Initial analyte concentration in the sample solution, SLM thickness, applied potential, permittivity, diffusion coefficient, and the reservoir pH within both the sample and acceptor, can be considered as process variables. Predicted results revealed that the most important factors playing key role in EME, are the analyte diffusivity, distribution coefficient of the analyte as well as the level of protonation in both the donor and acceptor solutions. The proposed model is helpful in predicting the mass transfer behavior of the EME process in practical applications.

Extraction and electrochemical sensing of pesticides in food and environmental samples by use of polydopamine-based materials

Polydopamine has high adsorption capacities for pollutants such as pesticides in food and environmental matrices. Consequently, it has found applications in some sorbent-based micro-extraction techniques such as solid phase micro-extraction and magnetic solid phase extraction. This paper gives a detailed review of the application of polydopamine-based adsorbents for the extraction of pesticides in food and environmental matrices using these techniques. The adhesive properties of polydopamine have made it to be a suitable material for the immobilisation of the components of electrochemical sensors used to detect pesticides in food and environmental matrices. This paper also gives a comprehensive review on the application of polydopamine in electrochemical sensors such as acetylcholinesterase sensors, molecularly imprinted sensors and aptasensors. The use of polydopamine-based adsorbents during the extraction and electrochemical sensing of pesticides in food and environmental matrices is not free of challenges. In this review, the challenges encountered during the use of polydopamine-based adsorbents are also discussed.

Miniaturized sample preparation techniques and ambient mass spectrometry as approaches for food residue analysis

Analytical methods such as liquid chromatography (LC) and mass spectrometry (MS) are widely used techniques for the analyses of different classes of compounds. This is due to their highlighted capacity for separating and identifying components in complex matrices such food samples. However, in most cases, effective analysis of the target analyte becomes challenging due to the complexity of the sample, especially for quantification of trace concentrations. In this case, miniaturized sample preparation methods have been used as a strategy for analysis of complex matrices. This involves removing the interferents and concentrating the analytes in a sample. These methods combine simplicity and effectiveness and given their miniaturized scale, they are in accordance with green chemistry precepts. Besides, ambient mass spectrometry represents a new trend in fast and rapid analyses, especially for qualitative and screening analysis. However, for complex matrix analyses, sample preparation is still a difficult step and the miniaturized sample preparation techniques show great potential for an improved and widespread use of ambient mass spectrometry techniques. . This review aims to contribute as an overview of current miniaturized sample preparation techniques and ambient mass spectrometry methods as different approaches for selective and sensitive analysis of residues in food samples.

Restricted access supramolecular solvent based magnetic solvent bar liquid-phase microextraction for determination of non-steroidal anti-inflammatory drugs in human serum coupled with high performance liquid chromatography-tandem mass spectrometry

A hexafluroisopropanol (HFIP)-alkanol supramolecular solvent (SUPRAS) based magnetic solvent bar (MSB) liquid-phase microextraction (LPME) method was proposed for extraction of non-steroidal anti-inflammatory drugs (NSAIDs, including ketoprofen, naproxen, indomethacin and diclofenac) in human serum. The restricted access HFIP-alkanol SUPRAS was prepared by injecting a mixture of HFIP and alkanol into water. A stainless-steel needle was inserted into a piece of hollow fiber to prepare a magnetic bar. Then the magnetic bar was dipped in SUPRAS to impregnate the wall pores of the hollow fiber, followed by placing it into the serum sample for extraction. Only 4 μL of SUPRAS was consumed per bar. The MSB not only functioned for stirring, but also played the role of extraction and magnetic separation. Under the optimal extraction conditions (seven MSBs, extraction time 33 min and stirring rate 730 rpm), which was obtained by one variable-at-a-time and response surface methodology, the novel MSB-LPME was coupled with high performance liquid chromatography-tandem mass spectrometry to determine NSAIDs in human serum. The method showed a good linear relationship (correlation coefficients ≥ 0.9939). Method limits of detection and method limits of quantitation were in the range of 0.25-0.95 μg L^-1 and 0.83-3.16 μg L^-1, respectively. The recoveries for the spiked human serum samples ranged from 86.8% to 125.1% with intra- and inter-day relative standard deviations less than 9.2% and 18.1%, respectively. Moreover, the method did not require a protein precipitation step, and matrix effects of 72.8%-117.7% showed little interference with mass spectrometry detection, which was due to the double cleanup provided by the restricted access property of SUPRAS and the filtration capacity of hollow fiber. The HFIP-alkanol SUPRAS-based MSB-LPME method proved to be simple, highly efficient and environment-friendly for the pretreatment of serum/plasma.

Application of Hollow Fibre-Liquid Phase Microextraction Technique for Isolation and Pre-Concentration of Pharmaceuticals in Water

In this article, a comprehensive review of applications of the hollow fibre-liquid phase microextraction (HF-LPME) for the isolation and pre-concentration of pharmaceuticals in water samples is presented. HF-LPME is simple, affordable, selective, and sensitive with high enrichment factors of up to 27,000-fold reported for pharmaceutical analysis. Both configurations (two- and three-phase extraction systems) of HF-LPME have been applied in the extraction of pharmaceuticals from water, with the three-phase system being more prominent. When compared to most common sample preparation techniques such as solid phase extraction, HF-LPME is a greener analytical chemistry process due to reduced solvent consumption, miniaturization, and the ability to automate. However, the automation comes at an added cost related to instrumental set-up, but a reduced cost is associated with lower reagent consumption as well as shortened overall workload and time. Currently, many researchers are investigating ionic liquids and deep eutectic solvents as environmentally friendly chemicals that could lead to full classification of HF-LPME as a green analytical procedure.

Development of Membrane-Based Inverted Liquid-Liquid Extraction for the Simultaneous Extraction of Eight Metals in Seawater before ICP-OES Analysis

In this work, we developed an extraction technique that can handle simple as well as complex matrixed liquid (aqueous) samples. In the standard liquid-liquid extraction, it is quite challenging to deal with complex liquid samples as they may complicate the process of phase separation and may lead to the formation of multiple layers. To resolve this issue, we have proposed a simple but unique idea that suggests the packing of the liquid samples inside a porous membrane bag. The edges of the membrane bag can be sealed using an electrical heat-sealer. The porous membrane bag filled with the liquid sample was immersed in an extraction solvent, and the extraction process was assisted by mechanical shaking. In order to demonstrate the proof of concept, a method was developed for the extraction of metals from seawater samples. The pH-adjusted sample, along with the complexing reagent, was packed inside the porous membrane bag, and the chelated complex was then extracted by immersing and shaking the bag inside the organic solvent. The solvent was then evaporated, and the chelated complex was dissolved/digested in acid with the aid of the heat. The final extract was subjected to Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) analysis. The proposed method was used for extraction of eight metals (Cd, Co, Cu, Mo, Ni, Pb, V and Zn) from seawater samples and good extraction recoveries (75-94%) were obtained.

Nanoliter-Scale Droplet-Droplet Microfluidic Microextraction Coupled with MALDI-TOF Mass Spectrometry for Metabolite Analysis of Cell Droplets

The further miniaturization of liquid-phase microextraction (LPME) systems has important significance and major challenges for microscale sample analysis. Herein, we developed a rapid and flexible droplet-droplet microfluidic microextraction approach to perform nanoliter-scale miniaturized sample pretreatment, by combining droplet-based microfluidics, robotic liquid handling, and LPME techniques. Differing from the previous microextraction methods, both the extractant and sample volumes were decreased from the microliter scale or even milliliter scale to the nanoliter scale. We utilized the ability of a liquid-handling robot to manipulate nanoliter-scale droplets and micrometer-scale positioning to overcome the scaling effect difficulties in performing liquid-liquid extraction of nanoliter-volume samples in microsystems. Two microextraction modes, droplet-in-droplet microfluidic microextraction and droplet-on-droplet microfluidic microextraction, were developed according to the different solubility properties of the extractants. Various factors affecting the microextraction process were investigated, including the extraction time, recovery method of the extractant droplet, static and dynamic extraction mode, and cross-contamination. To demonstrate the validity and adaptability of the pretreatment and analysis of droplet samples with complex matrices, the present microextraction system coupled with MALDI-TOF mass spectrometry (MS) detection was applied to the quantitative determination of 7-ethyl-10-hydroxylcamptothecin (SN-38), an active metabolite of the anticancer drug irinotecan, in 800-nL droplets containing HepG2 cells. A linear relationship (y = 0.0305x + 0.376, R² = 0.984) was obtained in the range of 4-100 ng/mL, with the limits of detection and quantitation being 2.2 and 4.5 ng/mL for SN-38, respectively.

Green analytical solutions for sample preparation: solid phase microextraction and related techniques

For at least three decades, the analytical chemistry community is striving to apply the principles of Green Chemistry to the development of analytical methods. Many efforts have been made to outline the concept of Green Analytical Chemistry, which helped to redefine analytical procedures and drastically changed the philosophy of analytical method development. This book chapter describes the 12 principles of Green Analytical Chemistry and various methodologies for the assessment of the greenness of analytical methods. The three main steps in the analytical method development – sample preparation, separation and detection- are described in a “green perspective”. Special emphasis is given to the description of green sample preparation procedures, in particular to Solid Phase Microextraction, that, since its introduction in 1989 by Janusz Pawliszyn, has drastically revolutionized the methodology of sample preparation, providing a convenient and green alternative to already existing methods.

Hollow fiber-based liquid phase microextraction followed by analytical instrumental techniques for quantitative analysis of heavy metal ions and pharmaceuticals

Hollow-fiber liquid-phase microextraction (HF-LPME) and electromembrane extraction (EME) are miniaturized extraction techniques, and have been coupled with various analytical instruments for trace analysis of heavy metals, drugs and other organic compounds, in recent years. HF-LPME and EME provide high selectivity, efficient sample cleanup and enrichment, and reduce the consumption of organic solvents to a few micro-liters per sample. HF-LPME and EME are compatible with different analytical instruments for chromatography, electrophoresis, atomic spectroscopy, mass spectrometry, and electrochemical detection. HF-LPME and EME have gained significant popularity during the recent years. This review focuses on hollow fiber based techniques (especially HF-LPME and EME) of heavy metals and pharmaceuticals (published 2017 to May 2019), and their combinations with atomic spectroscopy, UV-VIS spectrophotometry, high performance liquid chromatography, gas chromatography, capillary electrophoresis, and voltammetry.

Applications of Hollow-Fiber and Related Microextraction Techniques for the Determination of Pesticides in Environmental and Food Samples—A Mini Review

Pesticides represent one of the most important groups of analytes in environmental analysis. Moreover, their levels are very frequently determined in food and beverages due to the concern over their possible adverse health effects. Their concentration in samples is usually very low; thus, they have to be preconcentrated. Conventional solvent and solid-phase extractions are mainly used for this purpose, but miniaturized approaches are also being applied more and more often. The present review covers solvent microextractions that use a semi-permeable membrane barrier between the sample and the solvent. The main representatives of this approach are hollow-fiber microextraction (HFME), solvent bar microextraction (SBME), electromembrane extraction (EME), and different variations of those, such as combinations with other sorbent or solvent microextractions, electromigration, etc. The relevant research from the last decade, dealing with the application of these microextractions to the isolation of pesticides from various environmental and food samples, is critically discussed with emphasis on their strengths and weak points.

Hollow fiber liquid-phase microextraction based on the use of a rotating extraction cell: A green approach for trace determination of rhodamine 6G and methylene blue dyes

In this work, a novel mode of hollow fiber liquid-phase microextraction (HF-LPME) technique namely rotating extraction cell solvent bar microextraction (REC-SBME) was introduced. The proposed method was applied for the preconcentration of methylene blue (MB) and rhodamine 6G (RG) in some real samples, including soft drink, lipstick, environmental water, and wastewater samples. In the extraction setup, two pieces of hollow fibers were fixed on a mechanical support and immersed in a rotating extraction cell containing the sample solution during the extraction process. The rotation of the extraction cell by using an electric motor led to an enhancement in the mass transfer of the dyes from the sample solution into the organic acceptor phase. In the developed procedure, the UV-Vis spectrophotometry and HPLC-UV/Vis were employed as detection methods for the analysis of the acceptor phase and the obtained results were compared. Optimization of the extraction factors affecting the method, including organic solvent type, sample solution pH, extraction time, rotational rate, the volume of sample and acceptor solutions, salt addition, and temperature was performed in order to obtain the best preconcentration factor. Linear dynamic range obtained by HPLC-UV/Vis and spectrophotometry was observed in the ranges of 2.5-1200 ng mL^-1 for RG and 1.6-600 ng mL^-1 for MB with R² more than 0.9971. Also, relative standard deviation (RSD) values (n = 3) less than 3.8% were obtained. The good conformity of the obtained results makes UV-Vis spectrophotometric method an ideal tool for routine analysis of trace dyes in the complex matrices after REC-SBME.

Ballpoint connector-protected salt-oil-salt liquid phase microextraction for concentration and enrichment of trace anthraquinone compounds in rhubarb

This study proposed a new ballpoint connector-protected salt-oil-salt liquid phase microextraction for extraction and enrichment of trace rhein and chrysophanol in rhubarb prior to determination of the analytes by high performance liquid chromatography. In this study, a handy ballpoint connector (between ballpoint tip and ink chamber) was used as extraction device, in which its cavity was filled with n-octanol, and the bare n-octanol in its two opening ends was covered with a thin layer of sodium chloride film. The design subtly assembled salt film onto ballpoint connector for extraction and enrichment, which greatly improved the enrichment factors of the target analytes. Moreover, the novel procedure and its extraction mechanism were described and analyzed, and several crucial parameters reflecting the extraction effect were investigated and optimized. Under optimum conditions, high enrichment factors (247 and 127), good linearities with r ≥ 0.9998, limits of detection (0.6-1.1 ng/mL), relative standard deviations of intra- and interday (2.2-8.8% and 4.3-8.9%), and average recoveries (97.6-98.1%), were obtained, respectively. The proposed method can not only eliminate the negative effects from viscosity and ion strength at high salt concentration of sample phase, but also make salting-out effect be focused on small area so as to maximize the extraction effect.

A new microfluidic-chip device for selective and simultaneous extraction of drugs with various properties

In the present study, a newly designed microfluidic-chip device was used for the selective and simultaneous electromembrane extraction (EME) of drugs with different properties.