Microextraction Technique Research Articles

A review of new adsorbents for separation of BTEX biomarkers.

The biomarker analysis of benzene, toluene, ethylbenzene and xylene (BTEXs) in biological samples is the primary technique for evaluating these compounds in occupational and environmental exposures. The BTEX biomarkers are widely used to study the BTEX distribution in the environment and workplaces. Liquid-liquid extraction and solid-phase liquid extraction are among the most commonly used conventional methods to analyze biological indices of BTEXs. New methods have been proposed to analyze BTEX biomarkers using novel adsorbents such as sol-gel composite nanotubes, molecularly imprinted polymers and metal-organic frameworks, which are based on the application of needle trap devices, microextraction by packed sorbent, and solid-phase microextraction techniques. This paper provides an overview of new methods since 2015 regarding applying microextraction methods based on new adsorbents and analyzing BTEX biomarker compounds for occupational and environmental exposures. The results were compared with the liquid-phase microextraction methods recommended for urinary BTEX biomarkers.

Polydopamine-coated magnetic nanoparticles for the determination of nitro musks in environmental water samples by stir bar sorptive-dispersive microextraction

Magnetic-based microextraction approaches have gained popularity in recent years due to the magnetic properties of the extraction phases allowing to handle them easier and more efficiently. This work describes a magnetic-based analytical method for the determination of the family of nitro musks in environmental water samples. These compounds have been of great concern due to their environmental impacts and potential health effects. The method is based on stir bar sorptive-dispersive microextraction (SBSDME) as extraction approach, prior to thermal desorption coupled to gas chromatography-mass spectrometry analysis (TD-GC-MS). For this purpose, polydopamine-coated cobalt ferrite magnetic nanoparticles (CoFe2O4@PDA) were used as extraction material. The main parameters involved in the extraction procedure (i.e., sorbent amount, extraction time and ionic strength) as well as in the thermal desorption step (i.e., temperature and desorption time) were evaluated in order to obtain the highest sensitivity. Under the selected conditions, the method showed good linearity, limits of detection and quantification in the low ng L−1 range, intra- and inter-day repeatability with RSD <15%, and high enrichment factors (178–640). Finally, the method was applied to four environmental water samples of different origin. Relative recovery values ranging from 91 to 120% highlighted that the matrices under consideration do not affect the extraction process. This work constitutes the first time in which nitro musks compounds were selectively extracted by taking advantage the high potential that magnetic-based microextraction techniques offer, specially SBSDME.

Exploring the use of cork pellets in bar adsorptive microextraction for the determination of organochloride pesticides in water samples with gas chromatography/electron capture detection quantification

In this study, a biosorbent material with characteristics for the adsorption of organic compounds was used for a cork pellet-based bar adsorptive microextraction technique, as a new greener alternative for the determination of organochlorine compounds. Aldrin, chlordane, dieldrin, endrin, lindane, 4,4-DDD, 4,4-DDE, 4,4-DDT, α-endosulfan and β-endosulfan were analyzed in water samples (drinking water, stream water and river water) with separation/detection by gas chromatography and electron capture detection (GC/ECD). The parameters that can affect the sample preparation efficiency such as desorption solvent and time as well as extraction time and ionic strength were evaluated by multivariate and univariate designs. Cork pellets (10 × Ø 3 mm) were used for the extraction of 15 mL of sample in the optimal conditions: 60 min of agitation with no salt added to the sample, followed by desorption of the cork pellet with 120 µL of ethyl acetate for 30 min. The bar-to-bar RSD out with five different bars showed good results with RSD ≤ 15.6%, allowing the use of simultaneous extractions. LOD and LOQ values ranged from 3 to 15 ng L−1 and 10 to 50 ng L−1 respectively, and the determination coefficients were greater than 0.9869. The target analytes were not detected in the three analyzed samples. Therefore, the recovery study was performed fortifying the water samples. Analyte recovery ranged from 48.7 – 138.2% for drinking water, 40.2 – 128.2% for stream water and 67.5 – 128.7% for river water.

Recent Advances in Miniaturized Microextraction Techniques for the Determination of Bisphenols in Environmental Samples: An Overview of the Last Two Decades

Background: Bisphenols are major industrial chemicals that have raised public concern due to their endocrine disrupting properties and toxicity. Sample preparation is the most critical step for the determination of bisphenols, especially if the analyst has to deal with environmental samples which are complex matrices and the co-extraction and co-elution of other relevant compounds results in the enhancement or suppression of the analyte signal. The need for the precise determination of bisphenols has signaled the development of effective microextraction techniques according to the Green Analytical Chemistry (GAC) guidelines. Objective: The objective of this review is to gather and discuss all the recent advances in the development of microextraction techniques such as solid phase extraction (SPE), solid phase microextraction (SPME), magnetic solid phase microextraction (MSPE), liquid-phase microextraction (LPME), dispersive liquid-liquid microextraction (DLLME), stir bar sorptive extraction (SBSE), and matrix solid-phase dispersion (MSPD), that have been successfully applied in the extraction of bisphenols from environmental matrices. Conclusion: The analytical performance of the proposed techniques is critically discussed, highlighting the potential and the limitations of each method.

Green Miniaturized Extraction and Microextraction of Polycyclic Aromatic Hydrocarbons from Foods and Beverages

Background: Polycyclic aromatic hydrocarbons (PAHs) are common environmental contaminants consisting of two or more fused benzene rings. PAHs can be introduced into foodstuffs through different ways, such as smoking, roasting and grilling for meat and fish, absorption from the environment for edible oils, chemical treatment of crops for plant-based products, or contamination through packaging during storage. Due to the low concentrations of PAHs in foodstuffs, a clean-up and preconcentration sample preparation technique is of high importance. Until recently, solid-phase and liquid-liquid extraction were the most popular sample preparation techniques for the extraction of PAHs from food matrices. However, due to the fundamental drawbacks of those extraction procedures, a plethora of novel methods, including micro-extraction techniques and miniaturized extraction techniques, have been developed. Moreover, a wide variety of novel adsorbent materials (e.g., metal-organic frameworks, carbon-based materials, etc.) have been synthesized and applied for PAHs’ extraction. Objective: This review aims to discuss recent advances in the extraction techniques of PAHs from food samples, utilizing novel sample preparation approaches and adsorbents. Conclusion: Compared with the traditional sample preparation techniques, the herein discussed green miniaturized extraction and microextraction techniques offer multiple benefits, including simplicity, reduced sample preparation time, as well as reduced consumption of organic solvents.

A review of micro-solid-phase extraction techniques and devices applied in sample pretreatment coupled with chromatographic analysis

AbstractSample pretreatment is one of the most crucial and error-prone steps of an analytical procedure; it consents to improve selectivity and sensitivity by sample clean-up and pre-concentration. Nowadays, the arousing interest in greener and sustainable analytical chemistry has increased the development of microextraction techniques as alternative sample preparation procedures. In this review, we aimed to show two different categorizations of the most used micro-solid-phase extraction (μSPE) techniques. In essence, the first one concerns the solid-phase extraction (SPE) sorbent selection and structure: normal-phase, reversed-phase, ion-exchange, mixed-mode, molecular imprinted polymer, and special techniques (e.g., doped cartridges for specific analytes). The second is a grouping of the commercially available μSPE products in categories and sub-categories. We present every device and technology into the classifications paying attention to their historical development and the actual state of the art. So, this study aims to provide the state-of-the-art of μSPE techniques, highlighting their advantages, disadvantages, and possible future developments in sample pretreatment.

Application of robust syringe-to-syringe dispersive liquid-phase microextraction method for preconcentration and determination of mercury with the aid of an experimental design

ABSTRACT A simple and rapid syringe-to-syringe dispersive liquid-phase microextraction (SS-DLPME) technique has been developed for the separation and preconcentration of mercury combined with UV-Vis spectrophotometry. In this method, effective factors were screened using a Plackett–Burman design (PBD) and optimized using a Box–Behnken design (BBD). Under the optimized experimental conditions, the calibration curve was linear in the range of 5–400 µg L−1 with the coefficient of determination (r 2) of 0.997. The detection limit, intraday precision, inter-day precision and the enrichment factor (EF) were 1.60 μg L−1, 1.57%, 1.82% and 120, respectively. This method was successfully applied to the determination of Hg(II) in water, fish and human hair samples.

Salting-Out Induced Liquid-Liquid Microextraction: an Environmentally Friendly Approach to Preservative Determination in Food Samples

The salting-out induced liquid-liquid microextraction technique was properly evaluated for preservative determination in processed food samples. In the best conditions, 0.5 g sample and 4.5 mL acetate buffer, at pH 4.2, were extracted with 1 mL acetonitrile, followed by agitation, addition of 2 g MgSO4, a new agitation step, and centrifugation. Afterwards, the extract was diluted with ultrapure water and analyzed by high-performance liquid chromatography with ultraviolet detection. Correlation coefficients above 0.99, LOQs between 0.03 and 0.07 mg kg−1, and recoveries between 80 and 103%, with RSD ≤ 11%, were achieved. When applied to preservative determination in food samples, the method under evaluation provided similar results to those obtained by a previously validated one. Finally, this method is a good alternative to determining preservatives in food samples, with the advantages of being greener, cheaper, and faster than the official ones.

Research progress of microextraction by packed sorbent and its application in microvolume sample extraction

微萃取技术是分析化学领域发展迅速,且已经得到广泛应用的样品前处理技术。填充吸附剂微萃取(MEPS)是一种微量固相萃取技术,使用微量的吸附剂填充于微量注射器,通过反复抽推方式使样品多次流经吸附剂以完成样品吸附萃取过程,萃取后的样品可直接用于色谱分析。典型的MEPS萃取设备包括MEPS注射器和MEPS吸附床(BIN)。MEPS优化的主要因素为MEPS处理过程的参数,包括样品流速、样品量与样品萃取循环次数,吸附剂及淋洗、洗脱溶剂的种类和体积,还需要考虑样品基质对MEPS性能的影响和样品残留和重复使用问题。MEPS中最重要的部分是吸附剂,主要有商品化的MEPS吸附剂,包括硅基的Silica、C18、C8等,碳材料的Hypercarb和聚苯乙烯聚合物类的SDVB、HDVB吸附剂等。研究用的吸附剂包括分子印迹材料、限进分子印迹材料、碳基材料、导电聚合物类材料、改性硅基材料及共价-有机骨架材料等。MEPS结合多种分析仪器已经成功应用于从不同基质中提取单一或多种分析物,所涵盖基质包括生物样品(尿液、唾液、血浆或血液)、河流水体或生活污水以及几种食品和饮料。MEPS处理复杂生物基质样品时,通常需要稀释样品、除蛋白质等预处理。MEPS具有需要样品体积小、操作快速等特点,在生物基质样品分析中有望得到更广泛的使用。在环境样品中,该技术可与现场便携仪器联用,未来将有望在现场进行快速检测,并于易分解样品等方面发挥作用。

Novel materials as capillary coatings for in-tube solid-phase microextraction for bioanalysis.

In-tube solid-phase microextraction with a capillary column as extraction device can be directly coupled with high-performance liquid chromatography systems (HPLC). The in-tube solid-phase microextraction technique has been continuously developed since it was introduced in 1997. New couplings have also been evaluated on the basis of state-of-the-art HPLC instruments. Different types of capillaries (wall-coated open tubular, porous layer open tubular, sorbent-packed, porous monolithic rods, or fiber-packed) with selective stationary phases (monoliths, magnetic nanoparticles, conducting polymers, restricted access materials, ionic liquids, carbon, deep eutectic solvents, and hybrid materials) have been developed to boost in-tube solid-phase microextraction performance (sorption capacity and selectivity). This technique has been successfully applied to analyze biological samples (serum, plasma, whole blood, hair, urine, milk, skin, and saliva) for therapeutic drug monitoring, to study biomarkers, to detect illicit drugs, to conduct metabolomics studies, and to assess exposure to drugs. This review describes current advances in in-tube solid-phase microextraction extraction devices and their application in bioanalysis.

Recognition of pathogens in food matrixes based on the untargeted in vivo microbial metabolite profiling via a novel SPME/GC × GC-QTOFMS approach

Foodborne diseases incurred by pathogenic bacteria are one of the major threats in food safety, and thus it is important to develop facile and effective recognition methodology of pathogens in food. Herein, a new automatic approach for detection of in vivo volatile metabolites emitted from foodborne pathogens was proposed by coupling solid phase microextraction (SPME) technique with a comprehensive two-dimensional gas chromatography quadrupole time-of-flight mass spectrometry (GC × GC-QTOFMS). A novel polymer composite based SPME probe which possessed high-coverage of microbial metabolites was utilized in this contribution to realize the sensitive extraction of untargeted metabolites. As a result, a total of 126 in vivo metabolites generated by the investigated pathogens were detected and identified, with 33, 29, 25, 21 and 18 volatile metabolites belonging to Shigella sonnei, Escherichia coli, Salmonella typhimurium, Vibrio parahaemolyticus and Staphylococcus aureus, respectively. Multivariate statistical analyses were applied for further analysis of metabolic data and separation of responsive metabolic features among different microbial systems were found, which were also successfully verified in foodstuffs contaminated by microorganisms. The growth trend of the potential volatile markers of each pathogen in food samples kept consistent with that of the pure strain incubated in medium during the whole incubation time. This study promotes the application of SPME technology in microbial volatile metabolomics and contributes to the development of new approaches for foodborne pathogens recognition.

Enriching the nutritive value of marigold (Tagetes erecta L) crop residues as a ruminant feed by lactic acid bacteria\xa0during ensilage

BackgroundMarigold (Tagetes erecta L) accounts for over half of the world’s loose flower production, and marigold crop residue (MCR) are abundantly available and should be used as a forage. In this study, MCR from the last commercial flower pickings was ensilaged with lactic acid bacteria (LAB) and the shift in their volatile organic compounds (VOCs) profiles was monitored. Samples were collected at 6 different times during ensilage (3, 6, 9, 12, 15, 30 days) to determine and quantify the VOCs changes using a solid-phase microextraction (SPME) technique and gas chromatography – mass spectrometry (GC-MS).ResultsAfter 30 days, the caryophyllene and piperitone, which account for 14.7 and 12.1% of total VOCs, decreased by 32.9 and 9.6% respectively, alcohols increased from 2.8 to 8.1%, and the acetic acid content increased by 560%.ConclusionWe have confirmed LAB can degrade the content of terpenes and enhance the content of alcohols and acids in MCR, which was for the first time on terpene degradation in fodder by ensilage. These results have shed light on our understanding of how to improve fodder odor and to enhance terpene degradation by lactic acid bacteria fermentation.

Fundamentals and applications of stir bar sorptive dispersive microextraction: A tutorial review

Current trends in sample preparation focus on the miniaturization of the process resulting in what is known as microextraction techniques. Among them stir bar sorptive dispersive microextraction (SBSDME) is one of the most recent techniques. It was presented a few years ago as a hybrid microextraction technique that combines the principles of stir bar sorptive extraction (SBSE) and dispersive solid phase extraction (DSPE). This novel technique introduces, into the sample solution, a bar-shaped magnet coated with a magnetic (nano)material, which is maintained on the surface by magnetism. Once stirring starts, the competitive action between magnetism and rotational force is exploited. At low rotational speed the (nano)material is retained on the magnet reminding SBSE, whereas at high sufficiently rotational speed the rotational force surpasses magnetism so that the magnetic (nano)material is dispersed into the sample solution as in DSPE. Upon halting rotation, the magnetic field prevails again and attracts the magnetic (nano)material containing the analytes back on the surface of the stirring bar. Finally, the extracted analytes are chemically or thermally desorbed before their measurement with the appropriate analytical instrument. When compared separately to SBSE and DSPE procedures, SBSDME affords, in a single approach, advantages such as lower extraction times than SBSE and easier extraction and post-extraction treatment than DSPE. The main purpose of this tutorial review is to describe the fundamentals and the experimental variables involved in this technique, as well as to compile and critically discuss the published papers concerning analytical methods based on the use of the SBSDME approach, analyzing its evolution and future prospects.

Re-Analysis of Abdominal Gland Volatilome Secretions of the African Weaver Ant, Oecophylla longinoda (Hymenoptera: Formicidae).

The African weaver ant, Oecophylla longinoda, is used as a biological control agent for the management of pests. The ant has several exocrine glands in the abdomen, including Dufour’s, poison, rectal, and sternal glands, which are associated with pheromone secretions for intra-specific communication. Previous studies have analyzed the gland secretions of Dufour’s and poison glands. The chemistry of the rectal and sternal glands is unknown. We re-analyzed the secretions from Dufour’s and poison glands plus the rectal and sternal glands to compare their chemistries and identify additional components. We used the solid-phase microextraction (SPME) technique to collect gland headspace volatiles and solvent extraction for the secretions. Coupled gas chromatography–mass spectrometry (GC-MS) analysis detected a total of 78 components, of which 62 were being reported for the first time. These additional components included 32 hydrocarbons, 12 carboxylic acids, 5 aldehydes, 3 alcohols, 2 ketones, 4 terpenes, 3 sterols, and 1 benzenoid. The chemistry of Dufour’s and poison glands showed a strong overlap and was distinct from that of the rectal and sternal glands. The different gland mixtures may contribute to the different physiological and behavioral functions in this ant species.

Quantitative Measurement of Plasma Free Metanephrines by a Simple and Cost-Effective Microextraction Packed Sorbent with Porous Graphitic Carbon and Liquid Chromatography-Tandem Mass Spectrometry.

Plasma free metanephrines are widely used for the diagnosis of pheochromocytoma and paraganglioma (PPGL), yet quantifying metanephrines using a simple and cost-effective approach may be challenging due to preanalytical and analytical constraints. In this study, we established and validated a new method for quantitative measurement of plasma free metanephrines based on microextraction by packed sorbent (MEPS) with porous graphitic carbon (PGC) and liquid chromatography-tandem mass spectrometry (HILIC-MS/MS). The elution step was fully compatible with HILIC mode without evaporation and reconstitution. The analytes were well resolved, and potential interferences (54 substances) were investigated. This method was linear from 24.7–2717 pg/mL for metanephrine (MN) and 24.5–4010 pg/mL for normetanephrine (NMN) with a coefficient of determination (R2) higher than 0.994. The limit of MN and NMN detection were 12.4 pg/mL and 12.3 pg/mL, respectively. The intra- and interassay impressions were ≤12.8% for spiked quality controls and ≤13.6% for commercial quality controls; the method recoveries ranged within 88.0–109.0%, respectively. The area under the receiver operating characteristic (ROC) curve was 0.848 ± 0.047 for MN and 0.979 ± 0.021 for NMN. Validation that was performed by comparing clinical specimens with various biochemical results showed that plasma free metanephrines in a seated position had comparable sensitivity and lower specificity to urinary free metanephrines, which could be compensated by combining other biochemical tests. The newly developed MEPS method resulted as a time-saving, reliable, and cost-effective microextraction technique that can be applied for a successful screening of PPGL.

Hollow fiber liquid-phase microextraction combined with supercritical fluid chromatography coupled to mass spectrometry for multiclass emerging contaminant quantification in water samples.

The hollow fiber liquid-phase microextraction allows highly selective concentration of organic compounds that are at trace levels. The determination of those analytes through the supercritical fluid chromatography usage is associated with many analytical benefits, which are significantly increased when it is coupled to a mass spectrometry detector, thus providing an extremely sensitive analytical technique with minimal consumption of organic solvents. On account of this, a hollow fiber liquid-phase microextraction technique in two-phase mode combined with supercritical fluid chromatography coupled to mass spectrometry was developed for quantifying 19 multiclass emerging contaminants in water samples in a total chromatographic time of 5.5min. The analytical method used 40μL of 1-octanol placed in the porous-walled polypropylene fiber as the acceptor phase, and 1L of water sample was the donor phase. After extraction and quantification techniques were optimized in detail, a good determination coefficient (r2 > 0.9905) in the range of 0.1 to 100μgL-1, for most of the analytes, and an enrichment factor in the range of 7 to 28,985 were obtained. The recovery percentage (%R) and intraday precision (%RSD) were in the range of 80.80-123.40%, and from 0.48 to 16.89%, respectively. Limit of detection and quantification ranged from 1.90 to 35.66ngL-1, and from 3.41 to 62.11ngL-1, respectively. Finally, the developed method was successfully used for the determination of the 19 multiclass emerging contaminants in superficial and wastewater samples.

Sample preparation and instrumental methods for illicit drugs in environmental and biological samples: A review

Detection of illicit drugs in the environmental samples has been challenged as the consumption increases globally. Current review examines the recent developments and applications of sample preparation techniques for illicit drugs in solid, liquid, and gas samples. For solid samples, traditional sample preparation methods such as liquid-phase extraction, solid-phase extraction, and the ones with external energy including microwave-assisted, ultrasonic-assisted, and pressurized liquid extraction were commonly used. The sample preparation methods mainly applied for liquid samples were microextraction techniques including solid-phase microextraction, microextraction by packed sorbent, dispersive solid-phase extraction, dispersive liquid-liquid microextraction, hollow fiber-based liquid-phase microextraction, and so on. Capillary microextraction of volatiles and airborne particulate sampling were primarily utilized to extract illicit drugs from gas samples. Besides, the paper introduced recently developed instrumental techniques applied to detect illicit drugs. Liquid chromatograph mass spectrometry and gas chromatograph mass spectrometry were the most widely used methods for illicit drugs samples. In addition, the development of ambient mass spectrometry techniques, such as desorption electrospray ionization mass spectrometry and paper spray mass spectrometry, created potential for rapid in-situ analysis.

Simultaneous Chemical and Sensory Analysis of Domestic Cat Urine and Feces with Headspace Solid-Phase Microextraction and GC-MS-Olfactometry

The association between humans and cats (Felis catus) is well known. This domestic animal is also known for its malodorous urine and feces. The complexity of the odorous urine and feces impacts human life by triggering the human sensory organ in a negative way. The objective of this research was to identify the volatile organic chemicals (VOCs) and associated odors in cat urine and feces using gas chromatography–mass spectrometry and simultaneous sensory analysis of fresh and aged samples. The solid-phase microextraction (SPME) technique was used to preconcentrate the VOCs emitted from urine or feces samples. Twenty-one compounds were identified as emitted from fresh urine, whereas 64 compounds were emitted from fresh feces. A contrasting temporal impact was observed in the emission of VOCs for urine and feces. On aging, the emission increased to 34 detected chemicals for stale urine, whereas only 12 chemicals were detected in stale feces. Not all compounds were malodorous; some compounds had a pleasant hedonic smell to the human nose. Although trimethylamine, low-molecular-weight organic acids, and ketones were contributors to the odor to some extent, phenolic compounds and aromatic heterocyclic organic N compounds generated the most intense odors and substantially contributed to the overall malodor, as observed by this study. This work might be useful to formulate cat urine and feces odor remediation approaches to reduce odor impacts.

Sustainable green solvents for microextraction techniques: Recent developments and applications

The development and application of alternative green solvents in analytical techniques consist of trends in sample preparation, since this subject represents an important step toward sustainability in experimental procedures. This review is focused on the main theoretical aspects related to deep eutectic solvents (DES), switchable hydrophilicity solvents (SHS) and supramolecular solvents (SUPRAS). Recent applications are highlighted, particularly for the extraction of different analytes from environmental, biological and food matrices. Moreover, novel configurations are emphasized, aiming for efficient, automated and high-throughput procedures. This review also provides some critical points regarding the use of these solvents and their green aspects.

Electromembrane extraction of streptomycin from biological fluids

In this fundamental study, streptomycin was extracted successfully from urine and plasma using electromembrane extraction (EME). Streptomycin is an aminoglycoside with log P -7.6 and was selected as an extremely polar model analyte. EME is a microextraction technique, where charged analytes are extracted under the influence of an electrical field, from sample, through a supported liquid membrane (SLM), and into an acceptor solution. The SLM comprised 2-nitrophenyl pentyl ether (NPPE) mixed with bis(2-ethylhexyl) phosphate (DEHP). DEHP served as ionic carrier and facilitated transfer of streptomycin across the SLM. For EME from urine and protein precipitated plasma, the optimal DEHP content in the SLM was 45–50% w/w. From untreated plasma, the content of DEHP was increased to 75% w/w in order to suppress interference from plasma proteins. Most endogenous substances with UV absorbance were not extracted into the acceptor. Proteins and phospholipids were also discriminated, with <0.6% of proteins and <0.02% of phospholipids found in the acceptor after EME. Thus, despite the fact that the SLM was permeable to more polar molecules, the EME still provided very efficient sample cleanup. Extraction process efficiencies of 98% and 61% were achieved from urine and plasma, respectively, with linear calibration (R2 > 0.9929), absence of significant matrix effects (94–112%), accuracy of 94–125%, and RSD ≤ 15% except at LLOQ. The average current during extractions was 67 µA or less. The findings of this paper demonstrated that EME is feasible for extraction of basic analytes of extreme polarity.