Combination Of Microextraction Research Articles

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.

Volatilomic profile of the tree tomato (Solanum betaceum Cav.) pulp during ripening and senescence using HS–SPME with GC–MS

The volatilomic profile of the tree tomato (Solanum betaceum Cav.) pulp during ripening stages and senescence times was determined by headspace solid-phase microextraction in combination with gas chromatography-mass spectrometry. The HS-SPME-GC-MS analysis allowed the identification of 46 metabolites that produce the metabolic fingerprint of this fruit, the major compounds at all ripening stages and senescence times were ethyl butanoate, methyl butanoate, β-myrcene and eucalyptol. The composition in the different stages was subjected to principal component analysis (PCA), which explained 77.3% of the total variance in the principal components. It allowed to classify the samples by ripening stages and senescence times and it was corroborated with K-means clustering and dendrogram analyses. Through multivariate analyses PCA, partial least squares-discriminant analysis (PLS-DA), and heatmap it was possible to determine volatiles methyl (E)-2-hexenoate, 4-tert-butylcyclohexyl acetate, methyl benzoate, methyl (Z)-3-hexenoate, 3-methylbutyl acetate, β-thujene, cis-3-hexenol, hexanal and trans-2-hexenal as potential markers in the ripening stages, while volatiles propyl butanoate, ethyl octanoate, ethyl acetate, ethyl butanoate, β-myrcene and estragol predominated in the senescence times. HS-SPME-GC-MS analysis of volatiles in combination with the chemometric approach used in this research allowed to make a clear distinction between ripening stages and senescence times in common red variety of tree tomato pulp.

Identification of quality markers for the geographical and botanical differentiation of Mediterranean prickly pears based on conventional physicochemical parameters, volatile compounds, sugars and colour

Seventy-four prickly pear samples grown in Mediterranean countries (Cyprus, Greece, Italy and Spain) and 43 prickly pear samples, from 3 different Cypriot varieties (Yellow, Red and Spineless), were characterized and differentiated according to geographical and botanical origin. Prickly pear conventional quality parameters (pH, electrical conductivity, titratable acidity, moisture content, crude fat and protein, total carbohydrates and ash) were determined using official methods of analysis. Colour parameters were determined using HunterLab tristimulus colorimetry and individual sugars using UPLC–MS/MS. Volatile compounds were identified and semi-quantified using solid-phase microextraction in combination with gas chromatography–mass spectrometry. Multivariate analysis of variance (MANOVA) and linear discriminant analysis (LDA) were used to analyze the experimental data. Results showed that the combination of physicochemical parameters and volatiles gave a correct differentiation rate of 80.8% according to geographical origin while the combination of physicochemical parameters gave a correct differentiation rate 95.3% according to botanical origin using the cross-validation method.

Chemical composition of volatile components in the honey of some species of stingless bees

Using the technique of headspace solid-phase microextraction in combination with gas chromatography and mass spectrometric detection (HS-SPME/GC-MS), the composition of the volatile organic compounds (VOCs) of the honey of four species of stingless bees was studied in comparison with the honey of Apis mellifera bees. Peaks for 284 volatile components were registered on the chromatograms. Only eight components were present in all six studied samples. A high level of specificity in the composition of VOCs is a prerequisite for differentiating honey produced by different types of stingless bees and honey bees. Several specific features have been identified that are characteristic of the composition of VOCs in the honey of each species of stingless bees. These characteristics can be used to distinguish it from the honey of A. mellifera. The data obtained indicate the applicability of the HS-SPME/GC-MS technique for establishing the origin and for quality control of stingless bee honey.

Characterization and Differentiation of Fresh Orange Juice Variety Based on Conventional Physicochemical Parameters, Flavonoids, and Volatile Compounds Using Chemometrics.

The present study focused on the possibility of differentiating fresh-unprocessed orange juice according to botanical origin (variety), based on the use of conventional physico-chemical parameters, flavonoids, and volatile compounds, in combination with chemometrics. For this purpose, oranges from seven different varieties were collected during the harvest years of 2013–2014 and 2014–2015 from central and southern Greece. The physico-chemical parameters that were determined included: electrical conductivity, acidity, pH, and total soluble solids. The flavonoids: hesperidin, neohespseridin, quercetin, naringin, and naringenin were determined using high-performance liquid chromatography (HPLC-DAD). Finally, volatile compounds were determined using headspace solid-phase micro-extraction in combination with gas chromatography-mass spectrometry (HS-SPME/GC-MS). Statistical treatment of data by multivariate techniques showed that orange juice variety had a significant (p < 0.05) impact on the above analytical parameters. The classification rate for the differentiation of orange juice according to orange variety using multivariate analysis of variance (MANOVA) and linear discriminant analysis (LDA) was 89.3%, based on the cross-validation method.

Design of a combined microextraction and back-extraction technique for the analysis of mycotoxins in amaranth seeds

A methodology was optimized for the determination of the mycotoxins deoxynivalenol and zearalenone in Amaranthus-based samples. The extraction/preconcentration procedure consisted of an in-phase liquid-liquid microextraction based on the solidification of a floating organic drop followed by a double solvent-assisted back-extraction combined with liquid chromatography-tandem mass spectrometry (DLLME-SFO-SBE). The solvent assisted back-extraction enabled the direct injection of deoxynivalenol (DON) and zearalenone (ZEA) in the ultra-high performance liquid chromatography-tandem mass spectrometry system configured with an electrospray source operated in a positive polarity mode (UHPLC-ESI+-MS/MS). Parameters affecting the efficiency of the back-extraction procedure were evaluated and optimized, including the nature of the back-extractant volume and the agitation effect. Detection and quantification limits were in the range of 0.07−0.73 μg kg−1 and 0.22−0.91 μg kg−1. Acceptable extraction recoveries between 80.35 and 100.05 % and enrichment factors between 16 and 20-fold, with relative standard deviations < 10.12 %, were obtained. The method was successfully applied to the analysis of different types of Amaranthus samples. Concentration levels of deoxynivalenol from 10.62–76.86 μg kg-1 and zearalenone from 9.18–89.29 μg kg−1, were detected in seeds, flours, and the burst of Amaranthus. The proposed methodology is an easy, sensitive, and accurate analytical approach to determine deoxynivalenol and zearalenone in the mentioned food samples.

Microfluidic-based liquid-liquid microextraction in combination with smartphone-based on-chip detection for the determination of copper in biological, environmental, and food samples

In the present work, a simple and green microfluidic-based liquid-liquid microextraction in combination with smartphone-based on-chip detection was introduced for the determination of copper in environmental, biological, and food samples. The procedure was based on an ion-pair formation between tetrabutylammonium and tetrathiocyanatocuprate(II) anion, which was extracted with a suitable extractant and subsequent color sensing using a smartphone. All the steps were performed in a microchip. The smartphone was used as both a detector and a data processing unit. Different experimental parameters affecting analytical signal were studied and optimized. Under the optimum conditions, the method showed a linear dynamic range between 0.3 and 40 mg L−1 with a determination coefficient of 0.9953. The limits of detection and quantification were obtained 0.1 and 0.3 mg L−1, respectively. The method provided a precise determination with relative standard deviations in the range of 4.1–5.3%. Finally, the method was successfully applied for the determination of copper in whole blood, mushroom, wastewater, and tap water samples with spiking recoveries in the ranges of 80–98%, 96–108%, 95–107%, and 100–103%, respectively. In comparison with the atomic absorption technique, no significant difference was observed between the two methods in terms of accuracy.

Multivariate Cherry Quality Assessment Using Morphological, Biochemical and Volatile Compound Traits

ABSTRACT This study was carried out to evaluate fruit quality of five sweet cherry cultivars grown in Morocco, namely, Burlat, Van, Cerisette, Napoleon and Coeur de pigeon. Significant differences (p˂0.05) were observed across the five cultivars in fruit weight (5.24–8.72 g), geometric mean diameter (14.22–16.36 mm), pH (3.48–4.12), soluble solid content (17.70–24.50 °Brix), total phenolics (426.44–485.69 mg GAE/100 g fresh weight (fw)), total proanthocyanidins (51.17–131.20 mg CE/100 g fw) and total anthocyanins (194.53–267.67 mg cya-3-glu/100 g fw). The antioxidant activity was evaluated by three assays. The values were 11.96–21.04, 16.48–63.96 and 9.62–15.65 mmol TE/g for DPPH scavenging test, FRAP and ABTS, respectively. Volatile compounds were identified and semi-quantified in sweet cherry fruit using solid-phase microextraction in combination with gas chromatography/mass spectrometry (SPME-GC/MS). Nine volatile compounds (benzaldehyde, nonanal, ethyl hexanoate, ethyl octanoate, γ-terpinene, β-pinene, limonene, linalool and 2-ethyl-1-hexanol) were detected in all sweet cherry cultivars. Aldehydes compounds were the most abundant in sweet cherry aroma, followed by terpenes and esters. Correlation between all parameters showed varying trends.

A vinylpyrrolidone-based thin film microextraction in combination with direct solid-state spectrofluorimetry for determination of sartans in human plasma

A vinylpyrrolidone-ethylene glycol dimethacrylate-acrylic acid thin film was prepared on a polypropylene guard and its formulation was optimized for application in thin film microextraction followed by direct solid-state spectrofluorimetry method. The surface morphology, fluorescence property and extraction performance of the thin film were investigated systematically. The intra- and inter-batch reproducibilities of thin film fabrication were obtained 2.3 and 4.2%, respectively. The lifetime of each prepared thin film was 30 times with a relative standard deviation of less than 1.4%. The developed method was optimized for extraction of some sartans as angiotensin II receptors antagonist (including losartan, valsartan, and olmesartan) which have been used to control hypertension as the main causes of cardiovascular disease. The optimum extraction conditions achieved at 2- (for losartan) and 4- (for valsartan and olmesartan) sample pH, 500-rpm rotation rate and 30-min extraction time for all three analytes. At the optimum conditions, analyses of losartan, valsartan, and olmesartan were validated in the human plasma matrix. Broad linearity ranges with determination coefficients of more than 0.999 were achieved for each calibration curve. Limit of detection of the method was 0.5 ng mL−1 for all three analytes. The intra- and inter-day accuracies and precisions of the developed method were evaluated in spiked plasma samples at three concentration levels of each analyte with high recoveries of 95–101% and relative standard deviations less than 6%. This method provides a simple, sensitive, fast, and high-throughput analysis method with the possibility of effective extraction of at least 40 samples simultaneously without the necessity of protein precipitating, desorption, and solvent evaporation steps.

A micro-extraction method for use with 4 mm plate geometry in the Dynamic Shear Rheometer to evaluate asphalt binder rheology

Abstract Current procedures to extract and recover asphalt binders require a large amount of material and consequently a large volume of toxic solvents. To reduce exposure and consumption of such solvents, a micro-extraction method for extracting and recovering asphalt binder from small amounts of asphalt mix or reclaimed asphalt pavement (RAP) is presented. Sixteen laboratory long term aged mixes were used to extract the binder and evaluate its properties, using both the micro-extraction and conventional extraction methods. The Bending Beam Rheometer (BBR) and Dynamic Shear Rheometer (DSR) with the 4 mm parallel plate geometry were used to determine the low temperature properties of the extracted materials. The DSR was used with samples obtained using the conventional extraction method and proposed micro-extraction method. Low temperature properties from the three different procedures (conventional extraction with BBR, conventional extraction with DSR, and micro-extraction with DSR) were compared. Results indicate that the 4 mm plate method is a viable surrogate to measure low temperature properties in lieu of the BBR for recovered and recycled materials. The combined use of micro-extraction and 4 mm parallel plate geometry is a viable technique to extract binder from small amounts of asphalt materials. The combined micro-extraction and 4 mm method was also used to demonstrate the high variability (up to 12 °C low continuous grade) among different RAP stockpiles collected from across the state of Texas.

Quantitation of pyrazines in roasted green tea by infrared-assisted extraction coupled to headspace solid-phase microextraction in combination with GC-QqQ-MS/MS

Pyrazines play an important role in the characteristic flavor of roasted green tea due to powerful strong odours and low sensory thresholds. It is important to analyze these compounds reliably and rapidly in roasted green tea. In this study, infrared-assisted extraction coupled to headspace solid-phase microextraction (IRAE-HS-SPME) and gas chromatography-triple quadrupole-tandem mass spectrometry (GC-QqQ-MS/MS) were developed and validated to determine the pyrazines in roasted green tea. Good linear correlation coefficients (0.9955–0.9996) were obtained over the concentration ranges of 10–5000 ng/mL. The limits of detection (LODs) and limits of quantification (LOQs) for the pyrazines were in the range of 1.46–3.27 ng/mL and 4.89–10.90 ng/mL, respectively. The average recoveries varied from 84% to 119%. The method was used to analyze the pyrazines in roasted green tea manufactured by different final firing methods, the results revealed that microwave final firing method had maximum contents of pyrazines, and significantly improved the aroma quality. In addition, there were great disparities of pyrazines in flatten-shaped green tea and strip-shaped green tea according to the appearance. The result is expected to better understand the role of pyrazines related to aroma quality of roasted green tea and improve processing technology.

Exploiting the versatility of vacuum-assisted headspace solid-phase microextraction in combination with the selectivity of ionic liquid-based GC stationary phases to discriminate Boswellia spp. resins through their volatile and semivolatile fractions.

The frankincense resins, secreted from Boswellia species, are an uncommon example of a natural raw material where every class of terpenoids is present in similar proportions. Diterpenoids (serratol, incensole, and incensole acetate) are used to discriminate samples from different species and origins. Headspace solid-phase microextraction has been used for frankincense analysis, although it requires long sampling time for medium- to low-volatility markers; headspace solid-phase microextraction under vacuum can overcome this limit. Gas chromatography is used for analysis but the separation of incensole and serratol needs polar stationary phases. In this study, we develop a method to discriminate frankincenses based on vacuum-assisted headspace solid-phase microextraction combined with fast gas chromatography-mass spectrometry with ionic liquid-based stationary phases. The optimized conditions for solid samples were: air evacuation below 0°C, 15min of incubation time, and 15min of extraction time. Losses of volatiles due to vial air-evacuation in the presence of the sample were minimized by sample amount above 100mg and low sample temperature. Fast gas chromatography provides the baseline separation of all markers in 20min. By applying vacuum sampling and fast gas chromatography, the total analysis was reduced to 50min compared to 120min (60min sampling plus 60min analysis) as previously reported. The method was successfully applied to commercial frankincense samples.

Identifikacija isparljivih aromatičnih jedinjenja voćnih rakija metodom mikroekstrakcije na čvrstoj fazi u kombinaciji sa gasnom hromatografijom i masenom spektrometrijom

The optimization of the headspace solid-phase microextraction in combination with the gas chromatography-mass spectrometry (HS-SPME-GC/MS) for the qualitative identification of the aroma compounds in fruit spirits (Williams, plum spirit, grape spirit , apricot spirit) was the subject of the presented paper. The SPME extraction conditions (temperature, time, and NaCl amount) have been varied in order to achieve the more efficient chromatographic separation of the gas mixtures, to efficiently salt-out a higher number of less volatile compounds, and to save the energy during the sample preparation. Optimal parameters were determined as: T = 40 °C; m NaCl = 2 g; dilution = 10 times. According to the results obtained, the analyzed samples of Serbian fruit spirits produced from different fruits have a comparable composition of volatile aroma compounds to whiskey. The detection and definition of specific compounds that are "fingerprint" of fruit spirits could be an efficient method of the product authentication developing.

A combined microextraction procedure for isolation of polycyclic aromatic hydrocarbons in ambient fine air particulate matter with determination by gas chromatography-tandem mass spectrometry

A novel combined vortex-assisted dispersive liquid-liquid microextraction (VA-DLLME)–micro-solid-phase extraction (μ˗SPE) procedure for polycyclic aromatic hydrocarbons (PAHs) in ambient fine particulate matter of aerodynamic diameter of ≤ 2.5 µm (PM2.5), was developed. PM2.5 was collected on polytetrafluoroethylene (PTFE)-coated glass fiber filter, that was first processed by ultrasonicating in aqueous solution. Then, VA-DLLME, followed by µ-SPE, were applied to the solution using 1-octanol and graphene oxide as extractant and sorbent, respectively for extracting the PAHs. The PAHs were determined by gas chromatography–tandem mass spectrometry (GC–MS/MS). Parameters affecting the extraction efficiency including selection of the sorbent, duration of DLLME and µ-SPE, desorption solvent type, and ultrasonication-assisted desorption time were investigated. Under the optimum extraction conditions, the method exhibited linear ranges of 0.5–50 μg/L and 0.5–100 μg/L depending on the analytes. The limits of detection were in the range of 0.013 μg/L–0.135 μg/L. The developed method was applied to determine the PAHs in genuine PM2.5 samples collected on PTFE glass fiber filters. The concentration levels in the atmospheric PM2.5 were determined to be from below the limit of quantification to 0.135 ng/m3. The relative recoveries obtained from spiked concentrations at 1 μg/L and 5 μg/L were in the range 57˗88% with relative standard deviations <14%.

Inhibitory Abilities of Bacillus Isolates and Their Culture Filtrates against the Gray Mold Caused by Botrytis cinerea on Postharvest Fruit.

Botrytis cinerea, a major phytopathogenic fungus, has been reported to infect more than 200 crop species worldwide, and it causes massive losses in yield. The aim of this study was to evaluate the inhibitory abilities and effects of Bacillus amyloliquefaciens RS-25, Bacillus licheniformis MG-4, Bacillus subtilis Z-14, and Bacillus subtilis Pnf-4 and their culture filtrates and extracts against the gray mold caused by B. cinerea on postharvest tomato, strawberry, and grapefruit. The results revealed that the cells of Z-14, culture filtrate of RS-25, and cells of Z-14 showed the strongest biocontrol activity against the gray mold on the strawberry, grape, and tomato fruit, respectively. All the strains produced volatile organic compounds (VOCs), and the VOCs of Pnf-4 displayed the highest inhibition values. Based on headspace solid-phase microextraction in combination with gas chromatography-mass spectrometry, esters accounted for the largest percentage of the VOCs produced by RS-25, MG-4, Z-14, and Pnf-4 (36.80%, 29.58%, 30.78%, and 36.26%, respectively). All the strains showed potent cellulase and protease activities, but no chitinase activity. RS-25, Z-14, and MG-4, but not Pnf-4, grew on chrome azurol S agar, and an orange halo was formed around the colonies. All the strains showed biofilm formation, fruit colonization, and lipopeptide production, which may be the main modes of action of the antagonists against B. cinerea on the fruit. This study provides the basis for developing natural biocontrol agents against the gray mold caused by B. cinerea on postharvest fruit.

Black rice addition prompted the beer quality by the extrusion as pretreatment.

Flavor compounds, including total polyphenols, amino acids, and protein, in beer with extruded black rice as adjunct were detected and analyzed. Beer brewing technique has been intensively investigated in the past century. The chase of beer quality, including the color, flavor, foam, nutrition, and functionality, attracted considerable attention. Hence, headspace solid‐phase microextraction in combination with a gas chromatography coupled to mass spectrometry (HS‐SPME‐GC–MS) was used to analyze flavor compounds qualitatively and quantitatively. A total of one organic acid, one aromatic, ten alcohols and 23 esters were present in extruded black rice adjunct beer. Protein components and molecular weight were analyzed, and the results were consistent with those of traditional beer in terms of content of foam‐stabilizing protein. The contents of essential amino acid which is an important nutritive index were higher than those in traditional rice adjunct beer, especially valine (70.9 mg/L) and threonine (42.8 mg/L). The representative ingredients of extruded black rice adjunct beer were polyphenols, nerolidol, geraniol, and geranylgeraniol which affected the functionality and antioxidant ability.

Interrelation of Volatile Organic Compounds and Sensory Properties of Alternative and Torrefied Wood Pellets

The increasing demand for wood pellets on the market, which is caused by their excellent combustion properties, inspires the production as well as the utilization of alternative biomass pellets as fuel. However, the emission of volatile organic compounds gives pellet materials a distinct odor or off-odor, which is directly perceived by the end user. Thus, there is an urgent need for knowledge about the emitted volatile organic compounds and their potential formation pathways as well as their contributions to odor properties of the pellets. In this study, pellets made of biomass energy crops (i.e., straw or miscanthus), byproducts from the food industry (i.e., rapeseed, grapevine, or DDGS (dried distillers grains with solubles from beer production)), or eucalyptus, as well as torrefied pinewood and torrefied sprucewood were investigated with respect to the emitted volatile compounds and their possible impact on the pellet odor. Headspace solid-phase microextraction in combination with gas chromatography–mass spectrometry was used to enrich, separate, and identify the compounds. Techniques used in sensory science were applied to obtain information about the odor properties of the samples. A total of 59 volatile compounds (acids, aldehydes and ketones, alcohols, terpenes, heterocyclic compounds, and phenolic compounds) were identified with different compound ratios in the investigated materials. The use of multivariate statistical data analysis provided deep insight into product–compound interrelation. For pellets produced from bioenergy crops, as well as from byproducts from the food industry, the sensory properties of the pellets reflected the odor properties of the raw material. With respect to the volatiles from torrefied pellets, those volatiles that are formed during the torrefaction procedure dominate the odor of the torrefied pellets covering the genuine odor of the utilized wood. The results of this work serve as a substantiated basis for future production of pellets from alternative raw materials.

A novel stir bar sorptive-dispersive microextraction in combination with magnetically modified graphene for isolation of seven pesticides from water samples

A new sample preparation technique: stir bar sorptive-dispersive microextraction (SBSDμE) with magnetically modified graphene (G-Fe3O4) as the sorbent was applied to isolation of multiclass seven pesticides (boscalid, chlorpyrifos, deltamethrin, dimethenamid-P, dimoxystrobin, metazachlor and tebuconazol) from spiked water samples. Selected experimental parameters were studied, and the optimized extraction conditions were as follows: 20 mg of the sorbent, sample pH 6, adsorption time - 12 min, addition of 1 g NaCl and 4.5 mL of acetone as the desorbing solvent. At the optimized conditions the developed extraction method was compared with magnetic solid phase extraction (MSPE). Extractions were performed in four replicates at three concentration levels of the pesticides. The average extraction yields of all the pesticides for the SBSDμE and MSPE methods were 20–75% (RSD 1–12%) and 22–82% (RSD 2–13%), respectively. Compared with the MSPE method the proposed SBSDμE approach is more quick and convenient in collecting of the sorbent, as well as more effective in mixing of larger volume samples.

Zwitterionic polymeric ionic liquid-based sorbent coatings in solid phase microextraction for the determination of short chain free fatty acids

Five different zwitterionic sorbent coatings based on polymeric ionic liquids (PILs) were developed by the on fiber UV co-polymerization of the zwitterionic monomers 1-vinyl-3-(alkylsulfonate)imidazolium or 1-vinyl-3-(alkylcarboxylate)imidazolium and different dicationic ionic liquid (IL) crosslinkers. The developed sorbent coatings were applied in headspace solid-phase microextraction in combination with gas chromatography-mass spectrometry for the determination of short chain free fatty acids in wine. The sorbent coatings were found to extract these analytes via a non-competitive extraction mechanism. The methodology was optimized for the two best zwitterionic PIL coatings and compared to the commercially-available carboxen/polydimethylsiloxane (CAR/PDMS) and polyacrylate (PA) fibers. The sorbent coating based on the 1-vinyl-3-(propanesulfonate)imidazolium IL (Fiber 1) was more sensitive than PA while providing similar limits of detection to CAR/PDMS for the determination of analytes in a diluted synthetic wine sample. At the same time, Fiber 1 required lower extraction times (only 20 min versus 60 min for CAR/PDMS and 40 min for PA), exhibited higher reproducibility (with relative standard deviation lower than 8.9% for a spiked level of 7 µM) and was more tolerant to ethanol present within the sample. The zwitterionic PILs were also applied for the analysis of red wine, and the results were in agreement with those obtained for CAR/PDMS. The analytes were detected and quantified in the concentration range from 0.18 ± 0.03 mg L−1 to 4.8 ± 0.9 mg L−1, depending on the analyte and fiber.

Novel capsule phase microextraction in combination with high performance liquid chromatography with diode array detection for rapid monitoring of sulfonamide drugs in milk

Capsule phase microextraction is introduced herein for the first time to determine four sulfonamide residues in milk samples (sulfanilamide, sulfadiazine, sulfamethizole, and sulfathiazole). The technique eloquently integrates filtration and stirring mechanism into the extraction device, as such no filtration of the sample is needed prior to introducing the extraction device into the sample, and when placed on a magnetic stirrer, the device spins itself in order to diffuse the sample, resulting in faster extraction equilibrium. Microextraction capsules consist of three main parts; a magnet, a cellulose fiber substrate coated with high performance sol-gel hybrid organic-inorganic sorbent, and a porous membrane. Various encapsulated sol-gel sorbents were tested in standard solutions prepared in deionized water and milk samples under different operational conditions. Analyte extraction time and elution time, type of sol-gel sorbent, elution solvent, as well as the ratio of the sorbent to the elution solvent were among the optimized conditions. The protocols that yielded the best absolute recovery rates were subsequently tested in various milk samples. Method validation was performed in terms of linearity, accuracy and precision, reusability and ruggedness using the Youden test. The examined sulfonamides were subsequently analysed by reversed phase high performance liquid chromatography with diode array detection.