Stir Bar Sorptive Extraction Method Research Articles

An easy, low-cost and efficient method for the extraction of benzoic acid and sorbic acid from orange juice and cola soft drink based on PET plastic stir bar sorptive extraction

In this research, a simple, convenient and low-cost method was used for the simultaneous extraction of benzoic acid (BA) and sorbic acid (SA) with the help of stir bar sorptive extraction (SBSE) method followed by HPLC-UV. Polyethylene terephthalate (PET) was used to cover the stir bar. The source of PET was mineral water plastic bottles, which create a porous polymer coating after dissolving in trifluoroacetic acid (TFA) and mixing with polyvinylpyrrolidone (PVP). The simple strategy of converting waste PET plastic can not only reduce environmental pollution caused by microplastics, but also create an inexpensive and efficient material for coating of stir bar. The obtained polymer was identified by Fourier-transform infrared (FT-IR), field emission-scanning electronic microscope (FE-SEM), X-ray powder diffraction (XRD) and energy dispersion spectroscopy (EDS) techniques. After optimizing the factors affecting the extraction by Box-Behnken design and response surface methodology (RSM), a linear range of 10–7000 μg/L with a coefficient of determination (R2) of more than 0.9984 was obtained for the mentioned compounds. The detection limit for BA and SA was 6 and 5 μg/L, respectively. This method was successfully applied to measure BA and SA in cola soft drink and orange juice samples. The recovery of more than 92.4 % and the error of less than 5.1 % indicate the applicability of this method.

Green Analytical Method for Perfluorocarboxylic Acids (PFCAs) in Water of Stir Bar Sorptive Extraction Coupled with Thermal Desorption–Gas Chromatography—Mass Spectroscopy

Perfluoroalkyl carboxylic acids (PFCAs) are a significant group of per- and polyfluoroalkyl substances (PFASs). They are persistent organic chemicals manufactured for their resistance to heat, water, and stains. PFCAs are ubiquitous in the environment, particularly in surface water and wastewater, because they are widely used in everyday consumer products. This contamination poses a risk to drinking water supplies and human health, necessitating sensitive and effective analytical methods. Traditional liquid chromatography–tandem mass spectrometry (LC-MS/MS) is commonly used but involves complex sample handling and high costs. In this study, we developed an enhanced stir bar sorptive extraction (SBSE) method coupled with thermal desorption–gas chromatography–mass spectrometry (TD-GC-MS) for the analysis of PFCAs in water. This method demonstrates linearity, with R2 values from 0.9892 to 0.9988, and low limits of detection (LOD) between 21.17 ng/L and 73.96 ng/L. Recovery rates varied from 47 to 97%, suggesting efficient extraction. Compared to traditional methods, the developed SBSE technique requires only a 1 mL sample volume and minimal amounts of solvents, enhancing eco-friendliness and reducing potential contamination and handling errors. This method also demonstrated good precision and robustness across various water matrices. Overall, the developed method offers a precise, eco-friendly, and reliable approach for analyzing PFCAs in diverse water samples.

Aptamer-based stir bar sorptive extraction combined with MALDI-TOF-MS for the analysis of milk protein allergen β-lactoglobulin in foods

In this work, the preparation of an aptamer-based coating for stir bar sorptive extraction (SBSE) aimed at the selective clean-up and preconcentration of the allergenic milk protein β-lactoglobulin (β-LG) is described. To this end, a thiol-terminated aptamer was grafted onto a vinylized polytetrafluoroethylene stir bar via “thiol-ene” click chemistry. The aptamer affinity coating was characterized and several parameters that affect SBSE efficiency were evaluated. The optimized aptamer-based SBSE method combined with matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF-MS) analysis provided suitable linearity (0.25–50 µg·mL−1), satisfactory limit of detection (LOD) (0.08 µg·mL−1 β-LG), and relative standard deviations below 5.2 % among the extraction units, which could be reused for 10 extraction cycles and were stable for at least one month. The applicability of the developed method was successfully demonstrated by analyzing low levels of β-LG in different dairy-free food samples (i.e. a 100 % cocoa dark chocolate, a hydrolyzed hypoallergenic infant formula, and a white bread) and in white breads with declared and undeclared contents of milk (84 %<recoveries < 93 %).

Simultaneous determination of various heavy metal and arsenic ions in seafood using functionalized fibrous silica (KCC-1) coated stir bar sorptive extraction prior to inductively coupled plasma mass spectrometry

Heavy metal ions (HMIs) and arsenic ion with high bioavailability and toxicity in seafood pose a serious threat to human health by food chain. Herein, the functionalized fibrous silica (KCC-1) nanoparticles bearing thiol (-SH) and amine (-NH2) groups respectively were synthesized, characterized, and coated on stir bar sorptive extraction (SBSE) of trace cadmium (Cd), mercury (Hg), lead (Pb), copper (Cu), and arsenic (As) ions simultaneously in seafood prior to inductively coupled plasma mass spectrometry (ICP-MS). The optimal SBSE variables, such as sample pH (3–7), elution composition (1 M HNO3 and 0–4% (m/v) thiourea), and sample volume (5–25 mL), were optimized. The optimal sample pH (6), elution composition (1 M HNO3 and 2% (m/v) thiourea), and sample volume (20 mL), were obtained. The performance of KCC-1-SH SBSE method was superior to the KCC-1-NH2 SBSE method in terms of linearity (0.9981–0.9992), limit of detection (LOD, <0.08 μg kg−1), limit of quantification (LOQ, <0.60 μg kg−1), recovery (85.6–106.6%), and repeatability and reusability (no apparent loss in extraction efficiency after 18 times). The maximum residual limits of Cd, Hg, Pb, Cu, and As (V) in mussel, shellfish, and shrimp were all below 1, 1, 1.5, 20, and 76 mg kg−1, respectively. The results demonstrated that the method has a great potential for the daily monitoring of trace HMIs in these seafood products.

Covalent organic framework-V modified porous polypropylene hollow fiber with detachable dumbbell-shaped structure for stir bar sorptive extraction of benzophenones

Polypropylene hollow fiber is a kind of ideal material for stir bar sorptive extraction (SBSE) which possesses the advantages of porous structure, large specific surface area, high mechanical strength, and good solvent resistance. In this work, a novel SBSE device using the polypropylene hollow fiber-based stir bar with the detachable dumbbell-shaped structure was designed and prepared. Covalent organic framework-V (COF-V), which possesses porous structure, sphere shape with large specific surface area, was synthesized at room temperature and grown on polypropylene hollow fiber by polydopamine modification method. Compared with previous studies which used etched poly(ether ether ketone) as supporting material, polypropylene hollow fiber omitted the complicated, difficult and dangerous pretreatment process with high concentrated sulfuric acid. The immobilization of COF-V on the polypropylene hollow fiber significantly endows them with multiple interaction abilities including hydrophobic interaction and π-π interaction. The stir bar showed good performance and stability for the extraction of four benzophenones including BP-1, BP-6, BP-3 and Ph-BP. By coupling with HPLC-UV, the COF-V@polypropylene hollow fiber based SBSE method showed wide linear range (0.1-200ng/mL), excellent linearity (R2 ≥ 0.9979), high sensitivity (LODs in the range of 0.02-0.03ng/mL), and good repeatability (RSD ≤ 5.21%). This method was successfully applied to the analysis of benzophenones in soil and sunscreen samples.

Untargeted flavor profiling of lager beers by stir bar sorptive extraction –capillary gas chromatography – time-of-flight mass spectrometry: High analytical performance with a green touch

Beer is one of the most popular beverages in the world and its complex flavor is widely appreciated. Beer flavor profiling is important for brewers to optimize beer production and to guarantee odor quality and taste stability of the final products. This is especially the case for pale lager beers that represent the beer type with the largest worldwide production volume. In this study, the combination of stir bar sorptive extraction (SBSE) with capillary gas chromatography (GC) hyphenated to time-of-flight mass spectrometry (TOFMS) was used to perform a detailed aroma profiling of lager beer samples originating from Belgium, The Netherlands, and France. A generic SBSE method was applied resulting in a very broad extraction coverage of odor solutes, while the extraction process is miniaturized, unattended and solventless, meeting green analytical chemistry requirements. Using GC-TOFMS analysis operated in untargeted mode, MS deconvolution and statistical data analysis, with principal component and hierarchical clustering analysis, it was possible to clearly differentiate brands and origins of the beer samples and to identify marker compounds for flavor profiling of these closely related beer samples. An extended database of beer aroma compounds was created. The developed method can be applied in beer quality optimization and quality control in routine laboratories.

Molecularly imprinted electrospun nanofibre membrane assisted stir bar sorptive extraction for trace analysis of sulfonamides from animal feeds

The widespread addition of sulfa antibiotics in feeds has long been an environment safety issue. Therefore, it is quite meaningful to constantly propose better solutions for determining the sulfa antibiotics in the environment. Herein, molecularly imprinted electrospun nanofibre membrane (MIM) assisted stir bar sorptive extraction method for the determination sulfonamides (SAs) in feed was developed. In this study, molecularly imprinted polymers (MIPs) were firstly prepared via emulsion polymerization using sulfamonomethoxine as template. Then, the morphology-controllable MIM was obtained with MIPs-doping electro-spinning solution using electro-spinning technique. Next, MIM are coated on the magnetic stir bar by heat-sealing. Finally, MIM coated stir bar was used for selective enrichment of SAs. The obtained MIM exhibited excellent class selectivity towards SAs (the selectivity factor β is 2.3–2.7). The MIM coated stir bar can be directly applied to extract SAs from feed samples. Under the optimum extraction conditions, the detection limit of the method could reach 1.5−3.4ng/g. And satisfactory recoveries ranging from 80±6% to 89±7% were achieved under all three spiked levels for determination of four SAs in five different feed samples. The present work not only offers insights to develop magnetic stir bar using imprinted membrane, but also provides a new method for SAs extraction.

Principal Component Analysis of Hop-Derived Odorants Identified by Stir Bar Sorptive Extraction Method

Beers hopped with 79 varieties were brewed in small-scale fermenters, and 127 hop-derived compounds were picked up by comparing with the chromatogram of unhopped beer, after the analysis of the stir bar sorptive extraction gas chromatography-mass spectrometry method. The 127 hop-related flavor compounds were used to examine the interrelationship with the hop varieties by principal component analysis (PCA). Different varieties and amounts of hop pellets based on equal amounts of alpha-acids were added to the cooled wort. Addition of higher amounts of hops resulted in lower concentrations of apparent extracts of beer, suggesting the presence of dextrin-hydrolyzing enzymes in the hops. PCA largely established five directions. Direction I including Cascade, Amarillo, Citra, Simcoe, Mosaic, Wai-iti, and Hallertau Blanc varieties was linked to geraniol and citronellol, both known to contribute to citrus characteristics. Direction II including Bobek, Styrian Gold, and Moutueka varieties was associated with linalool and 6-methyl-5-hepten-2-one. Direction III including Hersbrucker and Saphir was linked to sesquiterpene alcohols. Direction IV was associated with hydrophobic monoterpenes, and direction V was linked to hydrophobic sesquiterpenes. Further study of these hop varieties and constituents can help advance our knowledge in using different hop varieties to achieve defined aroma and taste of beer.

Enhanced extraction using a combination of stir bar sorptive extraction and thin film-solid phase microextraction

Sorptive extraction techniques have experienced increased popularity, but they face limitations in dynamic range and sensitivity. In this study, a new method combining stir bar sorptive extraction (SBSE) and thin-film solid-phase microextraction (TFSPME) was developed, and optimization for extraction temperature (70 °C) and time (120 min) was carried out. Polydimethylsiloxane (PDMS)-coated SBSE and PDMS/carboxen (PDMS/CAR)-coated TFSPME were used, and both headspace and direct immersion extraction modes were also studied. Using 40 selected volatile compounds, the combined method generally gave a wider linearity range with lower minimum limits (2 to 3 orders), satisfactory coefficient of determination (R2>0.980), and improved sensitivity when compared to SBSE-only or TFSPME-only techniques. Furthermore, despite the combined use of two extraction devices, the repeatability (<13.1 %) and reproducibility (<13.4 %) of the combined method were comparable to SBSE-only or TFSPME-only results. Higher recoveries of up to 20% were also achieved by the combined method. Compared to the conventional SBSE method, the new method provided superior performance in terms of dynamic range and sensitivity for compounds of various polarities. In conclusion, this study provided insights on the suitability of the various extraction methods for compounds of different chemical properties which could aid in future applications for volatiles analysis in food, biological, and environmental sectors.

Stir bar sorptive extraction combined with deep eutectic solvent-based dispersive liquid–liquid microextraction: application in simultaneous derivatisation and extraction of acidic pesticides

ABSTRACTIn the present study, a stir bar sorptive extraction (SBSE) method coupled with deep eutectic solvent (DES)-based dispersive liquid–liquid microextraction (DLLME) has been developed for the simultaneous derivatisation and extraction of some acidic pesticides before their analysis by gas chromatography-mass spectrometry (GC-MS). In this method, initially, the analytes are adsorbed on a coated stir bar from an aqueous solution. Then, the stir bar is removed and a water-miscible DES is used to elute the analytes. Afterwards, butyl chloroformate (BCF) and a water-immiscible DES are added to the obtained elute as a derivatisation agent and an extraction solvent, respectively. In this work, the use of common toxic organic solvents is omitted, and for the first time, DESs are used as elution (for desorption of the analytes from stir bar), disperser and extraction solvents. Under the optimum conditions, the introduced method indicated high enhancement factor (EnF) (1743–3654), enrichment factor (EF) (1232–1532), and extraction recovery (ER) (74–92%), low limit of detection (LOD) (14–29 ng L–1) and limit of quantification (LOQ) (47–98 ng L–1), good linearity (r2 ≥ 0.9969) and satisfactory repeatabilities. Finally, the proposed method was applied in the analysis of the analytes in various fruit juice samples.

Determination of 117 endocrine disruptors (EDCs) in water using SBSE TD–GC-MS/MS under the European Water Framework Directive

The aim of this work is the highly sensitive determination of 117 contaminants in surface waters at very low concentrations. Gas chromatography-amenable priority compounds from the European Water Framework Directive (EWFD, 45 priority substances) and substances from the Turkish Regulation on the Management of Surface Water Quality (TRMSWQ, 250 substances) were analyzed. Almost a third to one half of the compounds in the TRMSWQ list were successfully detected in a single gas chromatography-tandem mass spectrometry (GC-MS/MS) injection. Analyzing these pollutants in water samples is difficult with conventional extraction methods. An efficient, easy and fast method for both extraction and analysis is thus important. Here, the stir bar sorptive extraction (SBSE) approach employing Twister® was used for analyte enrichment from 100mL water samples. The Twister apparatus was used for thermal desorption. Compounds were separated via gas chromatography (GC) and detected by tandem mass spectrometry (MS/MS) utilizing an Agilent 7000D MS instrument. The analysis method was comprehensively validated, and complied with the requirements of the EWFD and Turkish regulation for surface water quality for inland surface water. The method includes various endocrine disruptor compounds listed in the EWFD, such as polychlorinated biphenyls, polycyclic aromatics hydrocarbons, polybrominated diphenyl ethers, phenols, phthalates and pesticides. The method is also applicable for the analysis of similar contaminants that are not on this list. The analyzed pollutants have varying polarities based on octanol-water coefficients and are extracted by SBSE. This method may be preferred for the analysis of pollutants with an octanol-water partition coefficient (log Ko/w) higher than 2. The SBSE method, which is easy, lab-friendly and quick, taking a total of only 2h for parameter analysis, was optimized to reduce time and chemical usage. The entire extraction and analysis was completed in virtually 3h. The limits of quantification (LOQs) ranged from 0.12 to 50ng/L and complied with the requirements for analytical methods to be used in the analysis of the compounds included in the directives. Several quality parameters including linearity, trueness and precision were studied, with good results, and uncertainty was also estimated. Precision (in terms of relative standard deviation [RSD]) was lower than 40%, recoveries ranged from 60 to 120%, and determination coefficients were higher than 0.990 for all analytes. Graphical abstract.

Development of Head Space Sorptive Extraction Method for the Determination of Volatile Compounds in Beer and Comparison with Stir Bar Sorptive Extraction.

A headspace sorptive extraction method coupled with gas chromatography–mass spectrometry (HSSE–GC–MS) was developed for the determination of 37 volatile compounds in beer. After optimization of the extraction conditions, the best conditions for the analysis were stirring at 1000 rpm for 180 min, using an 8-mL sample with 25% NaCl. The analytical method provided excellent linearity values (R2 > 0.99) for the calibration of all the compounds studied, with the detection and quantification limits obtained being low enough for the determination of the compounds in the beers studied. When studying the repeatability of the method, it proved to be quite accurate, since RSD% values lower than 20% were obtained for all the compounds. On the other hand, the recovery study was successfully concluded, resulting in acceptable values for most of the compounds (80–120%). The optimised method was successfully applied to real beer samples of different types (ale, lager, stout and wheat). Finally, an analytical comparison of the optimised HSSE method, with a previously developed and validated stir bar sorptive extraction (SBSE) method was performed, obtaining similar concentration values by both methods for most compounds.

Development of a stir bar sorptive extraction method coupled to solidification of floating droplets dispersive liquid-liquid microextraction based on deep eutectic solvents for the extraction of acidic pesticides from tomato samples.

A stir bar sorptive extraction method coupled with deep eutectic solvent based solidification of floating organic droplets-dispersive liquid-liquid microextraction has been used for the simultaneous derivatization and extraction of some acidic pesticides in tomato samples. In this method, initially the analytes are adsorbed on a coated stir bar from tomato juice filled in a narrow tube. After extraction, the stir bar is removed and a water-miscible deep eutectic solvent is used to elute the analytes. Afterward, a derivatization agent and a water-immiscible deep eutectic solvent (as an extraction solvent) with melting point near to room temperature are added to the obtained eluant at µL-levels and the obtained mixture is rapidly injected into deionized water. Under the optimum conditions, the introduced method indicated high enhancement (1543-3353) and enrichment (2530-2999) factors, low limits of detection (7-14ng/L) and quantification (23-47ng/L), good linearity (r2 ≥ 0.9982), and satisfactory repeatabilities (relative standard deviation ≤12% for intra- and inter-day precisions at a concentration of 100ng/L of each analyte). Finally, the proposed method was applied in analysis of the analytes in tomato samples.

Chemometric analysis of Chinese red wines using stir bar sorptive extraction combined with GC–MS analysis

The aim of this work was to compare EG–Silicone and PDMS polymeric phases based on stir bar sorptive extraction method for the analysis of volatile compounds in Chinese red wines. The impact of vintages, regions and grape varieties on volatile compounds was also evaluated, and chemometric analyses were applied to achieve a possible differentiation of the wines. The results demonstrated that EG–Silicone Twister high correlation coefficients and low standard deviations were obtained for 58 major volatile compounds of wine by use of EG–silicon. Significant differences in the levels of certain volatiles were observed according to cultivars, vintages and geographical origins through analysis of variance. A satisfactory linear discriminant analysis resulted for red wines on the basis of cultivars, vintages and geographical origins was observed, in which the correct classification was 100% and the leave-one-out validation accuracy was 96.3%.

Assessment of Tokaj varietal wines with comprehensive two-dimensional gas chromatography coupled to high resolution mass spectrometry

Botrytised wines produced in Tokaj region belong to a special category of sweet wines described with a pleasant honey-like taste and a distinctive fruit flavour. Specific technological process of wine-making developed on macerating of noble-rotten berries in fermented juice or wine, results in alcoholic beverage indicated with the 'Protected Designation of Origin' label. A limited number of publications is devoted to analysis of Tokaj wines or by-products (e.g. individual varietal wines, essencia and must) which directly related to final characteristics of botrytized wine. A combination of two-dimensional gas chromatography connected to high-resolution mass spectrometry (GC × GC-HRTOFMS) offers enhanced separation and reliable identification of organic compounds presented in complex samples. In our study, this technique was applied to analyse varietal wines of the Tokaj wine region produced from three main grape cultivars (Furmint, Lipovina and Muscat Blanc à Petits Grains). The primary task was reliable separation and identification of low volatility compounds (acetamides, 2H-pyrrole- and 2H-pyran-based heterocyclic compounds and sulphur containing compounds) because of the lack of available information in this area. Thus, it revealed the presence of 1(3H)-isobenzofuranone, ethyl 1H-indole-3-acetate and 2-(methylmercapto)benzothiazole which were not previously detected in wine. Furthermore, trace aroma compounds (terpenoids and lactones) was quantified with modified stir bar sorptive extraction method which provided LOD and LOQ values of 2.3–4.7 ng/L and 7.7–15.8 ng/L, respectively. Linear calibration dependencies with correlation coefficients varying between 0.960 – 0.996 were obtained.

Development of a stir bar sorptive extraction method to study different beer styles volatile profiles.

A stir bar sorptive extraction method coupled to Gas Chromatography-Mass Spectrometry for the analysis of 52 volatile compounds in beer has been developed. The final optimized conditions were: 50 mL sample volume, 180 min extraction time, 25% (w/v) NaCl content and polydimethylsyloxane stir bars. Good values of linearity (R2 > 0.99) were achieved for the calibration lines of all the compounds. The limits of detection and quantification obtained were low enough for the determination of the volatile compounds in the samples and the recovery values obtained for the majority of the compounds were between 80% and 120%. The precision of the method was also studied and acceptable values for this type of extraction technique were obtained (<20%). 30 samples of different styles of beers (ale, lager, stout and wheat) were analysed and their aromatic profile was characterised. Multivariate statistical techniques allowed the correct classification of the samples according to their volatile composition.

Introduction of electropolymerization of pyrrole as a coating method for stir bar sorptive extraction of estradiol followed by gas chromatography

In this study, fabrication of a stir bar sorbent is presented by electropolymerization of pyrrole via cyclic voltametry for the first time. The fabricated stir bar was applied as an efficient sorbent for extraction and pre-concentration of trace amounts of estradiol in urine samples through stir bar sorptive extraction (SBSE) method followed by gas chromatography-flame ionization detector. For this purpose, first the surface of stainless steel rod was modified by hyroxide functional group. Then electropolymerization of pyrrole monomers took place on the surface of functionalized steel rod under the optimized conditions including pyrrole concentration of 0.03 mol L−1, equal concentration ratio of pyrrole to sodium dodecyl sulfate, 10 cycles of cyclic voltammetry and potential scan rate of 10 mV s−1. Characterization of the produced sorbent was confirmed by scanning electron microscope imaging and energy-dispersive X-ray and infrared spectroscopy. Evantually, under the optimized conditions, the stir bar sorbent was used for extraction of estradiol from human urine samples. The presented SBSE method showed a good linearity range of 50–700 ng mL−1 with coefficient of determination 0.9910, limit of detection 10 ng mL−1 and theoretical limit of quantification 33 ng mL−1. Moreover, better enrichment factor (87) and extraction recovery (43%) were obtained using the fabricated stir bar compared with two commercial stir bars for estradiol. The intra- and inter-bar relative recoveries were obtained 92.0% and their coefficient of variations were less than 5.4%.

Developed nano carbon-based coating for simultaneous extraction of potent central nervous system stimulants from urine media by stir bar sorptive extraction method coupled to high performance liquid chromatography

A nano graphene oxide sol-gel composite (NGO/sol-gel) applied as a coating of a capillary glass tube stir bar to develop a novel stir bar sorptive extraction (SBSE) method for simultaneous extraction of amphetamine (AMP) and methamphetamine (MET) from biological urine sample. Lab-synthesized NGO was applied with methyltrimethoxysilane (MTMOS) and Tetraethoxysilane (TEOS) as sol-gel precursor. NGO/sol-gel was deposited on the surface of a capillary glass tube to prepare stir bar sorptive extraction adsorbent by a simple and fast method. The scanning electron micrograph images showed a three dimensional structure of lab-made device suitable for SBSE method for simultaneous extraction of AMP and MET. Effective extraction parameters were investigated. Through studied suitable extraction conditions, satisfactory linearity was achieved in the concentration range of 50–2000 ngmL−1 for AMP and 40–2500 ngmL−1 for MET. The relative recovery of the analytes were 99.5 and 99.7% for AMP and MET, respectively for positive urine samples were studied by novel introduced method. The results cleared that NGO/sol-gel composite could be used as practical method in laboratories as an efficient SBSE adsorbent for drugs determination in urine matrix.

Novel Ceramic Carbon-Coated Magnetic Nanoparticles as Stir Bar Sorptive Extraction Coating for Simultaneous Extraction of Amphetamines from Urine Samples

The present paper describes a highly selective method for simultaneous determination of amphetamines in urine samples by stir bar sorptive extraction method using carbon-coated magnetic nanoparticles as novel coating for stir bar. Under optimized extraction conditions, a good linearity was observed in the concentration range of 20–2000 ng/mL for amphetamine, 20–2500 ng/mL for methamphetamine, and 30–1500 ng/mL for pseudoephedrine. The positive urine samples were examined by the developed proposed method with satisfactory recovery. Results showed that the developed stir bar sorptive extraction method could be applied in different forensic and clinical laboratories.

Zeolitic imidazole framework templated synthesis of nanoporous carbon as a coating for stir bar sorptive extraction of fluorouracil and phenobarbital in human body fluids

A simple and cost-effective method was developed to determine fluorouracil (5-FU) and phenobarbital (PHB) in human body fluids. A coating based on a zeolitic imidazole framework-67 (ZIF-67) template cobalt nanoporous carbon (Co-NPC) was synthesized by one-step carbonization of ZIF-67 without using any other carbon precursors in the present study. The prepared Co-NPC was then fabricated on the surface of a prepared stir bar to be used as stir bar sorptive extraction (SBSE) method. The extracted analytes were then analyzed via high performance liquid chromatography-ultraviolet detection (HPLC-UV). Plackett–Burman design was employed for screening the experimental factors. The effective factors were then optimized using Central Composite Design (CCD). Under the optimum conditions, limits of detections (LODs) of 5-FU were 0.36, 0.41 and 1.2 μg L−1 in water, urine and plasma samples, respectively. Limits of quantifications (LOQs) were also 1.2, 1.3 and 4.5 μg L−1 in water, urine and plasma samples, respectively. Relative standard deviations (RSDs) at a spiked concentration of 10 μg L−1 were 8.1, 7.9 and 8.6% (as intra-day RSD) in water, urine and plasma samples, respectively. The linear dynamic ranges (LDRs) were in the range of 1–200 μg L−1. Moreover, LODs of PHB were 0.21, 0.32 and 1.4 μg L−1 in water, urine and plasma samples, respectively. LOQs were also 0.9, 1.1 and 4.6 μg L−1 in water, urine and plasma samples, respectively. Relative standard deviations (RSDs) at a spiked concentration of 10 μg L−1 were 6.3, 6.5 and 6.9% (as intra-day RSD) in water, urine and plasma samples, respectively. The linear dynamic ranges (LDRs) were in the range of 1–500 μg L−1. The applicability of the method was investigated by the extraction and determination of the target analytes in different biological fluids including urine and plasma samples.