Bar Adsorptive Microextraction Research Articles

Bar adsorptive microextraction and liquid chromatography-diode array detection of synthetic cannabinoids in oral fluid.

In recent years, synthetic cannabinoids (SCs) have become a major public health issue. For this reason, there is a need for innovative analytical methods that allow its monitoring in biological matrices. In this work, we propose a novel methodology to screen eight SCs (AM-694, cumyl-5F-PINACA, MAM-2201, 5F-UR-144, JWH-018, JWH-122, UR-144 and APINACA) in oral fluids. A bar adsorptive microextraction method followed by microliquid desorption combined with high-performance liquid chromatography with diode array detection (BAµE-µLD/HPLC-DAD) was developed to monitor the target SCs. The main factors affecting the BAµE technology were fully optimized for oral fluid analysis. Under optimized experimental conditions, the proposed methodology showed good linear dynamic ranges from 20.0 to 2000.0 µg L-1 (r2 > 0.99, relative residuals < 15%), limits of detection between 2.0 and 5.0 µg L-1 and suitable average recovery yields (87.9-100.5%) for the eight studied SCs. The intra- and interday accuracies (bias ≤ ± 14.7%) and precisions (RSD ≤ 14.9%) were also evaluated at three spiking levels. The validated methodology was then assayed to oral fluid samples collected from several volunteers. The proposed analytical approach showed remarkable performance and could be an effective alternative for routine monitoring of the target compounds in oral fluid.

Screening Biogenic Volatile Organic Compounds from Common Portuguese Shrubs Using Headspace–Bar Adsorptive Microextraction (HS-BAµE)

In this study, headspace–bar adsorptive microextraction (HS-BAµE) combined with gas chromatography–mass spectrometry (GC-MS) was employed to screen the major biogenic volatile organic compounds (BVOCs) emitted by six different Portuguese shrub species (Erica scoparia L., Cistus ladanifer L., Cistus monspeliensis L., Lavandula stoechas L., Thymus villosus L., and Thymus camphoratus). The HS-BAµE/GC-MS methodology was developed, optimized, and validated using five common monoterpenoids (α-pinene, β-pinene, limonene, 1,8-cineole, and thymol) and one sesquiterpenoid (caryophyllene oxide). Under optimized experimental conditions (microextraction-sorbent phase: activated carbon (CN1), 3 h (35 °C); back-extraction: n-C6 (1 h)), good efficiencies (&gt;45%), low analytical thresholds (5.0–15.0 µg/L) and suitable linear dynamic ranges (20.0–120.0 µg/L, r2 &gt; 0.9872) were achieved, as well as acceptable intra and inter-day precisions (RSD ≤ 30.1%). Benchmarking the proposed methodology, HS-BAµE(CN1), against the reference methodology, HS-SPME(PDMS/DVB), revealed comparable analytical responses and demonstrated excellent reproducibility. Among the six shrub species studied, Thymus camphoratus exhibited the highest emissions of BVOCs from its leaves, notably, 1,8-cineole (4136.9 ± 6.3 µg/g), α-pinene (763.9 ± 0.5 µg/g), and β-pinene (259.3 ± 0.5 µg/g). It was also the only species found to release caryophyllene oxide (411.4 ± 0.3 µg/g). The observed levels suggest that these shrub species could potentially serve as fuel sources in the event of forest fires occurring under extreme conditions. In summary, the proposed methodology proved to be a favorable analytical alternative for screening BVOCs in plants. It not only exhibited remarkable performance but also demonstrated user- and eco-friendliness, cost-effectiveness, and ease of implementation.

Application of a bar adsorptive microextraction based methodology for doping control of alkylamine stimulants in urine matrices

To comply with ‘World Anti-Doping Agency’ (WADA) guidelines, doping control laboratories must continuously adjust their analytical procedures. Therefore, sample preparation continues to play a critical step in modern analytical strategies, namely by replacing the tedious, time and solvent consuming commonly employed (e.g. liquid-liquid extraction). The present contribution proposes, for the first time in doping control, bar adsorptive microextraction (BAμE) as an alternative analytical technique for the qualitative determination of six alkyl amine stimulants (AAs; 1,3-dimethylbutylamine, 1,4-dimethylpentylamine, heptaminol, isometheptene, octodrine and tuaminoheptane) in urine matrices followed by derivatization prior to gas chromatography coupled to mass spectrometry, operating in the selected ion monitoring mode acquisition (GC–MS(SIM)). After selecting the most selective coating phase, i.e., a mixed-mode reversed phase/strong anion exchange sorbent (P2), assays performed under optimized experimental conditions [microextraction - BAμE(P2), 1 h (1,000 rpm), pH 11, 10 % NaCl; back-extraction - methanol (150 μL), 30 min, under sonication], allowed remarkable recoveries ranging from 48.7 % (heptaminol, 200 ng/mL) to 83.1 % (1,4-dimethylpentylamine, 200 ng/mL). The validation assessment assays of the proposed methodology showed suitable limits of identification (5.0–35.0 ng/mL), appropriate linear dynamic ranges (5.0–200.0 ng/mL) and good determination coefficients (r2 > 0.9937), as well as excellent selectivity, robustness, accuracy and precision. To check whether the methodology is fit-for-purpose, four previously analysed proficiency urine samples were successfully tested, in which were unequivocally detected and identified some of the target AAs. The present methodology showed to be a remarkable alternative in comparison to other dedicated analytical approaches to screen AAs in urine matrices, since it is cost-effective, user- and eco-friendly, requiring low volume of urine sample (1 mL). The great potential of this analytical technology in doping control lies in a very effective microextraction combined with the minimization of potential interferents, presenting itself as an added value to be applied to other types of substances and complex matrices.

HS-BAμE: A New Alternative Approach for VOCs Analysis-Application for Monitoring Biogenic Emissions from Tree Species.

In this work, a new analytical approach is proposed for monitoring biogenic volatile organic compounds (BVOCs) by combining headspace bar adsorptive microextraction (HS-BAμE) with gas chromatography-mass spectrometry (GC-MS). The HS-BAμE methodology was developed, optimized, validated and applied for the analysis of BVOCs emitted from two tree species (Eucalyptus globulus Labill. and Pinus pinaster Aiton) and compared with headspace solid phase microextraction (HS-SPME), commonly accepted as a reference technique. To achieve optimum experimental conditions, numerous assays were carried out by both methodologies, studying the release of the five major monoterpenoids (α-pinene, β-pinene, myrcene, limonene and 1,8-cineole) from the leaves of the tree species, whereas the maximum selectivity and efficiency were obtained using an activated carbon and PDMS/DVB fiber as sorbent phases for HS-BAμE and HS-SPME, respectively. Under optimized experimental conditions, both methodologies showed similar profiling and proportional responses, although the latter present a higher sensitivity in the analytical configuration used. For the five monoterpenoids studied, acceptable detection limits (LODs = 5.0 μg L-1) and suitable linear dynamic ranges (20.0-100.0 mg L-1; r2 ≥ 0.9959) were achieved, and intra- and inter-day studies proved that both methodologies exhibited good results (RSD and %RE ≤ 19.9%), which indicates a good fit for the assessment of BVOCs by the HS-BAμE/GC-MS methodology. Assays performed on sampled leaves by both optimized and validated methodologies showed high levels of the five major BVOCs released from E. globulus Labill. (10.2 ± 1.3 to 7828.0 ± 40.0 μg g-1) and P. pinaster Aiton (9.2 ± 1.4 to 3503.8 ± 396.3 μg g-1), which might act as potential fuel during forest fire's propagation, particularly under extreme atmospheric conditions. This is the first time that BAμE technology was applied in the HS sampling mode, and, in addition to other advantages, it has proven to be an effective and promising analytical alternative for monitoring VOCs, given its great simplicity, easy handling and low cost.

Bar Adsorbent Microextraction with Carbon-Based Sorbent Layers for the Identification of Pharmaceutic Substances

Thirteen carbon materials were tested as sorbent layers in bar adsorbent microextraction (BA μE) to monitor hint amounts of 10 common pharmaceutical compounds (PhCs) in surface and groundwater matrices such as surface and groundwater, saltwater, spring water, and sewage. The persistence of trace amounts of three organophosphate insect repellent and cis and trans permethrin (PERM) in water quality matrices is suggested using bar adsorptive microextraction in conjunction with microliquid dissolution accompanied by significant volume injection-gas chromatography-mass spectroscopic analysis able to operate in the particular ion monitoring acquisition mode. Using BA μE to compare several sorbent coatings (five porous carbon and six polymers), it was discovered that activated carbon (AC2) was the optimum compromise among specificity and effectiveness. 17-estradiol, estrone, sulfamethoxazole, diclofenac, triclosan, gemfibrozil, 17-ethinylestradiol, mefenamic acid, and clofibric acid were chosen as system drugs to represent different treatment groups. Despite their lower porosity, statistics revealed that low-T-activated hydrochars, made from carbohydrates and a eutectic salt mixture at constant temperature (e.g., 180°C) and autogenerated pressures, could compete at the top level commercially carbonaceous materials in this purpose. These L-T-activated hydrochars had the best overall recovery (between 21.8 and 83.5 percent) for the simultaneous analysis of ten targeted PhCs with very different physical and chemical possessions, utilizing higher-efficiency liquid chromatography diode array identification.

A New Approach for Histamine Functionalized Nanoparticles as Sorbent Phase for Bar Adsorptive Microextraction (BAµE) and Determination of Parabens in Water by HPLC-DAD

In this study, for the first time, histamine-functionalized magnetic nanoparticles (HIS-MNP) were used as sorbent phase combined with bar adsorptive microextraction (BAµE) for the determination of methylparaben (MP), ethylparaben (EP), propylparaben (PP), and butylparaben (BP) in water samples by high performance liquid chromatography coupled with diode array detection (HPLC-DAD). Extraction and desorption conditions, including desorption time and solvent, ionic strength effect and extraction time, were investigated. The extractions were performed for 90 min, 30% of NaCl and sample pH 5. Desorption was carried out using 250 μL of acetonitrile:methanol (25:75 v/v) for 30 min. The limits of detection (LODs) were of 1.5 μg L−1 and limits of quantification (LOQs) were 5.0 μg L−1 for all analytes. The intra-day precision ranged from 1% for EP, PP and BP to 3% for MP, EP, PP and BP. The inter-day precision ranged from 3% for EP to 18% for BP. The relative recoveries varied from 81 to 125%, and relative standard deviations (RSD) ranged between 1 and 16%.

Simple Analytical Strategy for Screening Three Synthetic Cathinones (α-PVT, α-PVP, and MDPV) in Oral Fluids

Synthetic cathinones are analogue compounds of the plant based stimulant cathinone. Its use, abuse, and related consumption complications have steadily increased in the last years. For this reason, there is a need for innovative analytical approaches that enable its rapid screening in biological matrices (e.g., oral fluids). The present work proposes a new analytical methodology by combining bar adsorptive microextraction followed by microliquid desorption and gas chromatography coupled to mass spectrometry (BAµE-µLD/GC-MS) for screening three synthetic cathinones (α-PVP, α-PVT, and MDPV) in oral fluids. The optimization of the BAµE-µLD/GC-MS methodology was successfully applied for the analysis of the target compounds in oral fluids. The results show average recoveries between 43.1 and 52.3% for the three synthetic cathinones. Good selectivity was also noticed. The developed methodology presents itself as an alternative tool to screen these compounds in oral fluids. To the best of our knowledge, this is the first work that combines a microextraction sorption-based technique followed by GC-MS analysis for the screening of synthetic cathinones in oral fluids.

Application of Bar Adsorptive Microextraction for the Determination of Levels of Tricyclic Antidepressants in Urine Samples.

This work entailed the development, optimization, validation, and application of a novel analytical approach, using the bar adsorptive microextraction technique (BAμE), for the determination of the six most common tricyclic antidepressants (TCAs; amitriptyline, mianserin, trimipramine, imipramine, mirtazapine and dosulepin) in urine matrices. To achieve this goal, we employed, for the first time, new generation microextraction devices coated with convenient sorbent phases, polymers and novel activated carbons prepared from biomaterial waste, in combination with large-volume-injection gas chromatography-mass spectrometry operating in selected-ion monitoring mode (LVI-GC-MS(SIM)). Preliminary assays on sorbent coatings, showed that the polymeric phases present a much more effective performance, as the tested biosorbents exhibited low efficiency for application in microextraction techniques. By using BAμE coated with C18 polymer, under optimized experimental conditions, the detection limits achieved for the six TCAs ranged from 0.2 to 1.6 μg L−1 and, weighted linear regressions resulted in remarkable linearity (r2 > 0.9960) between 10.0 and 1000.0 μg L−1. The developed analytical methodology (BAμE(C18)/LVI-GC-MS(SIM)) provided suitable matrix effects (90.2–112.9%, RSD ≤ 13.9%), high recovery yields (92.3–111.5%, RSD ≤ 12.3%) and a remarkable overall process efficiency (ranging from 84.9% to 124.3%, RSD ≤ 13.9%). The developed and validated methodology was successfully applied for screening the six TCAs in real urine matrices. The proposed analytical methodology proved to be an eco-user-friendly approach to monitor trace levels of TCAs in complex urine matrices and an outstanding analytical alternative in comparison with other microextraction-based techniques.

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.

Designing a green device to BAμE: Recycled cork pellet as extraction phase for the determination of parabens in river water samples

This study reports a novel and environmentally friendly method based on bar adsorptive microextraction (BAμE) with cork pellet as extraction phase for the determination of methylparaben, ethylparaben, propylparaben and butylparaben in river water samples. This natural approach consists of a cork pellet recycled from wine stoppers used as biosorbent material to replace the traditional BAμE device. The analytical determinations were performed using a high-performance liquid chromatography-diode array detector (HPLC-DAD). Parameters such as type of desorption solvent, desorption and extraction time, sample pH and ionic strength were carefully optimized through univariate and multivariate approaches. Cork pellets of 15 mm length were inserted into vials containing 15 mL of water sample adjusted at pH 3 and 25% (w/v) of NaCl. The extraction step was carried out under agitation for 45 min followed by liquid desorption with 120 μL of methanol:acetonitrile (1:1 v/v) for 30 min. Satisfactory analytical performance was obtained with coefficients of determination ranging from 0.9921 for methylparaben to 0.9994 for propylparaben; intraday precision ranged from 6.7 to 18.3%, and interday precision varied from 7.2 to 20.0%. Accuracy was assessed through relative recovery assays and varied from 53 to 124%.

Bar adsorptive microextraction device coated with polyimide microsphere assembled by nanosheets combined with thermal desorption-gas chromatography for trace analysis of nitroaromatic explosives in environmental waters

Polyimide (PI) microspheres assembled by nanosheets were used for bar adsorptive microextraction (BAμE) for the first time. The PI microsphere possessed self-organized hierarchical nanostructure, large specific surface area (170 m2/g) and good thermostability (up to 400 °C). The BAμE device was prepared by adhering the PI microspheres on a quartz bar with Kapton double sided tape. Trace nitroaromatic explosives in environmental waters were extracted by the BAμE device, desorbed by thermal desorption (TD), and analyzed by gas chromatography-mass spectrometry (GC–MS). The reproducibility of five BAμE devices prepared in parallel was less than 13.0% (expressed as relative standard deviation, RSD). The BAμE device could stand up to 30 extraction/desorption cycles without decrease of extraction efficiency. The results of method validation showed that the BAμE-TD/GC–MS method possessed wide linearity (0.05–50 μg/L or 0.05–20 μg/L), high correlation coefficients (> 0.9987), good precision (RSDs < 11.8%), low detection limits (0.005–0.013 μg/L) and high enrichment factors (528–1410). Relative recoveries were in the range of 72.2–122.6% with RSDs between 0.1% and 10.5% for real water samples. These results proved that the proposed method was a good choice for determination of organic pollutants in water samples.

Bar Adsorptive Microextraction Coated with Carbon-based Phase Mixtures for Performance-Enhancement to Monitor Selected Benzotriazoles, Benzothiazoles, and Benzenesulfonamides in Environmental Water Matrices.

In the present work we propose, for the first time, bar adsorptive microextraction coated with carbon-based phase mixtures, followed by microliquid desorption and high performance liquid chromatography-diode array detection (BAμE-μLD/HPLC-DAD) analysis, to enhance the performance of the determination of traces of benzotriazoles (BTRs), benzothiazoles (BTs), and benzenesulfonamide derivatives (BSDs) in environmental water matrices. Assessing six carbon-based sorbents (CA1, CN1, B test EUR, SX PLUS, SX 1, and R) with different selectivity properties allowed us to tailor the best phase mixture (R, 12.5%/CN1, 87.5%) that has convenient porosity, texture, and surface chemistry (pHPZC,mix ~6.5) for trace analysis of benzenesulfonamide, 1-hydroxybenzotriazole, 1H-benzotriazole, 5-methyl-1H-benzotriazole, benzothiazole, and 1,3-benzothiazol-2-ol chemicals in aqueous media. Optimized experimental conditions provided average recoveries ranging from 37.9% to 59.2%, appropriate linear dynamic ranges (5.0 to 120.0 µg L−1; r2 ≥ 0.9964), limits of detection between 1.0 and 1.4 μg L−1, and good precisions (relative standard deviation (RSD) ≤ 9.3%). The proposed methodology (BAμE(R, 12.5%/CN1, 87.5%)-μLD/HPLC-DAD) also proved to be a suitable sorption-based static microextraction alternative to monitor traces of BTRs, BTs, and BSDs in rain, waste, tap, and estuarine water samples. From the data obtained, the proposed approach showed that the BAμE technique with the addition of lab-made devices allows users to adapt the technique to use sorbents or mixtures of sorbents with the best selectivity characteristics whenever distinct classes of target analytes occur simultaneously in the same application.

Application of bar adsorptive microextraction (BAµE) for the determination of pesticides and emerging contaminants in water used for rice cultivation in southern Brazil

Brazil is among the ten largest rice producers in the world, concentrating its production in the southern region. Anthropic activities, such as the disposal of chemicals in the ecosystem and consequently in the aquatic environment, end up harming the availability and quality of the water. Here, we developed an analytical method based on BAµE with WAX as an extraction phase for the determination of 5 pesticides and 2 emerging contaminants in water samples used in rice cultivation by HPLC–DAD. The method was fully optimized through univariate and multivariate approaches. The optimized condition was obtained with 145 min of extraction time, without salt addition and 35 min of desorption time using 250 μL of MeOH:AcEt (60:40, v/v). A reduced mass of extraction phase (around 4 mg) and sample and solvent volumes (15 mL and 300 µL, respectively) were used. The bars have a low cost and can be used up to 20 times without loss of extraction efficiency. Furthermore, the developed method presented high-throughput, because it uses a Voltage Regulator Variac system that allows the coupling of six magnetic stirrers simultaneously. The LODs ranged from 1.67 to 2.50 µg L−1 and the LOQs ranged from 5.00 to 7.50 µg L−1; both were below the VMP established by Ordinance 2.914/2011/MS for drinking water. Relative recoveries applied to the sample ranged from 80 to 121%. The intra-day and inter-day precision were up to 14% and 19%, respectively. The results were satisfactory, in accordance with the validation guidelines of the AOAC. Twenty-four samples collected in the Camboriu River Basin, which is influenced by rhiziculture, were analyzed and the analytes were not detected, as they are below the limits obtained in this method.

A Fast and Validated High Throughput Bar Adsorptive Microextraction (HT-BAµE) Method for the Determination of Ketamine and Norketamine in Urine Samples.

We developed, optimized and validated a fast analytical cycle using high throughput bar adsorptive microextraction and microliquid desorption (HT-BAμE-μLD) for the extraction and desorption of ketamine and norketamine in up to 100 urine samples simultaneously, resulting in an assay time of only 0.45 min/sample. The identification and quantification were carried out using large volume injection-gas chromatography-mass spectrometry operating in the selected ion monitoring mode (LVI-GC-MS(SIM)). Several parameters that could influencing HT-BAµE were assayed and optimized in order to maximize the recovery yields of ketamine and norketamine from aqueous media. These included sorbent selectivity, desorption solvent and time, as well as shaking rate, microextraction time, matrix pH, ionic strength and polarity. Under optimized experimental conditions, suitable sensitivity (1.0 μg L−1), accuracy (85.5–112.1%), precision (≤15%) and recovery yields (84.9–105.0%) were achieved. Compared to existing methods, the herein described analytical cycle is much faster, environmentally friendly and cost-effective for the quantification of ketamine and norketamine in urine samples. To our knowledge, this is the first work that employs a high throughput based microextraction approach for the simultaneous extraction and subsequent desorption of ketamine and norketamine in up to 100 urine samples simultaneously.

Carbon-Based Sorbent Coatings for the Determination of Pharmaceutical Compounds by Bar Adsorptive Microextraction.

Thirteen carbon materials comprising commercial activated carbons and lab-made materials (activated carbons, hydrochars, and low-T and high-T activated hydrochars) were assayed as sorbent coatings in bar adsorptive microextration (BAμE) to monitor trace levels of ten common pharmaceutical compounds (PhCs) in environmental water matrices including surface water, seawater, tap water, and wastewater. Polar and nonpolar pharmaceuticals were selected, sulfamethoxazole, triclosan, carbamazepine, diclofenac, mefenamic acid, 17-α-ethinylestradiol, 17-β-estradiol, estrone, gemfibrozil, and clofibric acid, as model compounds to cover distinct therapeutic classes. Despite having a less-developed porosity, data showed that "in-house" prepared low-T activated hydrochars, obtained from carbohydrates and an eutectic salt mixture at low temperature (i.e., 180 °C) and autogenerated pressure, compete with the best commercial activated carbons for this particular application. The combination of a micro and mesopore network with a rich oxygen-based surface chemistry yielding an acidic nature allowed these low-T activated hydrochars to present the best overall recoveries (between 20.9 and 82.4%) for the simultaneous determination of the ten target PhCs with very distinct chemical properties using high performance liquid chromatography-diode array detection (HPLC-DAD).

Evaluation of α- and β-Endosulfan Residues in Teas and Yerba Mate Infusions by Bar Adsorptive Microextraction and Large Volume Injection-Gas Chromatography Mass Spectrometry

Tea and yerba mate are traditional beverages prepared through the infusion of leaves of Camellia sinensis and Ilex paraguariensis, respectively. During this process, the leaching of pesticides onto the beverage, such as endosulfan, may occur. In this study, a bar adsorptive microextraction (BAµE) method prior to large gas chromatography mass spectrometry analysis was developed to analyze a- and b-endosulfan in teas and yerba mate infusions. Different sorbent coatings for BAµE were compared and the hydrophilic-lipophilic balanced polymer showed the best selectivity for endosulfan isomers. The method was validated providing good recoveries (varying from 80.4 ± 1.8 to 108 ± 4.9%) and linearities (r2 > 0.99), limits of detection from 8.0 to 4.0 µg kg-1 and limits of quantification from 40 to 20 µg kg-1 for a- and b-endosulfan, respectively. The application of the method in the analysis of real samples showed all free of endosulfan at the limit of detection of the analytical method.

High throughput bar adsorptive microextraction: A simple and effective analytical approach for the determination of nicotine and cotinine in urine samples

A simple, effective, convenient and environmentally friendly methodology using high throughput bar adsorptive microextraction (HT-BAμE) with microliquid desorption in combination with large volume injection-gas chromatography-mass spectrometry operating in the selected-ion monitoring acquisition mode (LVI–GC–MS(SIM)) was applied for the determination of nicotine and cotinine in urine samples. Under optimized experimental conditions, the developed methodology allowed for linear dynamic ranges between 20.0 and 2000.0 μg L-1 with determination coefficients of 0.9991 and 0.9992, as well as average recovery yields of 61.7–67.5% and 53.9–57.8% for nicotine and cotine, respectively. The developed methodology was applied to monitor urine samples from 86 volunteers having different smoking habits, where nicotine and cotinine were quantified in the range from 23.6 to 2612.6 μg L-1.The target compounds were extracted in a HT-BAμE apparatus, which allows for simultaneous microextraction and subsequent back-extraction of up to 100 samples. This is a major improvement over other microextraction techniques.The data from the proposed methodology were satisfactory and in line with current green analytical chemistry guidelines, and proved to be an effective sample preparation alternative with substantial potential for high throughput bioanalysis.

Monitoring traces of organochlorine pesticides in herbal matrices by bar adsorptive microextraction – Application to black tea and tobacco

ABSTRACT Bar adsorptive microextraction followed by microliquid desorption and gas chromatography-mass spectrometry, under the selected ion monitoring acquisition mode, has been developed for the determination of 20 organochlorine pesticides (OCPs) in herbal matrices. Assays performed on 25 mL of ultra-pure water samples spiked at the 2.0 µg L−1 level, yielded average recoveries ranging from 14.0% to 95.1% for the target OCPs, under optimised experimental conditions. The proposed analytical methodology demonstrated suitable detection limits (0.10–0.15 µg L−1) and good linear dynamic ranges (0.5–100.0 µg L−1) with determination coefficients equal or higher than 0.9900. The proposed methodology, by using the standard addition method, proved to be a suitable sorption-based static microextraction alternative to monitor traces of OCPs in black tea and tobacco products, in compliance with the green analytical chemistry principles.

Determination of Hydrophilic UV Filters in Real Matrices Using New-Generation Bar Adsorptive Microextraction Devices

In the present contribution, new-generation bar adsorptive microextraction devices combined with microliquid desorption, followed by high-performance liquid chromatography–diode array detection (BAµE-µLD/HPLC–DAD) are proposed for the determination of two very polar ultraviolet (UV) filters (2-phenylbenzimidazole-5-sulfonic acid (PBS) and 5-benzoyl-4-hydroxy-2-methoxybenzenesulfonic acid (BZ4)) in aqueous media. Different sorbents were evaluated as BAµE coating phases, in which polystyrene–divinylbenzene polymer showed the best selectivity for the analysis of both UV filters, with average extraction efficiency of 61.8 ± 9.1% for PBS and 69.5 ± 4.8% for BZ4. The validated method showed great reproducibility for the analysis of PBS and BZ4 UV filters, providing suitable limits of detection (0.04 µg L−1 and 0.20 µg L−1), as well as good linear dynamic ranges (0.16–16.0 and 0.8–80.0 µg L−1), respectively. The proposed methodology was applied for monitoring the target analytes in several real matrices, including tap, sea, and estuarine waters, as well as wastewater samples. Despite some matrix effects being observed for some real samples, good selectivity and linearity were obtained. The present contribution showed an innovative analytical cycle that includes the use of disposable devices, which make BAµE much more user-friendly and suitable for the routine work, being a remarkable analytical alternative for trace analysis of priority compounds in real matrices.

Porous polyimide particle-coated adsorptive microextraction bar combined with thermal desorption-gas chromatography for rapid determination of parabens in condiments

Bar adsorptive microextraction using polyimide (PI) particles as the extraction phase followed by thermal desorption and gas chromatography-mass spectrometry (BAμE/TD-GC-MS) was developed to detect parabens in condiments, such as soy sauce, vinegar, and cooking wine. The PI particles were prepared by pneumatic spray combined with the immersion-precipitation phase transformation method. The prepared particles have highly porous surfaces, on which the 10–60 nm open nanopores are closely packed. Particles between 250–500 μm were then sieved out and used as extraction phase for BAμE. In contrast to the smooth and dense surface of the conventional PI phase transformation bar, the macroscopic rough surface of the PI particle bar and its microscopic porous particle surfaces provided larger extraction interfaces and more surface adsorption sites, both of which enhanced the extraction mass flux. With an extraction time of 2 min, the absolute recoveries of parabens by the PI particle bar were 1.9˜2.7 times those obtained by the conventional PI phase transformation bar. The intrabatch and interbatch precisions of the PI particle bars were less than 4.6% and 7.5%, respectively, and the PI particle bar exhibited a long lifetime of more than 50 extraction/desorption cycles. To realize rapid determination of parabens, the extraction time was fixed at 2 min. The analytical performance for standard water samples showed wide linearity (0.14–50 μg/L) with good correlation coefficients (r > 0.9980), good precision (RSD < 5.6%), appropriate detection limits (0.005−0.008 μg/L), and high enrichment factors (305–626). For the analysis of parabens in diluted condiments, the relative recoveries were between 86.1% and 109.0% with RSDs ranging from 0.1%–8.7%.