Improvements on bar adsorptive microextraction (BAμE) technique--application for the determination of insecticide repellents in environmental water matrices

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.

Nicotine in Complex Samples: Recent Updates on the Pretreatment and Analysis Method

Nicotine is a significant evaluation index of tobacco and its related products' quality, but nicotine overdose can pose serious health hazards and cause addiction and dependence, thus it can be seen that it is necessary to find suitable and efficient detection methods to precisely detect nicotine in diverse samples and complex matrices. In this review, an updated summary of the latest trends in pretreatment and analytical techniques for nicotine is provided. We reviewed various sample pretreatment methods, such as solid phase extraction, solid phase microextraction, liquid phase microextraction, QuEChERS, etc., and diverse nicotine assay methods including liquid chromatography, gas chromatography, electrochemical sensors, etc., focusing on the developments since 2015. Furthermore, the recent progress in the applications and applicability of these techniques as well as our prospects for future developments are discussed.HighlightsUpdated pretreatment and analysis methods of nicotine were systematically summarized.Microextraction and automation were main development trends of nicotine pretreatment.The introduction of novel materials added luster to nicotine pretreatment.The evolutions of ion source and mass analyzer were emphasized.

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.

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.

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).

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.

A beta-cyclodextrin-functionalized magnetic metal organic framework for efficient extraction and determination of prochloraz and triazole fungicides in vegetables samples

A β-cyclodextrin-functionalized magnetic zinc-metal organic framework (M-MOF/β-CD) was synthesized via a facile one-pot reaction. M-MOF/β-CD was used as a magnetic porous absorbent for the extraction and determination of prochloraz and three triazole fungicides in vegetable samples. M-MOF/β-CD was prepared by creating MOF layers on the surface of a Fe₃O₄-graphene oxide (GO) nanocomposite and bonding them with β-CD molecules. Characterization suggested that a 3D porous structure was formed, with M-MOF/β-CD exhibiting high superparamagnetism and a large surface area. As a new strategy, integrating MOFs with Fe₃O₄-GO could improve their water-resistance and mechanical strength by providing a rigid nanosupport interface. Combining M-MOF and β-CD resulted in excellent selective adsorption capacities for prochloraz and three triazole fungicides. The static adsorption process was evaluated and the results were in good agreement with the Freundlich model. Subsequently, M-MOF/β-CD was applied to extracting prochloraz and triazole fungicides from tomato and lettuce vegetables, followed by HPLC-MS/MS determination. The limits of detection for the above fungicides were found to be 0.25-1.0 μg/L at a signal-to-noise ratio of 3, with spiked recoveries of 74.13%-119.83%, indicating that M-MOF/β-CD was promising for application to the extraction and determination of fungicides in complex matrices.

High throughput bar adsorptive microextraction: A novel cost-effective tool for monitoring benzodiazepines in large number of biological samples

In this work, we propose an innovative high throughput (HT) apparatus using the bar adsorptive microextraction (BAμE) technique, which enables the simultaneous enrichment of up to 100 samples. This novel configuration was combined with microliquid desorption and high-performance liquid chromatography-diode array detection to monitor trace levels of eight benzodiazepines (diazepam, prazepam, bromazepam, oxazepam, lorazepam, alprazolam, temazepam and loflazepate) in biological samples. The proposed methodology was fully developed, optimized and validated, resulting in suitable intraday and interday precision (RSD ≤ 15%), with recovery yields ranging from 33.0% to 104.5%. The lower limits of quantification were between 20.0 and 100.0 µg L^-1, using 1.0 mL of urine and 0.5 mL of plasma or serum samples. The application of the proposed methodology to real matrices resulted in average sample preparation time of around 2 min per sample, demonstrating that it is user-friendly, cost-effective and a rapid decision-making tool, whenever large number of samples are involved.

New-generation bar adsorptive microextraction (BAμE) devices for a better eco-user-friendly analytical approach-Application for the determination of antidepressant pharmaceuticals in biological fluids

The present contribution aims to design new-generation bar adsorptive microextraction (BAμE) devices that promote an innovative and much better user-friendly analytical approach. The novel BAμE devices were lab-made prepared having smaller dimensions by using flexible nylon-based supports (7.5 × 1.0 mm) coated with convenient sorbents (≈ 0.5 mg). This novel advance allows effective microextraction and back-extraction ('only single liquid desorption step') stages as well as interfacing enhancement with the instrumental systems dedicated for routine analysis. To evaluate the achievements of these improvements, four antidepressant agents (bupropion, citalopram, amitriptyline and trazodone) were used as model compounds in aqueous media combined with liquid chromatography (LC) systems. By using an N-vinylpyrrolidone based-polymer phase good selectivity and efficiency were obtained. Assays performed on 25 mL spiked aqueous samples, yielded average recoveries in between 67.8 ± 12.4% (bupropion) and 88.3 ± 12.1% (citalopram), under optimized experimental conditions. The analytical performance also showed convenient precision (RSD < 12%) and detection limits (50 ng L^-1), as well as linear dynamic ranges (160-2000 ng L^-1) with suitable determination coefficients (r² > 0.9820). The application of the proposed analytical approach on biological fluids showed negligible matrix effects by using the standard addition methodology. From the data obtained, the new-generation BAμE devices presented herein provide an innovative and robust analytical cycle, are simple to prepare, cost-effective, user-friendly and compatible with the current LC autosampler systems. Furthermore, the novel devices were designed to be disposable and used together with negligible amounts of organic solvents (100 μL) during back-extraction, in compliance with the green analytical chemistry principles. In short, the new-generation BAμE devices showed to be an eco-user-friendly approach for trace analysis of priority compounds in biological fluids and a versatile alternative over other well-stablished sorption-based microextraction techniques.

A new configuration for bar adsorptive microextraction (BAμE) for the quantification of biomarkers (hexanal and heptanal) in human urine by HPLC providing an alternative for early lung cancer diagnosis

In this paper, a remodeling of the bar adsorptive microextraction (BAμE) technique is proposed with impregnation of the derivatization reagent on the surface of the adsorptive bar containing a biosorbent material. The derivatization reagent was 2,4-dinitrophenylhydrazine (DNPH), which was adsorbed on the surface of the bar containing cork powder as the extractor phase for the determination of two aldehydes (hexanal and heptanal) which are known as lung cancer biomarkers in human urine samples. The derivatization reaction and the extraction occurred simultaneously on the surface of the bar (length 7.5 mm) under acidic conditions. The method optimization was carried out by univariate and multivariate analysis. The optimal conditions for the method were a DNPH to aldehydes ratio of 40:1, buffer solution of pH 4.0, extraction time of 60 min and liquid desorption of 10 min in 100 μL of acetonitrile. The aldehydes were analyzed by HPLC-DAD with a simple and fast (6 min) chromatographic run. The limits of detection (LODs) for hexanal and heptanal were 1.00 and 0.73 μmol L^-1, respectively. The relative recoveries in urine samples ranged from 88 to 111% with relative standard deviations (RSDs) being less than 7%. The method developed is of low cost and can be successfully used for the quantification of these two lung cancer biomarkers in human urine samples, potentially providing an early diagnosis of lung cancer.

Bar adsorptive microextraction technique - application for the determination of pharmaceuticals in real matrices

In the present work, bar adsorptive microextraction using miniaturized devices (7.5 × 3.0 mm) coated with suitable sorbent phases, combined with microliquid desorption (100 μL) followed by high-performance liquid chromatography with diode array detection (BAμE-μLD/HPLC-DAD), is proposed for the determination of trace level of six pharmaceuticals (furosemide, mebeverine, ketoprofen, naproxen, diclofenac and mefenamic acid) in environmental water and urine matrices. By comparing ten distinct sorbent materials (five polymeric and five activated carbons), the polymer P5 proved to be the most suitable to achieve the best selectivity and efficiency. The solvent volume minimization in the liquid desorption stage demonstrated remarkable effectiveness, being more environmentally friendly, and simultaneously increased the microextraction enrichment factor two-fold. Assays performed through BAμE(P5, 0.9 mg)-μLD(100 μL)/HPLC-DAD on 25 mL of ultrapure water samples spiked at the 4.0 μg/L level yielded average recoveries ranging from 91.4% (furosemide) to 101.0% (ketoprofen) with good precision (RSD < 10.6%), under optimized experimental conditions. The analytical performance showed convenient detection limits (25.0 - 120.0 ng/L), good linear dynamic ranges (0.1 to 24.0 μg/L), appropriate determination coefficients (r ² > 0.9983), and excellent repeatability through intraday (RSD < 10.4%)) and interday (RSD < 10.0%) assays. By using the standard addition methodology, the application of the present analytical approach on environmental waters and urine samples revealed the occurrence of trace levels of some pharmaceuticals. The solvent minimization during the back-extraction step associated with the miniaturization of BAμE devices proved to be a very promising analytical technology for static microextraction analysis. Graphical abstract BAμE operating under the floating sampling technology for the determination of pharmaceuticals in aqueous media.

Critical assessment of the ubiquitous occurrence and fate of the insect repellent N,N-diethyl-m-toluamide in water

The insect repellent diethyltoluamide (DEET) is among the most frequently detected organic chemical contaminants in water across a wide range of geographies from around the world. These observations are raising critical questions and increasing concerns regarding potential environmental relevance, particularly when the emergence of severe neurological conditions attributed to the Zika virus has increased the use of insect repellents. After dermal application, DEET is washed from the skin when bathing and enters the municipal sewer system before discharge into the environment. Mainly measured by gas chromatography or liquid chromatography coupled to mass spectrometry (GC-MS or LC-MS), more than 200 peer-reviewed publications have already reported concentrations of DEET ranging ng/L to mg/L in several water matrices from North America, Europe, Asia, Oceania, and more recently Africa and South America. While conventional wastewater treatment technology has limited capacity of removal, advanced technologies are capable of better attenuation and could lower the environmental discharge of organic contaminants, including DEET. For instance, adsorption on activated carbon, desalinating membrane processes (nanofiltration and reverse osmosis), ozonation, and advanced oxidation processes can achieve 50% to essentially 100% DEET attenuation. Despite the abundant literature on the topic, the ubiquity of DEET in the environment still raises questions due to the apparent lack of obvious spatio-temporal trends in concentrations measured in surface water, which does not fit the expected usage pattern of insect repellents. Moreover, two recent studies showed discrepancies between the concentrations obtained by GC-MS and LC-MS analyses. While the occurrence of DEET in the environment is well established, the concentrations reported should be interpreted cautiously, considering the disparities in methodologies applied and occurrence patterns observed. Therefore, this manuscript provides a critical overview of the origin of DEET in the environment, the relevant analytical methods, the occurrence reported in peer-reviewed literature, and the attenuation efficacy of water treatment processes.

Determination of Trace Levels of Irgarol in Estuarine Water Matrices by Bar Adsorptive Microextraction

Bar adsorptive microextraction (BAµE), using selective sorbent phases, followed by liquid desorption in combination with large volume injection-gas chromatography coupled to mass spectrometry (BAµE-LD/LVI-GC-MS), is proposed for the determination of trace levels of irgarol in estuarine water matrices. While we compared several polymers and activated carbons, one of the latter coatings showed much higher selectivity through BAµE. Assays performed on 25 mL of ultra-pure water sample fortified at 0.6 µg/L levels of irgarol yielded recoveries of 74.5 ± 8.6%, under optimized experimental conditions. The proposed analytical procedure showed convenient detection limits (16.0 ng/L) and good linear dynamic range (0.2-16.0 µg/L), with determination coefficients of 0.9982. Good precision was also achieved with RSD lower than 12.0%. The application of the present analytical approach on estuarine water samples by using the standard addition methodology revealed good sensitivity and linearity. The proposed methodology, using nanostructured sorbents and operating under the floating sampling technology, proved to be a suitable analytical alternative to monitor irgarol in estuarine water matrices. Moreover, it is easy to implement, reliable, sensitive, require low sample volume and have the possibility to choose the most selective sorbent coating according to the target compound involved.

A novel approach to bar adsorptive microextraction: Cork as extractor phase for determination of benzophenone, triclocarban and parabens in aqueous samples

This study describes the use of cork as a new coating for bar adsorptive microextraction (BAμE) and its application in determining benzophenone, triclocarban and parabens in aqueous samples by HPLC-DAD. In this study bars with 7.5 and 15 mm of length were used. The extraction and liquid desorption steps for BAμE were optimized employing multivariate and univariate procedures. The desorption time and solvent used for liquid desorption were optimized by univariate and multivariate studies, respectively. For the extraction step the sample pH was optimized by univariate experiments while the parameters extraction time and ionic strength were evaluated using the Doehlert design. The optimum extraction conditions were sample pH 5.5, NaCl concentration 25% and extraction time 90 min. Liquid desorption was carried out for 30 min with 250 μL (bar length of 15 mm) or 100 μL (bar length of 7.5 mm) of ACN:MeOH (50:50, v/v). The quantification limits varied between 1.6 and 20 μg L(-1) (bar length of 15 mm) and 0.64 and 8 μg L(-1) (bar length of 7.5 mm). The linear correlation coefficients were higher than 0.98 for both bars. The method with 7.5 mm bar length showed recovery values between 65 and 123%. The bar-to-bar reproducibility and the repeatability were lower than 13% (n = 2) and 14% (n = 3), respectively.

Application of bar adsorptive microextraction (BAμE) for anti-doping control screening of anabolic steroids in urine matrices

This study proposes a new analytical methodology for the determination of trace levels of testosterone (T) and epitestosterone (E) in urine matrices using bar adsorptive microextraction combined with liquid desorption followed by high-performance liquid chromatography with diode array detection (BAμE-LD/HPLC-DAD). The comparison of different sorbent coatings (five activated carbons, one styrene-divinylbenzene, two modified pyrrolidone, one ciano and one n-vinylpyrrolidone polymers) through BAμE showed that the latter phase presented much higher selectivity and capacity offering multiple mechanisms of interaction. Assays using this phase were performed on 25mL of water samples spiked at the 8.0μg/L level, yielded average recoveries of 92.1 and 93.4% for T and E, respectively, under optimized experimental conditions; BAμE (n-vinylpyrrolidone): 16h (1000rpm), pH 5.5; LD: acetonitrile, 30min under sonication treatment. From the developed analytical methodology, suitable detection limits were achieved (0.4μg/L) and good linear dynamic ranges (1.4-16.0μg/L) with remarkable determination coefficients (r(2)>0.9978). By using the standard addition methodology, the application of the present analytical approach on urine samples revealed good sensitivity. The proposed method, which operated under the floating sampling technology, proved to be a suitable sorption-based static microextraction alternative for screening T, E and the T/E ratio in urine samples for doping control purposes. The methodology showed to be easy to implement, demonstrating good reproducibility, sensitivity and robustness, allowing the possibility to choose the most selective sorbent coating according to the compounds of interest.