KIO3-catalyzed selective oxidation of thiols to disulfides in water under ambient conditions.

Herein, we report a KIO3-catalyzed oxidative coupling of thiols to their corresponding disulfides in water, in a short time and at ambient temperature. The reaction has a broad scope and exhibits good functional group tolerance, resulting in the desired products in excellent yields. This approach allows the reuse of the reaction system in multiple cycles and scale-up. Furthermore, the current protocol demonstrates compatibility for in situ generation of disulfides and post application in C(sp2)-H bond sulfenylation.

Polyaniline-silica doped with oxalic acid as a novel extractor phase in thin film solid-phase microextraction for determination of hormones in urine.

In this study, different polyanilines were synthesized and evaluated for the determination of three hormones, including 17-ß-estradiol, 17-α-ethinylestradiol, and estrone, in urine using a novel methodology based on thin film solid-phase microextraction technique, employing the sampling well plate system. The extractor phases, designated as polyaniline doped with hydrochloric acid, polyaniline doped with oxalic acid, polyaniline-silica doped with hydrochloric acid, and polyaniline-silica doped with oxalic acid, were characterized by electrical conductivity measurements, scanning electron microscopy, and Fourier transform infrared spectroscopy. The optimized extraction conditions were composed of 1.5 mL of urine and pH adjusted to 10, with no need to dilute sample and the desorption step, 300 µL of acetonitrile was used. The calibration curves were performed in the sample matrix, with detection and quantification limits ranged from 0.30 to 3.03 µg L-1 and from 1.0 to 10.0 µg L-1 , respectively, with r ≥ 0.9969. The relative recoveries ranged from 71% to 115%, and intraday precision showed values ≤12% and interday ≤20%. The applicability of the method was successfully evaluated, and six urine samples from female volunteers were analyzed. The analytes were not detected or were below the limits of quantification in these samples.

Magnetic restricted-access carbon nanotubes for SPME to determine cannabinoids in plasma samples by UHPLC-MS/MS.

This manuscript describes the development of magnetic restricted-access carbon nanotubes (M-RACNTs) for use as SPME sorbent to determine cannabidiol (CBD) and delta-9-tetrahydrocannabinol (THC) in human plasma samples by UHPLC-MS/MS. The adsorptive phase was immobilized on an SPME device by electromagnetic interactions between the M-RACNTs and a cylindrical neodymium magnet (3-mm diameter x 8-mm height) attached to a stainless-steel rod (3-mm diameter x 40-mm height). The M-RACNTs were synthesized by incorporating Fe3O4 magnetic nanoparticles (MNPs) into commercial carbon nanotubes (CNTs); then the surface of the resulting sorbent was further coated with a layer of bovine serum albumin (BSA). Characterization techniques (SEM, FTIR, and Zeta potential) confirmed the presence of both MNPs and BSA layer dispersed through the structure of the CNTs. The M-RACNTs presented adequate sorption capacity, stable physical/chemical characteristics, and appropriate magnetic properties. Protein exclusion capacity (about 98.5%) was attributed to the chemical diffusion barrier created by the BSA network at the outer surface of the sorbent. The SPME parameters (sample pH, equilibrium time, and desorption conditions) were optimized by design of experiments (fraction factorial planning). The method (validated according to the FDA guidelines) presented adequate selectivity and linearity (coefficient of determination higher than 0.99) at concentrations ranging from the lower limit of quantification (LLOQ) (10 ng mL-1) to the upper limit of quantification (ULOQ) (300 ng mL-1) for both CBD and THC. Precision and accuracy varied from 4.47 to 19.84% (LLOQ) and -6.90 to 17.78% (LLOQ), respectively. Carry-over and matrix effect were not significant. The method was successfully applied to determine plasmatic CBD levels in healthy volunteers attending a single session of oral drug administration and THC levels in frequent cannabis smokers.

Determination of hormones in urine by hollow fiber microporous membrane liquid-liquid extraction associated with 96-well plate system and HPLC-FLD detection.

In this work, hollow-fiber microporous membrane liquid-liquid extraction (HF-MMLLE) was associated with a 96-well plate system for the determination of estrone, 17-ß-estradiol, estriol and 17-α-ethinylestradiol in urine samples. This method exhibited some advantages, such as low cost, easy application, high-throughput and environmentally-friendly aspects. The type of organic solvent to fill the membrane, ionic strength effect, sample dilution, extraction and desorption time, and desorption solvent were examined. After the optimizations, the conditions were comprised of 45 min of extraction, 1-octanol as organic solvent and 15% (w/v) of NaCl; methanol was used as desorption solvent, and the desorption time was fixed at 10 min. The dilution of the sample increased the sensitivity due to the reduction of matrix effects; thus, urine samples were diluted 40-fold. The limits of detection ranged from 0.03 µg L-1 for 17-ß-estradiol to 15 µg L-1 for estrone, and the limits of quantification ranged from 0.1 µg L-1 for 17-ß-estradiol to 10 µg L-1 for estrone. The intra-day precision varied from 1.0% for estriol to 13.3% for 17-α-ethinylestradiol, and inter-day precision varied from 7.3% for estrone to 18.1% for estriol. The relative recoveries varied from 82 to 118%.

Multiclass determination of endocrine disruptors in urine by hollow fiber microporous membrane and liquid chromatography.

A simple and rapid methodology was developed using hollow fiber membrane microporous and a 96-well plate system for a high throughput multiclass determination of endocrine disruptors in human urine (diclofenac, diazepam, carbamazepine, ibuprofen, naproxen, carbofuran, methyl parathion, 17-α-ethynyl estradiol, bisphenol A and benzophenone). The quantification and detection of the chemicals were carried out by an HPLC-diode array detector. The fixed conditions for carrying out the method optimization were 1.5 mL of sample and 300 µL of solvent desorption. Multivariate and univariate models were applied to optimize the parameters of the method, achieving the following conditions: 20% diluted urine, 1-octanol of extraction solvent impregnated in the microporous membrane, 70 min extraction in pH 3.0 and 30 min with a mixture of 75% methanol and 25% acetonitrile (v/v) for the desorption. The R2 were ≤ 0.9973 for ibuprofen. The LOD ranged from 3.3 to 16.7 ng mL-1 and the LOQ from 10 to 50 ng mL-1. Relative recoveries ranged from 71% to 126%. The repeatability (n = 3) ranged from 0.22% to 12.01%, and the intermediate precision (n = 9) ranged from 0.13% to 17.76%. The method presents a good alternative for the determination of different classes of compounds in human urine.

Disposable pipette extraction: A critical review of concepts, applications, and directions.

Analytical chemistry has always been evolving towards techniques that are increasingly simple and effective and that conform to green principles. Disposable pipette extraction (DPX, also known as dispersive pipette tip solid phase extraction) is a recent technique that has become an interesting tool in sample preparation methodologies. The principle is based on a dynamic mixture between the matrix and the sorbent which allows rapid and effective extraction of analytes and provides vigorous clean-up of the samples. In the context of fitting in with green chemistry, DPX has contributed to replacing commercially available materials with natural alternative materials. The production of these materials is also simple, reduces sample/solvent volumes, consequently generates less waste and is less laborious and safer for the laboratory worker. This review is a source of information about the DPX technique, dealing with its basic concepts, procedure, optimizations, materials for the main applications published so far, which are in the food, environmental and biological (forensic) sciences.

A semi-quantitative model through PLS-DA in the evaluation of carbendazim in grape juices.

Carbendazim (CBZ) is a fungicide employed in grape crop disease controls, and its maximum residue limit in food is regulated by specialized agencies. This study aimed to determine the CBZ content in the grape juices in a semi-quantitative classification model based on portable Ultraviolet-Visible spectroscopy and partial least squares with discriminant analysis. The sensitivity and specificity of the obtained model ranged from 83 to 100%, with the external validation set. These results are therefore promising for industrial application, and the model presents robustness for the evaluation of grape juices produced from a different grape variety. The VIP scores allowed identifying important variables involved in class modeling. This study suggests a methodology that is fast and demands minimal sample preparation (only dilution), besides being less expensive compared to the traditional methods, free of reagent/solvent, contributing to quality control in the juice industry.

Application of Homogeneous Liquid-Liquid Microextraction With Switchable Hydrophilicity Solvents to the Determination of MDMA, MDA and NBOMes in Postmortem Blood Samples.

Synthetic drugs for recreational purposes are in constant evolution, and their consumption promotes a significant increase in intoxication cases, resulting in damaging public health. The development of analytical methodologies to confirm the consumption of illicit drugs in biological matrices is required for the control of these substances. This work exploited the development of an extraction method based on homogenous liquid-liquid microextraction with switchable hydrophilicity solvent (SHS) as extraction phase for the determination of the synthetic drugs 3,4-methylenedioxymethamphetamine, 3,4-methylenedioxyamphetamine and N-methoxybenzyl-methoxyphenylethylamine derivates (25B, 25C and 25I) in postmortem blood, followed by liquid chromatography coupled to mass spectrometry in tandem. The optimized sample preparation conditions consisted of using 250 µL of ZnSO4 10% and 50 µL of NaOH 1 mol/L in the protein precipitation step; N,N-dimethylcyclohexylamine was used as SHS, 650 µL of a mixture of SHS:HCl 6 mol/L (1:1 v/v), 500 µL of whole blood, 500 µL of NaOH 10 mol/L and 1 min of extraction time. The proposed method was validated, providing determination coefficients higher than 0.99 for all analytes; limit of detection and limit of quantitation ranged from 0.1 to 10 ng/mL; intra-run precision from 2.16% to 9.19%; inter-run precision from 2.39% to 9.59%; bias from 93.57% to 115.71% and matrix effects from 28.94% to 51.54%. The developed method was successfully applied to four authentic postmortem blood samples from synthetic drugs users, and it was found to be reliable with good selectivity.

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 ß-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.

Photocatalytic Cellulose-Paper: Deepening in the Sustainable and Synergic Combination of Sorption and Photodegradation.

Clean water is one of the sustainable development goals set by the United Nations for 2030. The development of effective but worldwide affordable strategies is essential to guarantee this achievement. Photocatalysis technology fulfills these criteria whenever the photocatalyst is sustainable and nontoxic. In this article, a cellulose-paper modified with a polyamide-titanium dioxide (TiO2) nanocomposite by dip-coating is evaluated to degrade estrogens efficiently under solar light. The study deepens on the synergic combination of the sorptive capacity of the polyamide and the activity of TiO2. The photocatalytic performance was studied under artificial and sunlight in a miniaturized experimental setup (batch of six reactors). Also, the effects of the dispersed/immobilized catalyst, irradiation time, and adsorption evaluation were studied under kinetic conditions. The photocatalyst composition, considering the polyamide (nylon-6) and TiO2 amounts and the dipping cycles, was studied by a response surface methodology, and the reusability of the photocatalytic cellulose-paper was investigated. The LED source provided removal efficiencies of 65, 62, and 52% (for estrone, 17ß-estradiol, and estriol, respectively) after 420 min of light exposure. Under sunlight, the efficiency increased up to 99.5% for estrone and 17ß-estradiol and 98.5% for estriol after 180 min of irradiation. The sustainable character of the cellulosic substrate, the low toxicity of the nanocomposite ingredients, and its performance under sunlight make the material attractive for in-field application.

The use of microwave-induced plasma optical emission spectrometry for fluorine determination and its application to tea infusions.

This study presents a novel method for fluorine quantification determination by microwave-induced plasma optical emission spectrometry (MIP-OES). Due to the low temperature of this plasma, atomic emission of fluorine could not be measured, instead CaF molecular emissions were measured by using a calcium solution mixed in the spray chamber with the sample using a T-piece. Several wavelengths were studied to find the best signal to noise ratio for fluorine determination and 530.45 nm was chosen. The limit of detection for the determination of fluorine via CaF using MIP-OES was 1.1 mg L-1. A linear response was observed over two orders of magnitude (R2 = 0.998). The developed method was applied to ten tea infusion samples from the UK and Saudi Arabia. The results were not significantly different (paired Student's t-test, p = 0.97) to the results obtained using the reference method, high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-GF MAS). The total fluorine in the tea infusions varied between 2.7 and 7.8 mg L-1; all of which were above the WHO recommended level of fluoride (0.8-1.5 mg L-1) in drinking water. This method can potentially be used for total fluorine determination and might be useful for fluorine speciation analysis when coupled with HPLC.

A proof-of-concept of parallel single-drop microextraction for the rapid and sensitive biomonitoring of pesticides in urine.

In this study, a lab-made parallel single-drop microextraction methodology using the magnetic ionic liquid trihexyltetradecylphosphonium tetrachloromanganate (II) as extraction solvent was developed to determine the pesticides tebuconazole, pendimethalin, dichlorodiphenyltrichloroethane, and dichlorodiphenyldichloroethylene in human urine samples. The experimental setup consisted of a 96-well plate system containing a set of magnetic pins that allowed for the manipulation of up to 96 samples simultaneously, providing an enhanced drop stability compared to traditional single-drop microextraction approaches. The optimal conditions employed 5.38 ± 0.55 mg of extraction solvent, 1.5 mL of diluted urine samples (1:10), extraction time of 130 min, and subsequent dilution in 20 µL of acetonitrile. The method exhibited satisfactory analytical performance, with limits of detection of 7.5 µg/L for all analytes and coefficients of determination higher than 0.9955. Intraday and interday precisions ranged from 3 to 17% (n = 3) and 15 to 18% (n = 9), respectively, with relative recovery of analytes ranging from 70 to 122%. The method proposed was successfully applied in two human urine samples and no sign of the analytes was detected. The results demonstrated that the proposed method allowed for cost-effective and high-throughput methodology to be explored as a valuable tool in bioanalytical applications.

Sustainable green solvents for microextraction techniques: Recent developments and applications.

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

Novel strategy for disposable pipette extraction (DPX): Low-cost Parallel-DPX for determination of phthalate migration from common plastic materials to saliva simulant with GC-MS.

In widespread use in commercial products as plasticizers, phthalic acid esters (phthalates) have worried researchers and society in general, given the negative impacts on living organisms, especially human health. Since they are not chemically linked to the polymeric matrix, their migration is evident for samples that come into contact with plastics that contain them, such as water, food and saliva. In this work, a new strategy is described, named parallel-disposable pipette extraction (Pa-DPX), in a fast, efficient and robust analytical method using five simultaneous extractions for the determination of migration of 6 phthalates from common plastic materials (children's toys, school supplies, dog toys and oral contact items) to saliva simulant, using gas chromatography-mass spectrometry (GC-MS). The optimized conditions were 5 extraction cycles with 1600 µL of saliva simulant and desorption with 200 µL of ethyl acetate using 5 cycles with the same aliquot. The calibration curves resulted in determination coefficients higher than 0.9915, limits of detection at 1.5 µg L-1, and the quantification limits were 5.0 µg L-1. Excellent results were obtained for repeatability (relative standard deviation ranging from 8.7% to 20.1% for 5 µg L-1) and intermediate precision, varying the day of analyses (7.9%-16.2%). The analyte recovery ranged from 75% to 114% for two different samples, in four different levels of concentration. The Pa-DPX-GC-MS method was successfully applied to determine the migration of PAE from 21 samples. At least one PAE was detected in 81% of samples, and di-n-octyl phthalate was found in higher concentration, achieving the migration of almost 30 µg per g of sample.

Determination of bisphenol A: Old problem, recent creative solutions based on novel materials.

Bisphenol A is a synthetic compound widely used in industry, in the production of polycarbonate, epoxy resins, and thermal paper, among others. Its annual production is estimated at millions of tons per year, demonstrating its importance. Despite its wide application in various everyday products, once in the environment (due to its disposal or leaching), it has high toxicity to humans and animal life, and this problem has been well known for years. Given this problem, many researchers seek alternatives for its monitoring in matrices such as natural water, waste, food, and biological matrices. For this, new advanced materials have been developed, characterized, and applied in creative ways for the preparation of samples for the determination of bisphenol A. This article aims to present some of these important and recent applications, describing the use of molecularly imprinted polymers, metal and covalent organic frameworks, ionic liquids and magnetic ionic liquids, and deep eutectic solvents as creative solutions in sample preparation for the long-standing problem of bisphenol A determination.

High-throughput approach for the in situ generation of magnetic ionic liquids in parallel-dispersive droplet extraction of organic micropollutants in aqueous environmental samples.

In this work, a novel and high-throughput parallel-dispersive droplet extraction (Pa-DDE) based on in situ formation of the hydrophobic MILs ([Co(C4IM)4+2]2[NTf2-], [Ni(C4IM)4+2]2[NTf2-] and [Ni(BeIM)4+2]2[NTf2-]) is demonstrated, for the first time, for the determination of benzophenone, metolachlor, triclocarban, pendimethalin, 4-methylbenzylidene camphor, and 2-ethylhexyl-4-methoxycinnamate from aqueous environmental samples. This experimental setup is comprised of a 96-well plate system containing a set of magnetic pins which were used to collect the MIL droplet after in situ formation. This consolidated system enabled simultaneous extraction of up to 96 samples and MIL production in one step. Using this apparatus, sample preparation times of 0.78 min per sample was achieved. The experimental conditions were carefully optimized using uni and multivariate approaches. The optimal conditions were comprised of sample volume of 1.25 mL, 4 mg of [Co(C4IM)4+2]2[Cl-] and 40 µL of LiNTf2 for the in situ formation, and dilution in 20 µL of acetonitrile. The analytical parameters of merit were successfully determined with LODs ranging from 7.5 to 25 µg L-1 and coefficients of determination higher than 0.989. Intraday and interday precision ranged from 6.4 to 20.6% (n = 3) and 11.6-22.9% (n = 9), respectively, with analyte relative recovery ranging between 53.9 and 129.1%.

A green approach to DDT degradation and metabolite monitoring in water comparing the hydrodechlorination efficiency of Pd, Au-on-Pd and Cu-on-Pd nanoparticle catalysis.

DDT (1,1,1-trichloro-2,2-bi(p-chlorophenyl)-ethane) and its metabolites (DDD, 1,1-dichloro-2,2-bis-(4'-chlorophenyl)ethane, and DDE, 1,1-dichloro-2,2-bis-(4'-chlorophenyl)ethylene) are persistent organic pollutants that can be catalytically degraded into a less toxic and less persistent compound. In this work, ecofriendly methodologies for catalyst synthesis, catalytic degradation of DDT and reaction monitoring have been proposed. Three types of Pd-based nanoparticles, NPs, (Pd, Au-on-Pd and Cu-on-Pd) were synthesized and used for catalytic hydrodechlorination of DDT and its metabolites. The structural and electronic properties of NPs were investigated using TEM and XAS spectroscopy. Au-on-Pd showed the highest hydrodechlorination efficiency within 1 h of reaction. To obtain the best reaction conditions, the effects of H2 flow and base addition Au-on-Pd NPs activity were investigated. To study the effectiveness of the different NPs, a solvent-free analytical method was optimized to detect and measure DDT and its by-products. The SPME-GC-MS method provided low detection limits (0.03 µg L-1) and high recovery (≥88.75%) and was a valuable tool for the NP degradation study. In this way, a green method for degradation and monitoring of DDT and its by-products in water was achieved.

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%.

A green - high throughput -extraction method based on hydrophobic natural deep eutectic solvent for the determination of emerging contaminants in water by high performance liquid chromatography - diode array detection.

This study reports the use ofa natural deep eutectic solvent (NADES) with hollow fiber-microporous membrane liquid-liquid microextraction (HF-MMLLE) for the multiclass determination of 11 compounds classified as emerging contaminantsin water. Different deep eutectic solvents were synthetized and Thymol: Camphor (1:1 molar fraction) wasused as extraction solvent. The Thymol:Camphor was impregnated into the polypropylene membrane porous for 10 min, replacing commonly used solvents (ex. hexane and octanol). The optimized parameters were obtained by multi and univariate models. Extractions were carried out for 50 min using 1.5 mL of water sample at pH 6 and without addition of salt while desorption was made in a mixture of acetone: methanol (3:1, v/v) for 15 min. Separation/quantification was conducted by HPLC with a diode array detection (DAD)and calibration curves were obtained for each analyte. Determination coefficients higher than 0.9906 and limits of detection ranged from 0.3 to 6.1 µg L-1. Intraday precision (n = 3) ranged from 1.6 to 18.4% and inter day from 5.0 to 21.3%. Relative recoveries were performed in tap and stream water and ranged from 64 to 123%.

Determination of pesticides of different chemical classes in drinking water of the state of Santa Catarina (Brazil) using solid-phase microextraction coupled to chromatographic determinations.

The evaluation of the concentration of pesticides in drinking water presents a real concern. In this study, a simple and rapid method based on solid-phase microextraction (SPME) followed by gas chromatography-mass spectrometry and electron capture detectors was developed aiming at multiclass determination of 23 pesticides regulated by the Brazilian legislation. The extraction was carried out by direct immersion mode (DI-SPME) using DVB/Car/PDMS fiber coating. In order to improve the extraction efficiency, parameters such as temperature, salting-out effect, and extraction time were optimized. The method was evaluated using drinking water samples spiked with the analytes at different concentrations, and it showed good linearity in the range studied. The values obtained for limits of quantification (LOQ) were below the limits established by Brazilian regulations. Accuracy and precision of the method exhibited satisfactory results, providing relative recoveries from 70 to 123.34% at three spiked levels, and the relative standard deviations ranged from 0.53 to 24.8%. The method was applied in 20 drinking water samples from 13 cities in the State of Santa Catarina, Brazil.