Selective Extraction Procedure Research Articles

New selective and sustainable ultrasound-assisted extraction procedure to recover carnosic and rosmarinic acids from Rosmarinus officinalis by sequential use of bio-based solvents

Carnosic (CA) and rosmarinic (RA) acids are the primary phenolic acids in hydrophilic rosemary extracts. Their combination exhibits high antioxidant activity and can be explored in several applications. This study aimed to develop an extraction procedure using bio-based solvents to recover two rosemary extracts, one rich in CA and the other in RA. By using ultrasound-assisted extraction (UAE) and a pool of 34 solvents, we evaluated nominal power (W), extraction time (min), and solvent water percentage (% H2O) regarding yield and selectivity. The authors propose a sequential UAE procedure validated by applying ethanol 99.5 % (v/v), 240 W, and 5 min to recover a rich fraction of 24.0 mgCA.gbiomass−1; followed by a second step using AmAc:LA (1:2 M ratio), 20 % H2O (m/m), 320 W, and 5 min that resulted in 8.4 mgRA.gbiomass−1. Our results indicate that modulating the solvent composition and process temperature is critical to increasing extraction yields and selectivity.

Development of paper-immobilized molecularly imprinted polymers by laser pointer activation for methamphetamine extraction with analysis by ion mobility spectrometry

A fast, simple, cheap, and versatile strategy has been proposed for the synthesis of paper-immobilized molecularly imprinted polymers (MIPs) by photoactivated bulk polymerization over a piece of nitrocellulose using a 405 nm laser pointer. Polymerization was carried out using a mixture of methacrylic acid and ethylene glycol dimethacrylate, using methamphetamine as template molecule and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide as radical initiator. After investigation of different polymerization parameters, the following experimental conditions were found to give best results: size of nitrocellulose strip (13.5 × 4.0 × 0.8 mm), type of porogen (acetonitrile), polymerization mixture volume (75 µL), and irradiation times (10 min). Experimental conditions (such as sample pH, extraction and desorption time, and type and volume of desorption solvent) were also adjusted for the extraction of methamphetamine using the proposed paper-MIP. Methamphetamine determination was carried out by ion mobility spectrometry providing a limit of detection of 14 µg L−1 and quantitative recoveries from 81 to 95% using spiked urine and oral fluid samples. The proposed paper-immobilized MIP device allows a simple and selective sample extraction procedure for the determination of methamphetamine in oral fluids and urine with a high portability, minimal solvent consumption, and reduced costs compared to other conventional approaches.

Vanadium Speciation in Ancient Shales Revealed through Synchrotron-Based X-ray Spectroscopy

Redox-sensitive trace elements, such as vanadium, are frequently used as paleoredox proxies to infer the redox status of ancient marine depositional environments. When applied to vanadium, this approach relies on an accurate understanding of vanadium geochemistry in marine sediments. This, in turn, requires the application of analytical techniques capable of providing reliable chemical information on vanadium host phases of vanadium and thus the ability to distinguish authigenic from detrital phases. The increasing availability of synchrotron-based X-ray spectroscopic techniques capable of providing chemical speciation information at both the bulk and micro-scale presents an opportunity to refine our understanding of vanadium geochemistry in ancient marine sediments. Here, we show the utility of synchrotron-based X-ray absorption near-edge structure (XANES) spectroscopy and scanning X-ray fluorescence microscopy (SXFM) for investigating vanadium host phases in ancient marine sediments. The studied samples from the 1400 Ma Xiamaling Formation came from strongly contrasting depositional settings (ranging from oxic to euxinic) with a wide range of vanadium enrichments (enrichment factors from 0.7 to 9.6), yet vanadium speciation determined by XANES was consistently found to be phyllosilicate-hosted vanadium (III). High-resolution elemental imaging by SXFM coupled with global statistical colocalization analyses revealed strong associations between vanadium and potassium, consistent with vanadium hosted by potassium-rich clay minerals. These findings, while demonstrating the power of synchrotron-based X-ray methods, imply that differentiating authigenic and detrital vanadium in ancient marine sediments is unlikely to be possible given that post-depositional processes result in similar chemical speciation for both fractions. This will also limit the reliability of vanadium isotope system studies that depend on differentiating authigenic and detrital fractions using selective extraction procedures.

Evaluating the “wrong-way-round” electrospray ionization of antiretroviral drugs for improved detection sensitivity

The presence of antiretroviral drugs (ARVDs) in the aquatic environment poses a significant health risk to the ecosystem. The dilution of these compounds during wastewater treatment processes, followed by discharge into the environment, results in extremely low concentrations in the range of ng/L. Therefore, to enable detection of these low concentrations, it is important to determine the most efficient electrospray ionization (ESI) mode using the right mobile phase modifier and to establish a selective extraction procedure. In this study, we compared the ESI intensity in the positive and negative mode using both formic acid (FA) and ammonium hydroxide (NH4OH) as mobile phase modifiers. The results revealed a phenomenon known as the “wrong-way-round” (WWR) ESI in which high intensity [M + H]+ ions were detected under basic conditions using NH4OH as modifier and, similarly, high intensity [M-H]− ions were detected under acidic conditions using FA as modifier. Furthermore, mixed-mode strong cation (MCX) and mixed-mode strong anion (MAX) exchange sorbents were evaluated for extraction recoveries, which yielded extraction recoveries between 60 and 100%. Finally, the recoveries obtained using mixed-mode ion exchange sorbents compared to ion production during the ESI process provide evidence that ions produced in solution do not necessarily reflect the ions that are produced during the ESI process. Based on the results of this study, it is recommended to evaluate the optimal ionization mode under basic and acidic conditions, instead of defaulting to the use of acidic modifiers with positive ion detection.

Rapid thermoscanning technique for direct analysis of mercury species in contaminated sediments: From pure compounds to real sample application

Mercury (Hg) in aquatic environments accumulates in sediments in several chemical forms, both inorganic and organic, which are often determined through time-consuming selective and sequential extraction procedures. Thermal desorption technique (pyrolysis) coupled with continuous determination by atomic absorption spectrometry (AAS) may be an easy-to-use alternative technique for the rapid identification and quantification of Hg species in the solid matrix. This technique is based on the gradual heating of a sample that releases Hg at different temperature intervals depending on its chemical form. Thus, a single Hg species that desorbs at a specific temperature may be identified via a thermogram of the sample.In this work, several commercial pure Hg compounds, natural Hg mineral species (red cinnabar, α-HgS) and one compound synthesised in the lab (α-FeOOHHg) were mixed with synthetic calcium carbonate (CaCO3), silica (SiO2) and natural matrices (silicate and carbonate marine sediments) which were then desorbed in order to determine the desorption peak temperatures corresponding to each Hg species. Moreover, possible interference caused by the matrix was also considered. The results obtained from 52 desorbed MIX samples displayed different desorption temperatures for the same Hg species depending on the matrix used. Indeed, Hg species mixed with synthetic SiO2 desorbed at a temperature lower than the same species mixed with synthetic CaCO3 with a difference of approximately 100 °C.The analytical approach was applied to selected coastal sediments from the Gulf of Trieste (Northern Adriatic Sea, Italy), contaminated by Hg from the five centuries of cinnabar (α-HgS) mining activity from Idrija (Slovenia), in order to identify the unknown Hg species. The results revealed the presence of two peaks with a distinct temperature of desorption (∼250 and 350 °C). The highest temperature corresponds to the mostly refractory red cinnabar (α-HgS) compound, whereas the lowest temperature is related to other species (e.g. β-HgS) that may also include Hg associated with more mobile and potentially bio-accessible species (e.g. α-FeOOHHg) if compared to α-HgS. This methodological approach is a rapid and cost-effective technique useful to preliminarily quantify more stable Hg species (mainly α-HgS), underlining the relevance in considering the chemical form of the element rather than merely the total concentration for simplifying the environmental management of Hg-contaminated sediments.

Selective extraction of gambierone and related metabolites in Gambierdiscus silvae using m-aminophenylboronic acid–agarose gel and liquid chromatography–high-resolution mass spectrometric detection

Gambierdiscus spp. are epi-benthic dinoflagellates that have been associated with ciguatera poisoning. These microalgae can have complex secondary metabolite profiles including ciguatoxins, maitotoxins, and gambierones, with varying compositions and toxicities across species and strains. Given this chemical diversity there is a need to develop selective and sensitive methods for secondary metabolite profiling. In this study, we used a cultured Caribbean strain of Gambierdiscus silvae to develop sample preparation and analysis strategies for characterizing vic-diol containing secondary metabolites. A pooled cellular extract was first screened by liquid chromatography–high-resolution mass spectrometry (LC–HRMS) for ciguatoxin-related compounds, which resulted in the confirmation of gambierone (1) and a novel isomer of 44-methylgambierone (3). Treatment of the extract with periodate confirmed that the gambierones each contained one reactive vic-diol, which was exploited for the development of a selective extraction procedure using m-aminophenylboronic acid gel and the non-aqueous binding solvent chloroform. Using this non-traditional boronate affinity procedure, LC–HRMS also revealed the presence of additional sulfated polycyclic ethers in the gambierone-containing vic-diol fraction, while pigments and other contaminants were removed. The developed tools could be applied to screen collections of Gambierdiscus and other benthic algae to provide additional chemical characterization of gambierone-related compounds. The selective extraction procedure may also prove useful as a step in the isolation of these sulfated polyethers for structural, toxicological and biotransformation studies.

Chitosan biofilms: Insights for the selective electromembrane extraction of fluoroquinolones from biological samples

A selective electromembrane extraction procedure for the extraction of Enrofloxacin, Marbofloxacin and Flumequine, usually employed as antibiotic in veterinarian use, is proposed by using a chitosan biofilm, composed by 60% (w/w) chitosan and 40% (w/w) Aliquat®336, as active biopolymeric support. The interaction mechanism occurring between the target drugs and the biopolymer has been deeply studied using the Quantum Theory of Atoms in Molecules. The obtained results show the interaction between the extracted fluoroquinolones and the biomembrane is stabilized by two hydrogen bonds formed between both the carboxyl and keto groups of the drugs with both the amine and hydroxyl groups of glucosamine in the biopolymer. The energetic results agree with the high extraction efficiency obtained for Marbofloxacin, Enrofloxacin and Flumequine in terms of enrichment factors (83, 82 and 58, respectively) in presence of other fluoroquinolones. Under optimum conditions, the proposed electromembrane extraction method exhibits wide linear ranges of 4.2–200 μg L−1, 5.6–200 μg L−1 and 5.1–200 μg L−1, respectively; low limits of detection close to 1.3 μg L−1 and appropriate repeatability (relative standard deviation values 4–7%).

Co-immobilized Alcohol Dehydrogenase and Glucose Dehydrogenase with Resin Extraction for Continuous Production of Chiral Diaryl Alcohol.

Ni2+-functionalized porous ceramic/agarose composite beads (Ni-NTA Cerose) can be used as carrier materials to immobilize enzymes harboring a metal affinity tag. Here, a 6×His-tag fusion alcohol dehydrogenase Mu-S5 and glucose dehydrogenase from Bacillus megaterium (BmGDH) were co-immobilized on Ni-NTA Cerose to construct a packed bed reactor (PBR) for the continuous synthesis of the chiral intermediate (S)-(4-chlorophenyl)-(pyridin-2-yl) methanol ((S)-CPMA) NADPH recycling, and in situ product adsorption was achieved simultaneously by assembling a D101 macroporous resin column after the PBR. Using an optimum enzyme activity ratio of 2:1 (Mu-S5: BmGDH) and hydroxypropyl-β-cyclodextrin as co-solvent, a space-time yield of 1560 g/(L·d) could be achieved in the first three days at a flow rate of 5 mL/min and substrate concentration of 10 mM. With simplified selective adsorption and extraction procedures, (S)-CPMA was obtained in 84% isolated yield.

Synthesis and characterization of molecularly imprinted polymers for the selective extraction of oxazepam from complex environmental and biological samples.

Oxazepam, one of the most frequently prescribed anxiolytic drugs, is not completely removed from wastewater with conventional treatment processes. It can thus be found at trace levels in environmental water, with human urine constituting the major source of contamination. This study focused on the development and characterization of molecularly imprinted polymers (MIPs) for the selective solid-phase extraction of oxazepam at trace levels from environmental water and human urine samples. Two MIPs were synthesized, and their selectivity in pure organic and aqueous media were assayed. After optimizing the extraction procedure adapted to a large sample volume to reach a high enrichment factor, the most promising MIP was applied to the selective extraction of oxazepam from environmental water. Extraction recoveries of 83 ± 12, 92 ± 4 and 89 ± 10% were obtained using the MIP for tap, mineral and river water, respectively, while a recovery close to 40% was obtained on the corresponding non-imprinted polymer (NIP). Thanks to the high enrichment factors, a limit of quantification (LOQ) of 4.5ngL-1 was obtained for river water. A selective extraction procedure was also developed for urine samples and gave rise to extraction recoveries close to 95% for the MIP and only 23% for the NIP. Using the MIP, a LOQ of 357ngL-1 was obtained for oxazepam in urine. The use of the MIP also helped to limit the matrix effects encountered for the quantification of oxazepam in environmental samples and in human urine samples after extraction on an Oasis HLB sorbent.

Separation and determination of Pb (II) ions from aqueous media by cloud point extraction

A simple, effective and highly selective cloud point extraction procedure was performed for enrichment of Pb (II) from aqueous matrix. The process depends on the formation of a stable complex between Pb (II) ions and Azure A compound at pH 6.0. The formed complex was extracted into micelle phase “Tergitol-NP7” at 25°C. This method was used for preconcentration of Pb (II) before its determination by FAAS. The values of limit of detection and limit of quantification were determined as 2.5 and 4.7 μg l-1, respectively. The enrichment factor of the method was determined as 10 for 50 ml sample volume. Pb2+ analyte was quantitatively extracted and successfully determined in the presence of the most common foreign ions. The proposed method was then employed for the analysis of Pb (II) in natural and wastewater samples.

Assessment of selective sequential extraction procedure for determining arsenic partitioning in copper slag

Abstract An optimized selective sequential extraction (SSE) procedure was developed to assess the arsenic (As) partitioning in copper slag. The potential As species in copper slag are partitioned into the readily soluble As, dissolvable arsenates, sparingly soluble arsenates, As residing in sulfides, arsenopyrite and metal As, as well as As incorporated into glassy silicates. The inductively coupled plasma atomic emission spectrometry (ICP-AES), scanning electronic microscopy (SEM), transmission electron microscope (TEM), X-ray diffractometry (XRD) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the leachates and residues produced from the operation scheme. The selectivity and recovery of extractants were evaluated through single-phase extraction procedures. Partitioning data of As in slag samples show good agreement with the reported works and the total As recovery of each operation is over 90%. This suggests that the optimized SEE scheme can be reliably employed for As partitioning in As-bearing byproducts from copper smelting.

Selective cloud point extraction of thorium (IV) using tetraazonium based ionic liquid

This study involves the synthesis and characterization of a new tetra-cationic surface-active ionic liquid (SAIL) based on tetraazonia-tricyclo[3.3.1.13,7]decane derivative. The surface properties of the synthesized SAIL revealed good surface activity, self-aggregation and clouding ability indicating its feasibility in surfactant-mediated extraction applications. Applying the synthesized SAIL combined with Triton X-100 as a mixed surfactant system in cloud point extraction of Th(IV) ions resulted in a sensitive and selective extraction procedure. Arsenazo III was used as Th(IV) chelating agent and the pre-concentrated chelate was spectrophotometrically determined. The main variables affecting the extraction efficiency were systematically investigated. The highest extraction efficiency was achieved at pH 5.0 with 2.5 × 10−3 mol L-1 SAIL and 1.0 % (v/v) Triton X-100. At the optimized conditions, the developed method exhibited a linear working range from 10.0 to 100.0 ng mL-1 with a detection limit of 77.0×10-2 ng mL−1. The interfering impact of various ions on Th(IV) extraction efficiency was evaluated. The applicability and reliability of the developed method were evaluated by determining Th(IV) at trace levels in various water samples and the obtained recovery values were ranging from 98.0 to 101.4%. The developed CPE method is sensitive, simple, reliable and consistent with the green chemistry principles.

Acetonitrile-Hexane Extraction Route to Pure Sulfonium Salts.

A rapid, simple procedure is described for synthesizing trialkyl, dialkylaryl, and alkyldiaryl sulfonium salts that features a selective extraction procedure to access analytically pure sulfonium salts. Alkylation of dialkylsulfides, alkylarylsulfides, and diarylsulfides followed by partitioning between acetonitrile and hexanes efficiently separates nonpolar reactants and byproducts, the usual impurities, to afford analytically pure crystalline and noncrystalline sulfonium salts. The method is efficient, general, and particularly well suited for the preparation of oily sulfonium salts that are otherwise extremely difficult to purify.

Simultaneous speciation analysis of mercury in marine origin samples by high performance liquid chromatography and species - specific isotope dilution inductively coupled plasma mass spectrometry

Species-specific isotope dilution inductively coupled plasma quadrupole mass spectrometry reference method and high-performance liquid chromatography were applied for simultaneous determination of mercury species in marine samples. Different extraction protocols for mercury species were tested and evaluated. It was found that after exposure to microwave energy the inorganic mercury (iHg) and methyl mercury (MeHg) can be completely extracted from marine biota sample by 4.5 mol L−1 HCl as well as by 3.0 mol L−1 HNO3 and further separated with HPLC. The obtained results for iHg and MeHg in the IAEA-461 certified reference material (CRM) clam Gafrarium tumidum biota sample were as follow: (341 ± 21) μg kg−1 or (338 ± 15) μg kg−1 and (61.3 ± 2.2) μg kg−1 (recovery of (98.4 ± 3.6) %) or (61.1 ± 2.8) μg kg−1 (recovery of (98.1 ± 4.6) %), respectively when diluted HCl or HNO3 were applied in the extraction step. However, these protocols are not applicable to marine sediment samples, where the iHg is the predominant form. Therefore, one selective extraction procedure for MeHg from sediment was applied to make possible its separation and quantification. This procedure consisted of series of subsequent extraction steps at room temperature: first with a mixture of H2SO4/KBr/CuSO4, next with organic solvent dichloromethane and as a final step one back-extraction with Na2S2O3 solution. The combination of the selective extraction with the ID calibration approach was found to be an efficient way for the simultaneous determination and separation of both MeHg and iHg species in one chromatographic run. The proposed procedure was successfully used for the determination of mercury species in the IAEA-405 sediment CRM and further applied for the simultaneous measurements of iHg and MeHg in a candidate CRM – the IAEA-475 sediment sample. The determined mass fractions were (30.1 ± 1.6) μg kg−1 and (196 ± 8) ng kg−1 for iHg and MeHg, respectively. The difference between obtained in this study results and those from the reference IAEA-475 values was 1.5% and further validated the developed in this study analytical methodology. To the best of our knowledge, this selective procedure for MeHg extraction was never used before for the simultaneous quantification of mercury species in marine sediment.

Relationship between enrichment, toxicity, and chemical bioavailability of heavy metals in sediments of the Cai River estuary.

This study focuses on heavy metals (HMs) (Cr, Co, Ni, Cu, Zn, and Pb) along with Al, Fe, Mn, organic carbon (TOC), and carbonates (TIC) detected in surface sediments from the River Cai-Nha Trang Bay estuarine system (South China Sea). The enrichment factors (EFAl and EFFe), Geoaccumulation Index (Igeo), Adverse Effect Index (AEI), and toxic units (TUs) were used to assess the HM enrichment and toxicity in the sediments. The selective single-step extraction procedure was applied to determine the chemical forms of HMs in order to assess their potential bioavailability. The EF and Igeo calculations suggest that sedimentary Fe, Mn, Cr, Co, Ni, and Cu are derived mainly from natural sources (EFAl and EFFe < 1.5 and Igeo < 0 at all sampling sites), while the moderate Pb enrichment (EFAl and EFFe ≥ 2 and Igeo ≥ 1 at all sampling sites) may indicate a moderate contamination. Cr, Cu, and Zn suggest low potential toxicity, while both Ni and Pb show above threshold AEI levels (AEI ≥ 1) and contribute up to 30-40% to the sum of toxic units (∑TUs) at all sampling sites. According to their comparative ability to mobilize metals from the sediments, the single extractants applied were arranged in descending order: acetic acid > ammonium oxalate >> sodium pyrophosphate. All single-step extractants mobilized substantive amounts of Pb (7-30% of total content, on average) from sediments, indicating considerable potential bioavailability. Among HMs studied, the percentage of acid-soluble Pb (23-35%) significantly exceeded the respective ranges in the sediments of other coastal regions. Pearson's correlation and PCA analyses revealed that among HMs studied, Cr, Ni, and Co enrichment is positively associated with the salinity gradient due to the accumulation of the most fine-grained Fe-rich aluminosilicate host minerals in the bay zone, while sediments in the transitional zone are mainly enriched in Cu, Zn, and Pb due to the local accumulation of metal-rich detrital heavy minerals. The percentages of bioavailable forms of most of the HMs are negatively associated with the salinity gradient due to the preferential accumulation with fluvial Fe/Mn oxyhydroxides in the frontal and transitional zones. Generally, distribution of the enrichment indices of most of the HMs is not associated or even negatively associated with the percentage of the bioavailable forms. The intensity of monsoonal precipitation is shown to be an essential factor in the natural enrichment of estuarine sediments with bioavailable metals. Determining the local geochemical background of HMs and Pb, in particular, is a major goal for future study.

Geochemical assessment of platinum group metals for phytomining

Abstract Phytomining is suggested as a technology to obtain platinum group metals (PGMs) nanoparticles from plants grown on the mineralized soils or tailings. Samples from North American Palladium (Canada) and gossans from Broken Hill (BH) (Australia) were studied to assess the possibility of using these PGM-rich samples as substrates for phytomining. The bioavailability of PGMs was indirectly assessed using geochemical procedures. The selective extractions showed that the highest available concentration of Pd is 5.38 ppm in BH gossan 1. The extraction of PGMs by ammonium acetate, fulvic acid or citrate-dithionite indicates natural availability to plants. The BH gossan 1 was the best of the five studied samples for phytomining of Pd due to available Pd concentration (> 2 mg/kg), low Electric Conductivity (< 2dS/m), high CEC (Cation Exchange Capacity) (38.8 meq/100g), and proper pH (6.5). Cu-tolerant plant species should be chosen to grow on BH gossan 1. A criterium for choosing substrates for phytomining of Pd was developed comprising various classical soil parameters plus selective extraction procedures.

Selective separation of gadolinium from a series of f-block elements by cloud point extraction and its application for analysis of real samples

A selective and effective cloud point extraction procedure was presented for separation of Gd3+ from other f-block elements (i.e. La3+, Ce3+, Nd3+, Sm3+, Ho3+, Er3+, Th4+ and U6+). The procedure depends on the formation of stable hydrophobic complex between Gd3+ and quercetin at pH 3.0. The formed complex was extracted at room temperature into surfactant rich phase “Triton X-114” in the presence of 0.1 mol L−1 KI. The procedure was also used for enrichment of Gd3+ prior its determination by ICP-OES. At optimum conditions, the proposed procedure displays good analytical linearity (0.1–200 μg L−1) with limit of detection and limit of quantification of 0.03 and 0.11 μg L−1, respectively. The enrichment factor was 49.2 for 50 mL sample. The analyte was quantitatively tolerated in the presence of most concomitant ions. The procedure was then employed for the analysis of Gd3+ in ore, urine and synthetic samples.

Ultrasound assisted combined molecularly imprinted polymer for the selective micro-solid phase extraction and determination of aflatoxins in fish feed using liquid chromatography-tandem mass spectrometry

A combined procedure based on using ultrasounds for target isolation followed by porous membrane-protected micro solid phase extraction using a molecularly imprinted polymer as an adsorbent has been developed as a highly selective extraction and clean-up procedure for isolating aflatoxins B1, B2, G1, and G2 from fish feed before ultra-high-performance liquid chromatography tandem mass spectrometry determination. Polymeric adsorbent beads have been synthesized by the precipitation polymerization method which guarantees a homogeneous particles size distribution and the integrity of the generated imprinted cavities. In addition, polymerization was performed using a higher proportion of organic solvent (toluene) in the porogen mixture, which generates MIP particles adequate for interacting with targets dissolved in organic (hydro-organic) mixtures (extracts from fish feed). These approaches led to a selective and high efficient pre-concentration method for AFs. Ultrasound-assisted extraction (10 mL of 60:40 acetonitrile/0.1 M KH2PO4 pH 6.0, 40% amplitude, continuous sonication for 7.0 min) allowed an efficient aflatoxins isolation from fish feed. In addition, the resulting pH of the extract (pH 7.0) has been found to be the optimum for performing clean-up/pre-concentration (enrichment factor of 33.3) by molecularly imprinted polymer based micro-solid phase extraction (orbital horizontal shaking speed at 150 rpm for 10 min for loading, and 5 mL of 95:5 acetonitrile/formic acid as eluting solution using ultrasounds 35 kHz for 15 min). The current proposal was shown to be an accurate and precise method through relative standard deviation of intraday and inter-day tests below 20% and analytical recoveries in the range of 80–100%. The limits of detection were within the 0.42–1.15 μg kg−1 range, quite lower than those established by European Commission guidelines for aflatoxins in animal feeds.

Chemical mobility of inorganic elements in stream sediments of a semiarid zone impacted by ancient mine residues

Water availability is a worldwide issue, particularly in semiarid zones. Therefore, it is necessary to know the geochemical processes involved in the mobility of contaminant sources to ensure adequate quality for this resource. Some mining areas of México are of economic importance; however, they are also the sources of large quantities of mine residues, such as the site included in this study. As an important aspect of understanding contaminant mobility in sediments and water, a thorough mineralogical characterization is paramount to identify sources and sinks for relevant elements, in this case, potentially toxic elements (PTEs) such as arsenic (As), lead (Pb) and cadmium (Cd); hence, scanning electron microscopy (SEM), X-ray diffraction (XRD) and chemical analysis were used. The total geochemical distribution was established by means of a modified selective sequential extraction procedure. The results showed that sediments constitute an effective attenuation substrate for mobilized PTEs to groundwater. Hence, arsenic and cadmium were stabilized in the sediments and/or the vadose zone, and although Pb and Zn were identified in groundwater with concentrations above the background values, they were below drinking water standards. Sulfate and total hardness concentrations in the groundwater confirmed the impact of acid mine drainage (AMD) infiltration. Considering that similar sites in Mexico are found along the Sierra Madre Oriental, the methodology of this study could be applied to understand the mobility of PTEs in the sediments and waters of semiarid environments.

High-throughput and selective solid-phase extraction of urinary catecholamines by crown ether-modified resin composite fiber

In the present study, we developed a simple and high-throughput solid phase extraction (SPE) procedure for selective extraction of catecholamines (CAs) in urine samples. The SPE adsorbents were electrospun composite fibers functionalized with 4-carboxybenzo-18-crown-6 ether modified XAD resin and polystyrene, which were packed into 96-well columns and used for high-throughput selective extraction of CAs in healthy human urine samples. Moreover, the extraction efficiency of packed-fiber SPE (PFSPE) was examined by high performance liquid chromatography coupled with fluorescence detector. The parameters affecting the extraction efficiency and impurity removal efficiency were optimized, and good linearity ranging from 0.5 to 400 ng/mL was obtained with a low limit of detection (LOD, 0.2–0.5 ng/mL) and a good repeatability (2.7%–3.7%, n = 6). The extraction recoveries of three CAs ranged from 70.5% to 119.5%. Furthermore, stable and reliable results obtained by the fluorescence detector were superior to those obtained by the electrochemical detector. Collectively, PFSPE coupled with 96-well columns was a simple, rapid, selective, high-throughput and cost-efficient method, and the proposed method could be applied in clinical chemistry.