High Enrichment Factors Research Articles

A green miniaturized aqueous biphasic system prepared with cholinium chloride and a phosphate salt to extract and preconcentrate personal care products in wastewater samples

A miniaturized extraction/preconcentration method based on an aqueous biphasic system (μ-ABS) was developed with reagents commonly used as food additives: cholinium chloride (ChCl) as main extraction phase, K2HPO4 as salting-out agent, and water as the main component (being the sample for analyses). With the aim of obtaining high enrichment factors, miniaturization, and adequate analytical performance, a point in the biphasic region with the lowest amount of ChCl was selected, corresponding to 1.55% (w/w) of ChCl, 59.5% (w/w) of K2HPO4, and 38.95% (w/w) of water. The green μ-ABS (attending to its main elements and performance mode) was used in combination with high-performance liquid chromatography with diode-array detection (HPLC-DAD) for the determination of 9 personal care products in wastewater samples. The μ-ABS-HPLC-DAD method showed high enrichment factors (up to 100), and quantitative extraction efficiencies for those compounds containing OH groups in their structure, which can undergo hydrogen bonding with ChCl. Thus, limits of quantification down to 0.8 µg·L-1 and extraction efficiencies between 66.4 and 108% (concentration levels of 1.3 and 13 µg·L-1) were reached for the group of parabens and the UV-filter benzophenone-3. The method is characterized by the use of non-harmful reagents and the absence of organic solvents in the entire sample preparation procedure, while being simple, low-cost, easily compatible with HPLC, and highly efficient.

Research progress of solid phase extraction materials in the application of metal ion pretreatment

为避免摄入过量重金属、危害人类健康,应提高对金属离子的检测能力。常用的金属检测技术如电感耦合等离子体质谱、电热原子吸收光谱、火焰原子吸收光谱等可以有效识别痕量重金属,并且具有多组分分析能力以及检出限低、产量高等优点。但复杂样品本身浓度较低且基质干扰大,因此检测前需进行前处理以消除基质干扰,满足低浓度和小体积样品的检测需求。固相萃取是富集样品中金属离子常用的方法之一,开发能够进行高效、快速富集分离的固相萃取新材料及前处理技术是金属离子检测的关键。限制接触碳纳米管、纳米吸附剂、纳米粒子载体、磁性纳米粒子等纳米材料可提供大的比表面积和可调的官能团,以促进金属离子吸收,其优越的光学性能则可用于荧光和比色检测;高分子聚合物具有卓越的机械性能和化学稳定性,可用于微量金属粒子的前富集、分离和检测;离子印迹聚合物对目标离子具有选择性识别能力的空间结构,可以吸附待分离体系中的金属离子;双功能材料可同时进行多种金属离子的萃取和快速定量检测,新型的光敏络合物则可以将结合态的金属离子转变为游离态,使其被多种生物传感器快速检测,也可以研究生物体内金属离子的信号传递过程。该文综述了纳米材料、聚合物、功能材料等新型固相萃取材料的特点及在复杂样品前处理中的应用和研究进展,并对其未来发展方向进行了展望。

Assessment of metal contamination in deposited dust of the industrial area and some streets - Aden city, Yemen

Air pollution from pollutant emissions has become a threat to the biological system and human health. The concentration levels and sources of heavy metals contamination were studied in deposited dust samples collected from various locations, including five different activity areas: industrial, highways, residential, mixed use and a remote area from contaminants in Aden, Yemen. Metal content of Cd, Pb, Cu, Zn, Co, Cr, Mn and Fe in dust was analyzed by Atomic Absorption Spectrophotometer (AAS). The results showed high concentration levels of Cd and Pb in industrial and residential areas. Deposited dust contamination was assessed by various methods: Enrichment factor (EF), Contamination factor (CF), Degree of contamination (DC) and potential ecological index (RI). The enrichment factor indicated extremely high enrichment of Cd, Pb and Zn. High EF of Cd, Pb and Zn showed that anthropogenic sources contribute a substantial amount of these metals to dust deposited. Contamination factor analysis showed that dust samples are significantly contaminated by Cd and Pb. Individual ecological risk (Er) indicated low to high contamination of Cd, but low contamination of Pb, Cr, Cu, Co and Zn. The degree of contamination (DC) and Potential ecological risk index (RI) indicated that most of the study areas demonstrated “Moderate to considerable category” risk index. The result suggest mixed origin of pollution sources; including Man-made sources, traffic sources, and lithogenic occurrences of the metals from construction sources and road construction currently in some of the sites studied.

Simultaneous extraction of six phthalic acid esters from polyethylene terephthalate (PET) bottled water using poly (ionic liquid) functionalised silica coated-iron oxide nanoparticles: a risk assessment study

ABSTRACT In this research, a poly (ionic liquid) functionalised silica-coated magnetic nanoparticles were synthesised for the first time and utilised as a novel adsorbent for the simultaneous extraction of six phthalic acid esters from polyethylene terephthalate bottled drinking water samples. The adsorbent was prepared by grafting poly (1-benzyl-3-vinyl-1 H-imidazol-3-ium chloride) onto silica-coated Fe3O4nanoparticles via Cu(0)-mediated reversible-deactivation radical polymerisation method. Various techniques were used to characterise the synthesised nanomaterials. A qualitative analysis was performed using ultra-performance liquid chromatography triple–quadrupole tandem mass spectrometry. Response surface methodology based on central composite design was used to optimise the extraction procedure and the optimised condition for each factor was; pH of3.9, 22 mg of adsorbent, 3.5 min extraction time, 3 min desorption time, 340 µL of elution solvent (methanol).The results of the validation of the method indicated its acceptable accuracy (88.6-100.1%), good linearity (r > 0.995), satisfactory repeatabilities (RSDs ≤ 6% for intra- and inter–day precisions) and high enrichment factors (535–572). The limits of detection and limits of quantification of the proposed method achieved were 1.1-4.6 ngL–1and 3.6-15.3 ngL–1, respectively. In this study, six common PAEs, including dimethyl phthalate, diethyl phthalate, dibutyl phthalate, benzyl butyl phthalate, bis (2-ethylhexyl) phthalate, and di-n–octyl phthalate, were found in PET bottled water within the range of 0.21-0.94 μgL–1, under different storage conditions. Nevertheless, only a negligible risk is caused by the PAEs in PET bottled water for consumers following the recommendations, such as storing at a common place (25°C), in a short period away from the sun.

Development of derivatization/air‐assisted liquid‐liquid microextraction procedure for analyzing short‐chain fatty acids; assessment of the analytes in fruit juice samples

AbstractAn air‐assisted liquid‐liquid microextraction method has been developed by gas chromatography‐flame ionization detection for the extraction, derivatization, and determination of five short chain fatty acids including acetic acid, propionic acid, butyric acid, valeric acid, and caproic acid from different fruit juices. In this method, butyl chloroformate was used as extraction solvent and derivatization agent, simultaneously. For this purpose, sample solution was adjusted at pH 8 and then mixed with picoline (as a catalyst). Next, a few microliters of butyl chloroformate was added to the solution and after performing predetermined extraction cycles, the obtained cloudy solution was centrifuged. An aliquot of the sedimented phase was injected into the determination system. Low limits of detection (3.23–9.63 ng/mL) and quantification (10.8–32.4 ng/mL) were obtained. The method had a proper repeatability (relative standard deviations ≤ 7.38%) for intra‐ (n = 6) and interday (n = 5) precisions at a concentration of 50 ng/mL (each analyte). High enrichment factors (360–415), extraction recoveries (72–93%), and enhancement factors (1126–1852) were obtained. The developed method was successfully used in determination of the analytes in the studied samples.

Solvent-Free Synthesis of Phenolic Hydroxyl Enriched Ordered Mesoporous Polymer as an Efficient Solid-Phase Microextraction Coating for the Determination of Trace Phenols in Food Samples

The determination of trace phenols in food samples is of great significance, but it is still very challenging due to the low concentration and complex matrix. A robust method was developed to determine trace phenols in food sample by combining headspace-solid phase microextraction (HS-SPME) with gas chromatography-mass spectrometry (GC-MS). The hydroxylated ordered mesoporous polymer (OMP-OH) synthesized by solvent-free strategy possessed ordered mesoporous structure and high specific surface area and was used as SPME fiber coating. Factors affecting the extraction efficiency were optimized, including extraction time, extraction temperature, pH value, salt effect, and desorption conditions. Under the optimal conditions, OMP-OH coating exhibited a high capability for the enrichment of phenols, which was 2~8 times that of commercial SPME coating. Moreover, the coating can be reused for more than 150 times without a significant change in performance. Linear ranges of this method were 0.5~10000 ng L−1, of which 5~10000 ng L−1 for 2-nitrophenol and 1~10000 ng L−1 for 2, 4-dichlorophenol. The limits of detection (LODs) for phenols in tomato and grape are 0.19~2.13 ng L−1 and 0.21~2.41 ng L−1, respectively. High enrichment factors (439~1851), good precision (RSD< 8.87%), and superior reproducibility (RSD< 10.0%) were obtained. Ultimately, the established method was successfully applied to quantify the phenols in real food samples, i.e., tomato and grape. The results demonstrated that the established method was very promising for the determination of trace phenols in food samples with complex matrix.

Development of a green in-situ derivatization and deep eutectic solvent-based dispersive liquid–liquid microextraction method for analysis of short-chain fatty acids in beverage samples optimized by response surface methodology

An in-situ dispersive liquid–liquid microextraction and derivatization method based on deep eutectic solvent has been developed for the analysis of five short chain fatty acids (as model compounds) in different beverage samples prior to their determination by gas chromatography-flame ionization detection. In this method, 2-butanol was used as dispersive solvent derivatization reagent. For this purpose, the sample solution is transferred into a test tube and after dissolving sodium chloride in the solution, a suitable volume of HCl solution is added as catalyst. Thus, a mixture of 2-butanol and ethyl methyl ammonium chloride-carvacrol deep eutectic solvent (as an extraction solvent) is prepared and the mixture is quickly injected into the solution. The analytes are derivatized and extracted into the fine droplets of extracting agent, simultaneously. After centrifugation, an aliquot of the sedimented phase is injected into the separation system. Low limits of detection (0.89–6.6 µg L-1) and quantification (3.1–22.3 µg L-1) were obtained. Good repeatabilities with relative standard deviations ≤9.2% were obtained at the selected three concentrations. Also high enrichment factors, extraction recoveries, and enhancement factors were obtained within the ranges of 223–270, 76–92%, and 1074–1845, respectively. The developed method was successfully used in determination of the analytes in different beverage samples.

Polydopamine-coated magnetic nanoparticles for the determination of nitro musks in environmental water samples by stir bar sorptive-dispersive microextraction

Magnetic-based microextraction approaches have gained popularity in recent years due to the magnetic properties of the extraction phases allowing to handle them easier and more efficiently. This work describes a magnetic-based analytical method for the determination of the family of nitro musks in environmental water samples. These compounds have been of great concern due to their environmental impacts and potential health effects. The method is based on stir bar sorptive-dispersive microextraction (SBSDME) as extraction approach, prior to thermal desorption coupled to gas chromatography-mass spectrometry analysis (TD-GC-MS). For this purpose, polydopamine-coated cobalt ferrite magnetic nanoparticles (CoFe2O4@PDA) were used as extraction material. The main parameters involved in the extraction procedure (i.e., sorbent amount, extraction time and ionic strength) as well as in the thermal desorption step (i.e., temperature and desorption time) were evaluated in order to obtain the highest sensitivity. Under the selected conditions, the method showed good linearity, limits of detection and quantification in the low ng L−1 range, intra- and inter-day repeatability with RSD <15%, and high enrichment factors (178–640). Finally, the method was applied to four environmental water samples of different origin. Relative recovery values ranging from 91 to 120% highlighted that the matrices under consideration do not affect the extraction process. This work constitutes the first time in which nitro musks compounds were selectively extracted by taking advantage the high potential that magnetic-based microextraction techniques offer, specially SBSDME.

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.

Simultaneous enrichment of inorganic and organic species of lead and mercury in pg L−1 levels by solid phase extraction online combined with high performance liquid chromatography and inductively coupled plasma mass spectrometry

Quantification of ultra-trace inorganic and organic species of lead and mercury in unpolluted environmental water is crucial to estimate the mobility, toxicity and bioavailability and interactions. Simultaneous pre-concentration of Pb and Hg species in pg L−1 levels followed by multi-elemental speciation analysis makes great sense to a large set of unstable samples because of time advantages. Herein simultaneous enrichment and speciation analysis of ultra-trace lead and mercury in water was developed by online solid-phase extraction coupled with high performance liquid chromatography and inductively coupled plasma mass spectrometry (SPE-HPLC-ICP-MS) for this aim. Pb(II), trimethyl lead (TML), triethyl lead (TEL), Hg(II), methylmercury (MeHg) and ethylmercury (EtHg) were baseline separated in 11 min under gradient elution using 5 mM l-cysteine (Cys) at pH 2.5 in the 0–1 and 4–15 min and 5 mM Cys + 0.5 mM tetrabutyl ammonium hydroxide solution at pH 2.5 in the 1–4 min. Lead and mercury species in 10 mL intact water samples were adsorbed on a 1 cm C18 enrichment column pre-conditioned with 10 mL of 1 mM 2-mercaptoethanol at 10 mL min−1, and then directly desorbed by the mobile phases. High enrichment factors (459 for Pb(II), 1248 for TML, 1627 for TEL, 2485 for Hg(II), 1984 for MeHg and 1866 for EtHg) were obtained with good relative standard deviations (<5%), leading to low LODs (0.001–0.011 ng L−1) and LOQs (0.004–0.036 ng L−1). Good accuracy of this method was validated by two certified reference materials of total lead in water (GBW08601) and total mercury in water (GBW08603) along with spiked recoveries (89–93%). The method was applied to analyze trace lead and mercury species in river, lake, tap and rain water, and purified and mineral water. Inorganic lead of 13–68 ng L−1 and inorganic mercury of 21–49 ng L−1 were measured in the nine water samples whereas TML, TEL and MeHg were not detected with 2–5 ng L−1 EtHg presented only in one river water and tap water.

Combining a liquid-liquid extraction with successive air assisted liquid-liquid microextraction for the analysis of phytosterols present in animal based butter and oil samples

In this study, an elevated temperature liquid–liquid extraction combined method with successive air-assisted liquid–liquid microextraction has been proposed for the extraction of four phytosterols in cow milk butter and animal oil samples prior to gas chromatography–flame ionization detector. The method is started by combining a few grams of the melted butter or oil samples with ethanol. The mixture is vortexed and placed into a water-bath adjusted at 50 ⁰C. After a few minutes, the mixture is allowed to cool at room temperature. In this step, the butter or oil is become stiff and ethanol is collected on top of the sample. The separated ethanol phase is collected and mixed with deionized water to obtain a homogenous solution. After that, a few microliters of ethyl methyl ammonium chloride: pivalic acid deep eutectic solvent is added into the solution and the mixture was pulled into a glass test tube and pushed back to the tube for five times. After centrifugation, whole of the collected phase at the bottom of tube was withdrawn and transferred into a microtube and contacted with sodium hydroxide solution. The mixture is withdrawn and released to the tube 2 times to remove the extracted fatty acids. The validation data verified that high enrichment factors (385-450) and extraction recoveries (77–90%), low limits of quantification (2.6–5.2 ng g–1) and detection (0.73–1.5 ng g–1), and satisfactory relative standard deviations (≤ 9.3%) can be obtained with this method. At last, the developed method was successfully used for the analysis of phytosterols in various butter and oil samples marketed in Tabriz, Iran.

Finding evidence at a crime scene: Sensitive determination of benzodiazepine residues in drink and food paraphernalia by HPLC-HRMS/MS

Benzodiazepines are often used in drug-facilitated crimes, including robberies and sexual assaults, because their administration can make victims more compliant. The development of methods to assess the presence of these substances in connection with criminal acts is therefore crucial. The proposed method involved the use of single-use disposable swabs for the collection of drug residues on the surface of different items such as plastic or ceramic cups, drinking glasses and metal teaspoons or other items, which are commonly found at crime scenes. The extracts obtained from the swabs were then cleaned up and concentrated by means of dispersive liquid-liquid microextraction (dLLME); this procedure provided a high enrichment factor and consequently an improved sensitivity, which is particularly useful in cases where items may have been accidentally or deliberately cleaned before collection.Qualitative and semi-quantitative analysis was performed by means of an HPLC-HRMS/MS system. Two different precursor ion/fragment ion transitions were selected for each analyte to ensure a satisfactory number of identification points. The presented method was validated according to international guidelines and then applied to a real case, in which some dirty and soapy glasses were the only relevant evidence to evaluate the possible covert drugging of a rape victim.

Facile fabrication of magnetic covalent organic frameworks and their application in selective enrichment of polychlorinated naphthalenes from fine particulate matter.

Magnetic covalent organic frameworks (Fe3O4@TPPCl4) were synthesized via a one-pot process in which magnetic nanoparticles (Fe3O4@MNP) served as a magnetic core and 2,4,6-trihydroxy-1,3,5-benzenetricarbaldehyde (TP) and 2,2',5,5'-tetrachlorobenzidine (PCl4) as two building blocks to form a shell. The as-prepared Fe3O4@TPPCl4 nanoparticles have superior features, including large surface area (186.5m2g-1), high porosity, strong magnetic responsiveness (42.6emug-1), high chlorine content, and outstanding thermal stability, which make them an ideal adsorbent for highly selective enrichment of polychlorinated naphthalenes (PCNs). Combining with atmospheric pressure gas chromatography tandem mass spectrometry (APGC-MS/MS), a simple analytical method of Fe3O4@TPPCl4-based magnetic solid-phase extraction (MSPE)-APGC-MS/MS was developed, which exhibited good linearity (r ≥ 0.9991) for eight PCNs in the concentration range 0.1-100ngL-1. Moreover, low detection limits (0.005-0.325ngL-1), high enrichment factors (46.62-81.97-fold), and good relative standard deviations (RSDs) of inter-day (n = 3, 1.64 to 7.44%) and day-to-day (n = 3, 2.62 to 8.23%) were achieved. This method was successfully applied to the selective enrichment of PCNs in fine particulate matter (PM)2.5 samples, and ultra-trace PCNs were found in the range 1.56-3.75ngkg-1 with satisfactory recoveries (93.11-105.81%). The successful application demonstrated the great potential of Fe3O4@TPPCl4 nanoparticles as an adsorbent for enrichment ofhalogenated compounds. Schematic presented one-pot synthesis of magnetic covalent organic framework nanocomposites (Fe3O4@TPPCl4) and their application in the selective enrichment of PCNs from PM2.5 prior to APGC-MS/MS analysis.

Triazine-based covalent porous organic polymer for the online in-tube solid-phase microextraction of polycyclic aromatic hydrocarbons prior to high-performance liquid chromatography-diode array detection

A triazine-based covalent organic porous polymer (COP) was synthesized from the monomers 1,3,5-triphenylbenzene and tricyanogen chloride via the Friedel-Crafts reaction and characterized in detail using Brunauer-Emmett-Teller analysis, X-ray photoelectron spectroscopy, elemental analysis, and scanning electron microscopy, which confirmed that the COP had a rough surface and suitable extraction site. It was then employed in in-tube solid-phase microextraction combined with a high-performance liquid chromatography-diode array detector. The COP adsorbent was evaluated with different types of analyte, including estrogens, polycyclic aromatic hydrocarbons (PAHs), and plasticizers. The COP produced its best performance with PAHs. In order to obtain the highest extraction efficiency for PAHs, the main influential factors were optimized. Furthermore, a sensitive analytical method was established with the limits of detection of 0.004-0.010 µg L−1, high enrichment factor of 1110-2763, and wide linear ranges (0.013-20.0 µg L−1, 0.016-20.0 µg L−1 and 0.033-20.0 µg L−1). The relative standard deviation in intra-day and inter-day tests was also controlled to be within 0.3-3.1%. The proposed method was employed in the online detection of trace PAHs in real water samples, with satisfactory results obtained.

Combination of temperature-assisted ternary phase homogenous liquid-liquid extraction with deep eutectic solvent-based dispersive liquid-liquid microextraction for the extraction of phytosterols from cow milk and cream samples.

A three-phase homogenous liquid-liquid extraction method followed by deep eutectic solvent-based dispersive liquid-liquid microextraction has been used for the extraction and preconcentration of some phytosterols from cow milk and cream samples. In this method, cow milk or melted cream was transferred into a glass test tube and a mixture of sodium hydroxide solution (as fatty acids saponification agent) and acetonitrile (as extraction/dispersive solvent) was added to the solution. The mixture was shaken manually and placed in a water bath. After dissolving sodium chloride and centrifugation, the obtained supernatant phase (acetonitrile) was removed and mixed with ethyl methyl ammonium chloride: phenyl acetic acid deep eutectic solvent at microliter level. Under optimum conditions, low limits of detection (1.6-4.1μg/L) and quantification (5.3-13.1μg/L), high enrichment factors (138-207), and extraction recoveries (55-83%), and good precision (relative standard deviations ≤ 6.8%) can be obtained. The method was done on different milk and cream samples and the results showed that total phytosterols level in all samples were in the permitted level established by the National Standard Organization Guidelines, except for three cream samples.

Development of an ultrasonic and heat-assisted liquid–liquid extraction method combined with deep eutectic solvent-based dispersive liquid–liquid microextraction for the extraction of some phytosterols from cow milk butter samples

In this study, an ultrasonic and heat-assisted liquid–liquid extraction method combined with deep eutectic solvent-based dispersive liquid–liquid microextraction procedure was developed for the extraction of four phytosterols from cow milk butters. The analytes were determined by gas chromatography-flame ionization detector without derivatization. Initially, the sample was transferred into a falcon tube and placed into a sonication bath adjusted at 50 °C. Afterward, ethanol was mixed with the butter and the mixture was sonicated. After centrifugation, the ethanolic phase collected on top of the sample was withdrawn. After addition of a few microliters, ethyl (methyl) ammonium chloride/pivalic acid deep eutectic solvent, the mixture was sucked into a glass syringe and injected hastily into deionized water. The turbid solution was centrifuged and the sedimented phase was removed. Then, it was contacted with sodium hydroxide solution to remove the extracted fatty acids. The proposed method presented high enrichment factors (340–425) and extraction recoveries (68–85%), low limits of detection (0.51–1.3 ng g−1) and quantification (1.7–4.3 ng g−1) and acceptable relative standard deviations (≤ 8.4%). The analytes contents of several cow milk butter samples were extracted and quantified with the developed method and the results were compared with ISO 23349.

Construction of hydroxyl functionalized magnetic porous organic framework for the effective detection of organic micropollutants in water, drink and cucumber samples

Organic micropollutants have been extensively detected in environmental waters, posing severe hazards to organisms and humans. Effective detection of micropollutants in environmental water and food samples is of significant importance. Herein, a novel magnetic porous organic framework (labeled as M-Qu-POF) was synthesized using natural quercetin as building units via a facile azo-coupling reaction for the first time. Featuring with good magnetism, intrinsic porosity, high surface area and hydrophilic-lipophilic (amphiphilic) structure, the M-Qu-POF displayed high adsorption capacity for phenylurea herbicides (PUHs) pollutants. The adsorption mechanism was investigated by theory calculation, confirming that the hydrogen bonds interaction, π-π interactions and electrostatic interactions play an important role in the adsorption. With the M-Qu-POF as adsorbent, a magnetic solid phase extraction-high performance liquid chromatography method was first established for simultaneous enrichment and detection of six PUHs in environmental water, tea drink and cucumber samples. Under the optimized experimental conditions, good linear range, low detection limits and high enrichment factors were obtained. The method was successfully applied for determination of PUHs in environmental water, tea drink and cucumber samples with satisfactory recoveries (80.0–118%). The result demonstrates that the M-Qu-POF material has a good application prospect in the detection of other organic micropollutants.

Deep‐Water Formation in the North Pacific During the Late Miocene Global Cooling

AbstractA multiproxy study including organic carbon and bulk nitrogen isotopes along with major and trace element concentrations in sediments from Integrated Ocean Drilling Program (IODP) Sites U1425 and U1430 in the Japan Sea have been conducted in order to trace deep‐water evolution in the Japan Sea and the North Pacific since the late Miocene. The high total organic carbon (TOC) flux, as well as other published geochemical and sedimentary evidence, indicates the occurrence of anoxic deep‐water in the Japan Sea before ∼7.4 Ma. The low‐nitrogen isotope values probably suggest nearly complete denitrification. In contrast, the sharply enhanced biological production but decreased burial of organic matter during ∼7.4–4 Ma, as shown by high enrichment factor of Ba (BaEF) values, together with low TOC flux, highlights enhanced deep‐water oxygenation in the Japan Sea during that time. We suggest that deep‐water formation in the North Pacific ventilated the deep Japan Sea via northern deep seaways before the sea became semi‐closed in the early Pliocene. The synchronously increased equator‐to‐pole temperature gradients driven by late Miocene global cooling may have caused southward shift of mid‐latitude storm tracks, coupled with the weakened East Asian summer monsoon and moisture transport, leading to decreased precipitation in mid‐latitude regions. The potential increases in surface salinity in the North Pacific may have broken the ocean stratification and favored deep‐water formation, and further caused deep‐water ventilation in the Japan Sea.

Mercury, Platinum, Antimony and Other Trace Elements in the Atmospheric Environment of the Urban Area of Mexico City: Use of Ficus benjamina as Biomonitor.

The application of Sb, Pt and Hg in the development of new strategic technologies has increased significantly in recent years. This study evaluates the impact of vehicular traffic on the rise in emission of Sb, Pt and Hg in the atmospheric environmen of Mexico City and their correlation to Co, Cr, Cu, Ni, Pb, V and Zn. Ficus benjamina leaves were collected as biomonitor of atmospheric metals deposited in areas exposed to heavy vehicular traffic. High enrichment factor values (metal(loid) concentration/background values) were calculated: 146 (Sb), 52.8 (Pb), 29.7 (Pt) and 25.1 (Cr). Enrichment factors of Ni, Zn, Co, V, Cu and Hg decrease in that order and are <10. Principal component analysis allows recognize that most of the analyzed metal(loids) are related to traffic sources; Ni and Cr are also attributable to an additional anthropogenic source. No relationship was found relating Pb to vehicular sources.

Development of a Stirring-Dependent Magnetic Dispersive Solid Phase Extraction Method Coupled with Ferrofluid-Based Dispersive Liquid–Liquid Microextraction for the Extraction of Some Pyrethroid Pesticides from Fruit Juices

In the present work, a new and efficient sample treatment method based on the combination of stirring-dependent magnetic dispersive solid phase microextraction and ferrofluid-based dispersive liquid–liquid microextraction has been developed for the extraction of some pyrethroid pesticides (bifenthrin, phenothrin, tetramethrin, cyhalothrin, permethrin, and cypermethrin) from fruit juices prior to their determination with gas chromatography–mass spectrometry. For this purpose, a few milligrams of a synthesized magnetic sorbent (Fe3O4@polythiophene) is added into a sample solution containing the analytes and stirred at high rate. By this action, particles of the magnetic sorbent are detached from the magnetic stir bar surface and completely dispersed throughout the solution. After stopping stirring, the particles containing the adsorbed analytes are rapidly returned onto the stir bar. Then, the stir bar is taken and eluted with an appropriate solvent to desorb the analytes. Afterward, the eluent is mixed with a few microliters of a synthesized ferrofluid and the mixture is rapidly injected into deionized water placed in a conical glass test tube for more enrichment of the analytes. In the next step, the ferrofluid settled down at the bottom of the tube in the presence of an external magnet and the supernatant is discarded. After back-extraction of the analytes with n-hexane, an aliquot of the extract is injected into the determination system. Under optimal conditions, the developed method offered high enrichment factors (1380–1660) and extraction recoveries (69–83%), and low limits of detection (4.0–12 ng L−1) and quantification (14–40 ng L−1). The relative standard deviations were ≤ 7.1% for intra-day (n = 6) and inter-day (n = 4) precisions at a concentration of 250 ng L−1 of each analyte. Finally, six different fruit juice samples were successfully analyzed by the introduced method and cypermethrin was detected in apple juice at a concentration of 110 ± 0.5 ng L−1.