Detection Of Polychlorinated Biphenyls Research Articles

Reusable pyrene-based fluorescent organogels for polychlorinated biphenyl detection and removal

Highly toxic hydrophobic polychlorinated biphenyls (PCBs) pollutants are resistant to degradation, and limited methods are available for their elimination, leading to their long-term persistence in ecosystems, which can harm humans and the environment. Therefore, early detection, removal, and continuous monitoring of PCBs are crucial. In this study, a novel fluorescent polymeric probe (P1) to detect PCB congeners (77, 118, and 126) in water was developed. P1 was synthesized by incorporating N,N’-dimethylacrylamide (DMAA) and pyren-1-ylmethyl methacrylate (PyMMA) to form p(DMAA-co-PyMMA). P1 demonstrated high sensitivity toward the most toxic coplanar PCB congeners, 77 and 126, via a fluorescence turn-on mechanism. This sensitivity was attributed to hydrophobic and π–π interactions between the PCBs and PyMMA units of P1. The detection limits for PCB congeners 77 and 126 were determined to be 0.028 and 0.039 mM, respectively. However, PCB 118, a mixed planar congener, exhibited less detection sensitivity than PCB 77 and 126. A porous three-dimensional polymeric organogel (OG) comprising butyl acrylate, PyMMA, and a cross-linker ethylene glycol dimethacrylate was synthesized for practical application. The OG selectively removed PCBs compared to other competing pollutants due to the high hydrophobicity of the PCBs, achieving removal rates of 63 % for PCB 77 and 55 % for PCB 126. The large surface area of the OG facilitated enhanced hydrophobic and π-π interactions between the PCBs and pyrene units. This work emphasizes the efficacy of P1 in detecting PCBs and the potential of using OG in eliminating PCBs, offering a viable method for monitoring and remedying PCB-contaminated environments.

Detection of PCBs and OCPs in the Irtysh River Water (GC-MS/MS) and ecological risk assessment

This study optimized a gas chromatography-tandem triple quadrupole mass spectrometry (GC-MS/MS) method for the determination of 21 persistent organic pollutants (POPs) in Irtysh River water, including 14 organochlorines (OCPs) and 7 polychlorinated biphenyls (PCBs). Factors such as column temperature ramping, selection of qualitative and quantitative ion pairs and collision energy were considered to achieve perfect separation and accurate quantification of all 21 target compounds. The limits of detection (LOD) for PCBs and OCPs ranged from 0.21 to 1.18 ng/L. Applying this method to detect POPs in the Irtysh River revealed concentrations of OCPs ranging from ND to 20.2 ng/L and PCBs from ND to 0.411 ng/L. Source analysis indicated that POPs in the Irtysh River mainly originate from historical industrial and agricultural activities, particularly the deliberate use of pesticides. To ensure ecological safety and human health, expanding the range of target analytes and monitoring periods is necessary. This study provides:•Qualitative and quantitative analysis methods for 7 PCBs and 14 OCPs.•Recoveries achieved ranged between 74.6 to 109 % with RSD less than 15 %.•Analysis of sources, transport pathways, accumulation status, and ecological risks of PCBs and OCPs in the Irtysh River.

Ultra-stable Co3O4/NiCo2O4 double-shelled hollow nanocages as headspace solid-phase microextraction coating for enhanced capture of polychlorinated biphenyls

Polychlorinated biphenyls (PCBs) are persistent toxic pollutants that tend to accumulate in food and cause damage to human health. This work reports the ultra-sensitive detection of PCBs in beverage samples (green tea, honey, and bottled drinking water) by headspace solid-phase microextraction (HS-SPME) coupled with a gas chromatography-flame ionization detector (GC-FID). The Ultra-stable Co3O4/NiCo2O4 double-shelled hollow nanocages (DSHNC) as SPME fiber coating were synthesized with pyrolysis of zeolitic imidazolate framework-67/layered double hydroxide precursor. The fiber coating material Co3O4/NiCo2O4 DSHNC demonstrated excellent thermal stability (＞1000 °C) and long usage lifespan (≥160 times). The extract ability to polar PCBs was significantly enhanced by oxygen-containing groups, π-π stacking, and electrostatic interaction. Experiments results illustrated that the adsorption is controlled by chemical adsorption with a monolayer molecular adsorption. The HS-SPME-GC-FID method possessed good linearity (R2 ≥ 0.9961) in the linear range of 0.10–50000 pg·mL−1 and low detection limits (0.03–1.5 pg·mL−1). The enrichment factors were determined between 6884 and 9765. The method was successfully applied to enrich PCBs in real samples and obtained a good recovery rate in the range of 78.26–112.1 %.

A simultaneous dispersive liquid-liquid microextraction and GC-MS determination of PCBs and PAHs in nature waters

The subject of this study is polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) – super ecotoxicants and widely distributed organic pollutants in natural waters. Their danger lies in acute toxicity, cumulative action, and long-term effects on living organisms. The degree of water ecosystem pollution is assessed based on the levels of indicator compounds, with 16 PAHs and 7 PCBs. Assessing the levels of these super ecotoxicants when they are simultaneously present in natural waters is an urgent task of ecological monitoring in order to obtain reliable information about the pollution level of the water body. The aim of this study is to evaluate the possibility of dispersive liquid-liquid microextraction (DLLME) of PCBs and PAHs and GC-MS determination in natural waters in their simultaneous presence. To achieve the set goal, the peculiarities of simultaneous extraction and determination of PAHs and PCBs from natural waters were studied. The selected range of analyte concentrations was determined based on literature data on environmental monitoring and the maximum allowable concentrations (MAC) of the investigated components in natural waters. The similarity of the applied methods for extraction and detection of PAHs and PCBs allowed for the justification of the approach to selecting a universal sample preparation scheme for simultaneous extraction and GC-MS determination of both classes of analytes. The possibilities of modifications of DLLME extraction of PAHs and PCBs, differing in dispersion method and nature of the extractor, were studied in combination with chromatographic-mass spectrometric determination of the analytes. Simultaneous extraction of super-toxicants was achieved by applying DLLME with a binary dispersant – 500 μl acetone + 500 μl acetonitrile and 150 μl chloroform as the extractor. The chloroform extract after DLLME extraction of the analytes without re-dissolution was used for GC-MS determination of 16 PAHs and 7 PCBs on a specific 60 m long capillary column with a 5% polyarylene + 95% dimethylpolysiloxane stationary phase with gradual heating of the thermostat from 60 to 290°C. Using the selected ion monitoring (SIM) mode increased the reliability of component identification in matrices of natural waters. The possibility of mutual influence of ecotoxicants on their extraction in the presence of each other was studied. Dispersive liquid-liquid microextraction with a binary dispersant provided simultaneous extraction of analytes at a level of 80-97%. The proposed analysis scheme allowed for GC-MS determination of 16 PAHs and 7 PCBs in the presence of each other in natural waters over a wide range of concentrations (0.02-40 μg/L) with an accuracy of 7-18% (PAHs) and 11-18% (PCBs). The relative standard deviations of repeatability and reproducibility for PAHs were in the ranges of 3.1-6.5% and 4.3-7.7%, respectively, and for PCBs 2.8-5.3% and 3.4-6.0%.

Method development for gas chromatography‐tandem mass spectrometry analysis of trace level polycyclicaromatic hydrocarbons, alkyl polycyclicaromatic hydrocarbons, polychlorinated biphenyls, and organochlorinepesticides in pine needle specimen

AbstractPolycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and organochlorine pesticides (OCPs) have been important monitoring targets in the atmosphere due to their deleterious biological effects. Pine needles have been used to monitor atmospheric pollutants. An analytical method was developed to measure 21 PAHs, 14 alkyl PAHs, 7 PCBs, and 23 OCPs in pine needles using ultrasonically assisted extraction and gas chromatography‐tandem mass spectrometry (GC–MS/MS). The ranges of the lower limits of detection of PAHs, PCBs, and OCPs were 0.01–0.05, 0.02–0.06, and 0.01–0.07 μg/kg, respectively. The feasibility of the proposed method was validated by analyzing dust standard reference materials of the samples, which gave satisfactory results with a precision of 0.83%–7.80% (PAHs), 0.93%–4.78% (PCBs), and 0.73%–4.71% (OCPs), and an accuracy of 89.2%–102% (PAHs), 94.6%–109% (PCBs), and 99.4%–102% (OCPs). The PAHs, PCBs, and OCPS were determined from real pine needle samples using the developed method.

Integrating CRISPR-Cas12a with catalytic hairpin assembly as a logic gate biosensing platform for the detection of polychlorinated biphenyls in water samples

Polychlorinated biphenyls (PCBs) are ubiquitous persistent organic pollutants that cause harmful effects on environmental safety and human health. There is an urgent need to develop an intelligent method for PCBs sensing. In this work, we proposed a logic gate biosensing platform for simultaneous detection of multiple PCBs. 2,3′,5,5′-tetrachlorobiphenyl (PCB72) and 3,3′,4,4′-tetrachlorobiphenyl (PCB77) were used as the two inputs to construct biocomputing logic gates. We used 0 and 1 to encode the inputs and outputs. The aptamer was used to recognize the inputs and release the trigger DNA. A catalytic hairpin assembly (CHA) module is designed to convert and amplify each trigger DNA into multiple programmable DNA duplexes, which initiate the trans-cleavage activity of CRISPR/Cas12a for the signal output. The activated Cas12 cleaves the BHQ-Cy5 modified single-stranded DNA (ssDNA) to yield the fluorescence reporting signals. In the YES logic gate, PCB72 was used as the only input to carry out the logic operation. In the OR, AND, and INHIBIT logic gates, PCB72 and PCB77 were used as the two inputs. The output signals can be visualized by the naked eye under UV light transilluminators or quantified by a microplate reader. Our constructed biosensing platform possesses the merits of multiple combinations of inputs, intuitive digital output, and high flexibility and scalability, which holds great promise for the intelligent detection of different PCBs.

Towards miniaturized electrochemical sensors for monitoring of polychlorinated biphenyls.

Pollution of our environment as a result of industrialization and other human activities is a growing concern due to the harmful effects of most chemicals that are released into the environment. Of particular interest are the persistent organic pollutants (POPs) that are reported to be toxic and build up in the environment due to their persistence. Among the POPs are polychlorinated biphenyls (PCBs), which were widely used in the past in various applications ranging from additives in pesticides to dielectric fluids in electrical equipment. As a way of protecting the one health trilogy (environment, human and animal health), their determination in the environment is a paramount call that has seen researchers continue to provide advanced technologies towards achieving this goal. These technologies involve the conventional gold standard gas chromatography systems coupled to sensitive detectors that can detect trace level concentrations. They have come in handy in monitoring of PCBs but their application for routing monitoring may not be sustainable because of the cost of operation associated with them and the need for experts to run the equipment. As a result, there is need for affordable systems that are still able to achieve the required sensitivity for routine monitoring and real-time data acquisition. Sensor systems fit very well in this category since they can be miniaturized for affordability and portray many other desirable features. PCBs as environmentally relevant environmental pollutants have received minimal attention with regards to sensor development and this review highlights the efforts that have been made so far. It provides in-depth discussions on electrochemical sensors and the various modifications that have been employed to date to achieve detection of PCBs at low concentrations as well as the future prospects in remote and routine monitoring.

A Facile and Rapid Strategy for Quantifying PCBs in Cereals Based on Dispersive Solid-Phase Extraction and Gas Chromatography-Mass Spectrometry: A Reference for Safety Concerns in Sustainable Textiles.

Cereals and their derivative products such as starch and cyclodextrin are significant natural materials for sustainable textile processing (e.g., sizing, dispersing, etc.). However, the contamination of cereals with polychlorinated biphenyls (PCBs) is often neglected, which has led to increasing concerns due to the adverse effects on end users. Therefore, monitoring PCBs in cereals is of great importance in preventing health risks. However, high starch, protein, and fat contents make cereals a complicated matrix and can challenge the analysis of PCBs in cereals. This work describes a facile and rapid strategy for quantifying 18 PCBs in cereals that included corn, wheat, and rice through dispersive solid-phase extraction and gas chromatography with mass spectrometry. Importantly, this was the first time that carboxyl-modified, multi-walled carbon nanotubes were incorporated in the detection of PCBs in cereals. The influences of several parameters on the extraction and clean-up efficiency were investigated; these included the type and volume of extraction solvent, sonication time, and the type and dosage of the adsorbent. The matrix effects on quantification were also evaluated. This approach exhibited a better clean-up performance. All the analytes showed weak matrix effects, and thus a solvent standard plot could be prepared for their quantification. Spiking experiments in the selected matrices at three concentration levels from 0.5 to 10 μg/kg resulted in satisfactory recoveries that ranged from 79.2% to 110.5% with relative standard deviations (RSDs; n = 6) less than 10.3%. The limits of detection (LODs) and quantification (LOQs) ranged from 0.04 to 0.1 μg/kg and 0.1 to 0.4 μg/kg, respectively. The practical application of this method was investigated by analyzing actual cereal samples, which demonstrated that the proposed approach was a facile and efficient strategy for PCB determination and provided a reference for the safety evaluation of sustainable textiles. The method also could be generalized to other troublesome samples for testing of multiple PCBs.

A Novel Label-Free Electrochemical Immunosensor Based on a Self-Assembled Monolayer-Modified Electrode for Polychlorinated Biphenyl (PCB) in Environmental Analysis

PCBs (polychlorinated biphenyls) are a very large group of organic compounds that have between two and ten chlorine atoms attached to the biphenyl. These compounds have an acute impact as environmental pollutants, causing cancer and other adverse health effects in humans. It is therefore imperative to develop techniques for the cost-effective detection of PCBs at very low concentrations in ecosystems. In this paper, a novel label-free, indirect, competitive electrochemical immunosensor was first developed with a PCB-BSA conjugate. It is shown herein to compete with free PCBs for binding to the anti-PCB polyclonal primary antibody (IgY). Then, we used a secondary antibody to enhance the sensitivity of the sensor for the detection of PCB in a sample. It has been successfully immobilized on an 11-mercaptoundecanoic acid (11-MUA)-modified gold electrode via a carbodiimide-coupling reaction using cross-linking 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) on the electrode surface. The immunosensor was investigated by cyclic voltammetry and differential pulse voltammetry in a standard solution of [Fe(CN)6]3−/4−. A linear range of 0.011–220 ng/mL−1 and a limit of detection (LOD) of 0.11 ng/mL−1 for PCBs detection were achieved by the developed immunosensor, showing advantages over conventional assays. The novel label-free electrochemical immunosensor discussed in this paper is a solution for simple, rapid, cost-effective sample screening in a portable, disposable format. The proposed immunosensor has good sensitivity, and it can prove to be an adequate real-time monitoring solution for PCBs in soil samples or other samples.

Esterified-sawdust decorated with AgNPs as solid-phase extraction membranes for enrichment and high-sensitivity detection of polychlorinated biphenyls

Polychlorinated biphenyls (PCBs) are a class of persistent organic pollutants, which cause serious harm to human health and ecological environment. Thus, a low-cost membrane was developed for highly effective removal and rapid surface-enhanced Raman scattering (SERS) detection of PCBs by filling esterified-sawdust (CA-SD) modified with silver nanoparticles (AgNPs) into solid phase extraction (SPE) column. SD was first modified by an esterification cross-linking strategy and then AgNPs were anchored on the CA-SD to prepare highly sensitive and reproducible SERS substrates (AgNPs/CA-SD). Due to the contraction of the surface area of the CA-SD caused by drying, the gap between the AgNPs could be reduced, thereby generating a large number of hot spots and driving more target molecules into them to obtain the enhanced SERS signals. The AgNPs/CA-SD-based SPE membrane showed excellent SERS activity with an enhancement factor of 5.98 × 108 for the R6G analysis. The proposed SERS-active SPE membrane with functionalization of mercapto-β-cyclodextrin was further developed for the determination of PCB-77 and PCB-1 with the LODs of 1.43 × 10−9 M and 2.12 × 10−8 M, respectively. In addition, each PCB in the mixed sample could be quickly distinguished based on the characteristic peaks. The current research exhibits great potential for the simultaneous detection of multiple environmental contaminants and can meet the needs of on-site emergency detection.

Visual Test Paper for on-Site Polychlorinated Biphenyls Detection and Its Logic Gate Applications.

A visual detection method was proposed for polychlorinated biphenyls (PCBs) detection using lateral flow test paper as the sensing platform. The aptamer sequence was used to recognize the target 3,3',4,4'-tetrachlorobiphenyl (PCB77). The integration of Zn2+-dependent DNAzyme with toehold-mediated strand displacement reaction significantly improved the response signals. Gold nanoparticles were utilized as the signal tracers in the test paper, making the results visible directly by the naked eye. Under optimal conditions, the paper enables the visual detection of PCB77 as low as 10 pM without additional instrumentation. The assay displays a high selectivity for PCB77 against potential interfering molecules. The visual test paper is robust and has been applied to the detection of PCB77 in milk samples with good recovery and satisfactory accuracy. Using two different PCBs (PCB77 and PCB72) as inputs, we further fabricated OR and AND logic gates, which is conducive to the development of an intelligent detection strategy for PCBs monitoring. Given the attractive characteristics of disposability, low cost, logic operation, and intuitive output, the test paper shows great promise for on-site screening of PCBs in resource-limited areas.

Electrochemical Development of an Immunosensor for Detection Polychlorinated biphenyls (PCBs) for Environmental Analysis

Polychlorinated biphenyls (PCBs) are a highly toxic family of synthetic chemical compounds. PCBs are widely spread in the environment and their toxicity can cause serious ailments to living organisms such as cancer; therefore, developing a device for the detection of PCBs in the environment is significant. In this paper, polyclonal primary anti-PCB antibodies were immobilized onto a gold screen-printed electrode with the purpose of creating an electrochemical immunosensor for the detection of Aroclor 1254. It was modified with 11-mercaptoundecanoic acid (11-MUA) and the activation of the carboxylic acid terminal was performed by cross-linking 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hyrodsuccinmide (NHS) on the electrode surface. Cyclic voltammetry, electrochemical impedance spectroscopy (EIS), linear sweep voltammetry, atomic force microscopy (AFM), scanning electron microscopy (SEM), and contact angle measurement were employed to characterize SAM development on the gold electrode. Using a competitive assay, a 0.09 ng/mL−1 limit of detection and a linear range of 0.101–220 ng/mL−1 were determined. The self-assembled monolayers (SAM) were successful in encapsulating the PCBs on the immunosensor. The electrochemical detection showed better resolution when compared to traditional methods such as the ELISA optical technique. The novel electrochemical immunosensor approach that is discussed in this paper has the potential to offer rapid sample screening in a portable, disposable format and could contribute to the effective control and prevention of PCBs in the environment.

Magnetic solid phase extraction based on Fe3O4@SiO2@CTS nano adsorbent for the sensitive detection of trace polychlorinated biphenyls in environmental water samples

In this study, a magnetic composite material was developed by bonding the modified natural polysaccharide chitosan (CTS) with SiO2 on the surface of magnetic Fe3O4 nanoparticles to detect polychlorinated biphenyls (PCBs). The structural, porosity, and magnetic properties of Fe3O4@SiO2@CTS were characterized by scanning electron microscopy, infrared spectroscopy, X-ray diffraction, nitrogen sorption, and vibrating sample magnetometry. Various experimental parameters affecting the extraction capacity were investigated, including extraction time, desorption time, desorption solvent, solution pH value, and salt ion concentration. Results showed that Fe3O4@SiO2@CTS exhibited excellent selectivity, easy separation by magnet, and reusability (at least 10 cycles). Under optimized experimental condition, this magnetic solid phase extraction material was applied to detect three PCBs with low limits of detection of 0.02–0.15 μg·L−1. The linear correlation coefficient was higher than 0.998, while the recoveries ranged between 90.34% and 106.99% with the relative standard deviation less than 11.31%. The practical application of Fe3O4@SiO2@CTS was verified through quantitative analysis of PCB residues in environmental water, supporting its promising role in simple, convenient, and low-cost detection of PCBs in real environmental samples.

Highly sensitive and selective detection of PCB 77 using an aptamer-catalytic hairpin assembly in an aquatic environment.

Polychlorinated biphenyls (PCBs) are synthetic organic compounds that are extremely difficult to break down in water and can accumulate in human fat and organisms. However, methods that can be used to detect large amounts of PCBs remain unsatisfactory, as they are generally overly sensitive and involve complex operations. An aptamer-based catalytic hairpin assembly (aptamer-CHA) reaction for the selective detection of 3,3′,4,4′-tetrachlorobiphenyl (PCB 77) was developed. It combines the advantages of aptamers and signal amplification reactions. The aptamer selectivity recognizes the target, PCB 77, which triggers the sensitive CHA reaction to produce a fluorescence signal. CHA is a sensitive enzyme-free signal amplification method suitable for on-site detection. Therefore, the identification aptamer is the basis for the quantitative detection of PCB 77, with a detection range of 0.01 μg L−1 to 500 μg L−1 and a detection limit of 0.01 μg L−1. In this study, the aptamer was used to improve the selectivity of the reaction, and the CHA reaction improved the sensitivity of the detection system. Such high-sensitivity PCB detection capabilities with simplified procedures may be useful for real-time field detection and other monitoring tasks. This method can be used as a rapid fluorescence detection strategy for other targets in aquatic environments.

Simultaneous determination of PCBs, OCPs and PAHs in mussel by ultrasound-assisted cloudy extraction and gas chromatography–tandem mass spectrometry

ABSTRACT A method for the simultaneous determination in mussel of 8 polychlorinated biphenyls (PCBs), 23 organochlorine pesticides (OCPs), and 35 polycyclic aromatic hydrocarbons (PAHs), including alkyl-PAHs, was optimised using ultrasound-assisted cloudy extraction and gas chromatography–tandem mass spectrometry (GC-MS/MS). Optimal selection of the extraction solvent and the dispersing solvent contributed to a high extraction yield and a clean extract. The ranges of the lower limits of detection of PCBs, OCPs and PAHs were 0.012–0.058, 0.01–0.29 and 0.01–0.5 μg kg−1, respectively. The feasibility of the proposed method was validated by analysing standard reference materials of mussel with satisfactory results. The precision achieved by this method was in the range of 0.677–2.69% (PCBs), 1.14–6.60% (OCPs) and 0.694–7.46% (PAHs), and its accuracy was in the range of 101–104% (PCBs), 99.6–106% (OCPs) and 101–110% (PAHs). The advantages of the method include the simultaneous measurement of 66 analytes and the simplicity, low cost and high sensitivity of the procedure. When the proposed method was used to analyse the target compounds in 11 mussel samples, the analytical results displayed a concentration range of 0.41–0.45 µg kg−1 for PCBs, 0.26–6.49 µg kg−1 for OCPs, and 3.48–30.69 µg kg−1 for PAHs.

An ultrasensitive platform for PCB77 detection: New strategy for liquid crystal-based aptasensor fabrication

Polychlorinated biphenyls (PCBs) are considered persistent bio-accumulative toxicants which threats global food safety and environmental health. Traditional analytical techniques for detection of PCBs are time-consuming and they do not satisfy urgent need for rapid and accurate monitoring of these persistent pollutants. Biosensor technology may be promising in this respect. Here we demonstrate a novel liquid crystal (LC)-based aptasensing platform as a promising label-free and rapid biosensor for PCB77 detection. This novel molecular strategy utilize triple-helix molecular conformational switch which is mediated formation of duplex on sensing platform in presence of target. Duplex forming leads to optical change from dark to bright in a liquid crystal based aptasensor. The limit of quantification of the LC-aptasensor to PCB77 is 1.5 × 10−5 μg/L with comparable selectivity. Besides, we also demonstrated that this system is able to detect PCB77 in tap water, environmental water and milk. This strategy has potential for label-free and portable detection of different targets without any aptamer sequence length restrictions.

Determination of 32 polychlorinated biphenyls in aquatic products by gas chromatography-high-resolution mass spectrometry with accelerated solvent extraction-purification simultaneously coupled to isotope internal standard method

Gas chromatography (GC)-high-resolution mass spectrometry (HRMS) with accelerated solvent extraction (ASE)-purification simultaneously coupled to the isotope internal standard method is proposed for the determination of 32 polychlorinated biphenyls (PCBs) in aquatic products. Synchronous purification was achieved by adding 2 g of anhydrous sodium sulfate, 1 g of Cleanert Florisil, and 50 g of neutral alumina as the adsorbent to the ASE system. The PCBs were extracted from aquatic product samples using a dichloromethane-n-hexane (1:1, v/v) mixture at 100 ℃ with two extraction cycles. The extracting solution was purified twice with 0.5 mL concentrated sulfuric acid. After concentration to a constant volume, the target compounds were detected by GC-HRMS and quantified by the isotope internal standard method. Under the optimized conditions, the relative standard deviations (RSDs) of the mean relative response factor (RRF) for the 32 PCBs in the range of 0.1-20 μg/L were less than 15%. The limits of quantification were 0.3-1.9 ng/kg. At three spiked levels (5, 20, and 50 ng/kg) in grass carp and sea bass, the recoveries of the 32 PCBs were between 71.9% and 119.0%, with the RSDs varying from 3.5% to 19.6%. This method effectively reduces the matrix interference and shows high sensitivity, good reproducibility, and stable recovery, thus proving useful for the detection of PCBs in aquatic products.

Magnetic stir bars with hyperbranched aptamer as coating for selective, effective headspace extraction of trace polychlorinated biphenyls in soils

It is challenging to greatly increase of the extraction selectivity and efficiency by stir bar sorptive extraction of ultra-trace polychlorinated biphenyls (PCBs) in complex environmental matrix, e.g., soils. To fulfill this purpose, one of the critical works is to prepare some coatings with high selectivity, adsorptive capacity and reusability. It is also important to develop some green, simple methods for preperation the coatings. In this work, a kind of highly efficient and bioactive coating based on hyperbranched aptamer (HB-Apt) was constructed via hybridization chain reaction (HCR). Then, the HB-Apt was coated on a magnetic stir bar and applied to headspace extraction of PCB72 and PCB106 in soils. The core-shell gold magnetic particles (Fe3O4@AuNPs, AuMNPs for short) was employed as the substrate to immobilize the HB-Apt. The extracted PCBs on the stir bar could be easily eluted in ethanol by stirring, and then sampled in gas chromatography-mass spectrometry (GC-MS) for qualification. The ultra-low detection limit (0.003–0.005 ng•g−1), good linearity (0.01–500 ng•g−1, R2≥0.994) and reproducibility (RSD: 4.58–6.53%) were obtained. Compared with the common aptamer coating, the HB-Apt coating exhibited good selectivity and higher extraction capacity. The results might be related to the fact that there are more aptamer fragments grated on the HB-Apt coating than those of the common aptamer coating. The magnetic stir bar can not only be employed for easy headspace extraction, but also facilitate separation and elution. Moreover, the coating could be recycled for at least 60 times before recoveries of the PCB72 and PCB106 in the spiked samples drop below 90%. All these indicated that the assay is simple, robust, environment friendly and promising for detection of trace PCBs in complex environmental samples.

Polychlorinated biphenyl detection in organic solvents with paper-based analytical devices

ABSTRACT Sample pretreatment process is usually performed before real sample detection. Extraction is one of the most prevalent pretreatment methods. Due to the unequal solubility in two liquid phases, target is extracted (usually from water to organic phase) and further detected with laboratory instruments. Although the analytical instruments have high sensitivity and selectivity, they are relatively expensive and require skilful hands, which is restricted to laboratory use. Here, paper-based analytical devices (μPADs) for measuring samples extracted with organic solvents were tested. The μPADs were employed as a filter for buffer exchange, allowing the transfer of targets from organic solvent to water-based buffer, which could be specifically detected by water-based assays. As an example, polychlorinated biphenyls (PCBs) in n-hexane were detected with aptamer and gold nanoparticles (AuNPs) on μPADs within 30 min. The result of colour change can be recognized from 70.0 ng/L with a low loading amount (0.5 μL). Instead of laboratory instrumental analysis with relative high cost, this assay showed the promising utility of μPADs for target detection after sample pretreatment, which could be utilized as a general platform for inexpensive onsite detection.

Label-free and highly selective electrochemical aptasensor for detection of PCBs based on nickel hexacyanoferrate nanoparticles/reduced graphene oxides hybrids

In consideration of the urgent need to determine polychlorinated biphenyls (PCBs) in the environment, a label-free and highly selective electrochemical aptasensor was constructed for determining PCBs based on nickel hexacyanoferrate nanoparticles (NiHCF NPs)/reduced graphene oxides (rGO) hybrids. NiHCF NPs/rGO hybrids with small size of about 5 nm NiHCF NPs were synthesized for the first time by in situ co-deposition of NiHCF NPs on rGO surface. In the hybrids, rGO with large area and good conductivity can supply more space for loading NiHCF NPs and improve the conductivity of the hybrids. NiHCF NPs that can be used to be act as a signal probe exhibit a couple of well-defined peaks with highly reversible redox ability and good stability. Here, PCB77 as a model molecule, the anti-PCB77 aptamer was anchored on the NiHCF NPs/rGO hybrids by covalent bonding reaction. The design aptasensor for detecting PCB77 exhibits a favorable linear response from 1.0 to 100.0 ng/L with a low detection limit of 0.22 ng/L. Meanwhile, it displays good selectivity for PCB77 detection due to the specificity and high affinity of aptamer to PCB77. Additionally, the application of the aptasensor was evaluated in real environmental samples.