Detection Of Polycyclic Aromatic Hydrocarbons Research Articles

MOF-derived porous carbon microspheres Ni@C-acid as solid-phase microextraction coating for extraction of polycyclic aromatic hydrocarbons from tea infusions

The improvement of the stability and adsorption properties of materials on targets in sample pre-treatment has long been an objective. Extensive efforts have been made to achieve this goal. In this work, metal-organic framework Ni-MOF precursors were first synthesized by solvothermal method using polyvinylpyrrolidone (PVP) as an ideal templating agent, stabiliser and nanoparticle dispersant. After carbonization and acid washing, the nanoporous carbon microspheres material (Ni@C-acid) was obtained. Compared with the material without acid treatment (Ni@C), the specific surface area, pore volume, adsorption performance of Ni@C-acid were increased. Thanks to its excellent characteristics (high stability, abundant benzene rings), Ni@C-acid was used as fiber coatings in headspace solid-phase microextraction (HS-SPME) technology for extraction and preconcentration of polycyclic aromatic hydrocarbons (PAHs) prior to gas chromatography-flame ionization detector (GC-FID) analysis. The experimental parameters of extraction temperature, extraction time, agitation speed, desorption temperature, desorption time and sodium chloride (NaCl) concentration were studied. Under optimal experimental conditions, the wide linear range (0.01-30 ng mL−1), the good correlation coefficient (0.9916-0.9984), the low detection limit (0.003-0.011 ng mL−1), and the high enrichment factor (5273-13793) were obtained. The established method was successfully used for the detection of trace PAHs in actual tea infusions samples and satisfied recoveries ranging from 80.94-118.62 % were achieved. The present work provides a simple method for the preparation of highly stable and adsorbable porous carbon microsphere materials with potential applications in the extraction of environmental pollutants.

Correction of the Effect of Humic Acids on the Fluorescence Detection of Polycyclic Aromatic Hydrocarbons by Combination Spectroscopy.

Polycyclic aromatic hydrocarbons (PAHs) are widely distributed in soil and water, but fluorescence spectroscopy for PAHs is often interfered with organic matter in the environment. The aim of this paper is to evaluate a correction method using combined spectral technology in an environment where humic acids and PAHs coexist. In the present work, humic acids and benzo[ghi]perylene were analyzed in various concentrations using fluorescence and near-infrared (NIR) spectroscopy from single and mixed samples. The NIR prediction model of humic acids in mixed samples was established based on synergy interval partial least squares, and the standard curve of fluorescence spectra for humic acids was established at 478 nm (characteristic wavelength of benzo[ghi]perylene). The fluorescence intensity of humic acids in the mixed sample was predicted from the content derived from the NIR spectra. The final correction was carried out by their exclusion from the fluorescence of the mixture at the same wavelength. The corrected fluorescence intensity was linearly correlated with the concentration of benzo[ghi]perylene with R2 = 0.8362, while R2 = 0.3538 before correction. These results give a new insight into the calibration modeling of the combined spectral method.

Trace Determination of Phenanthrene and Fluorene in Beverages Using D-μ-SPE and Liquid Chromatography Analysis

Dispersive micro solid phase extraction (D-μ-SPE) method using Graphene Oxide (GO) for the extraction and pre-concentration of selected polycyclic aromatic hydrocarbons (PAHs) from beverage samples prior to high-performance liquid chromatography - diode array detector (HPLC - DAD) is reported. Selected PAHs Fluorene (FLU) and Phenanthrene (PHE) were used as targeted analytes. An experimental design using Response Surface Methodology (RSM) and Box–Box–Behnken design (BBD) was performed to evaluate the interactive effects of three significant parameters: mass of sorbent, sample volume and extraction time. Under the optimum conditions, the method revealed good linearity (R2 = 0.9995 – 0.9998) over a concentration range of 0.5 – 5.0 mg L-1. The limit of detection (LOD) was in the range of 0.03 – 0.24 mg L-1 with satisfactory relative recoveries (81 – 99 %) and good relative standard deviation (RSD) of ≤ 3.80 % (n = 3). The method was successfully applied to tea, coffee, and milk samples and proved to be a simple, rapid, and reliable method with good extraction efficiencies for the detection of PAHs in beverage samples.

A durable hydrophobicity hydrazone covalent organic framework coating for solid phase microextraction of polycyclic aromatic hydrocarbons in food and environmental sample

In this study, a durable hydrophobicity hydrazone covalent organic framework (BTCH-PTA-COF) has been developed as fiber coating, which was applied to solid-phase microextraction (SPME) of polycyclic aromatic hydrocarbons (PAHs). The hydrophobic and π-π packing interactions between BTCH-PTA-COF and PAHs were confirmed by contact angle experiments and Van der Waals surface electrostatic potential analysis. Further, large specific surface area, good chemical and thermal stability have positive promoting effect on extraction. The method of wide linearity (0.25–300 µg·L−1), low detection limits (0.03–0.05 µg·L−1) and high enrichment factors (767–1411) for the detection of PAHs is explored, coupling BTCH-PTA-COF based SPME with gas chromatography with hydrogen flame detector (GC-FID). The relative standard deviations (RSDs) for inter-day and intra-day extractions of PAHs are ranging from 4.1 % to 9.6 % and 2.9 % to 6.4 %, respectively. The method successfully detected and quantified trace PAHs in tea beverages and river water samples with recoveries from 88.5 % to 104.8 %. The BTCH-PTA-COF coated fiber is ultra-stable in recycled extraction and reused at least 120 times, which could surpass published and commercial SPME fiber.

An ultra-stable and sensitive Ag-HP-β-CD/GO/NCF SERS substrate combine with the coffee-ring effect strategy for trace PAHs detection

This study proposes an ultra-stable and highly sensitive SERS substrate based on Ag nanoparticles/graphene oxide nanosheets hybrids decorated nanocellulose fiber (Ag/GO/NCF), which was further functionalized with hydroxypropyl-β-cyclodextrin (Ag-HP-β-CD/GO/NCF) for the trace detection of polycyclic aromatic hydrocarbons (PAHs). The Ag/GO hybrid structure enables the substrate to exhibit high SERS activity through the synergistic effect of electromagnetic and chemical enhancement. Simultaneously, the three-dimensional skeleton structure of NCF serves as a support matrix, ensuring the exceptional stability of the substrate. Furthermore, this study introduces a SERS measurement strategy utilizing the coffee-ring effect and explores parameters optimization to further enhance the detection sensitivity while maintaining the homogeneity and reproducibility. With the affinity effect of HP-β-CD and the enrichment effect of the delocalized π-electron system in GO, the hydrophobic PAHs could easily approach the SERS hotspots and achieve their trace detection. The limit of detection (LOD) for four representative PAHs, including pyrene, fluoranthene, phenanthrene and fluorene, are found to be 3.32 ug/L, 3.65 ug/L, 40.97 ug/L and 56.24 ug/L, respectively. These results highlight the potential application of this highly efficient SERS platform in environmental monitoring.

Hierarchical metal-dielectric-metal nanostructures as SERS sensors for sensitive detection of polycyclic aromatic hydrocarbons

Due to the wide variety, inaccessible self-degradation, high mutagenicity and carcinogenicity of polycyclic aromatic hydrocarbons (PAHs), it still remains challenging to efficiently identify them, especially in real environment. Herein, we develop a bottom-up self-assembly strategy to construct a sandwich-like hierarchical metal-dielectric-metal system composed of mercaptan-modified Au nanospheres-graphene oxide (GO)-Ag nanowires as surface-enhanced Raman spectroscopy (SERS) sensors for sensitive detection of PAHs. The synergistic integration of metallic layers and the organic mercaptan and GO layer not only provides localized enhanced electromagnetic field region which is induced by the nanogap between the top Au nanospheres and the bottom Ag nanowires, but also effectively traps PAHs in the middle layer through hydrophobic interaction of mercaptan and π-π stacking interaction of GO. By rationally optimizing the SERS substrates, the lowest detection concentrations of pyrene, anthracene, phenanthrene and benzo[a]pyrene could be reached, respectively, at 10−8 M, 10−8 M, 10−8 M and 10−7 M. The hierarchical system shows excellent uniformity, reproducibility and is able to identify various types of PAHs in multi-component mixtures as well as in real water environment. This strategy can provide a general platform to identify hazardous pollutants that are hydrophobic or contain benzene rings, such as pesticides, dyes and polychlorinated biphenyls.

Detection of polycyclic aromatic hydrocarbons on a sample of comets

Detection of polycyclic aromatic hydrocarbons on a sample of comets

A novel exfoliated graphite-based device for passive sampling and detection of polycyclic aromatic hydrocarbons in air

Water scarcity is a major problem in the Sub-Saharan Africa, as such rainwater harvesting is considered as an alternative source of water. However, air pollution may affect the quality of taken rainwater. Specifically, particle-bound polycyclic aromatic hydrocarbons (PAHs) a class of persistent organic pollutants (POPs) known to have toxic effects on human beings and environmental sectors. In this study, a novel electrode material called exfoliated graphite (EG) was synthesized and used as sorbent material in fabrication of passive sampler and electrode device for the monitoring of polycyclic aromatic hydrocarbons (PAHs) in air. The surface morphology, structure, surface functionality of the materials were investigated using, Scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR) techniques. A sorption kinetic’s evaluation of EG was conducted. It was found that EG has shown an outstanding affinity towards detection of PAHs with maximum partition coefficients. Moreover, EG electrode-based device was developed and utilized for detection of PAHs in air through electrochemical technique. This was conducted by exposing the sampler to PAHs gases for 12 days, thereafter it was transferred to a blank supporting electrolyte and analyzed using differential pulse voltammetry (DPV). The EG-based tubular sampler was calibrated in a laboratory flow-through exposure experiment. Furthermore, the effects of time and pollutants concentration were examined under controlled experimental conditions. Most importantly, extraction of the sampler was performed, followed by determination of PAHs using gas chromatography-mass spectrometer (GC–MS). As the result, uptake of PAHs onto the EG tubular based sampler was observed with linear uptake throughout the exposure time. Interestingly, an increasing of uptake by PAHs was indicated when the concentration of the pollutant was increased. These results imply that EG showed a great potential and preferable candidate for monitoring of PAHs in air.

Green preparation of magnetic pyrene-based hyper-cross-linked polymer using dual-purpose ferric chloride reagent for extraction of polycyclic aromatic hydrocarbons from natural water bodies

A magnetic hyper-cross-linked polymer Fe3O4/HCPPYR was prepared using pyrene as the monomer and formaldehyde dimethyl acetal (FDA) as the cross-linking agent. The objective of green chemistry was achieved by employing FeCl3 during the synthesis, as it played a dual role of a catalyst for the Friedel-Crafts reaction and an iron source for the synthesis of magnetic Fe3O4, thus maximizing efficiency and minimizing waste. Fe3O4/HCPPYR was applied as a sorbent for magnetic solid-phase extraction (MSPE) to extract fifteen polycyclic aromatic hydrocarbons (PAHs) from water. The effects of different parameters such as the quantity of adsorbent, the extraction time, the desorption conditions, the pH value and the effect of the salt concentration on the extraction efficiency were optimized. A simple and efficient method in combination with gas chromatography-mass spectrometry (GC–MS) (Fe3O4/HCPPYR−MSPE/GC–MS) was developed and successfully applied for the detection of PAHs in environmental water samples The analytical method showed LODs in the range of 0.004−0.06 µg L−1, which proved to be adequate for the detection all 15 PAHs at trace concentration. Spiked recoveries of PAHs in actual water samples ranged from 85.2 % to 118.5 % with relative standard deviations (RSDs) below 10.2%. These results indicate that the method has a good potential for reusability and possesses excellent sensitivity. This study showcased the potential of Fe3O4/HCPPYR composites in effectively removing organic pollutants from the aqueous environments, demonstrating their ability for water treatment applications.

Determination of Polycyclic Aromatic Hydrocarbons (PAHs) and Phthalates in Human Placenta by Mixed Hexane/Ether Extraction and Gas Chromatography-Mass Spectrometry/Mass Spectrometry (GC-MS/MS).

In this study, we evaluated the extraction effect of three different extractants, namely hexane + ether (v/v = 3:1), acetonitrile and ethyl acetate, on polycyclic aromatic hydrocarbons (PAHs) and phthalic acid esters (PAEs) in placenta detected and analysed by triple quadrupole gas chromatography-mass spectrometry (GC-MS/MS). The results showed that n-hexane + ether (v/v = 3:1) had the highest extraction efficiency. Under the optimal conditions, the limits of detection (LOD) for the 10 PAHs were 0.003-0.0167 μg/L with relative standard deviations (RSD) of 1.4-5.48% and detection rates of 68.19-107.05%, and the correlation coefficients were (R2, 0.9982-0.9999). The LODs for the nine PAEs were 0.0015-3.5714 μg/L and the correlation coefficients were (R2, 0.9982-0.9999). The limits of detection (S/N = 3) for the nine PAHs were 0.0015-0.5714 μg/L with relative standard deviations (RSD) of 3.15-8.37%, and the detection rates were 80.45-112.59% with correlations of (R2, 0.9972-0.9998). The method was applied to the analysis of PAHs and phthalates in placenta samples from pregnant women. The method's accuracy and applicability were demonstrated. In comparison with other methods for the detection of PAEs and PAHs, the method proposed in this paper has a wider linear range, lower minimum detection limit and comparable recovery with good correlation. This paper is dedicated to providing another method for improving the performance of extracting solid tissues.

Quantification of polycyclic aromatic hydrocarbons in roasted Tan lamb using fluorescence hyperspectral imaging technology

Polycyclic aromatic hydrocarbons (PAHs) are one of the main harmful substances produced during the roasting of lamb. In this study, fluorescence hyperspectral imaging (FHSI) at different excitation wavelengths was used for the rapid determination of total PAHs (T-PAHs) content in roasted Tan lamb. Heterogeneous two-dimensional correlation spectroscopy (H2D-COS) was performed to resolve the fluorescence hyperspectral peaks. Competitive adaptive reweighed sampling (CARS), uninformative variable elimination (UVE), variable combination population analysis (VCPA), iterative retained information variable (IRIV) and interval variable iterative spatial shrinkage analysis (iVISSA) methods were employed to extract effective wavelengths to reduce data dimensionality. Partial least squares regression (PLSR), least squares support vector machine (LS-SVM) and convolutional neural network (CNN) algorithms were used to develop the T-PAHs content prediction model. For the FHSI at 357 nm excitation wavelength, the Smoothing-CARS-PLSR quantitative prediction model worked the best, with RC2 and RP2 reaching 0.9011 and 0.9169, and RMSEC and RMSEP reaching 0.0179 mg/kg and 0.0181 mg/kg, respectively. For the FHSI at 452 nm excitation wavelength, Smoothing-VCPA-CNN showed the best results, with RC2 and RP2 of 0.9199 and 0.9189, and RMSEC and RMSEP reaching 0.0175 mg/kg and 0.0171 mg/kg, respectively. This study provided a reference for the quantitative detection of PAHs.

Preparation of Novel Solid Phase Extraction Sorbents for Polycyclic Aromatic Hydrocarbons (PAHs) in Aqueous Media.

In this study, functionalized mesoporous silica was prepared and characterized as a stationary phase using various analytical and solid-state techniques, including a Fourier-transform infrared (FTIR) spectrometer, thermogravimetric analysis, and nitrogen sorption. The results confirmed the successful synthesis of the hybrid stationary phase. The potential of the prepared hybrid mesoporous silica as a solid-phase extraction (SPE) stationary phase for separating and enriching polycyclic aromatic hydrocarbons (PAHs) in both spiked water samples and real water samples was evaluated. The analysis involved extracting the PAHs from the water samples using solid-phase extraction and analyzing the extracts using a two-dimensional gas chromatograph coupled to a time-of-flight mass spectrometer (GC × GC-TOFMS). The synthesized sorbent exhibited outstanding performance in extracting PAHs from both spiked water samples and real water samples. In the spiked water samples, the recoveries of the PAHs ranged from 79.87% to 95.67%, with relative standard deviations (RSDs) ranging from 1.85% to 8.83%. The limits of detection (LOD) for the PAHs were in the range of 0.03 µg/L to 0.04 µg/L, while the limits of quantification (LOQ) ranged from 0.05 µg/L to 3.14 µg/L. Furthermore, all the calibration curves showed linearity, with correlation coefficients (r) above 0.98. Additionally, the results from real water samples indicated that the levels of individual PAH detected ranged from 0.57 to 12.31 µg/L with a total of 44.67 µg/L. These findings demonstrate the effectiveness of the hybrid mesoporous silica as a promising stationary phase for solid-phase extraction and sensitive detection of PAHs in water samples.

SERS with Flexible β-CD@AuNP/PTFE Substrates for In Situ Detection and Identification of PAH Residues on Fruit and Vegetable Surfaces Combined with Lightweight Network.

The detection of polycyclic aromatic hydrocarbons (PAHs) on fruit and vegetable surfaces is important for protecting human health and ensuring food safety. In this study, a method for the in situ detection and identification of PAH residues on fruit and vegetable surfaces was developed using surface-enhanced Raman spectroscopy (SERS) based on a flexible substrate and lightweight deep learning network. The flexible SERS substrate was fabricated by assembling β-cyclodextrin-modified gold nanoparticles (β-CD@AuNPs) on polytetrafluoroethylene (PTFE) film coated with perfluorinated liquid (β-CD@AuNP/PTFE). The concentrations of benzo(a)pyrene (BaP), naphthalene (Nap), and pyrene (Pyr) residues on fruit and vegetable surfaces could be detected at 0.25, 0.5, and 0.25 μg/cm2, respectively, and all the relative standard deviations (RSD) were less than 10%, indicating that the β-CD@AuNP/PTFE exhibited high sensitivity and stability. The lightweight network was then used to construct a classification model for identifying various PAH residues. ShuffleNet obtained the best results with accuracies of 100%, 96.61%, and 97.63% for the training, validation, and prediction datasets, respectively. The proposed method realised the in situ detection and identification of various PAH residues on fruit and vegetables with simplicity, celerity, and sensitivity, demonstrating great potential for the rapid, nondestructive analysis of surface contaminant residues in the food-safety field.

Metal-Organic Framework ZIF-67@NiCo-LDHs for Extraction of Polycyclic Aromatic Hydrocarbons of Water Sample

In this study, solid-phase microextraction (SPME) fiber adsorbents were coated with the metal-organic framework ZIF-67 and protected by layered double hydroxides (LDH) nanotubes. The findings unequivocally show that the extraction selectivity is dependent on the surface element composition of coatings produced from ZIF-67. The ZIF-67@NiCo-LDHs coating was chosen for the enrichment and detection of polycyclic aromatic hydrocarbons (PAH) in water samples due to its long-term stability and superior extraction selectivity. The calibration curves were dynamically linear and ranged from 0.00 to 100 g L−1 at the optimum circumstances, with correlation values (R 2) above 0.996–0.999. LOD values ranged from 0.07 to 0.5 ng L−1. Under ideal circumstances, the test compounds’’ repeatability for one fiber (n = 3), expressed as relative standard deviation (RSD%), ranged between 7.5 and 9.2%. Additionally, the synthetic fiber displayed 40 cycles of extraction and desorption and perfectly controlled development.

Recent trends in polycyclic aromatic hydrocarbons pollution distribution and counteracting bio-remediation strategies

Polycyclic aromatic hydrocarbons (PAHs) are distributed worldwide due to long-term anthropogenic pollution sources. PAHs are recalcitrant and highly persistent in the environment due to their inherent properties, such as heterocyclic aromatic ring structures, thermostability, and hydrophobicity. They are highly toxic, carcinogenic, immunotoxic, teratogenic, and mutagenic to various life systems. This review focuses on the unique data of PAH sources, exposure routes, detection techniques, and harmful effects on the environment and human health. This review provides a comprehensive and systematic compilation of eco-friendly biological treatment solutions for PAH remediation, such as microbial remediation approaches utilizing microbial cultures. In situ and Ex situ bioremediation of PAH methods, including composting land farming, biopiles, bioreactors bioaugmentation, and phytoremediation processes, are discussed in detail, as is a summary of the factors affecting and limiting PAH bioremediation. This review provides an overview of emerging technologies that use multi-process combinatorial treatment approaches and answers to generating value-added by-products during PAH remediation.

Rapid and Sensitive Detection of Polycyclic Aromatic Hydrocarbons in Tea Leaves Using Magnetic Approach.

A rapid and efficient method using an alkyl-functionalized magnetic nanoparticles-based extraction technique combined with Ultra-High Performance Liquid Chromatography was developed for the detection of trace amounts of polycyclic aromatic hydrocarbons in tea leaves. As a popular coating for chromatographic column packing materials, C18-alkyl has been demonstrated to be effective in separating polycyclic aromatic hydrocarbons. Additionally, the magnetism of the nanomaterials accelerates the extraction process while their high surface ratio enables desirable dispersity in the sample matrix. Meanwhile, the adsorbents can be washed and reused 30 times without compromising recovery, which greatly reduces the budget. The effects of various parameters were investigated and optimized, and the recoveries for five analytes were in the range of 84.8-105.4%. The RSD of intra-day and inter-day were below 11.9% and 6.8%, respectively. The limits of detection and limits of quantification ranged from 1.69-9.97 ng g-1 and 5.12-30.21 ng g-1, indicating satisfactory sensitivity. Thus, the proposed methodology is rapid, highly efficient, and economical, and it expands the application of magnetic cleanup approaches in complex food matrices.

In situ growth of porous organic framework on iron wire for microextraction of polycyclic aromatic hydrocarbons

In this work, a novel spherical metal organic framework (MOF) was first in situ grown on the surface of iron wire (IW), in which IW served as the substrate and metal source for MOF (type NH2-MIL88) growth without adding additional metal salts in the process, while spherical NH2-MIL88 provided more active sites for further construction of multifunctional composites. Subsequently, a covalent organic framework (COF) was covalently bonded to the surface of the NH2-MIL88 to obtain the IW@NH2-MIL88@COF fibers, which were used for headspace solid-phase microextraction (HS-SPME) of polycyclic aromatic hydrocarbons (PAHs) in milk samples prior to determination by gas chromatography-flame ionization detection (GC-FID). Compared with the fiber prepared by physical coating, the IW@NH2-MIL88@COF fiber prepared by in situ growth and covalent bonding exhibits better stability and possesses more uniform layer. The extraction mechanism of the IW@NH2-MIL88@COF fiber for PAHs was discussed, which mainly owed to π-π interactions and hydrophobic interactions. After optimization of the primary extraction conditions, the SPME-GC-FID method was established for five PAHs with a wide linear range (1–200 ng mL−1), good linearity coefficient (0.9935–0.9987) and low detection limits (0.017–0.028 ng mL−1). The relative recoveries for PAHs detection in milk samples ranged from 64.69 to 113.97%. This work not only provides new ideas for the in situ growth of other types of MOF, but also provides new methods for the construction of multifunctional composites.

Determination of polycyclic aromatic hydrocarbons in Chinese herbal medicines by gas chromatography-mass spectrometry with graphene-functionalized nickel foam

Graphene-functionalized nickel foam (NF) sorbent materials were prepared and characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Thermogravimetric analysis. For the separation and detection of polycyclic aromatic hydrocarbons (PAHs) in five Chinese medicine samples, namely dandelion, fructus aurantii, peppermint, mulberry leaf and embryo chrysanthemum, a method combining dispersive micro-solid phase extraction and gas chromatography-mass spectrometry (GC–MS) was developed. Four conditions affecting the extraction efficiency, such as the type of desorption solvent, the amount of sorbent, the extraction time and the volume of water sample, were optimized. The results of the methodological validation showed that NF@SiO2@G was able to adsorb PAHs well and with good reproducibility. All analytes showed good linearity in the concentration range of 20–2000 ng/mL with coefficient of determination R2≥0.9956. The limit of detection was 0.98–13.34 ng/mL, and the limit of quantification ranged from 3.25 to 44.47 ng/mL. Both the intra-day and inter-day precision were lower than 15.46%, and the spiked recoveries were in the range of 75.5–118.4%. The total contents of the 16 PAHs contained in these five Chinese herbal medicines (CHMs) were varied from 450 to 1557 µg/kg. The results indicated that the graphene-functionalized NF sorbent combined with GC–MS can effectively detect PAHs in CHMs.

An electrochemically fabricated ZIF-67/[HOEMIM]BF4 coating for the solid-phase microextraction and detection of polycyclic aromatic hydrocarbons.

Coatings are considered to play a crucial role in solid-phase microextraction (SPME). In this work, a novel coating named ZIF-67/[HOEMIM]BF4 was fabricated through in situ potentiostatic electrodeposition in methanol solutions containing ZIF-67 precursors and 1-(2'-hydroxyethyl)-3-methylimidazolium tetrafluoroborate ([HOEMIM]BF4). Compared with the traditional solvothermal method, this method reduced the synthesis time and enabled ZIF-67 to grow directly on the surface of stainless-steel wire, effectively simplifying the preparation process and improving the coating reproducibility. Owing to the inherent characteristics such as high porosity and high thermal and mechanical stability, and the impressive morphological regulation and extraction function of [HOEMIM]BF4, the developed coating exhibited a prolonged service life and a better extraction capacity for trace polycyclic aromatic hydrocarbons (PAHs) compared to single ZIF-67 and commercial fibers. Under the optimal conditions, the linear range of the ZIF-67/[HOEMIM]BF4-based SPME-GC method was 0.01-500 μg L-1, and the detection limit was 0.27-5.2 ng L-1. When applied in the determination of PAHs in a real water sample, recoveries between 85.6-117.3% were obtained, indicating the potential of ZIF-67/[HOEMIM]BF4 in the high efficiency SPME and GC analysis of PAHs.

Multiplex SERS detection of polycyclic aromatic hydrocarbon (PAH) pollutants in water samples using gold nanostars and machine learning analysis.

Polycyclic aromatic hydrocarbons (PAHs) have attracted a lot of environmental concern because of their carcinogenic and mutagenic properties, and the fact they can easily contaminate natural resources such as drinking water and river water. This study presents a simple and sensitive point-of-care SERS detection of PAHs combined with machine learning algorithms to predict the PAH content more precisely and accurately in real-life samples such as drinking water and river water. We first synthesized multibranched sharp-spiked surfactant-free gold nanostars (GNSs) that can generate strong surface-enhanced Raman scattering (SERS) signals, which were further coated with cetyltrimethylammonium bromide (CTAB) for long-term stability of the GNSs as well as to trap PAHs. We utilized CTAB-capped GNSs for solution-based 'mix and detect' SERS sensing of various PAHs including pyrene (PY), nitro-pyrene (NP), anthracene (ANT), benzo[a]pyrene (BAP), and triphenylene (TP) spiked in drinking water and river water using a portable Raman module. Very low limits of detection (LOD) were achieved in the nanomolar range for the PAHs investigated. More importantly, the detected SERS signal was reproducible for over 90 days after synthesis. Furthermore, we analyzed the SERS data using artificial intelligence (AI) with machine learning algorithms based on the convolutional neural network (CNN) model in order to discriminate the PAHs in samples more precisely and accurately. Using a CNN classification model, we achieved a high prediction accuracy of 90% in the nanomolar detection range and an f1 score (harmonic mean of precision and recall) of 94%, and using a CNN regression model, achieved an RMSEconc = 1.07 × 10-1 μM. Overall, our SERS platform can be effectively and efficiently used for the accurate detection of PAHs in real-life samples, thus opening up a new, sensitive, selective, and practical approach for point-of-need SERS diagnosis of small molecules in complex practical environments.