To simultaneously enrich,separate,and determine five fluoroquinolone antibiotics(FQs)in marine crude drugs(MCDs),seawater and seafood,we conducted this study using vortex assisted dispersed liquid-liquid microextracti...To simultaneously enrich,separate,and determine five fluoroquinolone antibiotics(FQs)in marine crude drugs(MCDs),seawater and seafood,we conducted this study using vortex assisted dispersed liquid-liquid microextraction(DLLME),followed by capillary electrophoresis(CE)-UV.A single-variable optimization was employed to examine the factors influencing the separation effect of CE and the extraction efficiency of DLLME,including buffer solution,organic solvent,separation voltage,extractant,dispersant,and sample solution pH.Under the optimal conditions,the baseline separation of the five FQs was achieved within 6 min.The analytical performance of the method was assessed using six types of actual samples,including three MCDs of hippocampus,clam,and kelp,seawater,and two seafood of prawn and pomfret,demonstrating good linearity ranging from 0.1-5 or 0.01-5μg/mL.The limits of detection(LODs)and limits of quantification(LOQs)for the five FQs in MCDs were 0.0022-0.0292 and 0.0066-0.0973μg/mL,respectively.The LODs and LOQs in seawater and seafood were 0.0009-0.0262 and 0.0029-0.0874μg/mL,respectively.The matrix effects of this method were evaluated in the hippocampus,seawater,and prawn,and the results show that DLLME could effectively eliminate matrix interference.Satisfactory recovery rates were achieved in all the six tested actual samples.This developed DLLME-CE method was proven simple to operate,accurate and reliable,with high sensitivity,making it suitable for the analysis of multiple antibiotic residues in complex matrices.展开更多
A simple and sensitive analytical procedure for the determination of multi-component compounds in water samples was developed and optimized using the headspace solid-phase microextraction(HSSPME) coupled with gas chro...A simple and sensitive analytical procedure for the determination of multi-component compounds in water samples was developed and optimized using the headspace solid-phase microextraction(HSSPME) coupled with gas chromatography-mass spectrometry(GC-MS). Ten off-flavor compounds, including geosmin(GSM), 2-methylisoborneol(2-MIB), 2-isopropyl-3-methoxypyrazine(IPMP), 2-isobutyl-3-methoxypyrazine(IBMP), β-ionone, trans-2,cis-6-nonadienal(NDE), 2,3,4-trichloroanisole(2,3,4-TCA), 2,3,6-trichroloanisole(2,3,6-TCA), 2,4,6-trichloroanisole(2,4,6-TCA), and 2,4,6-tribromoanisole(2,4,6-TBA) were used as the target analytes. The optimization of extraction parameters including fibers types, extraction time, extraction temperature, stirring rate, sample volume, and ionic strength was carried out through the univariate approach. Ten off-flavor compounds were quantified within 50 min under the optimal conditions. Calibration curves with good linearity(r^2=0.990-0.998) were obtained in the range 1.0/2.0-100 ng/L, while the limits of detection for all compounds were lower than or close to the odor threshold concentration. Furthermore, the proposed method was applied to analyzing and determining the off-flavor compounds in real water samples from water-treatment plants.展开更多
A fast and simple method for determination of α, β, γ-hexachlorocyclohexanes (HCHs) in water using activated carbon fiber-solid phase microextraction(ACF-SPME) were studied. Results showed the performance of adsorp...A fast and simple method for determination of α, β, γ-hexachlorocyclohexanes (HCHs) in water using activated carbon fiber-solid phase microextraction(ACF-SPME) were studied. Results showed the performance of adsorption and desorption of three HCHs on ACF were excellent. A wide linear range from 10 to 100 μg/L and detection limits of the ng/L level were obtained using ACF-SPME with GC-MS in selected ion monitoring(SIM) acquisition mode. The proposed method was also successfully applied for determination of three HCHs in tap water. Compared to commercial fibers, ACF showed some advantages such as better resistance to solvents, higher thermal stability, longer lifetime and lower cost. The data demonstrated that GC-MS with ACF-SPME is well suitable for the analysis of HCHs in water.展开更多
In this work, solid-phase microextraction coupled with gas chromatography–mass spectrometry was developed to determine trace levels of nitrobenzene compounds in water and soil samples. Graphene was chosen as the extr...In this work, solid-phase microextraction coupled with gas chromatography–mass spectrometry was developed to determine trace levels of nitrobenzene compounds in water and soil samples. Graphene was chosen as the extraction material and its composite was coated on a stainless steel wire through sol–gel technique for the solid phase microextraction. The key parameters influencing the extraction efficiency were optimized. Under the optimal conditions, the linearity for the compounds was observed in the range of 0.02–15.0 mg/L for water samples, and 0.2–60.0 mg/kg for soil samples, with the correlation coefficients（r） of 0.9966–0.9987. The limits of detection of the method were 0.0025–0.005 mg/L for water samples, and 0.02–0.04 mg/kg for soil samples. The recoveries for the spiked samples were in the range of 72.0%–113.2%, and the precision, expressed as the relative standard deviations, was less than 12.1%.展开更多
Dispersive liquid-liquid microextraction (DLLME) followed by gas chromatography–flame ionization detection (GC-FID), as a simple, rapid and efficient method, was developed for the determination of amitraz in honey sa...Dispersive liquid-liquid microextraction (DLLME) followed by gas chromatography–flame ionization detection (GC-FID), as a simple, rapid and efficient method, was developed for the determination of amitraz in honey samples. This method involves the use of an appropriate mixture of the extraction and disperser solvents for the formation of a cloudy solution in 5.0 mL aqueous sample containing amitraz. After extraction, phase separation was performed by centrifugation and the concentrated amitraz in the sedimented phase was determined by gas chromatography—flame ionization detection (GC-FID). Some important parameters such as the type and volume of extraction and disperser solvents, and the effect of pH and salt on the extraction recovery of amitraz were investigated. Under the optimum conditions (13 μL of carbon tetrachloride as an extraction solvent, 1 mL of acetonitrile as a disperser solvent, no salt addition and pH 6) preconcentration factor and the extraction recovery were 955 and 95.5%, respectively. The linear range was 0.01 - 1.0 mg?kg–1 and the limit of detection was 0.0015 mg?kg–1. The relative standard deviation (RSD, n = 4) for 0.1 mg?kg–1 of amitraz was 3.2%. The recoveries of amitraz from honey samples at the spiking levels of 0.1 mg?kg-1 were 78.8 and 98.2%. The results indicated that DLLME is an efficient technique for the extraction of amitraz in honey samples.展开更多
Solid phase microextraction （SPME） is a solvent-flee method of sample collection. SPME is an appealing method for sample collection because it is designed for the sampling of trace level analytes with short sampling...Solid phase microextraction （SPME） is a solvent-flee method of sample collection. SPME is an appealing method for sample collection because it is designed for the sampling of trace level analytes with short sampling times in a variety of environments. Additionally, SPME can be used to directly deliver a sample to a gas chromatograph （GC） for analysis by means of thermal desorption. In this paper, the performance of SPME under dynamic conditions was investigated. Additionally, the competence of SPME sampling for the simultaneous analysis of multiple trace analytes was also evaluated. This work is discussed in the context of underground mine ventilation surveys but is applicable to any industry in which ventilation circuits must be evaluated. The results of this paper showed that the performance of the 100 ~m PDMS SPME fiber was both precise and rapid under dynamic conditions. This SPME fiber was also able to simultaneously collect sulfur hexafluoride （SF6） and perfluoromethylcyclohexane （PMCH） with adequate sensitivity.展开更多
Headspace solid-phase microextraction（HS-SPME） with sol-gel calix[6]arene-containing fiber followed by gas chromatography with a flame ionization detector was used to examine the composition and distribution of seve...Headspace solid-phase microextraction（HS-SPME） with sol-gel calix[6]arene-containing fiber followed by gas chromatography with a flame ionization detector was used to examine the composition and distribution of seven polycyclic aromatic hydrocarbons（PAHs） in water. The novel SPME fiber exhibited higher extraction efficiency to PAHs compared with poly（dimethylsiloxane） and other calixarene-containing fibers. Extraction/retention mechanism based on the interactions between calixarenes and PAHs was discussed. Owing to the good selectivity and high extraction capability of this calixarene fiber, low detection limits were obtained in a range of 0.34―6.50 ng/L and the relative standard deviation values were ≤12.3% for all of the analytes. The linear ranges of the proposed method were five orders of magnitude for the tested compounds, with linear correlation coefficients（r） greater than 0.998. The method was applied to the determination of polycyclic aromatic hydrocarbons in nine water sources in Wuhan City, China. Standard addition method was selected for the quantification and the recovery values were in a satisfactory range. Total PAHs concentrations in the nine surface water samples were found to vary between undetectable and 8.840 μg/L with two- and three-ring PAHs predominating.展开更多
A new liquid-liquid microextraction method based on the solidification of floating organic drops coupled with gas chromatography was developed for the determination of trace benzene, toluene and xylene（BTX） in water...A new liquid-liquid microextraction method based on the solidification of floating organic drops coupled with gas chromatography was developed for the determination of trace benzene, toluene and xylene（BTX） in water samples. In the microextraction procedure, a microdrop of n-decanol was delivered to the surface of the analytes’ solution, and stirred for a desired time. Following the absolute extraction, the sample vial was cooled in an ice bath for 10 min. The solidified n-decanol was then transferred into a plastic tube and melted naturally; and 1 μL of it was injected into gas chromatography for analysis. Factors relevant to the extraction efficiency were studied and optimized. The optimal experimental conditions were： 15 μL of n-decanol as extractive solvent, 30 mL of solution containing analytes, no salt, the stirring rate 400 r/min, the extraction temperature 30 °C, and the extraction time 30 min. Under those optimized conditions, the detection limit（LOD） of analytes was in a range of 0.05―0.10 ng/mL by the developed method. A good linearity（r0.99） in a calibration range of 0.01―100 μg/mL was obtained. The recoveries of the real samples at different spiked levels of BTX were in the range from 92.2% to 103.4%.展开更多
The chlorination process is one of the water treatment method used for the disinfection of water. The disinfection by products are trihalomethanes such as chloroform, dichloromethane, dibromochloromethane and bromofor...The chlorination process is one of the water treatment method used for the disinfection of water. The disinfection by products are trihalomethanes such as chloroform, dichloromethane, dibromochloromethane and bromoform. A headspace solid-phase microextraction method has been developed for determination oftrihalomethanes in water samples. The experimental parameters such as the stirring rate, extraction time, extraction temperature and desorption time were investigated. The linearity, detection limits and percentage recovery were evaluated. The optimum conditions were stirring rate 800 rpm/min, extraction time 6 min, extraction temperature 20 ~C, desorption time 2.5 min and desorption temperature 220 ~C. The detection limits were 0.01 ~g/L and the recoveries were in the range of 86-110 %, The proposed method was successfully applied to determination of THM4 in tap water samples. The THM4 contents were varied depending on the sample sites and the season. The total THM4 contents in cool, summer and rainy season were in the range of 27.58-41.89, 32.06-60.73 and 46.26-69.87 p.g/L, respectively. Confirmation of the detected compounds in water samples were performed by gas chromatograph-mass spectrometer. The mass spectra of the target compounds in water samples is in good agreement with trihalomethanes standard spectra.展开更多
In this work, biphenyl and biphenyl oxide were extracted by direct single drop microextraction (di- rect-SDME) and analyzed by gas chromatography flame ionization detection. The extraction occurred by suspending a 7 ...In this work, biphenyl and biphenyl oxide were extracted by direct single drop microextraction (di- rect-SDME) and analyzed by gas chromatography flame ionization detection. The extraction occurred by suspending a 7 μL drop of toluene (as extracting solvent) containing acetonaphton (as internal standard) from the tip of a microsyringe in direct-SDME, respectively. The effect of different parameters such as nature of extraction solvent, microdrop and sample temperatures, stirring rate, microdrop and sample volumes, ionic strength and extracting time on the extraction efficiency of the analytes were investigated and optimized. Under optimized conditions the detection limits (S/N = 3) of the biphenyl and biphenyl oxide were 1.80 ± 0.03 and 1.10 ± 0.02 μg?mL–1, respectively. Good linearity was obtained for both analytes using extraction techniques with the correlation coefficients at least 0.997 and the relative standard deviations (R.S.D.) were in the range of 1% - 3%. The percent recoveries of the analytes from spiked water samples were near to 100%展开更多
[Objectives]This study aimed to determine the volatile components in Santalum album Linn and gradually clarify the aroma composition of S.album Linn.[Methods]Solid-phase microextraction method was used to obtain the v...[Objectives]This study aimed to determine the volatile components in Santalum album Linn and gradually clarify the aroma composition of S.album Linn.[Methods]Solid-phase microextraction method was used to obtain the volatile components of S.album Linn.The aroma components were analyzed by gas chromatography-mass spectrometry and their relative contents were calculated using the area normalization method.[Results]In a dry state at room temperature,39 chemical components were identified from S.album Linn,mainly olefins(91.15%),alkanes(3.00%),alcohols(2.56%),esters(2.19%),ketones(0.55%),aldehydes(0.41%)and heterocyclics(0.14%).[Conclusions]This method has the advantages of low sample consumption,easy operation,rapid identification of aroma components and high sensitivity,and can effectively separate and determine volatile components in S.album Linn,realizing the rapid identification of different S.album Linn varieties and providing technical support for further research on Chinese medicinal materials.展开更多
The coating material is considered as the key of solid-phase microextraction(SPME)due to the fact that which has much effect on the selectivity and sensitivity of the analytical method.Herein,the porous hollow carbon ...The coating material is considered as the key of solid-phase microextraction(SPME)due to the fact that which has much effect on the selectivity and sensitivity of the analytical method.Herein,the porous hollow carbon nanospheres(PHCNs)were synthesized by selectively removing the interior part of solid inhomogeneous nanospheres with acetone.Using PHCNs as new coating material,a SPME fiber was prepared.To the best of our knowledge,PHCNs was utilized as a SPME fiber coating for the first time.The fiber coating material PHCNs demonstrated excellent thermal stability(>800℃)and long usage lifespan(≥60 times).A headspace SPME(HS-SPME)was established to non-contact extract and enrich polycyclic aromatic hydrocarbons(PAHs)prior to gas chromatography-flame ionization detector(GC-FID)analysis.The HS-SPME not only can eliminate non-volatile interferences from matrix,but also be able to protect fiber coating and prolong lifespan of fiber prober.The linearity in the linear range of 0.01-30 ng/m L and limits of detection from 0.003 ng/mL to 0.006 ng/mL were obtained by HS-SPME-GC-FID with PHCNs as fiber coating.The enrichment factors were calculated as 5420-9211 compared with conventional direct introduce analysis.The spiked recoveries of real samples including campus lake water and lime tree honey were obtained from 80.93%to 118.0%with relative standard deviation no higher than 10.6%.The π-π stacking interaction,CH/π interaction,and unique built-in cavities significantly enhance the extraction performance of PHCNs coating fiber to PAHs.This work demonstrated that the PHCNs as fiber coating materials present good application prospects for the extraction and enrichment of trace PAHs from complex matrixes.展开更多
It is crucial to develop arsenic removal adsorbents with strong sulfur resistance under middle-low-temperature flue gas conditions(<400℃).In this work,five Fe-Ce-La oxides were prepared by co-precipitation method,...It is crucial to develop arsenic removal adsorbents with strong sulfur resistance under middle-low-temperature flue gas conditions(<400℃).In this work,five Fe-Ce-La oxides were prepared by co-precipitation method,and FeCeLaO/SiO_(2)-Al_(2)O_(3) composite adsorbents were prepared by coupling fly ash-based Si-Al carriers.The active components Fe-Ce-La oxides and Si-Al carriers were characterized by TPD,TG,XRF,BET and XPS,respectively.The effects of temperature,Si/Al ratio and FeCeLaO loading rate on the sulfur resistance were investigated.Results show that the SO_(2) promotes the arsenic removal of Fe_(2)O_(3),CeLaO and FeCeLaO.At 400℃,the arsenic removal efficiencies of the three oxides increase from 45.3%,72.5% and 81.3% without SO_(2) to 62.6%,80.5%and 91.0%,respectively.The SO_(2) inhibits the arsenic removal of La_(2)O_(2)CO_(3) and FeLaO,and the inhibition effect is pronounced at high temperatures.The sulfur poisoning resistance of Si-Al carriers increases with the increase of Si/Al ratio.When the Si/Al ratio is increased to 9.74,the arsenic removal efficiency in the SO_(2) environment is 13.9% higher than that in the absence of SO_(2).Introducing FeCeLaO active components is beneficial for enhancing the SO_(2) poisoning resistance of Si-Al carriers.The strong sulfur resistance of the FeCeLaO/SiO_(2)-Al_(2)O_(3) composite adsorbent results from multiple factors:protective effects of Ce on Fe,La and Al;sulfation-induced generation of Ce^(3+)and surface-adsorbed oxygen;and strong surface acidity of SiO_(2).展开更多
The Savitzky-Golay(SG)filter,which employs polynomial least-squares approximations to smooth data and estimate derivatives,is widely used for processing noisy data.However,noise suppression by the SG filter is recogni...The Savitzky-Golay(SG)filter,which employs polynomial least-squares approximations to smooth data and estimate derivatives,is widely used for processing noisy data.However,noise suppression by the SG filter is recognized to be limited at data boundaries and high frequencies,which can significantly reduce the signal-to-noise ratio(SNR).To solve this problem,a novel method synergistically integrating Principal Component Analysis(PCA)with SG filtering is proposed in this paper.This approach avoids the is-sue of excessive smoothing associated with larger window sizes.The proposed PCA-SG filtering algorithm was applied to a CO gas sensing system based on Cavity Ring-Down Spectroscopy(CRDS).The perform-ance of the PCA-SG filtering algorithm is demonstrated through comparison with Moving Average Filtering(MAF),Wavelet Transformation(WT),Kalman Filtering(KF),and the SG filter.The results demonstrate that the proposed algorithm exhibits superior noise reduction capabilities compared to the other algorithms evaluated.The SNR of the ring-down signal was improved from 11.8612 dB to 29.0913 dB,and the stand-ard deviation of the extracted ring-down time constant was reduced from 0.037μs to 0.018μs.These results confirm that the proposed PCA-SG filtering algorithm effectively improves the smoothness of the ring-down curve data,demonstrating its feasibility.展开更多
Gas wells often encounter blockages in gas recovery channels owing to fluid accumulation during the later stages of extraction,which adversely affects subsequent recovery efforts.These undesirable conditions(e.g.,high...Gas wells often encounter blockages in gas recovery channels owing to fluid accumulation during the later stages of extraction,which adversely affects subsequent recovery efforts.These undesirable conditions(e.g.,high condensate content,high temperature,and high salinity)often affect foaming agent performance.In this study,surfactants were screened using an airflow method that closely resembles field treatment method.Notably,alcohol ether sulfates(AE_(n)S)with various polyoxyethylene(EO)units demonstrated exceptional performance in terms of liquid unloading efficiency and foam stability.At 80℃,the unloading efficiency of AE_(n)S with two EO units(AE_(2)S)in a high NaCl mass concentration(up to 200 g/L)and high condensate volume fraction(up to 20%)reached 84%.The dynamic surface tension and interfacial tension measured at the same temperature were used to analyze the influence of the diffusion rate and interfacial characteristics on the AE_(n)S foam,while the viscosity and liquid film thickness measurements reflected the mechanical strength and liquid-carrying capacity.In addition,transmission electron microscopy(TEM)revealed that AE_(2)S formed“dendritic”micellar aggregates at a high NaCl mass concentration,which significantly enhanced the viscosity and stability of the foam.The interactions among AE_(n)S,NaCl,and H2O were analyzed using molecular dynamics,and it was confirmed from a molecular mechanics perspective that a stable structure can form among the three,contributing to the foam stability.These findings demonstrate the significant potential of the AE_(2)S foam for gas well deliquification.展开更多
This paper examines how natural gas disperses vertically when high-pressure pipelines with large openings fail in unconfined environments,providing insight into hazardous gas cloud development and behavior.A comprehen...This paper examines how natural gas disperses vertically when high-pressure pipelines with large openings fail in unconfined environments,providing insight into hazardous gas cloud development and behavior.A comprehensive study was conducted using a full-scale field experiment(1,219 mm diameter,12 MPa pressure,100 mm aperture)combined with a validated computational fluid dynamics(CFD)numerical simulation model to systematically analyze the coupling effects of pipeline pressure and ambient wind speed.The results indicate that:(1)Pipeline pressure determines the vertical jet scale,where jet height is positively correlated with pressure;at 12 MPa,the maximum jet height reaches 69.4 m(approximately 2.65 times that at 4 MPa),and the lower explosive limit(LEL)cloud area follows a quadratic polynomial trend.(2)Ambient wind speed significantly alters the diffusion trajectory;at a wind speed of 10 m/s,the LEL gas cloud area expands by 1.69 times compared to calm conditions,while the jet height is suppressed to 29.9%of the calm wind value.(3)Our developed dynamic prediction model for the hazardous gas-cloud region achieves a determination coefficient of 0.975 and maintaining prediction errors maintained within approximately 12%.The proposed empirical correlations and dynamic prediction model provide essential quantitative data support for safety-distance design and emergency-response decision-making for high-pressure natural gas pipelines.展开更多
Selectivity remains a significant challenge for gas sensors. In contrast to conventional gas sensors that depend solely on conductivity to detect gases, we exploited a single NiO-doped SnO_(2) sensor to simultaneously...Selectivity remains a significant challenge for gas sensors. In contrast to conventional gas sensors that depend solely on conductivity to detect gases, we exploited a single NiO-doped SnO_(2) sensor to simultaneously monitor transient changes in both sensor conductivity and temperature. The distinct response profiles of H_(2) and NH_(3) gases were attributed to differences in their redox rates and enthalpy changes during chemical reactions, which provided an opportunity for gas identification using machine learning(ML) algorithms. The test results indicate that preprocessing the extracted calorimetric and chemi-resistive parameters using the principal component analysis(PCA), followed by the application of ML classifiers for identification,enables a 100% accuracy for both target analytes. This work presents a facile gas identification method that enhances chiplevel sensor applications while minimizing the need for complex sensor arrays.展开更多
Novel antibacterial strategies such as antibacterial photodynamic therapy(aPDT)and photothermal therapy(PTT)have gained significant attention,however,relying on a single-treatment approach still faces challenges of in...Novel antibacterial strategies such as antibacterial photodynamic therapy(aPDT)and photothermal therapy(PTT)have gained significant attention,however,relying on a single-treatment approach still faces challenges of insufficient therapeutic efficiency and the potential for drug resistance.In this study,a multimodal synergistic antibacterial nanoplatform by coupling a carbon monoxide(CO)donor(4-(3-hydroxy-4-oxo-4H-chromen-2-yl)benzoic acid(4-BA))with carbon dots(CDs)is developed,referred to as CDs-CO,which integrates multiple antibacterial modes of aPDT,PTT,and gas therapy.This nanoplatform is designed for highly efficient antibacterial action with a low risk of inducing drug resistance.CDs are engineered to possess tailored functions,including deep-red light-triggered heat and singlet oxygen(^(1)O_(2))production.After modification with 4-BA and exposure to 660 nm laser irradiation,CDs-CO exhibits favorable photothermal conversion efficiency(η=52.7%),robust ^(1)O_(2) generation,and ^(1)O_(2)-activated CO release.Antibacterial experiments demonstrated the excellent sterilization effects of CDs-CO against both Escherichia coli(E.coli)and Staphylococcus aureus(S.aureus),underscoring the enhanced antibacterial efficiency of this multimodal nanoplatform.This study offers a rational approach for designing multimodal synergistic antibacterial platforms,highlighting their potential for effectively treating bacterial infections.展开更多
Single-crystal GaN epilayers were irradiated with heavy inert gas ions(2.3-MeV Ne^(8+),5.3-MeV Kr^(19+))to fluences ranging from 1.0×1.0^(11) to 1.0×1.0^(15)ions∕cm^(2).The strain-related damage accumulatio...Single-crystal GaN epilayers were irradiated with heavy inert gas ions(2.3-MeV Ne^(8+),5.3-MeV Kr^(19+))to fluences ranging from 1.0×1.0^(11) to 1.0×1.0^(15)ions∕cm^(2).The strain-related damage accumulation versus ion fluences was studied using highresolution X-ray diffraction(HRXRD)and ultraviolet–visible(UV–Vis)spectroscopy.The results showed that the damage accumulation was mainly dominated by nuclear energy loss.When the ion fluence was less than∼0.055 displacement per atom(dpa),the lattice expansions and lattice strains markedly increased linearly with increasing ion fluences,accompanied by a slow enhancement in the dislocation densities,distortion parameters,and Urbach energy for both ion irradiations.Above this fluence(∼0.055 dpa),the lattice strains presented a slight increase,whereas a remarkable increase was observed in the dislocation densities,distortion parameters,and Urbach energy with the ion fluences after both ion irradiations.∼0.055 dpa is the threshold ion fluence for defect evolution and lattice damage related to strain.The mechanisms underlying the damage accumulation are discussed in detail.展开更多
基金Supported by the National Natural Science Foundation of China(No.22176210)the Major Innovation Fund of Shandong Province(No.2021ZDSYS23)。
文摘To simultaneously enrich,separate,and determine five fluoroquinolone antibiotics(FQs)in marine crude drugs(MCDs),seawater and seafood,we conducted this study using vortex assisted dispersed liquid-liquid microextraction(DLLME),followed by capillary electrophoresis(CE)-UV.A single-variable optimization was employed to examine the factors influencing the separation effect of CE and the extraction efficiency of DLLME,including buffer solution,organic solvent,separation voltage,extractant,dispersant,and sample solution pH.Under the optimal conditions,the baseline separation of the five FQs was achieved within 6 min.The analytical performance of the method was assessed using six types of actual samples,including three MCDs of hippocampus,clam,and kelp,seawater,and two seafood of prawn and pomfret,demonstrating good linearity ranging from 0.1-5 or 0.01-5μg/mL.The limits of detection(LODs)and limits of quantification(LOQs)for the five FQs in MCDs were 0.0022-0.0292 and 0.0066-0.0973μg/mL,respectively.The LODs and LOQs in seawater and seafood were 0.0009-0.0262 and 0.0029-0.0874μg/mL,respectively.The matrix effects of this method were evaluated in the hippocampus,seawater,and prawn,and the results show that DLLME could effectively eliminate matrix interference.Satisfactory recovery rates were achieved in all the six tested actual samples.This developed DLLME-CE method was proven simple to operate,accurate and reliable,with high sensitivity,making it suitable for the analysis of multiple antibiotic residues in complex matrices.
基金Project(21277175) supported by the National Natural Science Foundation of ChinaProject(JCYJ20120618164317119) supported by Shenzhen Special Fund for Development of Strategic Emerging,China
文摘A simple and sensitive analytical procedure for the determination of multi-component compounds in water samples was developed and optimized using the headspace solid-phase microextraction(HSSPME) coupled with gas chromatography-mass spectrometry(GC-MS). Ten off-flavor compounds, including geosmin(GSM), 2-methylisoborneol(2-MIB), 2-isopropyl-3-methoxypyrazine(IPMP), 2-isobutyl-3-methoxypyrazine(IBMP), β-ionone, trans-2,cis-6-nonadienal(NDE), 2,3,4-trichloroanisole(2,3,4-TCA), 2,3,6-trichroloanisole(2,3,6-TCA), 2,4,6-trichloroanisole(2,4,6-TCA), and 2,4,6-tribromoanisole(2,4,6-TBA) were used as the target analytes. The optimization of extraction parameters including fibers types, extraction time, extraction temperature, stirring rate, sample volume, and ionic strength was carried out through the univariate approach. Ten off-flavor compounds were quantified within 50 min under the optimal conditions. Calibration curves with good linearity(r^2=0.990-0.998) were obtained in the range 1.0/2.0-100 ng/L, while the limits of detection for all compounds were lower than or close to the odor threshold concentration. Furthermore, the proposed method was applied to analyzing and determining the off-flavor compounds in real water samples from water-treatment plants.
文摘A fast and simple method for determination of α, β, γ-hexachlorocyclohexanes (HCHs) in water using activated carbon fiber-solid phase microextraction(ACF-SPME) were studied. Results showed the performance of adsorption and desorption of three HCHs on ACF were excellent. A wide linear range from 10 to 100 μg/L and detection limits of the ng/L level were obtained using ACF-SPME with GC-MS in selected ion monitoring(SIM) acquisition mode. The proposed method was also successfully applied for determination of three HCHs in tap water. Compared to commercial fibers, ACF showed some advantages such as better resistance to solvents, higher thermal stability, longer lifetime and lower cost. The data demonstrated that GC-MS with ACF-SPME is well suitable for the analysis of HCHs in water.
基金Financial support from the National Natural Science Foundation of China(No.31171698)the Innovation Research Group Program of Department of Education of Hebei for Hebei Provincial Universities(No.LJRC009)the Natural Science Foundation of Hebei Province(No.B2012204028)
文摘In this work, solid-phase microextraction coupled with gas chromatography–mass spectrometry was developed to determine trace levels of nitrobenzene compounds in water and soil samples. Graphene was chosen as the extraction material and its composite was coated on a stainless steel wire through sol–gel technique for the solid phase microextraction. The key parameters influencing the extraction efficiency were optimized. Under the optimal conditions, the linearity for the compounds was observed in the range of 0.02–15.0 mg/L for water samples, and 0.2–60.0 mg/kg for soil samples, with the correlation coefficients（r） of 0.9966–0.9987. The limits of detection of the method were 0.0025–0.005 mg/L for water samples, and 0.02–0.04 mg/kg for soil samples. The recoveries for the spiked samples were in the range of 72.0%–113.2%, and the precision, expressed as the relative standard deviations, was less than 12.1%.
文摘Dispersive liquid-liquid microextraction (DLLME) followed by gas chromatography–flame ionization detection (GC-FID), as a simple, rapid and efficient method, was developed for the determination of amitraz in honey samples. This method involves the use of an appropriate mixture of the extraction and disperser solvents for the formation of a cloudy solution in 5.0 mL aqueous sample containing amitraz. After extraction, phase separation was performed by centrifugation and the concentrated amitraz in the sedimented phase was determined by gas chromatography—flame ionization detection (GC-FID). Some important parameters such as the type and volume of extraction and disperser solvents, and the effect of pH and salt on the extraction recovery of amitraz were investigated. Under the optimum conditions (13 μL of carbon tetrachloride as an extraction solvent, 1 mL of acetonitrile as a disperser solvent, no salt addition and pH 6) preconcentration factor and the extraction recovery were 955 and 95.5%, respectively. The linear range was 0.01 - 1.0 mg?kg–1 and the limit of detection was 0.0015 mg?kg–1. The relative standard deviation (RSD, n = 4) for 0.1 mg?kg–1 of amitraz was 3.2%. The recoveries of amitraz from honey samples at the spiking levels of 0.1 mg?kg-1 were 78.8 and 98.2%. The results indicated that DLLME is an efficient technique for the extraction of amitraz in honey samples.
基金Contract No.200-2009-31933,awarded by the National Institute for Occupational Safety and Health(NIOSH)
文摘Solid phase microextraction （SPME） is a solvent-flee method of sample collection. SPME is an appealing method for sample collection because it is designed for the sampling of trace level analytes with short sampling times in a variety of environments. Additionally, SPME can be used to directly deliver a sample to a gas chromatograph （GC） for analysis by means of thermal desorption. In this paper, the performance of SPME under dynamic conditions was investigated. Additionally, the competence of SPME sampling for the simultaneous analysis of multiple trace analytes was also evaluated. This work is discussed in the context of underground mine ventilation surveys but is applicable to any industry in which ventilation circuits must be evaluated. The results of this paper showed that the performance of the 100 ~m PDMS SPME fiber was both precise and rapid under dynamic conditions. This SPME fiber was also able to simultaneously collect sulfur hexafluoride （SF6） and perfluoromethylcyclohexane （PMCH） with adequate sensitivity.
基金Supported by the National Natural Science Foundation of China(No.30901007)the Fund of the Ministry of Education of China(No.081025)
文摘Headspace solid-phase microextraction（HS-SPME） with sol-gel calix[6]arene-containing fiber followed by gas chromatography with a flame ionization detector was used to examine the composition and distribution of seven polycyclic aromatic hydrocarbons（PAHs） in water. The novel SPME fiber exhibited higher extraction efficiency to PAHs compared with poly（dimethylsiloxane） and other calixarene-containing fibers. Extraction/retention mechanism based on the interactions between calixarenes and PAHs was discussed. Owing to the good selectivity and high extraction capability of this calixarene fiber, low detection limits were obtained in a range of 0.34―6.50 ng/L and the relative standard deviation values were ≤12.3% for all of the analytes. The linear ranges of the proposed method were five orders of magnitude for the tested compounds, with linear correlation coefficients（r） greater than 0.998. The method was applied to the determination of polycyclic aromatic hydrocarbons in nine water sources in Wuhan City, China. Standard addition method was selected for the quantification and the recovery values were in a satisfactory range. Total PAHs concentrations in the nine surface water samples were found to vary between undetectable and 8.840 μg/L with two- and three-ring PAHs predominating.
基金Supported by the National Natural Science Foundation of China(No.21105088)the Program for Science and Technology Projects of the Education Department of Fujian Province,China(No.JA10211)
文摘A new liquid-liquid microextraction method based on the solidification of floating organic drops coupled with gas chromatography was developed for the determination of trace benzene, toluene and xylene（BTX） in water samples. In the microextraction procedure, a microdrop of n-decanol was delivered to the surface of the analytes’ solution, and stirred for a desired time. Following the absolute extraction, the sample vial was cooled in an ice bath for 10 min. The solidified n-decanol was then transferred into a plastic tube and melted naturally; and 1 μL of it was injected into gas chromatography for analysis. Factors relevant to the extraction efficiency were studied and optimized. The optimal experimental conditions were： 15 μL of n-decanol as extractive solvent, 30 mL of solution containing analytes, no salt, the stirring rate 400 r/min, the extraction temperature 30 °C, and the extraction time 30 min. Under those optimized conditions, the detection limit（LOD） of analytes was in a range of 0.05―0.10 ng/mL by the developed method. A good linearity（r0.99） in a calibration range of 0.01―100 μg/mL was obtained. The recoveries of the real samples at different spiked levels of BTX were in the range from 92.2% to 103.4%.
文摘The chlorination process is one of the water treatment method used for the disinfection of water. The disinfection by products are trihalomethanes such as chloroform, dichloromethane, dibromochloromethane and bromoform. A headspace solid-phase microextraction method has been developed for determination oftrihalomethanes in water samples. The experimental parameters such as the stirring rate, extraction time, extraction temperature and desorption time were investigated. The linearity, detection limits and percentage recovery were evaluated. The optimum conditions were stirring rate 800 rpm/min, extraction time 6 min, extraction temperature 20 ~C, desorption time 2.5 min and desorption temperature 220 ~C. The detection limits were 0.01 ~g/L and the recoveries were in the range of 86-110 %, The proposed method was successfully applied to determination of THM4 in tap water samples. The THM4 contents were varied depending on the sample sites and the season. The total THM4 contents in cool, summer and rainy season were in the range of 27.58-41.89, 32.06-60.73 and 46.26-69.87 p.g/L, respectively. Confirmation of the detected compounds in water samples were performed by gas chromatograph-mass spectrometer. The mass spectra of the target compounds in water samples is in good agreement with trihalomethanes standard spectra.
文摘In this work, biphenyl and biphenyl oxide were extracted by direct single drop microextraction (di- rect-SDME) and analyzed by gas chromatography flame ionization detection. The extraction occurred by suspending a 7 μL drop of toluene (as extracting solvent) containing acetonaphton (as internal standard) from the tip of a microsyringe in direct-SDME, respectively. The effect of different parameters such as nature of extraction solvent, microdrop and sample temperatures, stirring rate, microdrop and sample volumes, ionic strength and extracting time on the extraction efficiency of the analytes were investigated and optimized. Under optimized conditions the detection limits (S/N = 3) of the biphenyl and biphenyl oxide were 1.80 ± 0.03 and 1.10 ± 0.02 μg?mL–1, respectively. Good linearity was obtained for both analytes using extraction techniques with the correlation coefficients at least 0.997 and the relative standard deviations (R.S.D.) were in the range of 1% - 3%. The percent recoveries of the analytes from spiked water samples were near to 100%
基金Nonprofit Institute Research Grant of Xinjiang Uygur Autonomous Region(KY2019056).
文摘[Objectives]This study aimed to determine the volatile components in Santalum album Linn and gradually clarify the aroma composition of S.album Linn.[Methods]Solid-phase microextraction method was used to obtain the volatile components of S.album Linn.The aroma components were analyzed by gas chromatography-mass spectrometry and their relative contents were calculated using the area normalization method.[Results]In a dry state at room temperature,39 chemical components were identified from S.album Linn,mainly olefins(91.15%),alkanes(3.00%),alcohols(2.56%),esters(2.19%),ketones(0.55%),aldehydes(0.41%)and heterocyclics(0.14%).[Conclusions]This method has the advantages of low sample consumption,easy operation,rapid identification of aroma components and high sensitivity,and can effectively separate and determine volatile components in S.album Linn,realizing the rapid identification of different S.album Linn varieties and providing technical support for further research on Chinese medicinal materials.
基金supported by National Natural Science Foundation of China(No.22376053)supported by the Natural Science Foundation of Henan Province,China(No.242300421034)Henan Key Scientific Research Programs to Universities and Colleges(No.22ZX003)。
文摘The coating material is considered as the key of solid-phase microextraction(SPME)due to the fact that which has much effect on the selectivity and sensitivity of the analytical method.Herein,the porous hollow carbon nanospheres(PHCNs)were synthesized by selectively removing the interior part of solid inhomogeneous nanospheres with acetone.Using PHCNs as new coating material,a SPME fiber was prepared.To the best of our knowledge,PHCNs was utilized as a SPME fiber coating for the first time.The fiber coating material PHCNs demonstrated excellent thermal stability(>800℃)and long usage lifespan(≥60 times).A headspace SPME(HS-SPME)was established to non-contact extract and enrich polycyclic aromatic hydrocarbons(PAHs)prior to gas chromatography-flame ionization detector(GC-FID)analysis.The HS-SPME not only can eliminate non-volatile interferences from matrix,but also be able to protect fiber coating and prolong lifespan of fiber prober.The linearity in the linear range of 0.01-30 ng/m L and limits of detection from 0.003 ng/mL to 0.006 ng/mL were obtained by HS-SPME-GC-FID with PHCNs as fiber coating.The enrichment factors were calculated as 5420-9211 compared with conventional direct introduce analysis.The spiked recoveries of real samples including campus lake water and lime tree honey were obtained from 80.93%to 118.0%with relative standard deviation no higher than 10.6%.The π-π stacking interaction,CH/π interaction,and unique built-in cavities significantly enhance the extraction performance of PHCNs coating fiber to PAHs.This work demonstrated that the PHCNs as fiber coating materials present good application prospects for the extraction and enrichment of trace PAHs from complex matrixes.
文摘It is crucial to develop arsenic removal adsorbents with strong sulfur resistance under middle-low-temperature flue gas conditions(<400℃).In this work,five Fe-Ce-La oxides were prepared by co-precipitation method,and FeCeLaO/SiO_(2)-Al_(2)O_(3) composite adsorbents were prepared by coupling fly ash-based Si-Al carriers.The active components Fe-Ce-La oxides and Si-Al carriers were characterized by TPD,TG,XRF,BET and XPS,respectively.The effects of temperature,Si/Al ratio and FeCeLaO loading rate on the sulfur resistance were investigated.Results show that the SO_(2) promotes the arsenic removal of Fe_(2)O_(3),CeLaO and FeCeLaO.At 400℃,the arsenic removal efficiencies of the three oxides increase from 45.3%,72.5% and 81.3% without SO_(2) to 62.6%,80.5%and 91.0%,respectively.The SO_(2) inhibits the arsenic removal of La_(2)O_(2)CO_(3) and FeLaO,and the inhibition effect is pronounced at high temperatures.The sulfur poisoning resistance of Si-Al carriers increases with the increase of Si/Al ratio.When the Si/Al ratio is increased to 9.74,the arsenic removal efficiency in the SO_(2) environment is 13.9% higher than that in the absence of SO_(2).Introducing FeCeLaO active components is beneficial for enhancing the SO_(2) poisoning resistance of Si-Al carriers.The strong sulfur resistance of the FeCeLaO/SiO_(2)-Al_(2)O_(3) composite adsorbent results from multiple factors:protective effects of Ce on Fe,La and Al;sulfation-induced generation of Ce^(3+)and surface-adsorbed oxygen;and strong surface acidity of SiO_(2).
文摘The Savitzky-Golay(SG)filter,which employs polynomial least-squares approximations to smooth data and estimate derivatives,is widely used for processing noisy data.However,noise suppression by the SG filter is recognized to be limited at data boundaries and high frequencies,which can significantly reduce the signal-to-noise ratio(SNR).To solve this problem,a novel method synergistically integrating Principal Component Analysis(PCA)with SG filtering is proposed in this paper.This approach avoids the is-sue of excessive smoothing associated with larger window sizes.The proposed PCA-SG filtering algorithm was applied to a CO gas sensing system based on Cavity Ring-Down Spectroscopy(CRDS).The perform-ance of the PCA-SG filtering algorithm is demonstrated through comparison with Moving Average Filtering(MAF),Wavelet Transformation(WT),Kalman Filtering(KF),and the SG filter.The results demonstrate that the proposed algorithm exhibits superior noise reduction capabilities compared to the other algorithms evaluated.The SNR of the ring-down signal was improved from 11.8612 dB to 29.0913 dB,and the stand-ard deviation of the extracted ring-down time constant was reduced from 0.037μs to 0.018μs.These results confirm that the proposed PCA-SG filtering algorithm effectively improves the smoothness of the ring-down curve data,demonstrating its feasibility.
文摘Gas wells often encounter blockages in gas recovery channels owing to fluid accumulation during the later stages of extraction,which adversely affects subsequent recovery efforts.These undesirable conditions(e.g.,high condensate content,high temperature,and high salinity)often affect foaming agent performance.In this study,surfactants were screened using an airflow method that closely resembles field treatment method.Notably,alcohol ether sulfates(AE_(n)S)with various polyoxyethylene(EO)units demonstrated exceptional performance in terms of liquid unloading efficiency and foam stability.At 80℃,the unloading efficiency of AE_(n)S with two EO units(AE_(2)S)in a high NaCl mass concentration(up to 200 g/L)and high condensate volume fraction(up to 20%)reached 84%.The dynamic surface tension and interfacial tension measured at the same temperature were used to analyze the influence of the diffusion rate and interfacial characteristics on the AE_(n)S foam,while the viscosity and liquid film thickness measurements reflected the mechanical strength and liquid-carrying capacity.In addition,transmission electron microscopy(TEM)revealed that AE_(2)S formed“dendritic”micellar aggregates at a high NaCl mass concentration,which significantly enhanced the viscosity and stability of the foam.The interactions among AE_(n)S,NaCl,and H2O were analyzed using molecular dynamics,and it was confirmed from a molecular mechanics perspective that a stable structure can form among the three,contributing to the foam stability.These findings demonstrate the significant potential of the AE_(2)S foam for gas well deliquification.
基金supported by the National Natural Science Foundation of China(Grant No.52574278)the Xinjiang Uygur Autonomous Region Key R&D Program Project(Grant No.2024B01003).
文摘This paper examines how natural gas disperses vertically when high-pressure pipelines with large openings fail in unconfined environments,providing insight into hazardous gas cloud development and behavior.A comprehensive study was conducted using a full-scale field experiment(1,219 mm diameter,12 MPa pressure,100 mm aperture)combined with a validated computational fluid dynamics(CFD)numerical simulation model to systematically analyze the coupling effects of pipeline pressure and ambient wind speed.The results indicate that:(1)Pipeline pressure determines the vertical jet scale,where jet height is positively correlated with pressure;at 12 MPa,the maximum jet height reaches 69.4 m(approximately 2.65 times that at 4 MPa),and the lower explosive limit(LEL)cloud area follows a quadratic polynomial trend.(2)Ambient wind speed significantly alters the diffusion trajectory;at a wind speed of 10 m/s,the LEL gas cloud area expands by 1.69 times compared to calm conditions,while the jet height is suppressed to 29.9%of the calm wind value.(3)Our developed dynamic prediction model for the hazardous gas-cloud region achieves a determination coefficient of 0.975 and maintaining prediction errors maintained within approximately 12%.The proposed empirical correlations and dynamic prediction model provide essential quantitative data support for safety-distance design and emergency-response decision-making for high-pressure natural gas pipelines.
基金supported in part by the National Natural Science Foundation of China (62431018)in part by the Guangzhou Municipal Science and Technology Bureau (SL2023A04J00435)in part by the One Hundred Youth Project of Guangdong University of Technology (263113873)。
文摘Selectivity remains a significant challenge for gas sensors. In contrast to conventional gas sensors that depend solely on conductivity to detect gases, we exploited a single NiO-doped SnO_(2) sensor to simultaneously monitor transient changes in both sensor conductivity and temperature. The distinct response profiles of H_(2) and NH_(3) gases were attributed to differences in their redox rates and enthalpy changes during chemical reactions, which provided an opportunity for gas identification using machine learning(ML) algorithms. The test results indicate that preprocessing the extracted calorimetric and chemi-resistive parameters using the principal component analysis(PCA), followed by the application of ML classifiers for identification,enables a 100% accuracy for both target analytes. This work presents a facile gas identification method that enhances chiplevel sensor applications while minimizing the need for complex sensor arrays.
基金supported by the National Natural Science Foundation of China(No.52173126)China Postdoctoral Science Foundation(No.2024M751152).
文摘Novel antibacterial strategies such as antibacterial photodynamic therapy(aPDT)and photothermal therapy(PTT)have gained significant attention,however,relying on a single-treatment approach still faces challenges of insufficient therapeutic efficiency and the potential for drug resistance.In this study,a multimodal synergistic antibacterial nanoplatform by coupling a carbon monoxide(CO)donor(4-(3-hydroxy-4-oxo-4H-chromen-2-yl)benzoic acid(4-BA))with carbon dots(CDs)is developed,referred to as CDs-CO,which integrates multiple antibacterial modes of aPDT,PTT,and gas therapy.This nanoplatform is designed for highly efficient antibacterial action with a low risk of inducing drug resistance.CDs are engineered to possess tailored functions,including deep-red light-triggered heat and singlet oxygen(^(1)O_(2))production.After modification with 4-BA and exposure to 660 nm laser irradiation,CDs-CO exhibits favorable photothermal conversion efficiency(η=52.7%),robust ^(1)O_(2) generation,and ^(1)O_(2)-activated CO release.Antibacterial experiments demonstrated the excellent sterilization effects of CDs-CO against both Escherichia coli(E.coli)and Staphylococcus aureus(S.aureus),underscoring the enhanced antibacterial efficiency of this multimodal nanoplatform.This study offers a rational approach for designing multimodal synergistic antibacterial platforms,highlighting their potential for effectively treating bacterial infections.
基金supported by the Program for National Natural Science Foundation of China(No.11675231)the Sichuan Science and Technology Program(Nos.2022YFG0263 and 2024NSFSC1097)the Scientific Research Starting Foundation for talents(Nos.21zx7109 and 22zx7175,24ycx1005).
文摘Single-crystal GaN epilayers were irradiated with heavy inert gas ions(2.3-MeV Ne^(8+),5.3-MeV Kr^(19+))to fluences ranging from 1.0×1.0^(11) to 1.0×1.0^(15)ions∕cm^(2).The strain-related damage accumulation versus ion fluences was studied using highresolution X-ray diffraction(HRXRD)and ultraviolet–visible(UV–Vis)spectroscopy.The results showed that the damage accumulation was mainly dominated by nuclear energy loss.When the ion fluence was less than∼0.055 displacement per atom(dpa),the lattice expansions and lattice strains markedly increased linearly with increasing ion fluences,accompanied by a slow enhancement in the dislocation densities,distortion parameters,and Urbach energy for both ion irradiations.Above this fluence(∼0.055 dpa),the lattice strains presented a slight increase,whereas a remarkable increase was observed in the dislocation densities,distortion parameters,and Urbach energy with the ion fluences after both ion irradiations.∼0.055 dpa is the threshold ion fluence for defect evolution and lattice damage related to strain.The mechanisms underlying the damage accumulation are discussed in detail.
