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Papers by Jingfu Liu

Journal of Analytical Atomic Spectrometry, 2016

This work presents magnetic solid-phase extraction coupled with ICP-MS for speciation analysis of... more This work presents magnetic solid-phase extraction coupled with ICP-MS for speciation analysis of silver sulfide nanoparticles (Ag2S NPs).

ACS Sustainable Chemistry & Engineering, 2017

Methods for the removal of silver nanoparticles (AgNPs) and their transformation products, silver... more Methods for the removal of silver nanoparticles (AgNPs) and their transformation products, silver-containing nanoparticles (AgCNPs), are important, because of their potential risks to the general population and the environment. In this study, aged iron oxide magnetic particles (IOMPs) were synthesized by a simple solvothermal reaction and used for the removal of AgCNPs. The prepared IOMPs exhibit a high adsorption capacity toward AgCNPs in aqueous medium. Kinetic studies indicated that the adsorption of AgCNPs is a pseudo-second-order process. The experimental data for the adsorption of AgCNPs follow the Langmuir isotherm model, and their maximum adsorption capacities were 19.9−62.8 mg/g at pH 6.2 and 298 K. The sorption mean free energy calculated by the Dubinin−Radushkevich isotherm was 4.09−5.17 kJ/mol, indicating the occurrence of physisorption, which was mainly due to the electrostatic interactions. The IOMP adsorbents maintained high removal efficiencies after four cycles of adsorption− desorption, suggesting good reusability of the developed IOMPs. Moreover, good removal efficiencies (63.3%−99.9%) and recoveries (67.1%−99.9%) were obtained from the real samples spiked with AgCNPs at levels of 10 μg/L, showing that the aged IOMPs could be used as efficient and low-cost adsorbents for the removal and recovery of AgCNPs from real waters.

Science of The Total Environment, 2016

Mass flow and mass balance are used to study the behaviors and fate of OPEs in STP • Activated sl... more Mass flow and mass balance are used to study the behaviors and fate of OPEs in STP • Activated sludge system plays an effective role in removing OPEs from raw sewage • The behavior and fate of individual OPE showed a polarity-specific feature. • Sorption of OPEs to suspended solids was resulted from hydrophobic interactions • OPE degradation in activated sludge system is more relevant to molecular structure

Environmental Science & Technology, 2017

This is the first study on organophosphate ester (OPEs) flame retardants and plasticizers in the ... more This is the first study on organophosphate ester (OPEs) flame retardants and plasticizers in the sediment of the Great Lakes. Concentrations of 14 OPEs were measured in three sediment cores and 88 Ponar surface grabs collected from Lakes Ontario, Michigan, and Superior of North America. The sum of these OPEs (Σ 14 OPEs) in Ponar grabs averaged 2.2, 4.7, and 16.6 ng g −1 dw in Lakes Superior, Michigan, and Ontario, respectively. Multiple linear regression analyses demonstrated statistically significant associations between logarithm concentrations of Σ 14 OPEs as well as selected congeners in surface grab samples and sediment organic carbon content as well as a newly developed urban distance factor. Temporal trends observed in dated sediment cores from Lake Michigan demonstrated that the recent increase in depositional flux to sediment is dominated by chlorinated OPEs, particularly tris(2chloroisopropyl) phosphate (TCPP), which has a doubling time of about 20 years. Downward diffusion within sediment may have caused vertical fractionation of OPEs over time. Two relatively hydrophilic OPEs including TCPP had much higher concentrations in sediment than estimated based on equilibria between water and sediment organic carbon. Approximately a quarter (17 tonnes) of the estimated total OPE burden (63 tonnes) in Lake Michigan resides in sediment, which may act as a secondary source releasing OPEs to the water column for years to come.

Journal of Environmental Sciences, 2015

Organophosphate esters (OPEs), used as flame retardants and plasticizers, are widely present in e... more Organophosphate esters (OPEs), used as flame retardants and plasticizers, are widely present in environmental waters. Development of accurate determination methods for trace OPEs in water is urgent for understanding the fate and risk of this class of emerging pollutants. However, the wide use of OPEs in experimental materials results in blank interference, which influences the accuracy of analytical results. In the present work, blank contamination and recovery of pretreatment procedures for analysis of OPEs in water samples were systematically examined for the first time. Blank contaminations were observed in filtration membranes, glass bottles, solid phase extraction cartridges, and nitrogen blowing instruments. These contaminations could be as high as 6.4-64 ng/L per treatment. Different kinds of membranes were compared in terms of contamination levels left after common glassware cleaning, and a special wash procedure was proposed to eliminate the contamination from membranes. Meanwhile, adsorption of highly hydrophobic OPEs on the inside wall of glass bottles was found to be 42.4%-86.1%, which was the primary cause of low recoveries and was significantly reduced by an additional washing step with acetonitrile. This work is expected to provide guidelines for the establishment of analysis methods for OPEs in aqueous samples.

International Journal of Environmental Analytical Chemistry, 2015

An efficient and fast microwave-assisted extraction (MAE) method followed by gas chromatographic ... more An efficient and fast microwave-assisted extraction (MAE) method followed by gas chromatographic separation with mass spectrometric detection (GC–MS) was developed for the extraction of 18 organochlorine pesticides (OCPs) from sediment. Parameters affecting the MAE procedure such as the type and volume of the extraction solvent, irradiation power, temperature and irradiation time were successfully optimised. Under the optimal conditions, extraction efficiencies in the range of 73.4–119% were obtained with THF–HEX (9:1, v/v) for all OCPs studied. The method was linear over the range of 2.9–5000 ng g−1 with determination coefficients (r2) higher than 0.992 for all analytes. The limits of detection, LODs (S/N = 3), obtained varied from 1.0 to 2.2 ng g−1 and limits of quantification, LOQs (S/N = 10) were between 2.9 and 6.8 ng g−1. The proposed method was successfully applied to the analysis of real sediment samples and acceptable recoveries from 70.1 to 124% with RSDs ≤14.8% were obtained. 10 OCPs were determined below their LOQ and 8 OCPs in the range of 124–2830 ng g−1. The MAE method was compared with Soxhlet, shake flask and ultrasonic solvent extraction techniques. Thus, the MAE–GC–MS method could efficiently be used for selective extraction and quantification of the target analytes from the complex sediment matrices.

Trac-Trends in Analytical Chemistry, 2012

There is a growing production and application of silver nanoparticles (AgNPs) (e.g., in cosmetics... more There is a growing production and application of silver nanoparticles (AgNPs) (e.g., in cosmetics products, food technology, textiles and fabrics, and medical products and devices). The rapid growth in the commercial use of AgNPs will inevitably increase exposure to silver in the environment and among the general population. Compared to the vast application of silver, information on the fate, the transformation and the toxicity of AgNPs is very limited. Lack of proper techniques to trace AgNPs in complex matrixes hinders investigation. Thus, development of methods for analysis of AgNPs is very important to achieve detailed insights into the fate, the transport and exposure of AgNPs in environment. This review presents state-of-the-art methods for separation, identification, characterization and quantification of AgNPs. We also discuss perspectives on future developments.

Acta Chimica Sinica, 2013

摘要本研究发展了一种采用磁性介孔微球 Fe 3 O 4 @nSiO 2 @mSiO 2 测定溶液中多环芳烃(PAHs)和牛血清蛋白(BSA)结合常数(K BSA)的方法. 在合成 Fe 3 ... more 摘要本研究发展了一种采用磁性介孔微球 Fe 3 O 4 @nSiO 2 @mSiO 2 测定溶液中多环芳烃(PAHs)和牛血清蛋白(BSA)结合常数(K BSA)的方法. 在合成 Fe 3 O 4 @nSiO 2 @mSiO 2 微球时, 将少量的十六烷基三甲基铵阳离子(CTAM ＋)模板保留在介孔内作为萃取水体中自由溶解态 PAHs 的吸附剂, 而与溶液中的 BSA 及其结合的 PAHs 则由于体积排阻作用不被萃取. 微球外层很薄的介孔层(≈50 nm)显著缩短了水体中 PAHs 向介孔内 CTAM ＋迁移的路径, 而微球较大的表面积(186 m 2 /g)和孔体积(0.16 cm 3 /g)增大了微球在水体中与 PAHs 的接触面积, 使其能够快速富集水体中的自由溶解态 PAHs, 萃取平衡时间(t 90%)仅为 66 min. 实验测定了不同 BSA 浓度条件下 PAHs 自由溶解态分数, 并据此计算得到 PAHs 与 BSA 的结合常数 lgK BSA ＝3.

Environmental Science-Processes & Impacts, 2013

Silver nanoparticles (AgNPs) are well known for their excellent antibacterial ability and superio... more Silver nanoparticles (AgNPs) are well known for their excellent antibacterial ability and superior physical properties, and are widely used in a growing number of applications ranging from home disinfectants and medical devices to water purificants. However, with the accelerating production and introduction of AgNPs into commercial products, there is likelihood of release into the environment, which raises health and environmental concerns. This article provides a critical review of the state-of-knowledge about AgNPs, involving the history, analysis, source, fate and transport, and potential risks of AgNPs. Although great efforts have been made in each of these aspects, there are still many questions to be answered to reach a comprehensive understanding of the positive and negative effects of AgNPs. In order to fully investigate the fate and transport of AgNPs in the environment, appropriate methods for the preconcentration, separation and speciation of AgNPs should be developed, and analytical tools for the characterization and detection of AgNPs in complicated environmental samples are also urgently needed. To elucidate the environmental transformation of AgNPs, the behavior of AgNPs should be thoroughly monitored in complex environmental relevant conditions. Furthermore, additional in vivo toxicity studies should be carried out to understand the exact toxicity mechanism of AgNPs, and to predict the health effects to humans. Environmental impact There is a growing production and application of silver nanoparticles (AgNPs) in various areas including catalysis, consumer products, food technology, textiles/ fabrics, as well as medical products and devices. It was reported that about 25% of the >1300 nanomaterial-containing consumer products contain AgNPs. The rapid growth in the commercial use of AgNPs will inevitably increase silver exposure in the environment and the general population. To correctly forecast their environmental and human health risks, a comprehensive understanding of the source, distribution, transformation and toxicity of AgNPs is needed. This article reviews the available information on the environmental and toxicological chemistry of AgNPs. There are still many gaps our knowledge that have to be lled to fully understand the benets and risks of AgNPs.

Nanoscale, 2014

AgNO 3 , poly(vinyl alcohol)-124 (PVA), sodium arsenate (As(V)), malachite green (MG), acetone, t... more AgNO 3 , poly(vinyl alcohol)-124 (PVA), sodium arsenate (As(V)), malachite green (MG), acetone, toluene, and chloroform were analytical grade and purchased from Sinopharm Chemical Reagent Co. (Beijing, China). KBH 4 was purchased from Jinke Chemical Research Institute (Tianjin, China). Dimethyldichlorosilane (DMCS) and other chemicals were purchased from Sigma-Aldrich (St. Louis, MO, US) and used without further purification. Ultrapure water was obtained from a Milli-Q ultrapure water system (Millipore, Bedford, MA). Different pH values of aqueous solutions were adjusted by NaOH or HCl. Nanoparticle synthesis.

TrAC Trends in Analytical Chemistry, 2012

Ionic liquids (ILs) are regarded as non-molecular solvents, as they are composed entirely of cati... more Ionic liquids (ILs) are regarded as non-molecular solvents, as they are composed entirely of cations and anions. ILs possess several excellent unique properties (e.g., low volatility, high thermal stability, specific electrochemical characteristics, easy design, tunable viscosity, and miscibility with water or organic solvents). These properties make ILs attractive candidates for various analytical applications, the number of publications on which has increased exponentially in the past decade. This article presents an overview of representative applications of ILs in advances in analytical chemistry that benefited from the unique properties of ILs, including the development achieved by using ILs as extraction solvents, dissolution solvents and separation media.

Spectrochimica Acta Part B: Atomic Spectroscopy, 2007

A new procedure, based on hollow fiber supported liquid membrane preconcentration coupled with gr... more A new procedure, based on hollow fiber supported liquid membrane preconcentration coupled with graphite furnace atomic absorption spectrometry (GFAAS) detection, was developed for the determination of trace Cd in seawater samples. With 1-octanol that contained a mixture of dithizone (carrier) and oleic acid immobilized in the pores of the polypropylene hollow fiber as a liquid membrane, Cd was selectively extracted from water samples into 0.05 M HNO 3 that filled the lumen of the hollow fiber as a stripping solution. The main extraction related parameters were optimized, and the effects of salinity and some coexisting interferants were also evaluated. Under the optimum extraction conditions, an enrichment factor of 387 was obtained for a 100-mL sample solution. In combination with graphite furnace atomic absorption spectrometry, a very low detection limit (0.8 ng L − 1) and a relative standard deviation (2.5% at 50 ng L − 1 level) were achieved. Five seawater samples were analyzed by the proposed method without dilution, with detected Cd concentration in the range of 56.4-264.8 ng L − 1 and the relative spiked recoveries over 89%. For comparison, these samples were also analyzed by the Inductively Coupled Plasma Mass Spectrometry (ICP-MS) method after a 10fold dilution for matrix effect elimination. Statistical analysis with a one-way ANOVA shows no significant differences (at 0.05 level) between the results obtained by the proposed and ICP-MS methods. Additionally, analysis of certified reference materials (GBW (E) 080040) shows good agreement with the certified value. These results indicate that this present method is very sensitive and reliable, and can effectively eliminate complex matrix interferences in seawater samples.

Microchimica Acta, 2004

In order to achieve rapid on-site screening and solve the problem of rapid pretreatment for the d... more In order to achieve rapid on-site screening and solve the problem of rapid pretreatment for the determination of lead (Pb 2+) and cadmium (Cd 2+) in cereals by a portable electrochemical analyzer with disposable screen-printed electrodes (SPEs), a new reliable and simple extraction method for Pb 2+ and Cd 2+ in cereals was developed. The Pb 2+ and Cd 2+ in cereals were purified by a mixed solution of 1 mol L À1 potassium iodide (KI)/5% vitamin C (VC)/ethyl acetate after being extracted by 10% HNO 3 , which transfers the Pb 2+ and Cd 2+ into ethyl acetate after a reaction with KI-VC. Then, the Pb 2+ and Cd 2+ were eluted from ethyl acetate with 5% HNO 3 and were determined by an electrochemical analyzer with screen printed electrodes. Under the optimized conditions, the matrix calibration curves of Pb 2+ and Cd 2+ in rice and wheat showed good linear relationships with R 2 > 0.996. The method shows a detection limit (LOD) for Cd 2+ in rice and wheat of 6.7 mg kg À1 and 11.5 mg kg À1 , and the corresponding values for Pb 2+ were 34.9 and 31.1 mg kg À1 , respectively. The relative standard deviation (RSD) was less than 8.7% for Cd 2+ and Pb 2+. In addition, the recoveries of the tested reference materials using this method were between 80% and 120%. From sample pretreatment to testing results, the whole process took no more than 25 min, and the operation was simple for operators, green to the environment, cheap in terms of instruments, and above all suitable for on-site detection. The results implied that this portable electrochemical method with new pretreatment may be a good choice for screening Pb 2+ and Cd 2+ in cereal samples on-site.

Microchimica Acta, 2009

Speciation of mercury was accomplished by using a simple interface with photo-induced chemical va... more Speciation of mercury was accomplished by using a simple interface with photo-induced chemical vapour generation in a high performance liquid chromatography-atomic fluorescence spectrometry (HPLC-AFS) hyphenated system. Acetic acid and 2-mercaptoethanol in the mobile phase were used as photochemical reagent. The operating parameters were optimized to give limits of detection of 0.53 µg L −1 , 0.22 µg L −1 , 0.18 µg L −1 and 0.25 µg L −1 for inorganic mercury, methylmercury, ethylmercury and phenylmercury, respectively. The method was validated with the certified reference material DORM-2 and applied to the analysis of seafood samples. The HPLC-AFS hyphenated system is simple, environmentally friendly, and represents an attractive alternative to the conventional peroxothiosulfate-borohydride method.

Journal of Analytical Atomic Spectrometry, 2007

A novel on-line coupled high performance liquid chromatography (HPLC)-hydride generation (HG)-mic... more A novel on-line coupled high performance liquid chromatography (HPLC)-hydride generation (HG)-microporous membrane gas-liquid separator (MGLS)-quartz surface-induced luminescence flame photometric detector (QSIL-FPD) system was developed for the speciation of methyltins. Methyltin compounds were separated by HPLC, and then on-line reacted with potassium borohydride to generate volatile hydride products. The volatile derivatization products were in-line separated from the liquid matrix with MGLS and further introduced into the cheap and specific QSIL-FPD for detection. With a mobile phase of 70% methanol, 3% acetic acid and 27% water, which contains 0.1% tropolone as complexant, at a 0.3 mL min À1 flow rate, monomethyltin (MMT), dimethyltin (DMT) and trimethyltin (TMT) were baseline separated in less than 13 minutes by reversed phase HPLC. Both derivatization reagents, 0.5% KBH 4 and 2% acetic acid, were introduced into the system simultaneously at the same flow rate of 0.4 mL min À1. Calibration curves, based on peak heights vs. concentration, were linear in the range of 1-100 ng mL À1 of methyltins with correlation coefficients of 0.9980, 0.9911 and 0.9975 for MMT, DMT and TMT, respectively. The relative standard deviations measured at 10 ng mL À1 (for MMT and DMT) and 5 ng mL À1 (for TMT) level were in the range of 2.0-3.8% (n = 3) for the studied methyltins, and the calculated detection limits (S/N = 3) for MMT, DMT and TMT were 1.69, 0.51 and 0.36 ng mL À1 , respectively. This developed method was applied to the speciation of methyltins in seawater with spiked recovery in the range of 95.9-100.7%. This method was also applied to the determination of the methyltin compounds in wastewater and the process solutions (the mixtures of methyltin trichloride and dimethyltin dichloride) which are the intermediates of methyltin mercaptide polyvinyl chloride heat stabilizer from a chemical factory.

Environmental Toxicology and Chemistry, 2009

A new sampling method, termed negligible depletion hollow fiber-protected liquid-phase microextra... more A new sampling method, termed negligible depletion hollow fiber-protected liquid-phase microextraction, was developed for sensing the freely dissolved concentration (C free) and evaluating the availability of atrazine (ATR), desethyl atrazine (DEA), and simazine (SIM) in water. The sampling device was prepared by impregnating 1-octanol to both the pores and the lumen of a piece of polypropylene microporous hollow fiber membrane. After equilibrium and negligible depletion extraction, the 1-octanol in the lumen of the hollow fiber (10 l) was collected for determination of triazines. Determination of C free and the distribution coefficient to 1-octanol (D OW) can be performed with this technique. A wide linear working range (1-200 g/L) and low detection limits (0.1-1 g/L) were obtained for triazines. Measured log D OW values of DEA (1.44 Ϯ 0.04), SIM (2.06 Ϯ 0.06), and ATR (2.33 Ϯ 0.05) agreed well with those reported in the literature. The measured D OW values were independent of the chemical concentration and sample pH (pH 3-10) and negligibly affected by the sample salinity (0-500 mM), suggesting that environmentally relevant pH and salinity have no significant effects on the availability of triazines. Although a slight (Յ31%) increase of C free was observed, one-way analysis of variance indicated the C free of triazines were not significantly affected by the presence of Aldrich humic acid, Acros humic acid, and bovine albumin V (dissolved organic carbon [DOC], 0-100 mg/L). From 3 to 36% of the spiked triazines, however, were found to associate with the dissolved organic matter (DOM) in surface-water samples (DOC, 32.0-61.9 mg/L), suggesting the origin of the DOM is a key parameter in determining its association with and, thus, the availability of triazines.

Environmental Science & Technology, 2013

Due to the widespread occurrence in the environment and potential risk toward organisms of fluoro... more Due to the widespread occurrence in the environment and potential risk toward organisms of fluoroquinolones (FQs), it is of importance to develop high efficient methods for assessing their occurrence and environmental risk. A monoclonal antibody (Mab) with broad cross-reactivity to FQs was produced by immunizing BALB/c mice with a synthesized immunogen prepared by conjugating ciprofloxacin with bovine serum albumin. This developed Mab (C2F3C2) showed broad and high cross-reactivity (40.3−116%) to 12 out of the 13 studied FQs. Using this Mab and norfloxacin conjugated with carrier protein ovalbumin as coating antigen, a timeresolved fluoroimmunoassay (TRFIA) method was developed for determining the total concentration of at least 12 FQs in environmental waters. The respective detection limit (LOD) and IC 50 calculated from the standard curve were 0.053 μg/L and 1.83 μg/L for enrofloxacin (ENR). The LODs of the other FQs, estimated based on the corresponding cross-reactivity and the LOD of ENR, were in the range of 0.051−0.10 μg/L. The developed TRFIA method showed good tolerance to various interfering substances present in environmental matrix at relevant levels, such as humic acids (0−10 mg/L DOC), water hardness (0−2% Ca 2+ and Mg 2+ , w/v), and heavy metals (0−1 mg/L). The spiked recoveries estimated by spiking 0.5, 1, and 2 μg/L of five representative FQs into various water samples including paddy water, tap water, pond water, and river water were in the range of 63−120%. The measured total FQ concentration by TRFIA agreed well with that of liquid chromatography−tandem mass spectrometry and was applied to directly evaluate the occurrence and environmental risk of FQs in the surface water of a case area. TRFIA showed high efficiency and great potential in environmental risk assessment as it measures directly the total concentration of a class of pollutants.

Chinese Science Bulletin, 2011

A novel dual-label time-resolved fluoroimmunoassay method was developed for the simultaneous dete... more A novel dual-label time-resolved fluoroimmunoassay method was developed for the simultaneous determination of chloramphenicol (CAP) and ractopamine (RAC) residues in 18 swine tissue samples, using anti-CAP and anti-RAC monoclonal antibodies labeled with europium (Eu 3+) and samarium (Sm 3+), respectively. The detection limits for CAP and RAC were 0.06 and 0.25 ng/g. The recovery from swine muscle samples was 102%-121% for CAP at spiking levels of 0.1-5 ng/g, and 69.8%-85.8% for RAC at spiking levels of 1-10 ng/g. The results obtained from the swine tissue samples using this method showed good agreement with those obtained using ELISA and GC-MS, with correlation coefficients (R) between 0.92-0.98.

Chinese Science Bulletin, 2012

Mercury (Hg), arsenic (As) and selenium (Se) are ubiquitous in the environment and exist in a var... more Mercury (Hg), arsenic (As) and selenium (Se) are ubiquitous in the environment and exist in a variety of species, which have great influence on their transport, bioaccumulation and toxicity. This review presents the recent research progress in speciation analysis of Hg, As, and Se, with emphasis on enhanced cold vapor generation as interface for liquid chromatography and atomic spectrometry, speciation of volatile species in gas phase, and isotope dilution technique to improve the precision and accuracy of speciation. Hyphenated techniques to characterize the complexes of Hg and As with phytochelatins and chromatographic separation coupled with multi-collector-inductively coupled plasma mass spectrometry to measure species-specific isotopic ratios, are also briefly discussed.