最新刊期
卷 40 ， 期 7 ， 2021
- 摘要：This paper is related to a method that magnetic composite material （Fe3O4@SiO2@β-CD） based on β-cyclodextrin（β-CD）was established by magnetic solid phase extraction－gas chromatography－mass spectrometry for determination of four pyrethroid pesticide residues in tobacco： bifenthrin， fenpropathrin， cyfluthrin and deltamethrin. The adsorption capacity for pyrethroid pesticides of composite materials bonded with different cyclodextrin derivatives， namely Fe3O4@SiO2@α-CD， Fe3O4@SiO2@β-CD and Fe3O4@SiO2@γ-CD， were studied and compared. The results of extraction experiments showed that the Fe3O4@SiO2@ β-CD had the superior extraction rate for four target analytes. The prepared Fe3O4@SiO2@β-CD was identified via scanning electron microscope， infrared spectroscopy， X-ray diffractometer and microporous adsorption material analysis tester. The effects of extraction time， desorption time， desorption solvent， solution pH value and salt ion concentration on the extraction performance of magnetic composite materials were investigated. Furthermore， the extraction capacity experiment was carried out to investigate the effect of β-CD modified magnetic composite material on the extraction performance. The results showed that the extraction capacity of Fe3O4@SiO2@β-CD material was enhanced significantly compared with unmodified Fe3O4 and Fe3O4@SiO2. An analytical method based on β-cyclodextrin magnetic composite magnetic solid phase extraction coupled with gas chromatography－mass spectrometry for the analysis of pyrethroid pesticide residues was established. The results show that the magnetic composite material Fe3O4@SiO2@β-CD can be used for the extraction and analysis of four pyrethroid pesticide residues in tobacco leaves. The linear ranges of four analytes are 0.1－3.0 mg/kg and the linear correlation coefficients are higher than 0.998. The detection limits are all 0.03 mg/kg. The recoveries of standard addition for four analytes are between 65.9% and 107%， and the relative standard deviations（n = 3） are between 0.70% and 12%.关键词：cyclodextrin;magnetic composite;magnetic solid-phase extraction;pyrethroid;tobacco leaf
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发布时间： - 摘要：A novel electrochemical genosensor was designed and fabricated for the detection of transgenic cauliflower mosaic virus 35S（CaMV 35S） promoter in this paper. Firstly， hemin functionalized reduced graphene oxide（Hemin－rGO） was prepared and modified onto the surface of a glassy carbon electrode（GCE）. And then， gold nanoparticles（AuNP） were electro-deposited on the surface of the Hemin－rGO to immobilize the thiolated capture DNA. By designing a sandwich-type sensing strategy， when the target sequence was present， the auxiliary DNA hybridized with the target and capture probe to form a double-strand and used its thiolated 5'-end to covalently bind to AuNP. Meanwhile， the amplified current response for the sensitive detection target CaMV 35S promoter sequence was obtained when the former was loaded with thionine（Thi）. Effects of buffer pH value， Thi concentration， soaking time of AuNP， and incubation time of DNA sequences were investigated. The optimal conditions were as follows： pH 7.4， Thi concentration ：0.5 mmol/L， soaking time of AuNP：40 min， incubation time of DNA sequences：60 min. Under the optimal conditions， there was a good linear relationship between DPV peak current and logarithms of the target concentration in the range of 1 × 10－16－1 × 10－10 mol/L， with a detection limit of 9.46 × 10－17 mol/L. The genosensor was applied to the detection of CaMV 35S promoter sequence in transgenic Arabidopsis samples with high selectivity， good stability and repeatability. The results obtained were consistent with those of the gel electrophoresis. This method has a good application prospect in the rapid detection and screening of genetically modified organism（GMO） ingredients in food， feed and other industrial products.关键词：genetically modified organism（GMO）;electrochemical genosensor;reduced graphene oxide;gold nanoparticle（AuNP）;thionine;hemin;label-free
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发布时间： - 摘要：Ru（bpy）32+－doped silica nanoparticles（RuSi NPs）， as one of the classical electrochemiluminescence（ECL） luminophores， not only simplify the immobilization process of Ru（bpy）32+， but also effectively improve the utilization rate of Ru（bpy）32+. However， the conductive inertness associated with Si significantly inhibits the electron transfer rate of Ru（bpy）32+， thereby significantly reducing the ECL emission efficiency of RuSi NPs， which， in turn，limits the application of RuSi NPs in ECL sensors. Herein， a kind of highly ordered flower-like hierarchical titanium dioxide micro-nanoparticles（fl-TiO2） with a uniform particle size approximately 5.0 μm were prepared by a solvothermal method. Furthermore， the amino-functionalized fl-TiO2（fl-TiO2-NH2） was synthesized by a simple post-synthesis grafting method using（3-aminopropyl） triethoxysilane（APTES） as the coupling agent. Subsequently， platinum nanoparticles（Pt NPs） were successfully assembled on the surface of fl-TiO2-NH2 via electrostatic interaction to fabricate a new kind of fl-TiO2/Pt NP composites（fl-TiO2/Pt NPs）. Finally， fl-TiO2/Pt NPs/RuSi NPs hybrids were prepared by mixing fl-TiO2/Pt NPs and RuSi NPs in redistilled water to form a uniform dispersed solution， which were immobilized on the surface of glassy carbon electrode（GCE） to develop a novel ECL sensor（fl-TiO2/Pt NPs/RuSi NPs/GCE）. The morphologies， structures， physical properties， and chemical compositions of different materials were characterized using techniques such as scanning electron microscopy， UV－Vis absorption spectroscopy， X-ray diffraction， and energy spectroscopy. The electrochemical behavior and ECL performance of the proposed ECL sensor were also studied using cyclic voltammetry， alternating current impedance， and ECL techniques. The experimental results suggested that the ECL intensity of RuSi NPs－tripropylamine（TPrA） system enhanced significantly owing to the excellent electrocatalytic activity of Pt NPs， and the large specific surface area of fl-TiO2 provided abundant binding sites for Pt NPs and RuSi NPs. Thus， the fl-TiO2/Pt NPs could be used as a novel ECL signal amplifier for enhancing the ECL emission efficiency of RuSi NPs－TPrA system. Under the optimized experimental conditions， the ECL intensity of fl-TiO2/Pt NPs/RuSi NPs was 1.5 and 1.8 times higher than that of fl-TiO2/RuSi NPs and pure RuSi NPs， respectively. Meanwhile， the stable ECL emission from fl-TiO2/Pt NPs/RuSi NPs－TPrA system could be strongly quenched by phenylephrine（PHE）. Based on the strong interaction between PHE and RuSi NPs， the designed ECL sensor demonstrated a wide linear range from 1.0 × 10－7 to 8.0 × 10－5 mol/L（r2 = 0.998 4） with a detection limit（S/N = 3） of 2.5 × 10－8 mol/L for PHE， and it was successfully applied to the determination of PHE in phenylephrine hydrochloride injection with excellent long-term stability， good reproducibility， and high selectivity. The recoveries ranged from 99.2% to 108%. This work proposes a novel ECL signal amplification strategy for the construction of ECL sensing platform， which is anticipated to extend the applications of ECL sensors in drug analysis.关键词：flower-like titanium dioxide;Pt NPs;Ru（bpy）+;electrochemiluminescence（ECL）;phenylephrine;signal amplification
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发布时间： - 摘要：A method suitable for qualitative and quantitative analysis was established to determine the main volatile organic compounds（VOCs） in poly（butylene adipate terephthalate）（PBAT） biodegradable films by headspace-solid-phase microextraction（HS－SPME） combined with comprehensive two-dimensional gas chromatography－time-of-flight mass spectrometry（GC × GC－TOF MS）. Effects of type of SPME fiber， equilibrium temperature， equilibrium time and extraction time on extraction efficiencies for VOCs in biodegradable films were investigated. The optimal SPME extraction conditions were as follows： polydimethylsiloxane－divinylbenzene－carboxen（PDMS－DVB－CAR） fiber was at 80 ℃ extraction temperature for equilibrium time of 10 min and extraction time of 40 min. Then the fiber was introduced into the GC × GC－TOF MS injector port and the extract was desorbed at 260 ℃ for 3 min. The VOCs were identified using standard mass spectrum databases and structure spectra and quantified by internal standard method. Results indicated that 55 VOCs in the biodegradable film were identified. Compared with one-dimensional GC－MS， GC × GC－TOF MS can effectively separate homologues， isomers， and interfering compounds， and then obtain more accurate quantitative results. The identified compounds can be divided into 9 types according to the compound structure， including： benzenes， naphthalenes， aldehydes and ketones， alcohols， esters， indenes， amines， phenols， others， etc. The intra-day and inter-day precision are both no more than 19% with good repeatability and reproducibility. The 55 VOCs in 4 kinds （A，B，C，D） of PBAT biodegradable films from different manufacturers were analyzed with multivariate statistical analysis. The principal component analysis（PCA） showed that PBAT A+B， PBAT C and PBAT D are obviously different， while PBAT A and PBAT B samples overlap. The PBAT biodegradable films from different manufacturers can be distinguished with VOCs composition， and each biodegradable film has a characteristic difference， The heatmap analysis shows the higher benzene homologues for PBAT D and naphthalene， amines， phenol for PBAT A+B， while lower VOCs for PBAT C. The method of combining HS－SPME and GC × GC－TOF MS has accurate， reliable， simple， rapid advantages and the VOCs results can provide reference value for the safety evaluation and use of PBAT biodegradable film.关键词：PBAT biodegradable films;headspace solid-phase microextraction;comprehensive two-dimensional gas chromatography－time-of-flight mass spectrometry;volatile organic compounds
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发布时间： - 摘要：In this study the censored data of inductively coupled plasma mass spectrometry with support vector machine were employed in order to identify honeys according to their botanical source. 97 samples were collected for this study， including four kinds of honeys such as vitex honey samples， acacia honey samples， sunflower honey samples and rape honey samples. After pretreated by microwave digestion， the 16 kinds of metal elements in honey samples were measured by inductively coupled plasma mass spectrometry and 13 kinds of metal elements with significant differences were studied. The support vector machine classification model based on Gaussian radial basis function was established by using the metal elements with and without censored data as input variables. Then， the penalty parameter c and the kernel function parameter g of the support vector machine model were optimized by three optimization algorithms： grid search， genetic algorithm and particle swarm optimization. The result showed that there are 9 kinds of metal elements have censored data， namely Al， Ti， Cr， Ni， As， Se， Cd， Ba， Pb. The analysis of variance results showed that 12 kinds of metal elements such as Na， Mg， Al， K， Ca， Mn， Ni， Cu， Zn， Se， Ba and Pb have extremely significant differences in 95% confidence interval（p < 0.01）， the element of As has significant differences in 95% confidence interval（p < 0.05） and the elements of Ti， Cr and Cd have no significant differences in 95% confidence interval（p > 0.05） among four different botanical source honeys. The censored data was processed to the one-half of the detection limit value by using the substitution method and the support vector machine model which established by censored data of metal elements as input variables has better results than the support vector machine model which without the censored data. The accuracy rate of the model established with censored data is 91.8%， while the accuracy rate of the model established without censored data is only 82.5%. Further optimization of penalty parameter c and kernel function parameter g in classification model by using grid search， genetic algorithm and particle swarm optimization， the support vector machine model with the penalty parameter c of 62.8 and the kernel function parameter g of 1.26 was the best by using particle swarm optimization. The correct rate of comprehensive discrimination of the best support vector machine classification model is 96.9%. It is concluded that it is feasible to identify honey botanical source through the substitution method which made the censored data to the one-half of the detection limit value and also shows that the optimized support vector machine model with censored data of inductively coupled plasma mass spectrometry can improve the accuracy of model discrimination and identify effectively honey samples from different botanical sources.关键词：inductively coupled plasma mass spectrometry;censored data;honey;botanical source;support vector machine;identification
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发布时间： - 摘要：In order to prevent the mildew of tissue paper and paper products， organic antibacterial agents are often used in the process of production, processing and storage. After a long-term accumulation and reaching a certain amount， the harm of the organic antibacterial agents to the environment and human body can not be ignored. However, there are few methods to detect a variety of organic antibacterial agents in tissue paper and paper products. A high performance liquid chromatographic（HPLC） method was established for the simultaneous extraction and determination of 19 organic antibacterial agents， including seven kinds of chlorophenols， six kinds of quaternary ammoniums and six kinds of p-hydroxybenzoic acid esters in tissue paper and paper products. The samples were firstly extracted twice with methanol containing 0.5% formic acid， then centrifuged at 9 000 r/min for 3 min and suctioned filtration with buchner funnel to collect filtrate. The filtrate was evaporated at 45 ℃ and condensed into about 1 mL， and then dried with nitrogen， dissolved with 2.0 mL methanol－water solution（1∶1， by volume）. 19 organic antibacterial agents were separated on a Welch Ultimate AQ C18 column（250 mm ×4.6 mm， 5 μm） by gradient elution， with methanol, acetonitrile and 0.05% phosphoric acid solution（containing 0.475 3 g tetrabutylammonium hydrogen sulfate） as mobile phases， then detected with photo-diode array detector（PDAD） at 191－400 nm. Results indicated that the calibration curves of chlorophenols， quaternary ammoniums and p-hydroxybenzoic acid esters showed good linear relationships in the ranges of 0.05－20 mg/L， 0.1－20 mg/L and 0.02－50 mg/L， respectively， with their correlation coefficients(r) not less than 0.996 0. The limits of detection(LOD， S/N ≥ 3) for 19 organic antibacterial agents were in the range of 0.05－0.3 mg/kg. The average recoveries of this method ranged from 74.8% to 101% with relative standard deviations(RSD， n=6) of 2.2%－5.6%. The developed method was used to evaluate the 19 organic antibacterial agents in wet tissue， facial tissue and paper cups. The results showed that the 19 organic antibacterial agents were not detected in facial tissue and paper cups. Chlorophenols were not found in wet tissue， but methyl 4-hydroxybenzoate was detected in two batches of wet tissue， with contents of 11.3 mg/kg and 15.4 mg/kg， respectively. Benzethonium chloride was detected in one batch of wet tissue， and the content was 132.3 mg/kg. Benzethonium chloride and cetylpyridinium chloride were simultaneously detected in one batch of wet tissues， and the contents were 152.2 mg/kg and 246.5 mg/kg， respectively. Therefore， the method is simple， rapid， accurate and reliable， and could be used to identify and detect 19 organic antibacterial agents in tissue paper and paper products.关键词：high performance liquid chromatography;tissue paper and products;organic antibacterial agent;chlorophenol;quaternary ammonium;p-hydroxybenzoic acid esters
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发布时间：2021-03-23 - 摘要：A liquid chromatography(LC) with ultrasonic extraction and online solid phase extraction(online SPE) concentration was developed for the determination of 15 polycyclic aromatic hydrocarbons(PAHs) in atmospheric particulate matters. Through the optimization of instrument analysis， sample extraction and preparation， and elimination of ion interference, the best experimental conditions were obtained. A slice of 1.4 cm2 was cut from a particulate filter membrane sample， and extracted with 2 mL acetonitrile by ultrasonic extration for 10 min. The extract was high-speedily centrifugated to remove the suspended particles， then prepared as an solution containing 25% (by volume) acetonitrile. 2 mL of the prepared solution was directly injected into the online SPE/LC. Online purification and enrichment of the samples were carried out on an Acclaim Polar Advantage Ⅱ C18 SPE column(50 mm × 4.6 mm， 3 μm). 15 PAHs were separated on a Hypersil Green PAH column(150 mm × 3 mm, 3 μm) with 0.05 mol/L ammonium acetate solution－acetonitrile as mobile phase， and detected by fluorescent detector. The linear correlation coefficients of the 15 PAHs were greater than 0.992. Calculated by air volume of 23 m3 and filter membrane area of 12 cm2， the limits of detection(LOD) of the method were in the range of 0.03 × 10－3－33.27 × 10－3 ng/m3 ， in which the LOD for benzo(a)pyrene(B(a)P) was 0.67 × 10－3 ng/m3. The recoveries for 15 PAHs at two spiked levels of 40 ng/L and 200 ng/L were in the ranges of 91.4%－126% and 103%－123%， with relative standard deviations(RSD， n=6) of 4.4%－10% and 5.2%－12%， respectively. The method is simple， sensitive and low sample consumptive(1.4 cm2)， and could meet the requirements for analysis of ultra-trace PAHs in atmospheric particulate matters.关键词：atmospheric particulate matters;polycyclic aromatic hydrocarbons(PAHs);liquid chromatography(LC);ultrasonic extraction;online solid phase extraction(online SPE);fluorescence detection
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发布时间： - 摘要：A chlorpyrifos molecularly imprinted polymer membrane was synthesized by electropolymerization， with BiOI nanosheets as the carrier， chlorpyrifos as the template molecule， p-mercaptoaniline as the functional monomer and glutaraldehyde as the crosslinking agent. Based on this， a dual-recognition photoelectrochemical sensor for chlorpyrifos（CPF）was constructed by immobilizing acetylcholinesterase（AChE） on the surface of the imprinted membrane. The current－time method （I－t） was used to detect chlorpyrifos in water samples.Acetylthiocholine chloride（ATCl） concentration and pH value were optimized. Results showed that，under the optimal experimental conditions（1.0 mmol/L ATCl，pH 7.0）， the peak currents and chlorpyrifos concentrations were linear in the ranges of 0.02－1.0 nmol/L and 20.0－200.0 nmol/L. The linear equations were inhibition rate（%） = 49.253 CCPF + 9.433（r2 = 0.998 6） and inhibition rate（%） = 0.193 CCPF + 57.599（r2 = 0.999 1）， respectively. The detection limit（S/N = 3） was 0.005 nmol/L. The sensor had a good selective recognition ability， reproducibility（RSD = 4.2%） and stability for chlorpyrifos. The method was successfully applied to the detection of trace chlorpyrifos in water samples， with spiked recoveries of 96.1% －108%， and RSDs of 2.8%－4.2%.关键词：BiOI nanosheets;chlorpyrifos;molecular imprinting;acetylcholinesterase（AChE）;water sample;photoelectrochemical sensor
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发布时间： - 摘要：A gas chromatography－tandem mass spectrometry（GC－MS/MS） method was established for the simultaneous determination of 10 alkaloids in refill solutions for electronic cigarettes. The instruments and pretreatment conditions were critically examined. The sample was added with 2.0 mL of 2% sodium hydroxide and extracted for 30 min with 10 mL of dichloromethane/methyl alcohol（4∶1， by volume）. The sample extracts were determined by gas chromatography－tandem mass spectrometry under multiple reaction monitoring（MRM） mode after removal of water with anhydrous magnesium sulfate. Results showed that nicotine and nine minor alkaloids presented good linear relationships in the concentration range of 25－1 000 μg/mL and 0.002 5－20 μg/mL， respectively. The linear correlation coefficients were above 0.997， the limits of detection（LOD） ranged from 0.004 0 mg/kg to 0.10 mg/kg， the limits of quantitation were 0.013－0.33 mg/kg， the recoveries ranged from 87.9% to 109% at three spiked levels， and the relative standard deviations（RSDs） for both intra-and inter-day were no more than 6.8% and 7.9%， respectively. The results indicated that the method was sensitive， accurate and reproducible， and suitable for the determination of 10 alkaloids in refill solutions for electronic cigarettes. The method was successfully applied to the analysis of 171 refill solutions for 23 brands. Nicotine levels in refill solutions varied considerably， ranging from 2.16 mg/g to 23.73 mg/g. The median concentrations of nine minor alkaloids were 0.06－7.35 mg/kg， with the detection rate ranging from 64.91% to 99.42%. The proportion of total minor alkaloids to nicotine content in nine electronic cigarette liquid samples was more than 1.0%.关键词：alkaloids;liquid－liquid extraction;gas chromatography－tandem mass spectrometry;refill solutions for electronic cigarettes
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发布时间： - 摘要：The car lampshade fragment is the physical evidence which often appears at the traffic accident case scene. In order to realize the accurate examination on the physical evidence of automobile lampshade， a spectral fusion technique combining the original spectrum and derivative spectrum was proposed. A total of 44 lampshades of different categories and brands were collected. The samples were analyzed by Fourier transform infrared spectroscopy （FTIR） to extract the original spectral data and first-order derivative spectral data， which were used to construct the classification model by combining with chemometrics. In Fisher discriminant analysis model， the classification accuracies for single original spectral data and first-derivative spectral data were 86.40% and 84.10%， respectively， while the classification accuracy for fused spectral data reached up to 93.20%， which was significantly higher than those for original spectral data and first-derivative spectral data. After the model optimization of principal component analysis， the classification accuracy for fusion spectrum reached up to 97.70%. In addition， when further classifying the lamp shade brands， the classification accuracy reached to 100.00%. The result of the experiment was ideal. However， in the K-nearest neighbor algorithm model， the classification accuracy was low due to the influence of uneven samples. Results showed that the spectral fusion technique based on the original spectrum and derivative spectrum could realize the accurate classification of automobile lampshade samples， which could provide a reference for the application of spectral fusion technique in the field of public security.关键词：automobile lampshade;Fourier transform infrared spectroscopy;spectral fusion;K-nearest neighbor algorithm;Fisher discriminant analysis
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发布时间： - 摘要：Different N-doped mesoporous carbons（N－CMK－3） were prepared by hard template method， using melamine， urea and ethylenediamine as nitrogen source， arabinose as carbon source and mesoporous silicon （SBA－15） as template agent. The samples were characterized by scanning electron microscopy（SEM）， transmission electron microscopy（TEM）， brunner emmet teller（BET）， X-ray diffraction（XRD） and X-ray photoelectron spectroscopy（XPS）. The N－CMK－3 were coated onto glassy carbon electrodes to construct electrochemical sensors. The electrochemical characteristics of N－CMK－3 modified electrodes were investigated by cyclic voltammetry. Effects of amount of modifier and pH value on the electrochemical behavior of nefopam hydrochloride were investigated. The results showed that， under the optimal experimental conditions of 6 µL modified dose and pH 4.5， nefopam hydrochloride had a good linear relationship（r2 = 0.992） between peak current and its concentration within 1.0 × 10－8－5.0 × 10－6 mol/L. The limit of detection（LOD， S/N = 3） was 5.3 × 10－9 mol/L．This method was applied to the detection of nafopam hydrochloride in human nafopam hydrochloride tablets， with recoveries of 95.9%－100%.关键词：N-doped mesoporous carbon;modified electrode;cyclic voltammetry;nefopam hydrochloride
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发布时间： - 摘要：Establishment of an accurate and efficient analytical method is the precondition to elaborate the mechanism of migration， transformation， fate and ecotoxicological effects of microplastics in the environment. The sample pre-processing methods， including four conditions of digestion and filter options were explored systematically in this paper， as well as the micro-infrared and Raman microscopy to detect microplastics. And it is the best digestion method using potassium hydroxide at 40 ℃ for 36 h and filter with mixed cellulose filter membrane. Based on research， the micro-infrared ATR， imaging mode and micro-Raman single-point detection mode could be used for detection when the microplastic particles are large， while the micro-Raman single-point detection mode or the imaging mode of micro-Raman and micro-infrared could be used for detection when the particles are small. Through the analysis of microplastics in typical bivalve marine organisms， the spectroscopic methods for microplastics detection were systematically explored in this paper.关键词：microplastics;bivalves;spectroscopy;analytical method
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发布时间：
Scientific Papers
- 摘要：Nowadays it is possible to automatically classify plastic waste by machine learning algorithms， which is of great significance for protecting the natural environment and saving resources. To establish better plastic classification models， the performances of multiplicative scatter correction－support vector machines(MSC－SVM) model and one-dimensional convolutional neural network(1D CNN) model were compared in identifying 4 types of plastic in this paper， as well as the accuracies of NIRS technique for classifying PP new raw material， PP recycled material， PE new raw material and PE recycled material， respectively. Based on the spectra data of 100 plastic samples， the experiment results showed that in validation set， the accuracy for MSC－SVM model is 90.8% while that for 1D CNN model is 91.5%. Particularly， 1D CNN model provided excellent classification results in identifying PE and PP new raw material samples with the accuracies reached up to 100%， which indicated that 1D CNN model is efficient to classify different types of plastic on small dataset.关键词：near-infrared spectroscopy;convolutional neural network;support vector machine;plastic classification
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发布时间： - 摘要：A reliable analytical method was developed for the simultaneous determination of 14 strobilurin fungicides in fruit wines based on ultra performance liquid chromatography－tandem mass spectrometry（UPLC－MS/MS） with QuEChERS. The samples were firstly extracted with acetonitrile， then purified by a modified QuEChERS method（200 mg C18 and 600 mg anhydrous MgSO4）， filtered through a 0.2 μm microporous membrane， and finally determined using the UPLC－MS/MS system. The seperation was performed on a Phenomenex Kinetex F5（3.0 mm × 100 mm， 2.6 μm） column by gradient elution， with acetonitrile and water as the mobile phases. The strobilurin fungicides were determined in positive electrospray ionization mode under multiple reaction monitoring（MRM） mode， and quantified by external standard method. Results showed that good linear relationships for the analytes existed in their respective ranges， with correlation coefficients（r2） all larger than 0.999. The limits of detection（LOD） and the limits of quantitation（LOQ） of the method were in the ranges of 0.002－0.723 μg/kg and 0.006－2.409 μg/kg， respectively. The recoveries for 14 strobilurin fungicides at three spiked levels of 5， 10 and 50 μg/kg ranged from 71.2% to 99.1% with relative standard deviations（RSD， n = 7） of 0.30%－9.4%. This method is simple， efficient， sensitive and accurate， and could be applied to the determination of strobilurin fungicide residues in fruit wine.关键词：ultra performance liquid chromatography－tandem mass spectrometry;QuEChERS;strobilurin fungicides;fruit wines
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发布时间：2021-04-07 - 摘要：A method was developed for the determination of residues of 7 antioxidants， i.e. antioxidant ZKF， antioxidant 259， antioxidant 1035， antioxidant 425， antioxidant 2246， antioxidant 1520 and antioxidant 565 in rubber seal gaskets for food contact by liquid chromatography－tandem mass spectrometry. By optimizing the chromatographic column， elution procedure and mass spectrometry conditions， the optimal detection conditions were determined. The rubber powder sample was obtained by freezing and grinding the rubber sample with a freezing grinding instrument. After comparing the recoveries of three kinds of filter membranes and high-speed centrifugation， the high-speed centrifugation method was adopted to pretreat the extract. In addition， three extraction methods including ultrasonic， reflux and microwave， and two extraction solvents including methanol and acetone were used to extract the antioxidants from the positive rubber powder samples to obtain the extraction solution. Microwave extraction with methanol was determined as the optimal pretreatment method with the extraction recovery and extraction efficiency as the evaluation indexes. The rubber powder samples（g） and methanol（mL） were mixed by the ratio of 1∶20， then extracted at 50 ℃ for 15 minutes under microwave condition. After high-speed centrifugation treatment， the extracted liquid samples were detected by liquid chromatography－tandem mass spectrometry. The separation was performed on an Acquity UPLC BEH C18（100 mm × 2.1 mm， 1.7 μm） column by gradient elution with acetonitrile－ammonium acetate aqueous solution（5 mmol/L） as the mobile phase， and the determination was carried out in positive and negative ion modes. Results showed that the limits of detection（LOD）， limits of quantitation（LOQ）， method limits of detection（MLOD） and method limits of quantitation（MLOQ） for the 7 antioxidants were in the ranges of 0.003－0.083 μg/L， 0.01－0.25 μg/L， 0.005－0.125 mg/kg and 0.02－0.40 mg/kg， respectively. There were good linear relationships for the 7 antioxidants in the mass concentration range of 0.01－0.5 mg/L， with their correlation coefficients（r2） all greater than 0.999. The average recoveries ranged from 73.1% to 120% with relative standard deviations（RSD， n=6） of 0.70%－9.3%， which indicated that the developed method was stable and accurate. Finally， 8 kinds of commercial food contact rubber gasket samples were detected by this method. It was found that antioxidant 259， antioxidant 425， antioxidant 1520 and antioxidant 2246 were detected in the commercial samples， while the others were undetected. This method could be used to detect 7 kinds of antioxidants simultaneously within 15 min， with a fast detection speed and a low detection limit， which could meet the needs for detection of antioxidants in food contact rubber materials and products.关键词：liquid chromatography－tandem mass spectrometry;rubber seal gasket for food contact;antioxidant;microwave extraction
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发布时间： - 摘要：A high performance liquid chromatography（HPLC）combined with resonance Rayleigh scattering（RRS） was developed for the determination of two H2-receptor blockers， famotidine（FMTD）and ranitidine（RNTD） in human urine. Separation conditions for HPLC were as follows： a volume ratio of 10 ： 90 for acetonitrile and sodium acetic acid（pH 4.5）， a flow rate of 0.5 mL/min， a Kinetex 5 µm C18 column（250 mm × 4.60 mm）， a sample size of 20 µL and a column temperature of 35 ℃. The optimal experimental conditions were investigated by a new post-column derivation method with metal ion Pd（Ⅱ） and dye erythrin（Ery） as the probes. Results showed that there were good linear relationships for FMTD and RNTD in the ranges of 0.024－25 μg/mL and 0.033－25 μg/mL， with their correlation coefficients（r） of 0.999 0 and 0.998 8， respectively. The detection limits（S/N） for FMTD and RNTD were 7.3 ng/mL and 10.1 ng/mL， respectively. This method was used for the determination of a known concentration of mixed samples. The spiked recoveries ranged from 97.8% to 102%， with relative standard deviations no more than 5.1%. Furthermore， the method was successfully applied to detect the content of FMTD in human urine， without any other matrixes in the urine to interfere the RRS signal. Therefore， the method is reliable and practical， and could be used to detect H2-receptor blockers in human urine.关键词：high performance liquid chromatography;resonance Rayleigh scattering;H2-receptor blockers;famotidine;ranitidine;urine
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发布时间： - 摘要：An ultra-performance liquid chromatography－tandem mass spectrometric（UPLC－MS/MS） method was developed for the determination of tretoquinol in pungent spice with MCX solid-phase extraction（SPE） purification. The samples were extracted with 0.2% acid ethanol， purified with a MCX column， and quantified by UPLC－MS/MS in MRM mode after gradient elution on an ACQUITY BEH C18 column with acetonitrile and 0.1% formic acid solution as mobile phase. The results showed that the calibration curves were linear in the range of 0.1－50 ng/mL with correlation coefficients（r） more than 0.998. The limits of detection （LODs） were 0.2 μg/kg and the limits of quantitation （LOQs） were 0.5 μg/kg. The average recoveries of tretoquinol at four different spiked levels （0.5， 2， 10， 100 μg/kg） ranged from 74.5% to 98.8%，with relative standard deviations（RSD） of 3.1%－9.1%. The proposed method is sensitive， accurate and reliable， and could be used for the determination of tretoquinol in pungent spice.关键词：tretoquinol;solid-phase extraction;ultra-performance liquid chromatography－tandem mass spectrometry（UPLC－MS/MS）;pungent spice
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Experimental Techniques and Methods
- 摘要：Covalent organic frameworks （COFs）are a recent class of porous functional materials composed of diverse light elements （C， H， O， N and B）through various robust covalent bonds. Their unique properties such as large surface areas， excellent stabilities， tunable pores， diverse functions and designable structures make COFs quite promising in analytical chemistry such as sample pretreatment and chromatographic separation. COFs used as novel stationary phases in high performance liquid chromatography （HPLC）， gas chromatography （GC）and capillary electrochromatography （CEC）have attracted great concerns recently. COFs with large surface area， good thermal and chemical stability are ideal candidates in GC. The good solvent stability and large surface area also make COFs potentially useful in HPLC and CEC. COFs used in chromatographic separation all possess good chemical stability， but have different specific surface area， topological structures， pore sizes， properties and selectivities， and are suitable for the resolution of different types of targets such as small organic molecules， position isomers and even chiral compounds. This review presents the recent progress on applications of COFs-based stationary phases and columns in chromatography. The preparation and applicability of these COFs-based stationary phases and columns in chromatographic separation are discussed. The application prospect of COFs in chromatographic separation is also presented.关键词：covalent－organic framework;stationary phase;high performance liquid chromatography（HPLC）;gas chromatography（GC）;capillary electrochromatography（CEC）
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发布时间： - 摘要：Advanced oxidation processes（AOPs）are widely applied to the treatment of organic pollutes， especially the treatment to the pollute that is hard to be removed by other methods. It is necessary to conduct qualitative and quantitative analyses on free radicals as the formation of strong oxidizing free radicals is the key factor in AOPs. An overview on the determination methods for free radicals generated from AOPs is provided in this paper， which include electron spin/paramagnetic resonance，high performance liquid chromatography， spectrophotometry， fluorescent spectrometry and electrochemical methods. The advantages and disadvantages of these methods are elaborated by comparing their veracity， accuracy and selectivity in qualitative and quantitative analysis processes. Finally， the perspectives for the development and application of these methods are further proposed in the paper.关键词：advanced oxidation processes;degradation of organic pollutants;active free radicals;qualitative and quantitative analysis;capture
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发布时间：
Reviews
- 摘要：Harmful components in dairy products include pesticide residues， veterinary drug residues， heavy metal residues， microorganisms， harmful additives and other noxious substances introduced from the packaging or transportation. These harmful components are harmful to people's health. However， it is a challenge to achieve accurate and rapid analysis of dairy products due to the diversity and substrates complexity of dairy samples， different structures and properties of various harmful substances， as well as their low content levels. Thus， to develop rapid and efficient sample preparation techniques， as well as accurate and sensitive analysis or detection methods is inevitable. In this paper， the progress in the preparation methods for dairy products in recent years is reviewed， including solid phase （micro）extraction， liquid phase （micro）extraction and immunoaffinity chromatography， etc. Meanwhile， this article introduces the progress of various analytical methods for these hazardous substances， such as chromatography， atomic spectroscopy， electrochemical analysis， biological immunoassay， molecular spectroscopy， etc. Furthermore， the advantages and disadvantages of laboratory analytical methods and on－site rapid detection methods are also compared， and the characteristics of these technologies are summarized. Finally， their future development trends are forecasted in the paper， anticipating to provide a support for the quality and safety supervision of dairy products in China.关键词：dairy products;harmful components;sample preparation;rapid detection
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发布时间：
Review
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