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2015 Volume 43 Issue 12
2015, 43(12): 1787-1793
doi: 10.11895/j.issn.0253-3820.100345
Abstract:
Bacillus thuringiensis(Bt), a unique bacterium which forms parasporal crystal protein and spore in parallel, is the most widely used environmentally in compatible biopesticide worldwide. Bt spore has a strong resistance to stress and adversity, and germinates rapidly once conditions are favorable for growth. In this work, differential interference contrast(DIC) microscopy was used to monitor the germination of individual Bt HD-1 spores, and the germination process was also investigated with Raman spectroscopy simultaneously. Experiment results showed that the decrease in normalized DIC intensity of Bt spore was consistent with the release of pyridine-2,6-pyridine dicarboxylic acid(dipicolinic acid[DPA]) determined by Raman spectroscopy. Temporal resolution of 6 seconds could well describe the dynamic process of spore germination. Bt spore showed similar germination kinetics triggered either by 10 mmol/L alanine at 37℃ in 25 mmol/L Tris-HCl buffer(pH 8.3) or in 25 mmol/L Hepes buffer(pH 7.4). Most spores did not germinate triggered by dodecylamine but germinated rapidly triggered by exogenous Ca-DPA. These results indicated that DIC microscopy imaging could be used to observe germination of individual Bt spores in real-time quantitatively, and help to the understanding of mechanisms of Bt spore germination and its heterogeneity.
Bacillus thuringiensis(Bt), a unique bacterium which forms parasporal crystal protein and spore in parallel, is the most widely used environmentally in compatible biopesticide worldwide. Bt spore has a strong resistance to stress and adversity, and germinates rapidly once conditions are favorable for growth. In this work, differential interference contrast(DIC) microscopy was used to monitor the germination of individual Bt HD-1 spores, and the germination process was also investigated with Raman spectroscopy simultaneously. Experiment results showed that the decrease in normalized DIC intensity of Bt spore was consistent with the release of pyridine-2,6-pyridine dicarboxylic acid(dipicolinic acid[DPA]) determined by Raman spectroscopy. Temporal resolution of 6 seconds could well describe the dynamic process of spore germination. Bt spore showed similar germination kinetics triggered either by 10 mmol/L alanine at 37℃ in 25 mmol/L Tris-HCl buffer(pH 8.3) or in 25 mmol/L Hepes buffer(pH 7.4). Most spores did not germinate triggered by dodecylamine but germinated rapidly triggered by exogenous Ca-DPA. These results indicated that DIC microscopy imaging could be used to observe germination of individual Bt spores in real-time quantitatively, and help to the understanding of mechanisms of Bt spore germination and its heterogeneity.
2015, 43(12): 1794-1800
doi: 10.11895/j.issn.0253-3820.150337
Abstract:
A nano-composite of phthalated Chitosan and magnetic ferroferric oxide nano-particle was prepared by mechanically mixing as method, and laccase was then adsorbed on the composite ot obtain immobilized laccase. Then the composite with laccase was dripped onto the surface of glassy carbon electrode and dried in air under room temperature to prepare laccase-immobilized biocathode. Catalytic effect in oxygen reduction reaction and performance of oxygen electrochemical sensor of this laccase-based electrode were systematically investigated by cyclic voltammetry, linear scanning voltammetry and chronoamperometry. Experimental results indicated that direct electron transfer between enzyme active centre T1 in laccase and conductive matrix ccould be achieved in solution without any electron relay, characterized with one-electron quasi-reversible redox reaction signal(Equilibrium potential:798 mV, very close to the formal potential of T1 centre in laccase 780 mV). It also featured with surface coverage of 1.5×10-9 mol/cm2 conductive enzyme molecules, electron relay rate of 0.05 s-1, onset potential for oxygen reduction of 930 mV, substrate turn-over frequency of 0.3 dioxygen molecules/s. Linear relationship in steady catalytic current of laccase-based electrode versus oxygen concentration was found within the oxygen concentration range of 2.6-33.9μmol/L under optimal conditions. This electrode as oxygen electrochemical sensor showed a low detection limit of 0.86μmol/L, high sensitivity(17.2μA·L/μmol), and Michaelis-Menten constant KM=131.1μmol/L. Further tests confirmed its excellent reproducibility and long-term usability in catalytic function towards oxygen reduction, with optimal pH=4.4.
A nano-composite of phthalated Chitosan and magnetic ferroferric oxide nano-particle was prepared by mechanically mixing as method, and laccase was then adsorbed on the composite ot obtain immobilized laccase. Then the composite with laccase was dripped onto the surface of glassy carbon electrode and dried in air under room temperature to prepare laccase-immobilized biocathode. Catalytic effect in oxygen reduction reaction and performance of oxygen electrochemical sensor of this laccase-based electrode were systematically investigated by cyclic voltammetry, linear scanning voltammetry and chronoamperometry. Experimental results indicated that direct electron transfer between enzyme active centre T1 in laccase and conductive matrix ccould be achieved in solution without any electron relay, characterized with one-electron quasi-reversible redox reaction signal(Equilibrium potential:798 mV, very close to the formal potential of T1 centre in laccase 780 mV). It also featured with surface coverage of 1.5×10-9 mol/cm2 conductive enzyme molecules, electron relay rate of 0.05 s-1, onset potential for oxygen reduction of 930 mV, substrate turn-over frequency of 0.3 dioxygen molecules/s. Linear relationship in steady catalytic current of laccase-based electrode versus oxygen concentration was found within the oxygen concentration range of 2.6-33.9μmol/L under optimal conditions. This electrode as oxygen electrochemical sensor showed a low detection limit of 0.86μmol/L, high sensitivity(17.2μA·L/μmol), and Michaelis-Menten constant KM=131.1μmol/L. Further tests confirmed its excellent reproducibility and long-term usability in catalytic function towards oxygen reduction, with optimal pH=4.4.
2015, 43(12): 1801-1807
doi: 10.11895/j.issn.0253-3820.150333
Abstract:
Based on photopolymerization property of poly(ethylene glycol) diacrylate(PEGDA), a 3D non-toxic, hydrophilic and biocompatible hydrogel microfluidic chip(60 mm×20 mm×3 mm), was specifically designed and fabricated. 2-Hydroxyethyl methacrylate(HEMA) was used to increase hydrophilicity of the chip, and 1-vinyl-2-pyrrolidone(NVP) was added to improve its toughness. The swelling ratio testing and the infrared spectrum characterization showed that the hydrogel microfluidic chip had excellent performance and stability. A colorimetric sensor array with 16 specific dyes was integrated into the chip for real-time detection of the metabolites of lung cells. The colorimetric value of the maps was extracted for calculating the squared Euclidean distance. The results of principal component analysis(PCA) suggested that the metabolic liquids of different lung cells could be easily distinguished. Thirty normal lung cell and lung cancer cell samples could be accurately clustered by hierarchical cluster analysis(HCA). The fabricated hydrogel microfluidic chip provides a novel method for clinically diagnosing.
Based on photopolymerization property of poly(ethylene glycol) diacrylate(PEGDA), a 3D non-toxic, hydrophilic and biocompatible hydrogel microfluidic chip(60 mm×20 mm×3 mm), was specifically designed and fabricated. 2-Hydroxyethyl methacrylate(HEMA) was used to increase hydrophilicity of the chip, and 1-vinyl-2-pyrrolidone(NVP) was added to improve its toughness. The swelling ratio testing and the infrared spectrum characterization showed that the hydrogel microfluidic chip had excellent performance and stability. A colorimetric sensor array with 16 specific dyes was integrated into the chip for real-time detection of the metabolites of lung cells. The colorimetric value of the maps was extracted for calculating the squared Euclidean distance. The results of principal component analysis(PCA) suggested that the metabolic liquids of different lung cells could be easily distinguished. Thirty normal lung cell and lung cancer cell samples could be accurately clustered by hierarchical cluster analysis(HCA). The fabricated hydrogel microfluidic chip provides a novel method for clinically diagnosing.
2015, 43(12): 1808-1813
doi: 10.11895/j.issn.0253-3820.150430
Abstract:
An intracellular metabonomics method based on gas chromatography coupled with mass spectrometer(GC-MS/MS) was established to explore the toxicity mechanism of aconitine and benzoylaconine. BeWo, the continuous cell lines originated from human placenta were selected to establish the in vitro placenta model. The intracellular metabolites were extracted after exposed with 5μg/mL aconitine and benzoylaconine for 0, 6, 12, 24 and 36 h, respectively. The intracellular metabolic profiling was acquired by GC-MS/MS. Orthogonal partial least squares discriminant analysis(OPLS-DA) score plot showed the time-dependent change of the metabolomics profiles between the control and intervention groups. After screened by variable influence on projection(VIP) value, one-way analysis of variance and searched with NIST 2014 database, we identified 11 metabolites, including proline, glycine, threonine, glutamic acid, N-acetylglutamine, glutamine, lysine, histidine, succinic acid, glucose and galactose, which mainly involved these pathways:(1) glutamine and glutamate metabolism,(2) glycine, serine and threonine metabolism,(3) alanine, aspartate and glutamate metabolism,(4) lysine degradation,(5) arginine and proline metabolism and(6) histidine metabolism. The results demonstrated that amino acid metabolism was the main metabolic pathway and responsible for the placental and fetal toxicity of aconitine and benzoylaconine.
An intracellular metabonomics method based on gas chromatography coupled with mass spectrometer(GC-MS/MS) was established to explore the toxicity mechanism of aconitine and benzoylaconine. BeWo, the continuous cell lines originated from human placenta were selected to establish the in vitro placenta model. The intracellular metabolites were extracted after exposed with 5μg/mL aconitine and benzoylaconine for 0, 6, 12, 24 and 36 h, respectively. The intracellular metabolic profiling was acquired by GC-MS/MS. Orthogonal partial least squares discriminant analysis(OPLS-DA) score plot showed the time-dependent change of the metabolomics profiles between the control and intervention groups. After screened by variable influence on projection(VIP) value, one-way analysis of variance and searched with NIST 2014 database, we identified 11 metabolites, including proline, glycine, threonine, glutamic acid, N-acetylglutamine, glutamine, lysine, histidine, succinic acid, glucose and galactose, which mainly involved these pathways:(1) glutamine and glutamate metabolism,(2) glycine, serine and threonine metabolism,(3) alanine, aspartate and glutamate metabolism,(4) lysine degradation,(5) arginine and proline metabolism and(6) histidine metabolism. The results demonstrated that amino acid metabolism was the main metabolic pathway and responsible for the placental and fetal toxicity of aconitine and benzoylaconine.
2015, 43(12): 1814-1819
doi: 10.11895/j.issn.0253-3820.150656
Abstract:
Differential mobility spectrometry(DMS), as a standard tool to detect submicron aerosol particles, is gradually expanding its application to molecular detection in recent years. However, the operating voltage(>1 kV) and gas flow(>100 L/min) of DMS are required in charged particles detection, whereas they are too large for field detection of ions. In this work, we designed a UV-DMS device with narrow gap ion drift tube, fabricated by thick film technology and able to operate under low flow rate(< 7 L/min) and low voltage(< 30 V). Four kinds of volatile organic compounds(VOCs)(acetone, 2-butatone, o-xylene, p-xylene) were chosen as examples to study the resolution, sensitivity and the obtaining of ion mobility. The results showed that the flow rate ratio of sheath gas and carrier gas Qs/Qa was the key parameter of UV-DMS resolution and sensitivity. The sensitivity of all examples increased significantly with Qs/Qa from 3 to 9 and then slowly decreased. Meanwhile, the resolution increased markedly with Qs/Qa from 3 to 6, and reached saturation during 6 to 10. Both sensitivity and resolution became unstable when Qs/Qa was over 10. The ion mobility deviation between experiment and reference was less than 3%. The detection limit was 0.6μg/L with S/N ratio of 3. This work provided a basis for the miniaturization and parameters optimization of DMS in molecular detection.
Differential mobility spectrometry(DMS), as a standard tool to detect submicron aerosol particles, is gradually expanding its application to molecular detection in recent years. However, the operating voltage(>1 kV) and gas flow(>100 L/min) of DMS are required in charged particles detection, whereas they are too large for field detection of ions. In this work, we designed a UV-DMS device with narrow gap ion drift tube, fabricated by thick film technology and able to operate under low flow rate(< 7 L/min) and low voltage(< 30 V). Four kinds of volatile organic compounds(VOCs)(acetone, 2-butatone, o-xylene, p-xylene) were chosen as examples to study the resolution, sensitivity and the obtaining of ion mobility. The results showed that the flow rate ratio of sheath gas and carrier gas Qs/Qa was the key parameter of UV-DMS resolution and sensitivity. The sensitivity of all examples increased significantly with Qs/Qa from 3 to 9 and then slowly decreased. Meanwhile, the resolution increased markedly with Qs/Qa from 3 to 6, and reached saturation during 6 to 10. Both sensitivity and resolution became unstable when Qs/Qa was over 10. The ion mobility deviation between experiment and reference was less than 3%. The detection limit was 0.6μg/L with S/N ratio of 3. This work provided a basis for the miniaturization and parameters optimization of DMS in molecular detection.
2015, 43(12): 1820-1828
doi: 10.11895/j.issn.0253-3820.150413
Abstract:
The synthesis and application of copper nanoclusters(CuNCs) as optical probe have attracted a great attention. The study shows that bovine serum albumin(BSA) CAN react with copper ions(Cu2+) in a base medium to form stable BSA-Cu complex. In the solution, the introduction of hydrogen peroxide can remarkably accelerate the formation of CuNCs. At the same time, the fluorescence intensity rapidly increases. Based on the fluorescence "light-on" response of BSA-Cu system, a kinetics method was developed for the fluorescent detection of hydrogen peroxide. The fluorescence intensity of BSA-Cu linearly increased with the increase of hydrogen peroxide in the range from 1.0×10-6 mol/L to 1.5×10-3 mol/L with the detection limit of 3.1×10-7 mol/L(S/N=3). After that, the collected BSA-Cu solution was placed until its fluorescence intensity increases to the maximum value, in which the Cu2+ ions were fully changed into CuNCs. The experiment demonstrated that the addition of L-cysteine into the solution led to an obvious fluorescence quenching. Based on the fluorescence "light-off" response of BSA-Cu system towards L-cysteine, an analytical method was established for the fluorescent determination of L-cysteine. The fluorescence intensity linearly reduced with the increase of L-cysteine concentration in the range of 2.0×10-4-1.0×10-2 mol/L with the detection limit of 5.7×10-5 mol/L(S/N=3). Finally, the resulted BSA-Cu waste was treated by high temperature ashing and then dissolving with sulfuric acid, in which the CuNCs were turned into Cu2+ ions. The resulting Cu2+ solution continued to be used for the detection of H2O2 and L-cysteine in the next cycle. In the work, the cycle detection of hydrogen peroxide and L-cysteine and reuse of copper could be achieved using the conversion between Cu2+ and copper nanoclusters. The method provides the characteristics of high sensitivity, low cost and environment-friendly, and can be widely used for routine analysis of hydrogen peroxide and L-cysteine.
The synthesis and application of copper nanoclusters(CuNCs) as optical probe have attracted a great attention. The study shows that bovine serum albumin(BSA) CAN react with copper ions(Cu2+) in a base medium to form stable BSA-Cu complex. In the solution, the introduction of hydrogen peroxide can remarkably accelerate the formation of CuNCs. At the same time, the fluorescence intensity rapidly increases. Based on the fluorescence "light-on" response of BSA-Cu system, a kinetics method was developed for the fluorescent detection of hydrogen peroxide. The fluorescence intensity of BSA-Cu linearly increased with the increase of hydrogen peroxide in the range from 1.0×10-6 mol/L to 1.5×10-3 mol/L with the detection limit of 3.1×10-7 mol/L(S/N=3). After that, the collected BSA-Cu solution was placed until its fluorescence intensity increases to the maximum value, in which the Cu2+ ions were fully changed into CuNCs. The experiment demonstrated that the addition of L-cysteine into the solution led to an obvious fluorescence quenching. Based on the fluorescence "light-off" response of BSA-Cu system towards L-cysteine, an analytical method was established for the fluorescent determination of L-cysteine. The fluorescence intensity linearly reduced with the increase of L-cysteine concentration in the range of 2.0×10-4-1.0×10-2 mol/L with the detection limit of 5.7×10-5 mol/L(S/N=3). Finally, the resulted BSA-Cu waste was treated by high temperature ashing and then dissolving with sulfuric acid, in which the CuNCs were turned into Cu2+ ions. The resulting Cu2+ solution continued to be used for the detection of H2O2 and L-cysteine in the next cycle. In the work, the cycle detection of hydrogen peroxide and L-cysteine and reuse of copper could be achieved using the conversion between Cu2+ and copper nanoclusters. The method provides the characteristics of high sensitivity, low cost and environment-friendly, and can be widely used for routine analysis of hydrogen peroxide and L-cysteine.
2015, 43(12): 1829-1836
doi: 10.11895/j.issn.0253-3820.150445
Abstract:
Nitroxyl(HNO), the one-electron reduced and protonated congener of nitric oxide(NO), has been demonstrated with excellent bio-pharmacological effects in cardiovascular disorder treatment, which is distinctive from that of NO. The high reactivity of HNO challenges the accurate detection. To resolve this problem, a near-infrared(NIR) metal-free fluorescent probe, ER-JN, was developed for the detection of intracellular HNO concentration in simulated physiological conditions and living cells. The probe was consisted of two moieties, the A BF2-chelated tetraarylazadipyrromethane fluorophore(aza-BODIPY) and the HNO recognition unit, diphenylphosphinobenzoyl group. The probe was purified by column chromatography on silica eluting with CH2Cl2 to give the product as a green solid with a yield of 28%. Our probe exhibited high sensitivity, good selectivity, and low cytotoxic effect, and could be applied to the fluorescent bio-imaging of HNO in simulated physiological conditions. When detected HNO, quantum yield increased from 0.01 to 0.35. The linear range located at 0-50μmol/L. The detection limit was 0.03μmol/L(S/N=3). With confocal laser scanning microscope imaging analysis, the probe could detect HNO concentration changes in living cells. Furthermore, the results of flow cytometry confirmed that our probe could be employed for the qualitative and quantitative detection of intracellular HNO concentration level. In this work, we found that probe ER-JN could not only detect HNO in aqueous and in living cells, but also targets endoplasmic reticulum. We anticipated that ER-JN would provide experimental bases in studying physiological and pathological functions of HNO in cells, in vitro and in vivo.
Nitroxyl(HNO), the one-electron reduced and protonated congener of nitric oxide(NO), has been demonstrated with excellent bio-pharmacological effects in cardiovascular disorder treatment, which is distinctive from that of NO. The high reactivity of HNO challenges the accurate detection. To resolve this problem, a near-infrared(NIR) metal-free fluorescent probe, ER-JN, was developed for the detection of intracellular HNO concentration in simulated physiological conditions and living cells. The probe was consisted of two moieties, the A BF2-chelated tetraarylazadipyrromethane fluorophore(aza-BODIPY) and the HNO recognition unit, diphenylphosphinobenzoyl group. The probe was purified by column chromatography on silica eluting with CH2Cl2 to give the product as a green solid with a yield of 28%. Our probe exhibited high sensitivity, good selectivity, and low cytotoxic effect, and could be applied to the fluorescent bio-imaging of HNO in simulated physiological conditions. When detected HNO, quantum yield increased from 0.01 to 0.35. The linear range located at 0-50μmol/L. The detection limit was 0.03μmol/L(S/N=3). With confocal laser scanning microscope imaging analysis, the probe could detect HNO concentration changes in living cells. Furthermore, the results of flow cytometry confirmed that our probe could be employed for the qualitative and quantitative detection of intracellular HNO concentration level. In this work, we found that probe ER-JN could not only detect HNO in aqueous and in living cells, but also targets endoplasmic reticulum. We anticipated that ER-JN would provide experimental bases in studying physiological and pathological functions of HNO in cells, in vitro and in vivo.
Immunochromatographic Assay for Quantitative Detection of Ochratoxin A in Maize by Quantum Dot Beads
2015, 43(12): 1837-1843
doi: 10.11895/j.issn.0253-3820.150468
Abstract:
Fluorescence probes were prepared by coupling the ascetic fluid containing anti-ochratoxin A(OTA) monoclonal antibody with quantum dot beads(QBs) using 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride method. The OTA-labeled bovine serum albumin(BSA) conjugates and donkey anti-mouse polyclonal antibodies were sprayed onto the nitrocellulose membrane as the test and control lines, respectively. The resultant fluorescence probes were introduced into the immunochromatographic strip(ICA) for sensitive, rapid and quantitative detection of OTA in maize based on the ratio of fluorescence intensities of test and control lines. The QBs-based ICA exhibited dynamic linear range for detection of OTA in maize extract from 0.05 ng/mL to 1.0 ng/mL(Y=0.259lnX+0.897, R2=0.995), with the median inhibitory concentration of(0.215±0.023) ng/mL(n=5). The detection limit for OTA was 0.05 ng/mL in maize extract, and the detection time of the proposed QBs-based ICA for each sample was 10 min. The recoveries of OTA at three spiked levels were 107.2%-125.5%, while relative standard deviations were below 10%. Forty natural maize samples were assayed using both QB-ICA and enzyme-linked immunosorbent assay, and the results from the two methods showed a highly significant correlation(R2=0.975).
Fluorescence probes were prepared by coupling the ascetic fluid containing anti-ochratoxin A(OTA) monoclonal antibody with quantum dot beads(QBs) using 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride method. The OTA-labeled bovine serum albumin(BSA) conjugates and donkey anti-mouse polyclonal antibodies were sprayed onto the nitrocellulose membrane as the test and control lines, respectively. The resultant fluorescence probes were introduced into the immunochromatographic strip(ICA) for sensitive, rapid and quantitative detection of OTA in maize based on the ratio of fluorescence intensities of test and control lines. The QBs-based ICA exhibited dynamic linear range for detection of OTA in maize extract from 0.05 ng/mL to 1.0 ng/mL(Y=0.259lnX+0.897, R2=0.995), with the median inhibitory concentration of(0.215±0.023) ng/mL(n=5). The detection limit for OTA was 0.05 ng/mL in maize extract, and the detection time of the proposed QBs-based ICA for each sample was 10 min. The recoveries of OTA at three spiked levels were 107.2%-125.5%, while relative standard deviations were below 10%. Forty natural maize samples were assayed using both QB-ICA and enzyme-linked immunosorbent assay, and the results from the two methods showed a highly significant correlation(R2=0.975).
2015, 43(12): 1844-1850
doi: 10.11895/j.issn.0253-3820.150396
Abstract:
An indium tin oxide(ITO) microelectrode was fabricated by etching the insulating layer of photosensitive dry film using lithography technology, then polypyrrole(PPy) layer with different thickness was electrodeposited on the surface of the ITO microelectrode by electrochemical cyclic voltammetry to get PPy-ITO microelectrode. The effect of the thickness of PPy layer on the impedance characteristic of PPy-ITO microelectrode was examined by electrochemical impedance spectroscopy(EIS). The biocompatibility of the PPy-ITO microelectrodes was investigated by adhesion and proliferation experiment of human lung cancer cell A549. Finally, using PPy-ITO microelectrode as sensing electrode, biology information on the adhesion, proliferation and epithelial-mesenchymal transition(EMT) of A549 was tested and analyzed by EIS and equivalent circuit fitting. The results showed that the PPy-ITO microelectrode prepared under optimal parameter(electrodeposition for five cycles) had a lower electrical impedance and a better cell compatibility than bare ITO microelectrode. The changes of cytoplasm membrane capacitance, intercellular resistance and the gap resistance between cell and polypyrrole film during the processes of adhesion, proliferation and epithelial-mesenchymal transition(EMT) of A549 could be detected by a cell impedance biosensor based on the PPy-ITO microelectrode.
An indium tin oxide(ITO) microelectrode was fabricated by etching the insulating layer of photosensitive dry film using lithography technology, then polypyrrole(PPy) layer with different thickness was electrodeposited on the surface of the ITO microelectrode by electrochemical cyclic voltammetry to get PPy-ITO microelectrode. The effect of the thickness of PPy layer on the impedance characteristic of PPy-ITO microelectrode was examined by electrochemical impedance spectroscopy(EIS). The biocompatibility of the PPy-ITO microelectrodes was investigated by adhesion and proliferation experiment of human lung cancer cell A549. Finally, using PPy-ITO microelectrode as sensing electrode, biology information on the adhesion, proliferation and epithelial-mesenchymal transition(EMT) of A549 was tested and analyzed by EIS and equivalent circuit fitting. The results showed that the PPy-ITO microelectrode prepared under optimal parameter(electrodeposition for five cycles) had a lower electrical impedance and a better cell compatibility than bare ITO microelectrode. The changes of cytoplasm membrane capacitance, intercellular resistance and the gap resistance between cell and polypyrrole film during the processes of adhesion, proliferation and epithelial-mesenchymal transition(EMT) of A549 could be detected by a cell impedance biosensor based on the PPy-ITO microelectrode.
2015, 43(12): 1851-1858
doi: 10.11895/j.issn.0253-3820.150370
Abstract:
A novel method was developed for the rapid determination of five alternaria mycotoxins, alternariol, alternariol monomethyl ether, altenuene, tentoxin and tenuazonic acid, in citrus using ultra-high performance liquid chromatography-tandem mass spectrometry. The sample was prepared using the modified QuEChERS(quick, easy, cheap, effective, rigged, and safe) method to complete the extraction and clean-up steps in one procedure. In this QuEChERS method, sample was extracted with acetonitrile(1.5% formic acid), then salted out with anhydrous MgSO4 and NaCl, separated on an ACQUITY UPLC BEH C18 with gradient elution by using acetonitrile and 0.1% formic acid aqueous as eluant, and detected by UPLC-MS/MS under negative(ESI+) electrospray ionization and MRM models. Under these conditions, five alternaria mycotoxins made a good linearity in the concentration range of 2.0-100μg/L with R2>0.9922, and the limits of detection of the instrument were in the range of 0.11-0.91μg/kg. Three spiked levels of five altenaria mycotoxins at 5, 20 and 100μg/kg were investigated, and the recoveries ranged from 71% to 112% with the relative standard deviations(RSDs) varying from 1.1% to 9.9%, which met the requirement of mycotoxins determination.
A novel method was developed for the rapid determination of five alternaria mycotoxins, alternariol, alternariol monomethyl ether, altenuene, tentoxin and tenuazonic acid, in citrus using ultra-high performance liquid chromatography-tandem mass spectrometry. The sample was prepared using the modified QuEChERS(quick, easy, cheap, effective, rigged, and safe) method to complete the extraction and clean-up steps in one procedure. In this QuEChERS method, sample was extracted with acetonitrile(1.5% formic acid), then salted out with anhydrous MgSO4 and NaCl, separated on an ACQUITY UPLC BEH C18 with gradient elution by using acetonitrile and 0.1% formic acid aqueous as eluant, and detected by UPLC-MS/MS under negative(ESI+) electrospray ionization and MRM models. Under these conditions, five alternaria mycotoxins made a good linearity in the concentration range of 2.0-100μg/L with R2>0.9922, and the limits of detection of the instrument were in the range of 0.11-0.91μg/kg. Three spiked levels of five altenaria mycotoxins at 5, 20 and 100μg/kg were investigated, and the recoveries ranged from 71% to 112% with the relative standard deviations(RSDs) varying from 1.1% to 9.9%, which met the requirement of mycotoxins determination.
2015, 43(12): 1859-1863
doi: 10.11895/j.issn.0253-3820.150340
Abstract:
Nitrogen-doped graphene was synthesized by one-step hydrothermal method. A nitrogen-doped graphene-chitosan modified electrode(N-GN-CS/GCE) was prepared and the electrochemical behavior of uric acid in the presence of a large amount of ascorbic acid was investigated at the modified electrode. The peak current of uric acid at the modified electrode was 7 times as that at unmodified electrode. The peak separation of uric acid and ascorbic acid was 362 mV and uric acid could be accurately determined in the presence of a large amount of ascorbic acid. Some experimental parameters such as dopping volume, pH and scan rate were optimized and a standard curve was also established using differential pulse voltammetry. The linear range between the peak current and the concentration of uric acid was 0.1~20μmol/L and 20-400μmol/L, and the detection limit was estimated to be 0.01μmol/L. The proposed method was applied to the analysis of uric acid in human urine sample with recoveries between 99.7% and 103.4%.
Nitrogen-doped graphene was synthesized by one-step hydrothermal method. A nitrogen-doped graphene-chitosan modified electrode(N-GN-CS/GCE) was prepared and the electrochemical behavior of uric acid in the presence of a large amount of ascorbic acid was investigated at the modified electrode. The peak current of uric acid at the modified electrode was 7 times as that at unmodified electrode. The peak separation of uric acid and ascorbic acid was 362 mV and uric acid could be accurately determined in the presence of a large amount of ascorbic acid. Some experimental parameters such as dopping volume, pH and scan rate were optimized and a standard curve was also established using differential pulse voltammetry. The linear range between the peak current and the concentration of uric acid was 0.1~20μmol/L and 20-400μmol/L, and the detection limit was estimated to be 0.01μmol/L. The proposed method was applied to the analysis of uric acid in human urine sample with recoveries between 99.7% and 103.4%.
2015, 43(12): 1864-1869
doi: 10.11895/j.issn.0253-3820.150416
Abstract:
Hydroxypropyl chitosan(HPCS) with various degrees of deacetylation(DD 98%-55%) was successfully prepared by the reaction of pre-basified N-acetylchitosan and propylene epoxide with ispropanol as solvent. The acetylations of chitosan at N-position were carried out by changing the dosage of acetic anhydride in acetic acid-water-methanol solution. The hydroxypropyl substitution mainly occurred at both C3-OH and C6-OH groups, which was approved by FTIR and 1H-NMR. The aggregation behavior of HPCS samples was carefully investigated by gel permeation chromatography with multi-angle light scattering(GPC-MALS), dynamic light scattering(DLS), fluorescence spectrometry and atomic force microscope(AFM). The results indicated that HPCS single chains and aggregates were coexistence in aqueous solution. With the increasing content of N-acetyl of HPCS, the apparent aggregation number increased. The critical aggregation concentration(CAC) from DLS were 1.09 mg/mL for HPCS with DD 98% and 1.67 mg/mL for HPCS with DD 75%, which were consistent with the results of pyrene probe fluoresce spectrometry. The content of N-acetyl groups had an effect on the CAC values. Two types of HPCS(DD 55%) aggregates occurred in aqueous solution. The majority was smaller aggregates with lower than 13 nm in height after film pilling and 70-200 nm in length, while the minority(about 20%) was comparatively larger aggregates with about 13-31.4 nm in height after film pilling and 200-610 nm in length.
Hydroxypropyl chitosan(HPCS) with various degrees of deacetylation(DD 98%-55%) was successfully prepared by the reaction of pre-basified N-acetylchitosan and propylene epoxide with ispropanol as solvent. The acetylations of chitosan at N-position were carried out by changing the dosage of acetic anhydride in acetic acid-water-methanol solution. The hydroxypropyl substitution mainly occurred at both C3-OH and C6-OH groups, which was approved by FTIR and 1H-NMR. The aggregation behavior of HPCS samples was carefully investigated by gel permeation chromatography with multi-angle light scattering(GPC-MALS), dynamic light scattering(DLS), fluorescence spectrometry and atomic force microscope(AFM). The results indicated that HPCS single chains and aggregates were coexistence in aqueous solution. With the increasing content of N-acetyl of HPCS, the apparent aggregation number increased. The critical aggregation concentration(CAC) from DLS were 1.09 mg/mL for HPCS with DD 98% and 1.67 mg/mL for HPCS with DD 75%, which were consistent with the results of pyrene probe fluoresce spectrometry. The content of N-acetyl groups had an effect on the CAC values. Two types of HPCS(DD 55%) aggregates occurred in aqueous solution. The majority was smaller aggregates with lower than 13 nm in height after film pilling and 70-200 nm in length, while the minority(about 20%) was comparatively larger aggregates with about 13-31.4 nm in height after film pilling and 200-610 nm in length.
2015, 43(12): 1870-1875
doi: 10.11895/j.issn.0253-3820.150331
Abstract:
Fluorescence analysis was performed to explore the role of reactive oxygen species(ROS) in the proliferation of myofibroblasts(myoFbs) induced by angiotensin Ⅱ(AngⅡ). Primary cultures of neonatal rat myoFbs were obtained by enzymatic dissociation of Wistar rat neonates, and myoFbs were cultured under 10% fetal bovine serum. MyoFbs of 2-3 generation cultured in vitro were used in experiments and divided into three groups which were treated by AngⅡ, AngⅡ +N-acetyl-L-cysteine(NAC), and normal culture medium, respectively. MyoFbs were cultured for 12, 24 and 36 h. In the experiment, the proliferation rate of myoFbs induced by AngⅡ under different concentrations of 3-(4,5)-dimethylthiazo(-z-yl)-3,5-diphenyl-etrazoliumromide(MTT) was detected, the ROS levels of myoFbs were detected by fluorescent probes in 2',7'-dichlorofluorescein fluorescence Huang Shuang acetate(DCFH-DA), and the contents and levels of oxygen free radicals(·OH) in three groups were detected by spectrophotometry, immunocytochemical staining and fluorescence confocal. Immunocytochemical staining and fluorescence confocal analysis was used to measure membrane translocation and expression of p-protein kinase Cα(p-PKCα). The results showed that myoFbs incubated with AngⅡ(10-8-10-6 mol/L) for 24 h increased the proliferation rate(the value of η(%) was 170.15) and ROS, especially the content of·OH(94.53±1.68) reached the highest level. The immunocytochemistry, confocal fluorescence staining and image analysis result showed that AngⅡ could increase the translocation and expression of p-PKCα in membrane(p<0.001vs control group); NAC could inhibit the proliferation of myoFbs induced by AngⅡ(the value of η(%) was 117.05), decrease the content of ROS and the levels of·OH(75.57±1.48), and inhibit the translocation and expression of p-PKCα in membrane.
Fluorescence analysis was performed to explore the role of reactive oxygen species(ROS) in the proliferation of myofibroblasts(myoFbs) induced by angiotensin Ⅱ(AngⅡ). Primary cultures of neonatal rat myoFbs were obtained by enzymatic dissociation of Wistar rat neonates, and myoFbs were cultured under 10% fetal bovine serum. MyoFbs of 2-3 generation cultured in vitro were used in experiments and divided into three groups which were treated by AngⅡ, AngⅡ +N-acetyl-L-cysteine(NAC), and normal culture medium, respectively. MyoFbs were cultured for 12, 24 and 36 h. In the experiment, the proliferation rate of myoFbs induced by AngⅡ under different concentrations of 3-(4,5)-dimethylthiazo(-z-yl)-3,5-diphenyl-etrazoliumromide(MTT) was detected, the ROS levels of myoFbs were detected by fluorescent probes in 2',7'-dichlorofluorescein fluorescence Huang Shuang acetate(DCFH-DA), and the contents and levels of oxygen free radicals(·OH) in three groups were detected by spectrophotometry, immunocytochemical staining and fluorescence confocal. Immunocytochemical staining and fluorescence confocal analysis was used to measure membrane translocation and expression of p-protein kinase Cα(p-PKCα). The results showed that myoFbs incubated with AngⅡ(10-8-10-6 mol/L) for 24 h increased the proliferation rate(the value of η(%) was 170.15) and ROS, especially the content of·OH(94.53±1.68) reached the highest level. The immunocytochemistry, confocal fluorescence staining and image analysis result showed that AngⅡ could increase the translocation and expression of p-PKCα in membrane(p<0.001vs control group); NAC could inhibit the proliferation of myoFbs induced by AngⅡ(the value of η(%) was 117.05), decrease the content of ROS and the levels of·OH(75.57±1.48), and inhibit the translocation and expression of p-PKCα in membrane.
2015, 43(12): 1876-1881
doi: 10.11895/j.issn.0253-3820.150567
Abstract:
A rapid analytical method was established for the determination of trace amounts of microcystins(MC-LR) in environmental water samples by magnetic solid phase extraction(MSPE) coupled with HPLC/UV based on a magnetic bentonite sorbent fabricated by solvothermal synthesis method. Several factors influencing the extraction efficiency of MC-LR, such as sorbent amount, pH condition, sample volume, adsorption and desorption time, and desorption solvent were investigated and optimized. Under the optimal extraction conditions, the limits of detection and quantification for the method were 0.75 ng/L and 1.5 ng/L respectively, which was far below the guideline recommended by the World Health Organisation. The method showed a good linearity(R2=0. 9993) in the ranges of 0.25-250μg/L for MC-LR. The MSPE sorbent was simple in preparation, low cost and magnetizable, and the developed MSPE-HPLV method was suitable for the rapid and sensitive determination of MC-LR in nature water samples.
A rapid analytical method was established for the determination of trace amounts of microcystins(MC-LR) in environmental water samples by magnetic solid phase extraction(MSPE) coupled with HPLC/UV based on a magnetic bentonite sorbent fabricated by solvothermal synthesis method. Several factors influencing the extraction efficiency of MC-LR, such as sorbent amount, pH condition, sample volume, adsorption and desorption time, and desorption solvent were investigated and optimized. Under the optimal extraction conditions, the limits of detection and quantification for the method were 0.75 ng/L and 1.5 ng/L respectively, which was far below the guideline recommended by the World Health Organisation. The method showed a good linearity(R2=0. 9993) in the ranges of 0.25-250μg/L for MC-LR. The MSPE sorbent was simple in preparation, low cost and magnetizable, and the developed MSPE-HPLV method was suitable for the rapid and sensitive determination of MC-LR in nature water samples.
2015, 43(12): 1882-1887
doi: 10.11895/j.issn.0253-3820.150426
Abstract:
In this study, magnetic solid-phase extraction(MSPE) combined with capillary electrophoresis was developed for the simultaneous determination of four triazine pesticides in aqueous solution. The obtained magnetic nanocomposite(graphene/Fe3O4, G/Fe3O4) as adsorbent for MSPE endowed the method with good enrichment for triazine pesticides. The MSPE conditions such as pH of sample solution, amount of adsorbent, extraction time and elutent were investigated. Under the optimal MSPE conditions including 20 mg of adsorbent(G/Fe3O4), 0.5 mL of acetone as eluent and 20 min of extraction time in pH 7.0 solution, good linearities were obtained for the analytes between peak area and concentration in the range of 5-500μg/L with correlation coefficients greater than 0.9909. Detection limits were less than 3.12μg/L. The relative standard deviations(RSDs) for both intra-and inter-day analysis(n=5) were in the range of 2.7%-12.7% and 7.7%-14.0%, respectively. The established method was applied to analyze the water samples(river water and tap water), and the mean recoveries of standard addition experiment were between 70.4% and 117.3% for all analytes(RSDs less than 11.5%).
In this study, magnetic solid-phase extraction(MSPE) combined with capillary electrophoresis was developed for the simultaneous determination of four triazine pesticides in aqueous solution. The obtained magnetic nanocomposite(graphene/Fe3O4, G/Fe3O4) as adsorbent for MSPE endowed the method with good enrichment for triazine pesticides. The MSPE conditions such as pH of sample solution, amount of adsorbent, extraction time and elutent were investigated. Under the optimal MSPE conditions including 20 mg of adsorbent(G/Fe3O4), 0.5 mL of acetone as eluent and 20 min of extraction time in pH 7.0 solution, good linearities were obtained for the analytes between peak area and concentration in the range of 5-500μg/L with correlation coefficients greater than 0.9909. Detection limits were less than 3.12μg/L. The relative standard deviations(RSDs) for both intra-and inter-day analysis(n=5) were in the range of 2.7%-12.7% and 7.7%-14.0%, respectively. The established method was applied to analyze the water samples(river water and tap water), and the mean recoveries of standard addition experiment were between 70.4% and 117.3% for all analytes(RSDs less than 11.5%).
2015, 43(12): 1888-1894
doi: 10.11895/j.issn.0253-3820.150581
Abstract:
Sensitive high resolution ion microprobe(SHRIMP) IIe MC has been widely used in the oxygen isotopes analysis of zircon, apatite, calcium carbonate, etc.. This study provides guidance for SHRIMP IIe MC high precision O-isotope analysis. We have established the secondary ion extraction structure of SIMION simulation model and discussed the cause and influencing factors of edge effect and X-Y effect in oxygen isotopes analysis. Higher δ18O precision can be reached by limiting O-isotope analysis position(the sample is located at the center of the mount within 10 mm diameter and the target surface roughness is less than 1μm). The internal precision of single spot of zircon δ18O is better than 0.15‰(1σ), with external precision better than 0.5%(95% confidence); the internal precision of the single analysis of Carbonate δ18O is better than 0.20‰(1σ), with external precision better than 0.6‰(95% confidence).
Sensitive high resolution ion microprobe(SHRIMP) IIe MC has been widely used in the oxygen isotopes analysis of zircon, apatite, calcium carbonate, etc.. This study provides guidance for SHRIMP IIe MC high precision O-isotope analysis. We have established the secondary ion extraction structure of SIMION simulation model and discussed the cause and influencing factors of edge effect and X-Y effect in oxygen isotopes analysis. Higher δ18O precision can be reached by limiting O-isotope analysis position(the sample is located at the center of the mount within 10 mm diameter and the target surface roughness is less than 1μm). The internal precision of single spot of zircon δ18O is better than 0.15‰(1σ), with external precision better than 0.5%(95% confidence); the internal precision of the single analysis of Carbonate δ18O is better than 0.20‰(1σ), with external precision better than 0.6‰(95% confidence).
2015, 43(12): 1895-1900
doi: 10.11895/j.issn.0253-3820.150418
Abstract:
Selective chemical extraction method was utilized to fractionally extract rare earth elements(REEs) in cobalt-rich crusts and bedrock samples from the Pacific survey area, and REEs concentrations were determined by inductively coupled plasma mass spectrometry(ICP-MS). A method was established for the chemical phases analysis of REEs in cobalt-rich crusts. The results showed that the REEs enrichment in different phases in cobalt-rich crusts conformed to the following order:iron oxide phase >manganese oxide phase >residual phase >carbonate phase >adsorbed phase. About 70.2%-73.9% of total REEs contents were mainly enriched in the iron oxide phase and the recoveries were 94.8%-105.9%. Therefore, most of REEs were controlled by amorphous FeOOH minerals. In different geological bodies, occurrence phase of REEs had significant difference. REEs were mainly enriched in the carbonate phase in carbonate rock, the residual phase in basalt and phosphate rock, and the iron oxide phase in cobalt-rich crusts and polymetallic nodules. In different structural layer of cobalt-rich crusts, REEs in the new layer were mainly enriched in the iron oxide phase, and REEs in the old layer were mainly enriched in the residual phase. It suggested that phospharization played a more significant role on the REEs enrichment in the old layer.
Selective chemical extraction method was utilized to fractionally extract rare earth elements(REEs) in cobalt-rich crusts and bedrock samples from the Pacific survey area, and REEs concentrations were determined by inductively coupled plasma mass spectrometry(ICP-MS). A method was established for the chemical phases analysis of REEs in cobalt-rich crusts. The results showed that the REEs enrichment in different phases in cobalt-rich crusts conformed to the following order:iron oxide phase >manganese oxide phase >residual phase >carbonate phase >adsorbed phase. About 70.2%-73.9% of total REEs contents were mainly enriched in the iron oxide phase and the recoveries were 94.8%-105.9%. Therefore, most of REEs were controlled by amorphous FeOOH minerals. In different geological bodies, occurrence phase of REEs had significant difference. REEs were mainly enriched in the carbonate phase in carbonate rock, the residual phase in basalt and phosphate rock, and the iron oxide phase in cobalt-rich crusts and polymetallic nodules. In different structural layer of cobalt-rich crusts, REEs in the new layer were mainly enriched in the iron oxide phase, and REEs in the old layer were mainly enriched in the residual phase. It suggested that phospharization played a more significant role on the REEs enrichment in the old layer.
2015, 43(12): 1901-1905
doi: 10.11895/j.issn.0253-3820.150703
Abstract:
A method was developed for the determination of different valence states of chromium in duplicate diets. Samples were dried with freeze drying machine, then added to the microwave tube with 5% tetrabutyl ammonium hydroxide solution and digested for 30 min at 120℃. Finally, the extracts were made up to 25 mL, then centrifugated. The supernatant liquor was collected and filtered for further analysis by HPLC-ICP-MS. The linearity range was 0.5-50μg/L, and the correlation coefficients were above 0.999. The limits of detection of Cr(Ⅲ) and Cr(Ⅵ)(S/N=3) were 0.32, 0.35μg/kg and the limits of quantitative(S/N=10) were 1.00μg/kg. The recoveries were 80.7%-90.3% at spiked level between 20μg/kg and 200μg/kg with relative standard deviations under 5%. The proposed method was successfully used to detect Cr(Ⅲ) and Cr(Ⅵ) in 60 duplicate diets. The concentrations of Cr(Ⅲ) were 9.22-139μg/kg and the concentrations of Cr(Ⅵ) were 8.74-182μg/kg with average concentrations of 36.8μg/kg and 43.6μg/kg, respectively.
A method was developed for the determination of different valence states of chromium in duplicate diets. Samples were dried with freeze drying machine, then added to the microwave tube with 5% tetrabutyl ammonium hydroxide solution and digested for 30 min at 120℃. Finally, the extracts were made up to 25 mL, then centrifugated. The supernatant liquor was collected and filtered for further analysis by HPLC-ICP-MS. The linearity range was 0.5-50μg/L, and the correlation coefficients were above 0.999. The limits of detection of Cr(Ⅲ) and Cr(Ⅵ)(S/N=3) were 0.32, 0.35μg/kg and the limits of quantitative(S/N=10) were 1.00μg/kg. The recoveries were 80.7%-90.3% at spiked level between 20μg/kg and 200μg/kg with relative standard deviations under 5%. The proposed method was successfully used to detect Cr(Ⅲ) and Cr(Ⅵ) in 60 duplicate diets. The concentrations of Cr(Ⅲ) were 9.22-139μg/kg and the concentrations of Cr(Ⅵ) were 8.74-182μg/kg with average concentrations of 36.8μg/kg and 43.6μg/kg, respectively.
2015, 43(12): 1906-1912
doi: 10.11895/j.issn.0253-3820.150372
Abstract:
The fluorinated graphite was prepared by fluoridation of pre-oxidized graphite to fabricate modified glassy carbon electrode(FFPGO/GCE). The electrochemical behaviors of catechol(CC) and hydroquinone(HQ) at the modified electrode were investigated by cyclic voltammetry(CV). Effects of experimental parameters such as pH, scan rate, and amount of drop coating on the simultaneous determination of CC and HQ were investigated. Under the optimized conditions, in 0.2 mol/L phosphate buffer solutions(pH 6.0), CC and HQ could be simultaneously determined on the FFPGO/GCE by differential pulse voltammetry(DPV). The oxidation peak current showed a good linear relationship with concentration of CC and HQ in the range of 1.0-150μmol/L. The detection limits were 0.31μmol/L(S/N=3) for CC and 0.43μmol/L(S/N=3) for HQ. Furthermore, the modified electrode exhibited good reproducibility, stability and selectivity. The modified electrode was used for determination of CC and HQ in imitative water samples with satisfactory results.
The fluorinated graphite was prepared by fluoridation of pre-oxidized graphite to fabricate modified glassy carbon electrode(FFPGO/GCE). The electrochemical behaviors of catechol(CC) and hydroquinone(HQ) at the modified electrode were investigated by cyclic voltammetry(CV). Effects of experimental parameters such as pH, scan rate, and amount of drop coating on the simultaneous determination of CC and HQ were investigated. Under the optimized conditions, in 0.2 mol/L phosphate buffer solutions(pH 6.0), CC and HQ could be simultaneously determined on the FFPGO/GCE by differential pulse voltammetry(DPV). The oxidation peak current showed a good linear relationship with concentration of CC and HQ in the range of 1.0-150μmol/L. The detection limits were 0.31μmol/L(S/N=3) for CC and 0.43μmol/L(S/N=3) for HQ. Furthermore, the modified electrode exhibited good reproducibility, stability and selectivity. The modified electrode was used for determination of CC and HQ in imitative water samples with satisfactory results.
2015, 43(12): 1913-1919
doi: 10.11895/j.issn.0253-3820.150706
Abstract:
Polyphenols are very important secondary metabolites for tobacco plants. They are also considered as the important flavor precursors for cigarette industry. A liquid chromatography-tandem mass spectrometry(LC-MS/MS)-based method was established for the simultaneous determination of 18 polyphenols in tobacco leaf. The developed method can be used to determine 15 more polyphenols compared to the standard method for industry(YC/T 202-2006). Different kinds of extraction solution were compared and a solution of methanol-water-chloroform(5:2:2, V/V) was selected for the extraction because of its highest yield. Method validation was performed and the result showed that all the 18 polyphenols have their linear correlation coefficients(R2) more than 0.99. The low limit of determination and the low limit of quantitation were in the range of 1-150μg/L and 6-350μg/L, respectively. Intra-day and Inter-day reproducibility were in the range of 2.4%-6.5% and 4.5%-10.1%, respectively. Recoveries were in the range of 89.5%-103.7%. The established method was then successfully used to analyze polyphenols of tobacco leaves planted under different environment temperatures. The polyphenols can be classified in four groups based on their response to the temperature changing:the concentration increase with the increasing environment temperature, the concentration decrease with the increasing environment temperature, the concentration decrease with the environment temperature changes from the normal set point, and the concentration does not change significantly with the changing environment temperature.
Polyphenols are very important secondary metabolites for tobacco plants. They are also considered as the important flavor precursors for cigarette industry. A liquid chromatography-tandem mass spectrometry(LC-MS/MS)-based method was established for the simultaneous determination of 18 polyphenols in tobacco leaf. The developed method can be used to determine 15 more polyphenols compared to the standard method for industry(YC/T 202-2006). Different kinds of extraction solution were compared and a solution of methanol-water-chloroform(5:2:2, V/V) was selected for the extraction because of its highest yield. Method validation was performed and the result showed that all the 18 polyphenols have their linear correlation coefficients(R2) more than 0.99. The low limit of determination and the low limit of quantitation were in the range of 1-150μg/L and 6-350μg/L, respectively. Intra-day and Inter-day reproducibility were in the range of 2.4%-6.5% and 4.5%-10.1%, respectively. Recoveries were in the range of 89.5%-103.7%. The established method was then successfully used to analyze polyphenols of tobacco leaves planted under different environment temperatures. The polyphenols can be classified in four groups based on their response to the temperature changing:the concentration increase with the increasing environment temperature, the concentration decrease with the increasing environment temperature, the concentration decrease with the environment temperature changes from the normal set point, and the concentration does not change significantly with the changing environment temperature.
2015, 43(12): 1920-1926
doi: 10.11895/j.issn.0253-3820.150514
Abstract:
A method for simultaneous quantification of 11 cholesterol oxidation products(COPs) in yolk of salted duck egg was developed by ultra performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS) with enzymatic treatment. Firstly, the yolk of salted duck egg was digested by lipase at 37℃, and COPs were extracted by n-hexane and diethyl ether mixture(8:2, V/V). The supernatant was enriched and purified by solid phase extraction of silica. Eleven COPs were separated by UPLC HSS T3 column(100 mm×2.1 mm, 0.3μm) with water and methanol/acetonitrile(1:1, V/V) both containing 0.1% formic acid. All COPs were simultaneously determined by UPLC-MS/MS with multiple reaction monitoring mode(MRM). The d7-7α-OH cholesterol was used as internal standard. The results showed that the linear ranges were 20-1200 ng/mL and 200-3500 ng/mL with correlation coefficient(r ≥ 0.996). The recoveries of three spiking levels were between 79.3% and 104.1%, and relative standard deviations(RSD) were 2.0% and 12.9%. The limit of quantification(LOQ) was 0.08-0.40μg/g. The established method with good repeatability and robust recovery can be applied to quantify the levels of 11 COPs in yolk of salted duck eggs.
A method for simultaneous quantification of 11 cholesterol oxidation products(COPs) in yolk of salted duck egg was developed by ultra performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS) with enzymatic treatment. Firstly, the yolk of salted duck egg was digested by lipase at 37℃, and COPs were extracted by n-hexane and diethyl ether mixture(8:2, V/V). The supernatant was enriched and purified by solid phase extraction of silica. Eleven COPs were separated by UPLC HSS T3 column(100 mm×2.1 mm, 0.3μm) with water and methanol/acetonitrile(1:1, V/V) both containing 0.1% formic acid. All COPs were simultaneously determined by UPLC-MS/MS with multiple reaction monitoring mode(MRM). The d7-7α-OH cholesterol was used as internal standard. The results showed that the linear ranges were 20-1200 ng/mL and 200-3500 ng/mL with correlation coefficient(r ≥ 0.996). The recoveries of three spiking levels were between 79.3% and 104.1%, and relative standard deviations(RSD) were 2.0% and 12.9%. The limit of quantification(LOQ) was 0.08-0.40μg/g. The established method with good repeatability and robust recovery can be applied to quantify the levels of 11 COPs in yolk of salted duck eggs.
2015, 43(12): 1927-1933
doi: 10.11895/j.issn.0253-3820.150178
Abstract:
There is a trouble for 1H NMR identification of non-phosphorus precursors of chemical warfare agents listed in Schedule 2, part B of Chemical Weapons Convention(CWC) in complex matrix. An alternative method was proposed for identification by in situ derivatization of the precursors containing hydroxyl functions with 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane(CTMP) in a NMR tube followed by phosphorus-31 NMR detection. The specificity, stability, sensitivity and selectivity of the method were evaluated with pinacol and three aminoalcohols isomers, 2-(N,N-dipropylamino)ethanol, 2-(N-butyl-N-ethylamino)ethanol and 2-(N-isopropyl-N-propylamino) ethanol. The results showed that the phosphorylation products were single, stable and allowing clear distinction between aminoalcohols isomers. The method was used for the detection and identification of three mixed aminoalcohols isomers present(at original concentration of 10μg/mL) in an organic sample from 32th OPCW Official Proficiency Tests.
There is a trouble for 1H NMR identification of non-phosphorus precursors of chemical warfare agents listed in Schedule 2, part B of Chemical Weapons Convention(CWC) in complex matrix. An alternative method was proposed for identification by in situ derivatization of the precursors containing hydroxyl functions with 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane(CTMP) in a NMR tube followed by phosphorus-31 NMR detection. The specificity, stability, sensitivity and selectivity of the method were evaluated with pinacol and three aminoalcohols isomers, 2-(N,N-dipropylamino)ethanol, 2-(N-butyl-N-ethylamino)ethanol and 2-(N-isopropyl-N-propylamino) ethanol. The results showed that the phosphorylation products were single, stable and allowing clear distinction between aminoalcohols isomers. The method was used for the detection and identification of three mixed aminoalcohols isomers present(at original concentration of 10μg/mL) in an organic sample from 32th OPCW Official Proficiency Tests.
2015, 43(12): 1934-1941
doi: 10.11895/j.issn.0253-3820.150332
Abstract:
To understand the size distribution characteristics of carbon-containing particles in Heshan, the air was sampled by a ten-stage micro orifice uniform deposit impactor(MOUDI) in July, 2014 and January, 2015 in Guangdong Atmospheric Supersite. The organic carbon(OC) and elemental carbon(EC) were analyzed using a thermal/optical carbon analyzer(Sunset Lab Inc., USA). The results revealed that particlate matter(PM), OC and EC were mainly enriched in < 3.2μm particle in Heshan summer and winter. OC and EC were more concentrated in the size range of 0.32-1.0μm. The mass concentrations in summer were(2.26±0.72) μg/m3 and(0.89±0.36) μg/m3 and in winter were(10.85±5.49) μg/m3 and(1.47±0.71) μg/m3 for OC and EC, respectively. It is demonstrated obviously that the OC concentrations in sunny days were greater than rainy days, but EC did not changed significantly. Higher mass concentrations of PM, OC and EC in all sizes were found in hazy days compared to clear days. The correlations between OC and EC as well as the mass concentration of SOC varied as the weather type changed.
To understand the size distribution characteristics of carbon-containing particles in Heshan, the air was sampled by a ten-stage micro orifice uniform deposit impactor(MOUDI) in July, 2014 and January, 2015 in Guangdong Atmospheric Supersite. The organic carbon(OC) and elemental carbon(EC) were analyzed using a thermal/optical carbon analyzer(Sunset Lab Inc., USA). The results revealed that particlate matter(PM), OC and EC were mainly enriched in < 3.2μm particle in Heshan summer and winter. OC and EC were more concentrated in the size range of 0.32-1.0μm. The mass concentrations in summer were(2.26±0.72) μg/m3 and(0.89±0.36) μg/m3 and in winter were(10.85±5.49) μg/m3 and(1.47±0.71) μg/m3 for OC and EC, respectively. It is demonstrated obviously that the OC concentrations in sunny days were greater than rainy days, but EC did not changed significantly. Higher mass concentrations of PM, OC and EC in all sizes were found in hazy days compared to clear days. The correlations between OC and EC as well as the mass concentration of SOC varied as the weather type changed.
2015, 43(12): 1942-1954
doi: 10.11895/j.issn.0253-3820.100509
Abstract:
Recently, with the development of lab-on-a-chip researches, the use of microfluidics to precisely control the droplet behavior in microchannel has received more and more research attention. This article introduces the basic theory and mechanism of the droplets coalescence, and then carefully reviews the passive methods of droplets coalescence used in current researches by changing microchannel geometry and adding surfactants. The active methods to trigger droplet fusion such as applied electric field, magnetic fields, temperature gradients, surface acoustic wave and focused lasers are also introduced briefly. We also introduce the fluid dynamics of the droplets coalescence and forecast its progress at last to provide useful guidance for microfluidic devices design and wide use of the drop-based microfluidics.
Recently, with the development of lab-on-a-chip researches, the use of microfluidics to precisely control the droplet behavior in microchannel has received more and more research attention. This article introduces the basic theory and mechanism of the droplets coalescence, and then carefully reviews the passive methods of droplets coalescence used in current researches by changing microchannel geometry and adding surfactants. The active methods to trigger droplet fusion such as applied electric field, magnetic fields, temperature gradients, surface acoustic wave and focused lasers are also introduced briefly. We also introduce the fluid dynamics of the droplets coalescence and forecast its progress at last to provide useful guidance for microfluidic devices design and wide use of the drop-based microfluidics.
2015, 43(12): 1955-1961
doi: 10.11895/j.issn.0253-3820.150520
Abstract:
A novel quadrupole mass spectrometer using microwave plasma torch as the ionization source was developed(MPT-QMS) for the analysis of trace metal elements in water samples. The influence of ion funnel on instrument performance and analytical outputs was studied and illustrated. The results showed that it could lead to effective collision induced dissociation(CID) by modulating the RF voltage of the ion funnel, which quantitatively broke polyatomic ions produced by MPT into mono-atomic ions. Such effect significantly reduced the complexity of the mass spectrum caused by multi-atom ions. In contrast to a linear ion trap mass spectrometer(LTQ) without ion funnel, the result of MPT-QMS was easier to be identified. A mixed sample containing 20 metal elements was detected by this instrument, the detection limits of most elements were between 0.02 and 1.4 ng/mL. Compared to ICP-MS, MPT-QMS was only 10% of power and gas consumption, and was suitable for the analysis of water samples when carried by a vehicle.
A novel quadrupole mass spectrometer using microwave plasma torch as the ionization source was developed(MPT-QMS) for the analysis of trace metal elements in water samples. The influence of ion funnel on instrument performance and analytical outputs was studied and illustrated. The results showed that it could lead to effective collision induced dissociation(CID) by modulating the RF voltage of the ion funnel, which quantitatively broke polyatomic ions produced by MPT into mono-atomic ions. Such effect significantly reduced the complexity of the mass spectrum caused by multi-atom ions. In contrast to a linear ion trap mass spectrometer(LTQ) without ion funnel, the result of MPT-QMS was easier to be identified. A mixed sample containing 20 metal elements was detected by this instrument, the detection limits of most elements were between 0.02 and 1.4 ng/mL. Compared to ICP-MS, MPT-QMS was only 10% of power and gas consumption, and was suitable for the analysis of water samples when carried by a vehicle.
