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2020 Volume 48 Issue 6
2020, 48(6): 685-694
doi: 10.19756/j.issn.0253-3820.191379
Abstract:
Tau protein, simply referred to as Tau, is a type of microtubule-associated protein involved in the development of the nervous system. After experiencing conformational changes, abnormal mRNA splicing, etc., Tau dissociates from microtubules and undergoes a series of post-translational modification (PTM) to form pathological aggregation, which induces neurodegenerative diseases and tauopathies eventually. Numerous clinical studies suggest that studying the pathological process of Tau protein, analyzing and evaluating its PTM and quantitative detection of concentration changes are of great significance for the early diagnosis, tracking, prevention and treatment of tauopathies. In this paper, the conventional methods of Tau protein at home and abroad were summarized and compared. Specifically, the related applications and latest research progress of optical and electrochemical biosensors were mainly described. Furthermore, the summary of its future directions and the potential applications were proposed, which provided reference for the further research and application.
Tau protein, simply referred to as Tau, is a type of microtubule-associated protein involved in the development of the nervous system. After experiencing conformational changes, abnormal mRNA splicing, etc., Tau dissociates from microtubules and undergoes a series of post-translational modification (PTM) to form pathological aggregation, which induces neurodegenerative diseases and tauopathies eventually. Numerous clinical studies suggest that studying the pathological process of Tau protein, analyzing and evaluating its PTM and quantitative detection of concentration changes are of great significance for the early diagnosis, tracking, prevention and treatment of tauopathies. In this paper, the conventional methods of Tau protein at home and abroad were summarized and compared. Specifically, the related applications and latest research progress of optical and electrochemical biosensors were mainly described. Furthermore, the summary of its future directions and the potential applications were proposed, which provided reference for the further research and application.
2020, 48(6): 695-702
doi: 10.19756/j.issn.0253-3820.201007
Abstract:
A multi-layer paper supported co-culture system was developed for investigation of the interactions between breast cancer cells and lung fibroblasts mediated by exosomes. Within the multi-layer structure, the tumor layer and the recruitment layer were impregnated with breast cancer cells and lung fibroblasts, respectively, and these two layers were separated by the invasion layers. The co-culture device was constructed by assembling multiple layers of paper. Disassembling such a device enabled cells on each layer to be analyzed individually, which was used to study cell interactions from both time and space aspects. The impregnation of either breast cancer cells or the breast cancer cells derived exosomes on the tumor layer resulted in conversion of lung fibroblasts on the recruitment layer into cancer-associated fibroblasts. The cancer-associated fibroblasts induced by exosomes were thereafter seeded on the recruitment layer, which showed stronger breast cancer cell recruitment than primary cells. These results suggest that the conversion of host-organ fibroblasts mediated by tumor exosomes is essential for the formation of pre-metastasis niche, and the pre-metastasis niche in turn recruits tumor cells to achieve organotropic metastasis.
A multi-layer paper supported co-culture system was developed for investigation of the interactions between breast cancer cells and lung fibroblasts mediated by exosomes. Within the multi-layer structure, the tumor layer and the recruitment layer were impregnated with breast cancer cells and lung fibroblasts, respectively, and these two layers were separated by the invasion layers. The co-culture device was constructed by assembling multiple layers of paper. Disassembling such a device enabled cells on each layer to be analyzed individually, which was used to study cell interactions from both time and space aspects. The impregnation of either breast cancer cells or the breast cancer cells derived exosomes on the tumor layer resulted in conversion of lung fibroblasts on the recruitment layer into cancer-associated fibroblasts. The cancer-associated fibroblasts induced by exosomes were thereafter seeded on the recruitment layer, which showed stronger breast cancer cell recruitment than primary cells. These results suggest that the conversion of host-organ fibroblasts mediated by tumor exosomes is essential for the formation of pre-metastasis niche, and the pre-metastasis niche in turn recruits tumor cells to achieve organotropic metastasis.
2020, 48(6): 703-711
doi: 10.19756/j.issn.0253-3820.201065
Abstract:
The g-C3N4 was found to active the activity of horseradish peroxidase (HRP) for catalyzing the oxidation of the typical substrate of 3,3',5,5'-tetramethylbenzidine (TMB) under visible light irradiation. Based on this, a novel sandwich-type immunosensor colorimetric strategy was developed for the highly sensitive detection of α-fetoprotein (AFP). In this assay, the capture antibodies (Ab1) attached to the 96-well plates was used to capture the target of AFP, and then reacted with the detection antibody (Ab2) and HRP co-immobilized gold nanoparticles (AuNPs) (i.e., the bioconjugates of the Ab2-AuNPs-HRP), which was assisted by the formation of the tyramide-HRP repeats to amplify the signal. The addition of the g-C3N4 activated the HRP under visible light for oxidizing TMB, producing the absorption signal at 652 nm (for oxidized TMB) that correlated to the concentrations of AFP in the range from 0.5 pg/mL to 0.1 μg/mL. A limit of detection (LOD) of 0.17 pg/mL was obtained (S/N=3). The developed immunoassay could be facilely operated with wide detection range and high sensitivity, showing great promise for real sample detection.
The g-C3N4 was found to active the activity of horseradish peroxidase (HRP) for catalyzing the oxidation of the typical substrate of 3,3',5,5'-tetramethylbenzidine (TMB) under visible light irradiation. Based on this, a novel sandwich-type immunosensor colorimetric strategy was developed for the highly sensitive detection of α-fetoprotein (AFP). In this assay, the capture antibodies (Ab1) attached to the 96-well plates was used to capture the target of AFP, and then reacted with the detection antibody (Ab2) and HRP co-immobilized gold nanoparticles (AuNPs) (i.e., the bioconjugates of the Ab2-AuNPs-HRP), which was assisted by the formation of the tyramide-HRP repeats to amplify the signal. The addition of the g-C3N4 activated the HRP under visible light for oxidizing TMB, producing the absorption signal at 652 nm (for oxidized TMB) that correlated to the concentrations of AFP in the range from 0.5 pg/mL to 0.1 μg/mL. A limit of detection (LOD) of 0.17 pg/mL was obtained (S/N=3). The developed immunoassay could be facilely operated with wide detection range and high sensitivity, showing great promise for real sample detection.
2020, 48(6): 712-720
doi: 10.19756/j.issn.0253-3820.201088
Abstract:
RNA interference (RNAi) strategy based on small interfering RNA (siRNA) has become a standard method in biomedical research. In recent years, RNAi has also made remarkable advances in clinical translation. However, the conventional cationic vectors for siRNA delivery have severe disadvantages such as low delivery efficiency, high cytotoxicity and lack of imaging function, which severely restrict the clinical translation of siRNA drugs. To address the shortcomings of conventional siRNA vectors, we herein reported a cationic gold nanocluster (CGN)-based nanovectors for siRNA delivery and fluorescence imaging. Firstly, we used BSA template to synthesize GN by biomineralization strategy. Then, the BSA-templated GN was modified with ethylene diamine (EDA) or ethylene dimethyl amine (DMA) to form CGN. We demonstrated that the CGN can efficiently deliver siRNA and significantly silence green fluorescence protein (GFP) expression in A549-GFP lung cancer cells. Finally, we investigated the ability of CGN for fluorescence tracing in vitro by using confocal laser scanning microscopic examination. This study demonstrated the potential of the CGN for siRNA delivery and fluorescence tracing in vitro.
RNA interference (RNAi) strategy based on small interfering RNA (siRNA) has become a standard method in biomedical research. In recent years, RNAi has also made remarkable advances in clinical translation. However, the conventional cationic vectors for siRNA delivery have severe disadvantages such as low delivery efficiency, high cytotoxicity and lack of imaging function, which severely restrict the clinical translation of siRNA drugs. To address the shortcomings of conventional siRNA vectors, we herein reported a cationic gold nanocluster (CGN)-based nanovectors for siRNA delivery and fluorescence imaging. Firstly, we used BSA template to synthesize GN by biomineralization strategy. Then, the BSA-templated GN was modified with ethylene diamine (EDA) or ethylene dimethyl amine (DMA) to form CGN. We demonstrated that the CGN can efficiently deliver siRNA and significantly silence green fluorescence protein (GFP) expression in A549-GFP lung cancer cells. Finally, we investigated the ability of CGN for fluorescence tracing in vitro by using confocal laser scanning microscopic examination. This study demonstrated the potential of the CGN for siRNA delivery and fluorescence tracing in vitro.
2020, 48(6): 721-726
doi: 10.19756/j.issn.0253-3820.201026
Abstract:
Fuel cell, as a prospective energy conversion device system, provides high conversion efficiency and cleaning products. However, the development of fuel cell is significantly hindered by the sluggish kinetics of the oxygen reduction reaction (ORR) in the cathode, so high-efficiency cathode catalyst is highly required. As the state-of-the-art electrocatalysts, platinum-based materials are still the primary choice for ORR, but a series of issues including high cost and scarcity of raw materials make the large-scale applications of fuel cell difficult. Consequently, the development of non-noble metal catalystsis is becoming more urgent to solve the issue of the fuel cell. Herein, the mesoporous carbon precursors were first synthesized by the soft template method. Then the mixture of cobalt salts and the carbon precursors was heated at 120℃ to evaporate the solvent, followed by the calcination at 750℃. X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), cyclic voltammetry (CV) and linear sweep voltammetry (LSV) were used to characterize the obtained catalysts. The results showed that the cobalt oxide nanoparticles were successfully supported on the mesoporous carbon materials with high surface area. In an alkaline medium, the as-prepared catalyst exhibited high electrocatalytic activity for ORR, which was comparable to that of commercial Pt/C. It also showed a higher stability than the Pt/C catalyst. The catalyst was expected to replace the expensive Pt as a new cathode material for fuel cells.
Fuel cell, as a prospective energy conversion device system, provides high conversion efficiency and cleaning products. However, the development of fuel cell is significantly hindered by the sluggish kinetics of the oxygen reduction reaction (ORR) in the cathode, so high-efficiency cathode catalyst is highly required. As the state-of-the-art electrocatalysts, platinum-based materials are still the primary choice for ORR, but a series of issues including high cost and scarcity of raw materials make the large-scale applications of fuel cell difficult. Consequently, the development of non-noble metal catalystsis is becoming more urgent to solve the issue of the fuel cell. Herein, the mesoporous carbon precursors were first synthesized by the soft template method. Then the mixture of cobalt salts and the carbon precursors was heated at 120℃ to evaporate the solvent, followed by the calcination at 750℃. X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), cyclic voltammetry (CV) and linear sweep voltammetry (LSV) were used to characterize the obtained catalysts. The results showed that the cobalt oxide nanoparticles were successfully supported on the mesoporous carbon materials with high surface area. In an alkaline medium, the as-prepared catalyst exhibited high electrocatalytic activity for ORR, which was comparable to that of commercial Pt/C. It also showed a higher stability than the Pt/C catalyst. The catalyst was expected to replace the expensive Pt as a new cathode material for fuel cells.
2020, 48(6): 727-732
doi: 10.19756/j.issn.0253-3820.201047
Abstract:
A cascade-catalyzed enzyme-free colorimetric sensor based on manganese dioxide (MnO2)-oxygen doped carbon nitride (OCN) composite was developed for glucose detection. The MnO2-OCN composite was prepared by chemically precipitating MnO2 crystals on the surface of OCN. The excellent peroxidase-like activity of OCN accelerated the consumption of H2O2 produced by MnO2 catalytic oxidation of glucose, which significantly improved the catalytic detection performance of glucose. The enzyme-free colorimetric sensor based on the MnO2-OCN composite had a wide detection range (0.05-2.00 mmol/L), with a limit of detection (LOD, S/N=3) of 23 μmol/L. The recoveries of glucose spiked in serum were 91.9%-94.3%. Meanwhile, the sensor had a good specificity towards the recognition and catalytic oxidation of glucose for colorimetric detection.
A cascade-catalyzed enzyme-free colorimetric sensor based on manganese dioxide (MnO2)-oxygen doped carbon nitride (OCN) composite was developed for glucose detection. The MnO2-OCN composite was prepared by chemically precipitating MnO2 crystals on the surface of OCN. The excellent peroxidase-like activity of OCN accelerated the consumption of H2O2 produced by MnO2 catalytic oxidation of glucose, which significantly improved the catalytic detection performance of glucose. The enzyme-free colorimetric sensor based on the MnO2-OCN composite had a wide detection range (0.05-2.00 mmol/L), with a limit of detection (LOD, S/N=3) of 23 μmol/L. The recoveries of glucose spiked in serum were 91.9%-94.3%. Meanwhile, the sensor had a good specificity towards the recognition and catalytic oxidation of glucose for colorimetric detection.
2020, 48(6): 733-741
doi: 10.19756/j.issn.0253-3820.191710
Abstract:
The plant metabolomics methods was applied to conduct multi-dimensional metabolome analysis of Artemisia rupestris L samples collected from Aletai fuyun and Hami for the first time based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) technique. The effect of ecological origin on endogenous metabolites was investigated from two perspectives, i. e. artificial and wild varieties, and three levels, i. e. flower, stem, and leaf. Meantime, 25 known representative metabolites in different groups were analyzed, as well as the interpreting metabolic characters of this plant of different origins. According to the results, significant discrepancies were presented in both artificial and wild varieties, especially for the latter one. For artificial varieties, 29 structural category known metabolites were screened out, including 10 flavonoids, 12 chlorogenic acid analogues, and 7 rupestonic acid derivatives; for wild varieties, 45 structural category known metabolites were screened out, including 17 flavonoids, 14 chlorogenic acid analogues, and 14 rupestonic acid derivatives. In addition, among the 25 known representative metabolites, 8 in artificial varieties and 11 in wild varieties showed differentiation in ecological origin. This study provided a novel research strategy for molecular basis origin identification and quality control of medicinal plant Artemisia rupestris L.
The plant metabolomics methods was applied to conduct multi-dimensional metabolome analysis of Artemisia rupestris L samples collected from Aletai fuyun and Hami for the first time based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) technique. The effect of ecological origin on endogenous metabolites was investigated from two perspectives, i. e. artificial and wild varieties, and three levels, i. e. flower, stem, and leaf. Meantime, 25 known representative metabolites in different groups were analyzed, as well as the interpreting metabolic characters of this plant of different origins. According to the results, significant discrepancies were presented in both artificial and wild varieties, especially for the latter one. For artificial varieties, 29 structural category known metabolites were screened out, including 10 flavonoids, 12 chlorogenic acid analogues, and 7 rupestonic acid derivatives; for wild varieties, 45 structural category known metabolites were screened out, including 17 flavonoids, 14 chlorogenic acid analogues, and 14 rupestonic acid derivatives. In addition, among the 25 known representative metabolites, 8 in artificial varieties and 11 in wild varieties showed differentiation in ecological origin. This study provided a novel research strategy for molecular basis origin identification and quality control of medicinal plant Artemisia rupestris L.
2020, 48(6): 742-749
doi: 10.19756/j.issn.0253-3820.191722
Abstract:
Simultaneous detection of small molecule neurotransmitters dopamine (DA) and 5-hydroxytryptamine (5-HT) has become a research hotpot in the field of life sciences. A single electrochemical detection mean is difficult to accurately identify analytes. Therefore, it is particularly important for the multimode simultaneous detection and analysis. In this study, a dual-functional gold nanoelectrode-nanopipette based on the nanopipette was constructed with electrochemical properties and Raman activity. On the basis of the carbon nanoelectrode-nanopipette, the apex of it deposited gold by electrochemistry and then enriched analytes by dielectrophoresis (DEP) method, which could be used for the detection of DA and 5-HT in low concentration. The results showed that this nanoelectrode achieved the enhanced electrochemical responses and differentiated the two. The introduced silver nanoparticles (AgNPs) were used as Raman enhancement factor and as the nanoparticles of analytes capturer. By utilizing DEP enrichment method, the Raman signal was enhanced by two orders of magnitude and the characteristic peaks of DA and 5-HT in the mixture were identified. When this nanoelectrode was applied in the analysis of serum samples, as the number of enrichment reached up to the third time, the enhanced electrochemical response could also be obtained, but this response was limited by the number of enrichments.
Simultaneous detection of small molecule neurotransmitters dopamine (DA) and 5-hydroxytryptamine (5-HT) has become a research hotpot in the field of life sciences. A single electrochemical detection mean is difficult to accurately identify analytes. Therefore, it is particularly important for the multimode simultaneous detection and analysis. In this study, a dual-functional gold nanoelectrode-nanopipette based on the nanopipette was constructed with electrochemical properties and Raman activity. On the basis of the carbon nanoelectrode-nanopipette, the apex of it deposited gold by electrochemistry and then enriched analytes by dielectrophoresis (DEP) method, which could be used for the detection of DA and 5-HT in low concentration. The results showed that this nanoelectrode achieved the enhanced electrochemical responses and differentiated the two. The introduced silver nanoparticles (AgNPs) were used as Raman enhancement factor and as the nanoparticles of analytes capturer. By utilizing DEP enrichment method, the Raman signal was enhanced by two orders of magnitude and the characteristic peaks of DA and 5-HT in the mixture were identified. When this nanoelectrode was applied in the analysis of serum samples, as the number of enrichment reached up to the third time, the enhanced electrochemical response could also be obtained, but this response was limited by the number of enrichments.
2020, 48(6): 750-756
doi: 10.19756/j.issn.0253-3820.191616
Abstract:
A novel headspace solid phase microextraction arrow (HS-SPME Arrow) method combined with gas chromatography-mass spectrometry (GC-MS) was developed for extraction and analysis of volatile organic compounds of Microcystis aeruginosa under simulated natural conditions. By selecting suitable extraction fibers, 210 kinds of volatile metabolites were identified by full scanning qualitative analysis from the samples of Microcystis aeruginosa in producing period. The metabolic changes of volatile molecules during the growth of Microcystis aeruginosa were analyzed by multivariate statistical analysis and clustering analysis. Chemometric analysis based on principal component analysis, partial least squares-discriminant analysis and heatmap associated with hierarchical cluster analysis provided a suitable tool to differentiate volatile organic compounds in algal material. And 10 metabolites in statistical significance were identified, including cyclohexanol, dimethyl trisulfide, benzenemethanol, camphor, 2-methoxyphenol, 3-hexene-1-ol, 2,4-decadienal, indole, citral and 1-nonanol. Parameters affecting the extraction, such as extraction temperature, time and salt were carefully optimized. In addition, the analysis conditions, including desorption temperature and time as well as gas chromatographic parameters, were optimized. The calibration curves showed a good linearity (correlation coefficient > 0.998) in the concentration range of 0.050-1000 ng/L. The detection limits of this method were 0.010-0.030 ng/L, and the recoveries at the concentration level of 100 ng/L were 76.3%-3.0%. The method was satisfactorily precise, with the RSDs of less than 12.7%. The new method was simple, quick, stable, and applicable to complex matrices. It was suitable to the determination of volatile metabolites in natural water at the early stage of blue-green algae bloom.
A novel headspace solid phase microextraction arrow (HS-SPME Arrow) method combined with gas chromatography-mass spectrometry (GC-MS) was developed for extraction and analysis of volatile organic compounds of Microcystis aeruginosa under simulated natural conditions. By selecting suitable extraction fibers, 210 kinds of volatile metabolites were identified by full scanning qualitative analysis from the samples of Microcystis aeruginosa in producing period. The metabolic changes of volatile molecules during the growth of Microcystis aeruginosa were analyzed by multivariate statistical analysis and clustering analysis. Chemometric analysis based on principal component analysis, partial least squares-discriminant analysis and heatmap associated with hierarchical cluster analysis provided a suitable tool to differentiate volatile organic compounds in algal material. And 10 metabolites in statistical significance were identified, including cyclohexanol, dimethyl trisulfide, benzenemethanol, camphor, 2-methoxyphenol, 3-hexene-1-ol, 2,4-decadienal, indole, citral and 1-nonanol. Parameters affecting the extraction, such as extraction temperature, time and salt were carefully optimized. In addition, the analysis conditions, including desorption temperature and time as well as gas chromatographic parameters, were optimized. The calibration curves showed a good linearity (correlation coefficient > 0.998) in the concentration range of 0.050-1000 ng/L. The detection limits of this method were 0.010-0.030 ng/L, and the recoveries at the concentration level of 100 ng/L were 76.3%-3.0%. The method was satisfactorily precise, with the RSDs of less than 12.7%. The new method was simple, quick, stable, and applicable to complex matrices. It was suitable to the determination of volatile metabolites in natural water at the early stage of blue-green algae bloom.
2020, 48(6): 757-764
doi: 10.19756/j.issn.0253-3820.191589
Abstract:
A molecularly imprinted electrochemical sensor based on graphene modified electrode was fabricated for determination of methyl parathion(MP). The molecularly imprinted polymer membrane was synthesized on the surface of graphene-modified glassy carbon electrode by using MP as template, methacrylic acid as functional monomer and ethylene glycol maleic rosinate acrylate as cross linker. The electrochemical properties of the sensor were investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Under optimal conditions, the peak current of the sensor showed a good linear correlation with the MP concentration in the range of 1.0×10-7-8.0×10-5 mol/L, with a detection limit of 5.0×10-8 mol/L (S/N=3). The linear regression equation was Ip (μA)=-0.65199-0.02387C (μmol/L), with a correlation coefficient (R2) of 0.9922. The adsorption model of the imprinted sensor was investigated, and the binding rate constant k was 20.2758 s. The sensor was successfully applied to determination of MP in tomato samples with recoveries of 95.0% to 100.3%.
A molecularly imprinted electrochemical sensor based on graphene modified electrode was fabricated for determination of methyl parathion(MP). The molecularly imprinted polymer membrane was synthesized on the surface of graphene-modified glassy carbon electrode by using MP as template, methacrylic acid as functional monomer and ethylene glycol maleic rosinate acrylate as cross linker. The electrochemical properties of the sensor were investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Under optimal conditions, the peak current of the sensor showed a good linear correlation with the MP concentration in the range of 1.0×10-7-8.0×10-5 mol/L, with a detection limit of 5.0×10-8 mol/L (S/N=3). The linear regression equation was Ip (μA)=-0.65199-0.02387C (μmol/L), with a correlation coefficient (R2) of 0.9922. The adsorption model of the imprinted sensor was investigated, and the binding rate constant k was 20.2758 s. The sensor was successfully applied to determination of MP in tomato samples with recoveries of 95.0% to 100.3%.
2020, 48(6): 765-773
doi: 10.19756/j.issn.0253-3820.201093
Abstract:
A sensitive analytical method for determination of 239Pu and 240Pu in environmental water samples was developed. By co-precipitation of plutonium with Ti(OH)3 followed by separation of plutonium using extraction chromatography with TEVA resin, a recovery of more than 80% for plutonium and a decontamination factor of 1.3×105 for uranium were achieved. A triple quadrupole inductively coupled plasma mass spectrometry (ICP-MS) method with dynamic collision/reaction cell was used for measurement of plutonium isotopes. By using NH3-He double gasses as collision/reaction gas, 238U1H+ ion interference to 239Pu was significantly suppressed and the final abundance sensitivity of 238U to m/z=239 was reduced to <1×10-11, meanwhile the sensitivity of 239Pu was improved to 990 cps/(pg/g). For 20 L of water sample, the detection limits of the method for 239Pu and 240Pu reached 1.28×10-7 Bq/L and 1.38×10-7 Bq/L, which enabled accurately determination of 239Pu and 240Pu in normal environmental water samples. The developed method was successfully applied to determine 239Pu and 240Pu in the spiked water and real environmental water samples. The results indicated this method was reliable and could be practically applied.
A sensitive analytical method for determination of 239Pu and 240Pu in environmental water samples was developed. By co-precipitation of plutonium with Ti(OH)3 followed by separation of plutonium using extraction chromatography with TEVA resin, a recovery of more than 80% for plutonium and a decontamination factor of 1.3×105 for uranium were achieved. A triple quadrupole inductively coupled plasma mass spectrometry (ICP-MS) method with dynamic collision/reaction cell was used for measurement of plutonium isotopes. By using NH3-He double gasses as collision/reaction gas, 238U1H+ ion interference to 239Pu was significantly suppressed and the final abundance sensitivity of 238U to m/z=239 was reduced to <1×10-11, meanwhile the sensitivity of 239Pu was improved to 990 cps/(pg/g). For 20 L of water sample, the detection limits of the method for 239Pu and 240Pu reached 1.28×10-7 Bq/L and 1.38×10-7 Bq/L, which enabled accurately determination of 239Pu and 240Pu in normal environmental water samples. The developed method was successfully applied to determine 239Pu and 240Pu in the spiked water and real environmental water samples. The results indicated this method was reliable and could be practically applied.
2020, 48(6): 774-779
doi: 10.19756/j.issn.0253-3820.191769
Abstract:
An interface of laser ablation and stable isotope mass spectrometry was developed for micro region organic carbon stable isotope analysis. Based on this, the13C/12C analytical method for organic carbon in standards and rice leaf based on laser ablation-isotope ratio mass spectrometry (LA-IRMS) was described. The results showed that this device could be used for the continuous on-line analysis of solid samples with high sensitivity, and the sampling amount was as low as tens of nanograms, which was 104 times lower than that of traditional EA-IRMS analysis. This method effectively avoided many fractionation factors in the process of sampling, transmission and ionization, and obtained repeatable and high-precision test results. Combined with the advantages of laser ablation technology in situ sampling, this technique could obtain high-resolution carbon isotope distribution information of solid samples. This in-situ and on-line solid organic carbon isotope measurement technique was stable, reliable and accurate, and had a huge application prospect in the fields of environment, agriculture, forestry and ecology in the future.
An interface of laser ablation and stable isotope mass spectrometry was developed for micro region organic carbon stable isotope analysis. Based on this, the13C/12C analytical method for organic carbon in standards and rice leaf based on laser ablation-isotope ratio mass spectrometry (LA-IRMS) was described. The results showed that this device could be used for the continuous on-line analysis of solid samples with high sensitivity, and the sampling amount was as low as tens of nanograms, which was 104 times lower than that of traditional EA-IRMS analysis. This method effectively avoided many fractionation factors in the process of sampling, transmission and ionization, and obtained repeatable and high-precision test results. Combined with the advantages of laser ablation technology in situ sampling, this technique could obtain high-resolution carbon isotope distribution information of solid samples. This in-situ and on-line solid organic carbon isotope measurement technique was stable, reliable and accurate, and had a huge application prospect in the fields of environment, agriculture, forestry and ecology in the future.
2020, 48(6): 780-785
doi: 10.19756/j.issn.0253-3820.191466
Abstract:
The nitrate (NONO3-) will produce a Cs2CNO+ isobaric of Cs2BO2+ when determining boron isotope of samples containing nitrate by thermal ionization mass spectrometry (TIMS), which reduces the ratio of 11B/10B in these samples and seriously interferes with the determination of boron isotope. However, the traditional two-step ion exchange method (ie. the first step of boron special effect resin, the second step of anion-cation exchange method) cannot effectively remove NONO3-. In this study, the pretreatment process of boron isotope in samples from the natural nitrate-type brine (NONO3- content was 1384 mg/L) was carried out. Three-step ion exchange method (ie. adding a step anion resin based two-step method) was used to reduce the content of NONO3- in the sample solution and eliminate the influence of NONO3- ion in the determination of boron isotope. The results showed that the three-step ion exchange method could further eliminate the content of NONO3- compared with the conventional two-step ion exchange method, reducing the interference of the isobaric determination of boron isotope. The recovery of boron in the sample pretreated by the three-step ion exchange method was over 90%, which fully met the requirements of boron isotope determination. In this process, there was no fractionation of boron isotope. This method was suitable for the high-precision boron isotope determination of nitrate-containing brine and effectively shortened the detection time.
The nitrate (NONO3-) will produce a Cs2CNO+ isobaric of Cs2BO2+ when determining boron isotope of samples containing nitrate by thermal ionization mass spectrometry (TIMS), which reduces the ratio of 11B/10B in these samples and seriously interferes with the determination of boron isotope. However, the traditional two-step ion exchange method (ie. the first step of boron special effect resin, the second step of anion-cation exchange method) cannot effectively remove NONO3-. In this study, the pretreatment process of boron isotope in samples from the natural nitrate-type brine (NONO3- content was 1384 mg/L) was carried out. Three-step ion exchange method (ie. adding a step anion resin based two-step method) was used to reduce the content of NONO3- in the sample solution and eliminate the influence of NONO3- ion in the determination of boron isotope. The results showed that the three-step ion exchange method could further eliminate the content of NONO3- compared with the conventional two-step ion exchange method, reducing the interference of the isobaric determination of boron isotope. The recovery of boron in the sample pretreated by the three-step ion exchange method was over 90%, which fully met the requirements of boron isotope determination. In this process, there was no fractionation of boron isotope. This method was suitable for the high-precision boron isotope determination of nitrate-containing brine and effectively shortened the detection time.
2020, 48(6): 786-793
doi: 10.19756/j.issn.0253-3820.191257
Abstract:
Isotope labeling in conjunction with high resolution mass spectrometry (HRMS) was used for investigation of transformation pathway in photosynthetic membrane lipids in Nitzschiaclosterium f. minutissima: diacylglycerol monogalactose (MGDG), diacylglycerol digalactose (DGDG), diacylglycerol thioglyceride (SQDG) and phosphatidylglycerol (PG), and had been demonstrated as a perfect superior tool to directly illuminate the transfer pathway of carbon in photosynthetic glycerolipids, which in contrast to previous studies where only changes in compositions were taken as evidence for these processes. The experimental results showed that 4 photosynthetic membrane lipids were labeled, and the labeling content increased gradually during the whole platform. Besides, spatial structure played a decisive role in labeling priority and provided insight into photosynthetic glycolipids synthesis in marine diatoms based on MS/MS, including suggestion of an preferably labeled of backbone-linked headgroups, and then was the glycerol skeleton and fatty acid substituents. It was also observed that 13C incorporated into those headgroups almost simultaneously. The method could directly and accurately illuminate the utilization of carbon atoms by photosynthetic glycerolipids in Nitzschiaclosterium f. minutissima. It provided a reference analysis platform for exploring the assimilation process of microalgae lipid biomarkers in the future by Sinonovaculaconstricta.
Isotope labeling in conjunction with high resolution mass spectrometry (HRMS) was used for investigation of transformation pathway in photosynthetic membrane lipids in Nitzschiaclosterium f. minutissima: diacylglycerol monogalactose (MGDG), diacylglycerol digalactose (DGDG), diacylglycerol thioglyceride (SQDG) and phosphatidylglycerol (PG), and had been demonstrated as a perfect superior tool to directly illuminate the transfer pathway of carbon in photosynthetic glycerolipids, which in contrast to previous studies where only changes in compositions were taken as evidence for these processes. The experimental results showed that 4 photosynthetic membrane lipids were labeled, and the labeling content increased gradually during the whole platform. Besides, spatial structure played a decisive role in labeling priority and provided insight into photosynthetic glycolipids synthesis in marine diatoms based on MS/MS, including suggestion of an preferably labeled of backbone-linked headgroups, and then was the glycerol skeleton and fatty acid substituents. It was also observed that 13C incorporated into those headgroups almost simultaneously. The method could directly and accurately illuminate the utilization of carbon atoms by photosynthetic glycerolipids in Nitzschiaclosterium f. minutissima. It provided a reference analysis platform for exploring the assimilation process of microalgae lipid biomarkers in the future by Sinonovaculaconstricta.
2020, 48(6): 794-801
doi: 10.19756/j.issn.0253-3820.201049
Abstract:
A method for detection of 9 kinds of aldehyde and ketone flavor compounds in mainstream smoke of heated tobacco products based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) was established. The target analytes in samples and standard solution were derivatized with 1-(2-hydrazinyl-2-oxoethyl)pyridin-1-bromide (Girard reagent P, GP) and d5-GP, respectively. The derivative products of the standard solution were used as stable isotope internal standards, and the target analytes were analyzed by multiple reaction monitoring mode. The limits of detection were 0.07-12.7 ng/mL under the optimum derivatization conditions. The target analytes exhibited a good linearity with the standard curve correlation coefficients (R2) of not less than 0.9937, and the relative standard deviation was 0.2%-11.6%. The recoveries of real samples at three spiked levels were 82.5%-118.0%. Finally, the method was successfully applied to the analysis of aldehyde and ketone flavor compounds in mainstream smoke of heated tobacco products.
A method for detection of 9 kinds of aldehyde and ketone flavor compounds in mainstream smoke of heated tobacco products based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) was established. The target analytes in samples and standard solution were derivatized with 1-(2-hydrazinyl-2-oxoethyl)pyridin-1-bromide (Girard reagent P, GP) and d5-GP, respectively. The derivative products of the standard solution were used as stable isotope internal standards, and the target analytes were analyzed by multiple reaction monitoring mode. The limits of detection were 0.07-12.7 ng/mL under the optimum derivatization conditions. The target analytes exhibited a good linearity with the standard curve correlation coefficients (R2) of not less than 0.9937, and the relative standard deviation was 0.2%-11.6%. The recoveries of real samples at three spiked levels were 82.5%-118.0%. Finally, the method was successfully applied to the analysis of aldehyde and ketone flavor compounds in mainstream smoke of heated tobacco products.
2020, 48(6): 802-810
doi: 10.19756/j.issn.0253-3820.191420
Abstract:
A 13C-quantitative nuclear magnetic resonance (qNMR) method was established for determination of content of fatty acid at different positions in edible oil. The positional specificity analysis of sn-1,3 and sn-2 in fatty acids in edible oil was performed using reverse-gated decoupling technique. The direct normal integral, deconvolution integral using different Lorentz-Gaussian ratios, and other data processing methods were compared for the analyzing 13C-qNMR unseparated peaks. Then the deconvolution integral with Lorentz-Gauss (3∶2) was selected to extract the quantitative peak areas of two unsaturated fatty acids at sn-1,3 and sn-2, linoleic acid and oleic acid. The content of unsaturated fatty acids in different positions showed that the saturated fatty acids, sn-1 linoleic acid, sn-2 linoleic acid, sn-1,3 oleic acid, sn-2 oleic acid were as follows: soybean oil (16.2%, 27.8%, 24.0%, 15.5%, 7.9% (w/w, the same below)); corn oil (15.3%, 30.7%, 20.5%, 20.1%, 13.3%); peanut oil (18.3%, 18.7%, 12.5%, 24.9%, 25.5%). The sn-1,3 linolenic acid, sn-2 linolenic acid in soybean oil were 4.5% and 4.1%, respectively, but were undetectable in corn oil and peanut oil. The result was in accordance with content of total linoleic acid and total oleic acid detected by above 1H-qNMR method. 13C-qNMR can be applied to distinguish the location and distribution of unsaturated fatty acids with easy sample preparation and flexible operation, providing a method for quantifying the specific triglyceride positional isomer component in edible oil without its standard sample.
A 13C-quantitative nuclear magnetic resonance (qNMR) method was established for determination of content of fatty acid at different positions in edible oil. The positional specificity analysis of sn-1,3 and sn-2 in fatty acids in edible oil was performed using reverse-gated decoupling technique. The direct normal integral, deconvolution integral using different Lorentz-Gaussian ratios, and other data processing methods were compared for the analyzing 13C-qNMR unseparated peaks. Then the deconvolution integral with Lorentz-Gauss (3∶2) was selected to extract the quantitative peak areas of two unsaturated fatty acids at sn-1,3 and sn-2, linoleic acid and oleic acid. The content of unsaturated fatty acids in different positions showed that the saturated fatty acids, sn-1 linoleic acid, sn-2 linoleic acid, sn-1,3 oleic acid, sn-2 oleic acid were as follows: soybean oil (16.2%, 27.8%, 24.0%, 15.5%, 7.9% (w/w, the same below)); corn oil (15.3%, 30.7%, 20.5%, 20.1%, 13.3%); peanut oil (18.3%, 18.7%, 12.5%, 24.9%, 25.5%). The sn-1,3 linolenic acid, sn-2 linolenic acid in soybean oil were 4.5% and 4.1%, respectively, but were undetectable in corn oil and peanut oil. The result was in accordance with content of total linoleic acid and total oleic acid detected by above 1H-qNMR method. 13C-qNMR can be applied to distinguish the location and distribution of unsaturated fatty acids with easy sample preparation and flexible operation, providing a method for quantifying the specific triglyceride positional isomer component in edible oil without its standard sample.
2020, 48(6): 811-816
doi: 10.19756/j.issn.0253-3820.191731
Abstract:
To rapidly determine Cr content in rice husks, laser induced breakdown spectroscopy (LIBS) was used to obtain plasma signal spectral data of Cr elements of rice in 24 groups of polluted paddy fields around Poyang Lake, Jiangxi Province. By constructing nine-point smoothing and normalized spectral pretreatment in the band range of 422.04-445.94 nm, 18 groups were selected as training samples and the other 6 groups as test samples, and thus a support vector machine (SVM) parameter adjustment optimization method based on particle swarm optimization (PSO) was proposed. The LIBS quantitative analysis model of Cr content by PSO-SVM intelligent algorithm was established, and the root mean square error (RMSE) of test set was 7.83 μg/g, the average absolute error percentage (MAPE) was 4.10%, the correlation coefficient between predicted value and true value was 0.9948. Under the same conditions, partial least square method (siPLS) was used to predict the concentration of 6 groups of samples, and it was found that the RMSE was 22.58 μg/g, the MAPE was 6.17%, and the correlation coefficient was 0.9840. The analysis results showed that the PSO-SVM regression quantitative method could be applied to the composition analysis of LIBS agricultural products, and its analysis effect was improved compared with siPLS.
To rapidly determine Cr content in rice husks, laser induced breakdown spectroscopy (LIBS) was used to obtain plasma signal spectral data of Cr elements of rice in 24 groups of polluted paddy fields around Poyang Lake, Jiangxi Province. By constructing nine-point smoothing and normalized spectral pretreatment in the band range of 422.04-445.94 nm, 18 groups were selected as training samples and the other 6 groups as test samples, and thus a support vector machine (SVM) parameter adjustment optimization method based on particle swarm optimization (PSO) was proposed. The LIBS quantitative analysis model of Cr content by PSO-SVM intelligent algorithm was established, and the root mean square error (RMSE) of test set was 7.83 μg/g, the average absolute error percentage (MAPE) was 4.10%, the correlation coefficient between predicted value and true value was 0.9948. Under the same conditions, partial least square method (siPLS) was used to predict the concentration of 6 groups of samples, and it was found that the RMSE was 22.58 μg/g, the MAPE was 6.17%, and the correlation coefficient was 0.9840. The analysis results showed that the PSO-SVM regression quantitative method could be applied to the composition analysis of LIBS agricultural products, and its analysis effect was improved compared with siPLS.
