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2018 Volume 46 Issue 4
2018, 46(4): 463-470
doi: 10.11895/j.issn.0253-3820.171415
Abstract:
Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is an important analytical technique for biological macromolecules, such as proteins, peptides and nucleic acid, especially in the field of microbial identification. Based on previous study, a linear MALDI-TOF MS has been designed and assembled for biological applications. The instrument comprises a vacuum system, a vacuum fast sample introduction system, an optical system, a time-of-flight mass analyzer, an ion source, a data acquisition system and an electric control system. The ion source adopts two-stage source acceleration, delayed extraction and dynamic pulse focusing technology. The time-of-flight distance of field-free drift region is about 1 meter. The optical system adopts a solid laser with adjustable frequency of 1-2000 Hz and spots of 20-100 μm. The angle of incidence laser is controlled at 5 degrees. A series of experiments are carried out to further evaluate the instrument performances. It can not only analyze the samples more than 199 kDa, but also achieve isotope resolution at 1000-3000 Da and up to 900(FWHM) at 5000-17000 Da. The minimum detectable concentration of gramicidin is 10 amol/μL, absolute sensitivity can reach up to 2.56 amol. Independent detection of saliva samples from different targets shows that the instrument has high reproducibility. We identified Escherichia Coli and Shigella spp, which are two common bacteria but difficult to be differentiated by mass spectrometry, showing its potential identification for clinical microorganism. In a summary, this instrument can play a role on clinical examination in the near future.
Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is an important analytical technique for biological macromolecules, such as proteins, peptides and nucleic acid, especially in the field of microbial identification. Based on previous study, a linear MALDI-TOF MS has been designed and assembled for biological applications. The instrument comprises a vacuum system, a vacuum fast sample introduction system, an optical system, a time-of-flight mass analyzer, an ion source, a data acquisition system and an electric control system. The ion source adopts two-stage source acceleration, delayed extraction and dynamic pulse focusing technology. The time-of-flight distance of field-free drift region is about 1 meter. The optical system adopts a solid laser with adjustable frequency of 1-2000 Hz and spots of 20-100 μm. The angle of incidence laser is controlled at 5 degrees. A series of experiments are carried out to further evaluate the instrument performances. It can not only analyze the samples more than 199 kDa, but also achieve isotope resolution at 1000-3000 Da and up to 900(FWHM) at 5000-17000 Da. The minimum detectable concentration of gramicidin is 10 amol/μL, absolute sensitivity can reach up to 2.56 amol. Independent detection of saliva samples from different targets shows that the instrument has high reproducibility. We identified Escherichia Coli and Shigella spp, which are two common bacteria but difficult to be differentiated by mass spectrometry, showing its potential identification for clinical microorganism. In a summary, this instrument can play a role on clinical examination in the near future.
2018, 46(4): 471-478
doi: 10.11895/j.issn.0253-3820.171234
Abstract:
Volatile organic compounds (VOCs) in ambient air can participate in photochemical reactions, which lead to the generation of secondary pollutants such as ozone and aerosol. So real-time and accurate monitoring of atmospheric VOCs plays an important role in the study of the causes of air pollution. On the basis of proton transfer reaction mass spectrometry (PTR-MS) research, a novel dipolar proton transfer reaction mass spectrometer (DP-PTR-MS) for real-time and on-line monitoring atmospheric VOCs was developed. Compared with the conventional PTR-MS with one kind of reagent ion H3O+, DP-PTR-MS had three kinds of reagent ions H3O+, OH-, (CH)2COH+, which could be switched according to the actual detection need. So DP-PTR-MS can improve the qualitative ability and expand the detection range effectively. The reagent ion H3O+ can be used for detecting VOCs whose proton affinities are greater than that of H2O. The reagent ion OH- can be used to identify VOCs cooperating with the reagent ion H3O+, and can also be used for detecting some inorganic substances such as CO2. The reagent ion (CH3)2COH+ can be used for accurately detecting NH3 under interference elimination circumstances. The limit of detection (LOD) and sensitivity of DP-PTR-MS were measured by using six kinds of standard gases. The results showed that the LOD for detecting toluene was 7×10-12 (V/V) and the sensitivity for detecting ammonia has reached 126 cps/10-9(V/V). The ambient air in Hefei city was on-line and real-time monitored for continuous 78 hours with DP-PTR-MS. The results showed that the newly developed DP-PTR-MS could be used for long-term and real-time monitoring atmospheric VOCs with the concentration of 10-12(V/V) level. DP-PTR-MS is an important tool for the study of the causes of atmospheric pollution and the monitoring of trace VOCs emissions.
Volatile organic compounds (VOCs) in ambient air can participate in photochemical reactions, which lead to the generation of secondary pollutants such as ozone and aerosol. So real-time and accurate monitoring of atmospheric VOCs plays an important role in the study of the causes of air pollution. On the basis of proton transfer reaction mass spectrometry (PTR-MS) research, a novel dipolar proton transfer reaction mass spectrometer (DP-PTR-MS) for real-time and on-line monitoring atmospheric VOCs was developed. Compared with the conventional PTR-MS with one kind of reagent ion H3O+, DP-PTR-MS had three kinds of reagent ions H3O+, OH-, (CH)2COH+, which could be switched according to the actual detection need. So DP-PTR-MS can improve the qualitative ability and expand the detection range effectively. The reagent ion H3O+ can be used for detecting VOCs whose proton affinities are greater than that of H2O. The reagent ion OH- can be used to identify VOCs cooperating with the reagent ion H3O+, and can also be used for detecting some inorganic substances such as CO2. The reagent ion (CH3)2COH+ can be used for accurately detecting NH3 under interference elimination circumstances. The limit of detection (LOD) and sensitivity of DP-PTR-MS were measured by using six kinds of standard gases. The results showed that the LOD for detecting toluene was 7×10-12 (V/V) and the sensitivity for detecting ammonia has reached 126 cps/10-9(V/V). The ambient air in Hefei city was on-line and real-time monitored for continuous 78 hours with DP-PTR-MS. The results showed that the newly developed DP-PTR-MS could be used for long-term and real-time monitoring atmospheric VOCs with the concentration of 10-12(V/V) level. DP-PTR-MS is an important tool for the study of the causes of atmospheric pollution and the monitoring of trace VOCs emissions.
2018, 46(4): 479-485
doi: 10.11895/j.issn.0253-3820.171370
Abstract:
A metabolic profiling analysis method for metabolomic studies of rice leaf was established based on HSS T3 combined with XBridge Amide Q-TOF LC/MS by comparing the influences of different extraction methods in rice leaves of metabolites. The extraction and separation of rice leaf metabolites using three different methods including methanol-chloroform-water, methanol-chloroform-ammonia, methanol-methyl tert-butyl ether -water and different chromatographic systems were compared by the numbers of peaks, identified metabolites and the metabolic pathways. The results showed that the method of methanol-chloroform-water reached the highest coverage rate of metabolites in rice leaves, and the maximum number of unique metabolites including prephenic acid, luteolin, α-linolenic acid, aconitic acid, gibberellin A12 aldehyde, isovitexin, L-Glutamate were detected. Metabolites with different polarity in rice leaf could be detected by HSS T3 and XBridge Amide. A total of 16 kinds of organic acids, 17 kinds of nucleotides, 21 kinds of amino acids, 66 kinds of fatty acids, 11 kinds of phospholipids and 7 kinds of sphingolipids were identified. XBridge Amide had an absolute advantage in detecting phospholipids and sphingolipids. The metabolic pathways involved purine metabolism, pyrimidine metabolism, tricarboxylic acid cycle, arginine metabolism, fatty acid metabolism, phospholipid metabolism, sphingolipid metabolism, phenylalanine metabolism and vitamin B2 synthesis. It showed certain complementarity between the two columns in identifying metabolites and involved the metabolic pathways. The established method is expected to be useful for the metabolomic studies of rice.
A metabolic profiling analysis method for metabolomic studies of rice leaf was established based on HSS T3 combined with XBridge Amide Q-TOF LC/MS by comparing the influences of different extraction methods in rice leaves of metabolites. The extraction and separation of rice leaf metabolites using three different methods including methanol-chloroform-water, methanol-chloroform-ammonia, methanol-methyl tert-butyl ether -water and different chromatographic systems were compared by the numbers of peaks, identified metabolites and the metabolic pathways. The results showed that the method of methanol-chloroform-water reached the highest coverage rate of metabolites in rice leaves, and the maximum number of unique metabolites including prephenic acid, luteolin, α-linolenic acid, aconitic acid, gibberellin A12 aldehyde, isovitexin, L-Glutamate were detected. Metabolites with different polarity in rice leaf could be detected by HSS T3 and XBridge Amide. A total of 16 kinds of organic acids, 17 kinds of nucleotides, 21 kinds of amino acids, 66 kinds of fatty acids, 11 kinds of phospholipids and 7 kinds of sphingolipids were identified. XBridge Amide had an absolute advantage in detecting phospholipids and sphingolipids. The metabolic pathways involved purine metabolism, pyrimidine metabolism, tricarboxylic acid cycle, arginine metabolism, fatty acid metabolism, phospholipid metabolism, sphingolipid metabolism, phenylalanine metabolism and vitamin B2 synthesis. It showed certain complementarity between the two columns in identifying metabolites and involved the metabolic pathways. The established method is expected to be useful for the metabolomic studies of rice.
2018, 46(4): 486-492
doi: 10.11895/j.issn.0253-3820.171171
Abstract:
A sensing system based on AuNP-AuNP-UCNP triple structure for efficient detection of dual targets was constructed. In the preparation of triple structure, the gold nanoparticles (AuNPs) and upconversion nanoparticles (NaYF4:Yb, Er, Gd, UCNPs) were synthesized and surface modified. Then the two nanoparticles and their aptamers were connected to form two kinds of optical fluorescent probes. A nucleic acid sequence that matches with two aptamers was designed, rendering the probes to get close based on the principle of complementary base pairing. On the basis of this, a sensing system with a triple structure was prepared, and its connecting effect was characterized by TEM. With this system, dual targets of bisphenol A and estradiol were efficiently and conveniently detected through quantitative determination by fluorescence and UV spectrophotometer. At reaction temperature of 30℃ and pH=7.8, this method exhibited good linear range for determination of bisphenol A and estradiol from 2 ng/mL to 200 ng/mL and from 10 ng/mL to 150 ng/mL, with limits of detection of 0.2 ng/mL and 0.5 ng/mL, respectively. This sensing system with the triple structure owned better specificity to structural and functional analogues, and showed good repeatability and stability. What's more, this sensing system was applied in actual water detection, with the recoveries between 86.1% and 107.4%, and the relative standard deviation below 6.8%. This method showed promising applications in other environmental estrogens in water samples.
A sensing system based on AuNP-AuNP-UCNP triple structure for efficient detection of dual targets was constructed. In the preparation of triple structure, the gold nanoparticles (AuNPs) and upconversion nanoparticles (NaYF4:Yb, Er, Gd, UCNPs) were synthesized and surface modified. Then the two nanoparticles and their aptamers were connected to form two kinds of optical fluorescent probes. A nucleic acid sequence that matches with two aptamers was designed, rendering the probes to get close based on the principle of complementary base pairing. On the basis of this, a sensing system with a triple structure was prepared, and its connecting effect was characterized by TEM. With this system, dual targets of bisphenol A and estradiol were efficiently and conveniently detected through quantitative determination by fluorescence and UV spectrophotometer. At reaction temperature of 30℃ and pH=7.8, this method exhibited good linear range for determination of bisphenol A and estradiol from 2 ng/mL to 200 ng/mL and from 10 ng/mL to 150 ng/mL, with limits of detection of 0.2 ng/mL and 0.5 ng/mL, respectively. This sensing system with the triple structure owned better specificity to structural and functional analogues, and showed good repeatability and stability. What's more, this sensing system was applied in actual water detection, with the recoveries between 86.1% and 107.4%, and the relative standard deviation below 6.8%. This method showed promising applications in other environmental estrogens in water samples.
2018, 46(4): 493-501
doi: 10.11895/j.issn.0253-3820.171055
Abstract:
A competitive electrochemical immunosensor based on the nano-composite material immobilization and enzymatic amplification was designed for detection of microcystin-LR. Gold nanoparticles/carboxylated multi-walled carbon nanotubes (AuNPs/c-MWCNTs) composite film, which formed by electrodepositing of AuNPs on the C-MWCNTs modified glassy carbon electrode, was used for the immobilization of the antibody of microcystin-LR (anti-MCLR). Horseradish peroxidase (HRP) was introduced onto the nanocomposite interface by HRP blocked sensing interface and specific capture of antibody with target. It could be employed to catalyze the reduction of H2O2, and to block the possible remaining active sites as well. A competitive immunoreaction between antigen and MCLR-HRP was used for target analysis. In the presence of H2O2 and hydroquinone (HQ), MCLR could be indirectly detected with differential pulse voltammetry (DPV) method by determining the reduction current of HQ. Under the optimal conditions, the proposed immunosensor exhibited wide linear ranges in the concentration ranges of 0.1-100.0 μg/L, with a detection limit of 0.038 μg/L (S/N=3, n=8). The immunosensor showed good specificity, stability and sensitivity. It was used to determine MCLR in real water samples with the recoveries of 72.9%-117.3%.
A competitive electrochemical immunosensor based on the nano-composite material immobilization and enzymatic amplification was designed for detection of microcystin-LR. Gold nanoparticles/carboxylated multi-walled carbon nanotubes (AuNPs/c-MWCNTs) composite film, which formed by electrodepositing of AuNPs on the C-MWCNTs modified glassy carbon electrode, was used for the immobilization of the antibody of microcystin-LR (anti-MCLR). Horseradish peroxidase (HRP) was introduced onto the nanocomposite interface by HRP blocked sensing interface and specific capture of antibody with target. It could be employed to catalyze the reduction of H2O2, and to block the possible remaining active sites as well. A competitive immunoreaction between antigen and MCLR-HRP was used for target analysis. In the presence of H2O2 and hydroquinone (HQ), MCLR could be indirectly detected with differential pulse voltammetry (DPV) method by determining the reduction current of HQ. Under the optimal conditions, the proposed immunosensor exhibited wide linear ranges in the concentration ranges of 0.1-100.0 μg/L, with a detection limit of 0.038 μg/L (S/N=3, n=8). The immunosensor showed good specificity, stability and sensitivity. It was used to determine MCLR in real water samples with the recoveries of 72.9%-117.3%.
2018, 46(4): 502-510
doi: 10.11895/j.issn.0253-3820.171392
Abstract:
A temperature-responsive hydrophilic block copolymer fluorescence sensor based on selective analysis of Al3+ was designed and synthesized. The polymer fluorescent probe (L64-BTPA-SHMA) was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization and characterized by 1H NMR, and the recognition performance of the polymer probe was studied by fluorescence spectroscopy. It was found that the fluorescence response of Al3+ detected by this polymer fluorescence probe was significantly affected by temperature. The higher the temperature, the lower the fluorescence intensity was observed. The results showed that 0.1 g/L polymer fluorescent probe had a good selectivity to Al3+ in buffer solution at 25℃ and pH 7.4, and was not affected by other metal ions. A fluorescence detection method based on this polymer probe for Al3+ was developed. In this method, the fluorescence intensity was linear with Al3+ concentration in the range of 2.0-18.0 μmol/L, with a correlation coefficient of 0.9977 and a detection limit of 1.43 μmol/L. The fluorescence response between the polymer fluorescence chemosensor and Al3+ could be altered by controlling the temperature change. The successful application of the polymer fluorescence probe for detecting Al3+ residues in agricultural products has practical application value.
A temperature-responsive hydrophilic block copolymer fluorescence sensor based on selective analysis of Al3+ was designed and synthesized. The polymer fluorescent probe (L64-BTPA-SHMA) was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization and characterized by 1H NMR, and the recognition performance of the polymer probe was studied by fluorescence spectroscopy. It was found that the fluorescence response of Al3+ detected by this polymer fluorescence probe was significantly affected by temperature. The higher the temperature, the lower the fluorescence intensity was observed. The results showed that 0.1 g/L polymer fluorescent probe had a good selectivity to Al3+ in buffer solution at 25℃ and pH 7.4, and was not affected by other metal ions. A fluorescence detection method based on this polymer probe for Al3+ was developed. In this method, the fluorescence intensity was linear with Al3+ concentration in the range of 2.0-18.0 μmol/L, with a correlation coefficient of 0.9977 and a detection limit of 1.43 μmol/L. The fluorescence response between the polymer fluorescence chemosensor and Al3+ could be altered by controlling the temperature change. The successful application of the polymer fluorescence probe for detecting Al3+ residues in agricultural products has practical application value.
2018, 46(4): 511-516
doi: 10.11895/j.issn.0253-3820.171222
Abstract:
A fluorescence enhancement probe (ZY8) for the detection of N2H4 was designed and synthesized by employing 3-hydroxyflavone as a fluorophore, and its spectral properties had been investigated. The results showed that ZY8 had relatively good selectivity and specificity to N2H4 in Tris-HCl-ethanol solution (9:1, V/V, pH 7.40). The fluorescent intensity of ZY8 exhibited good linear relationship with concentration of N2H4 in the concentration range of 1.6×10-7 mol/L-6.2×10-5 mol/L, and its detection limit was estimated to be 1.6×10-7 mol/L. ZY8 itself had weak fluorescence, upon addition of N2H4, an approximate 9-fold fluorescence enhancement was observed, and the color of the solution changed from light grayish green to bright grass-green at UV light of 365 nm. So ZY8 might be used to the visual recognition of N2H4. ZY8 could detect N2H4in near-physiological pH range, and it had fast response and strong anti-interference ability. Moreover, ZY8 could be loaded as test paper for naked-eye detection of N2H4 at mmol/L level in water solution, and it was also applied in the determination of N2H4 in various water samples by the standard addition recovery experiments, with the recovery ratio ranged from 96.0% to 104.2%%, and RSD of all < 4%. The results of this study demonstrated that ZY8 had potential application to the detection of N2H4 in the monitoring of environmental pollution.
A fluorescence enhancement probe (ZY8) for the detection of N2H4 was designed and synthesized by employing 3-hydroxyflavone as a fluorophore, and its spectral properties had been investigated. The results showed that ZY8 had relatively good selectivity and specificity to N2H4 in Tris-HCl-ethanol solution (9:1, V/V, pH 7.40). The fluorescent intensity of ZY8 exhibited good linear relationship with concentration of N2H4 in the concentration range of 1.6×10-7 mol/L-6.2×10-5 mol/L, and its detection limit was estimated to be 1.6×10-7 mol/L. ZY8 itself had weak fluorescence, upon addition of N2H4, an approximate 9-fold fluorescence enhancement was observed, and the color of the solution changed from light grayish green to bright grass-green at UV light of 365 nm. So ZY8 might be used to the visual recognition of N2H4. ZY8 could detect N2H4in near-physiological pH range, and it had fast response and strong anti-interference ability. Moreover, ZY8 could be loaded as test paper for naked-eye detection of N2H4 at mmol/L level in water solution, and it was also applied in the determination of N2H4 in various water samples by the standard addition recovery experiments, with the recovery ratio ranged from 96.0% to 104.2%%, and RSD of all < 4%. The results of this study demonstrated that ZY8 had potential application to the detection of N2H4 in the monitoring of environmental pollution.
2018, 46(4): 517-523
doi: 10.11895/j.issn.0253-3820.171353
Abstract:
A method for the determination of trace elements such as lead, arsenic and mercury in cream cosmetics by total reflection X-ray fluorescence spectrometry (TXRF) with suspension sampling was developed. The mixed solvents of water, tetrahydrofuran, methanol and were used to disperse paste, cream, and additives of triton X-100 to promote the test liquid uniform. The test suspension fluid were taken into the sample carrier, drying and then introduced into TXRF. Poly (1-vinylpyrrolidone-co-vinyl acetate) (P(VP-co-VAc)) was added to curing sediments, inhibiting proliferation. Triton X-100 and P(VP-co-VAc) were found to have the function of reducing mercury loss in the drying process. The loss of elements in the drying process and the effect of triton X-100 and P(VP-co-VAc) were investigated. The effect of cream matrix, element interference, spectral line and the inner standard were discussed. The calibration curves for quantitative analysis were established using matrix standards, so the error of software decomposition peak and the error caused by thick sample were avoided within a certain range. In this work, the linear correlation coefficients of Pb, As and Hg calibration curve were greater than 0.998 The detection limit of Pb, As and Hg in the solution were 0.005, 0.004 and 0.006 μg/mL, respectively. Relative standard diviations(RSDs, n=11) of Pb, As and Hg were 7.8%-14.9%, 6.6%-13.3% and 7.6%-14.6% respectively. The results of Pb, As, and Hg in cream cosmetics determinated by this method agreed with those obtained from inductively coupled plasma atomic emission spectrometry and the value of standard reference material. The TXRF method was proved to be accurate, simple and valuable in determination of trace heavy metal ions in cosmetic samples.
A method for the determination of trace elements such as lead, arsenic and mercury in cream cosmetics by total reflection X-ray fluorescence spectrometry (TXRF) with suspension sampling was developed. The mixed solvents of water, tetrahydrofuran, methanol and were used to disperse paste, cream, and additives of triton X-100 to promote the test liquid uniform. The test suspension fluid were taken into the sample carrier, drying and then introduced into TXRF. Poly (1-vinylpyrrolidone-co-vinyl acetate) (P(VP-co-VAc)) was added to curing sediments, inhibiting proliferation. Triton X-100 and P(VP-co-VAc) were found to have the function of reducing mercury loss in the drying process. The loss of elements in the drying process and the effect of triton X-100 and P(VP-co-VAc) were investigated. The effect of cream matrix, element interference, spectral line and the inner standard were discussed. The calibration curves for quantitative analysis were established using matrix standards, so the error of software decomposition peak and the error caused by thick sample were avoided within a certain range. In this work, the linear correlation coefficients of Pb, As and Hg calibration curve were greater than 0.998 The detection limit of Pb, As and Hg in the solution were 0.005, 0.004 and 0.006 μg/mL, respectively. Relative standard diviations(RSDs, n=11) of Pb, As and Hg were 7.8%-14.9%, 6.6%-13.3% and 7.6%-14.6% respectively. The results of Pb, As, and Hg in cream cosmetics determinated by this method agreed with those obtained from inductively coupled plasma atomic emission spectrometry and the value of standard reference material. The TXRF method was proved to be accurate, simple and valuable in determination of trace heavy metal ions in cosmetic samples.
2018, 46(4): 524-529
doi: 10.11895/j.issn.0253-3820.171360
Abstract:
A novel method for determination of methylamines and methylamine-N-oxides in fine particles using solid phase extraction (SPE) coupled with ion chromatography (IC) was developed. The experimental conditions including solid phase extraction and chromatographic condition were optimized. The quartz filter loaded with particulate matter (PM) samples was ultrasonically extracted with 20 mL of methanol and water (1:3, V/V) mixture and the extraction process repeated for another 2 times. After the extraction, a total of 60 mL of extraction solvent was dropped into the extraction equipment in solid phase column. The Agilent AccuBond C18 was chosen for enriching the methylamine, dimethylamine, trimethylamine and trimethylamine-N-oxide in fine particles. Under the optimum conditions, the target species on Agilent Accu Bond C18 were washed by 0.5 mL of acetonitrile solution and then concentrated into a constant volume (2 mL) before injecting into IC for analysis. A 250 mm×4 mm id PRP X-200 column was used for the separation of analytes at the temperature of 25oC. The mobile phase was a mixture of acetonitrile solution (3%, V/V) and nitric acid (5 mmol/L) with the flow rate being kept at 1 mL/min. The four aliphatic amine species were fully resolved and the separations were completed within 30 min. The linearity of the four compounds ranged from 0.45 to 1000 μg/kg with the precisions of 2%-4% and the detection limits of 0.002-0.003 μg/m3. The recoveries of four aliphatic amine species in real environmental samples were higher than 90%. This method was successfully applied to the analysis of real fine particle samples collected at Beijing. The concentrations of trimethylamine and methylamine-N-oxides were in the range of 0.01-0.08 μg/m3 and 0.02-0.14 μg/m3 for Beijing dust and haze samples, respectively.
A novel method for determination of methylamines and methylamine-N-oxides in fine particles using solid phase extraction (SPE) coupled with ion chromatography (IC) was developed. The experimental conditions including solid phase extraction and chromatographic condition were optimized. The quartz filter loaded with particulate matter (PM) samples was ultrasonically extracted with 20 mL of methanol and water (1:3, V/V) mixture and the extraction process repeated for another 2 times. After the extraction, a total of 60 mL of extraction solvent was dropped into the extraction equipment in solid phase column. The Agilent AccuBond C18 was chosen for enriching the methylamine, dimethylamine, trimethylamine and trimethylamine-N-oxide in fine particles. Under the optimum conditions, the target species on Agilent Accu Bond C18 were washed by 0.5 mL of acetonitrile solution and then concentrated into a constant volume (2 mL) before injecting into IC for analysis. A 250 mm×4 mm id PRP X-200 column was used for the separation of analytes at the temperature of 25oC. The mobile phase was a mixture of acetonitrile solution (3%, V/V) and nitric acid (5 mmol/L) with the flow rate being kept at 1 mL/min. The four aliphatic amine species were fully resolved and the separations were completed within 30 min. The linearity of the four compounds ranged from 0.45 to 1000 μg/kg with the precisions of 2%-4% and the detection limits of 0.002-0.003 μg/m3. The recoveries of four aliphatic amine species in real environmental samples were higher than 90%. This method was successfully applied to the analysis of real fine particle samples collected at Beijing. The concentrations of trimethylamine and methylamine-N-oxides were in the range of 0.01-0.08 μg/m3 and 0.02-0.14 μg/m3 for Beijing dust and haze samples, respectively.
2018, 46(4): 530-536
doi: 10.11895/j.issn.0253-3820.171465
Abstract:
A new derivative of ordered mesoporous carbon (GSH-CMK-3) has been prepared by chemical modification and functionalization of ordered mesoporous carbon with glutathione. The composite was fully characterized by means of Fourier transforming infrared spectroscopy (FT-IR), scanning electron microscope (SEM) image and thermogravimetric analysis (TGA). GSH-CMK-3 showed favorable chemical stability, thermal stability and excellent adsorption performance toward Cd2+ and a maximum adsorption capacity of 87.87 mg/g was achieved. The adsorption kinetic follows pseudo-second-order adsorption model. In a sequential injection mini-column separation system, 0.006 mol/L sulfourea (in 0.2 mol/L HNO3) was adopted as eluent and the elution efficiency was 96%. With a sample volume of 1000 μL and 50 μL of eluate, an enrichment factor of 17.3 was obtained. A procedure for on-line selective separation and preconcentration of trace Cd2+ was developed by graphite furnace atomic absorption spectrometry. Along with a detection limit of 1.9 ng/L (n=7, 3σ) and a linear range of 0.05-0.20 μg/L, a RSD of 2.9% (n=13, 100 ng/L) was achieved. The method was validated by analyzing Cd2+ in a certified reference material GBW08608.
A new derivative of ordered mesoporous carbon (GSH-CMK-3) has been prepared by chemical modification and functionalization of ordered mesoporous carbon with glutathione. The composite was fully characterized by means of Fourier transforming infrared spectroscopy (FT-IR), scanning electron microscope (SEM) image and thermogravimetric analysis (TGA). GSH-CMK-3 showed favorable chemical stability, thermal stability and excellent adsorption performance toward Cd2+ and a maximum adsorption capacity of 87.87 mg/g was achieved. The adsorption kinetic follows pseudo-second-order adsorption model. In a sequential injection mini-column separation system, 0.006 mol/L sulfourea (in 0.2 mol/L HNO3) was adopted as eluent and the elution efficiency was 96%. With a sample volume of 1000 μL and 50 μL of eluate, an enrichment factor of 17.3 was obtained. A procedure for on-line selective separation and preconcentration of trace Cd2+ was developed by graphite furnace atomic absorption spectrometry. Along with a detection limit of 1.9 ng/L (n=7, 3σ) and a linear range of 0.05-0.20 μg/L, a RSD of 2.9% (n=13, 100 ng/L) was achieved. The method was validated by analyzing Cd2+ in a certified reference material GBW08608.
2018, 46(4): 537-542
doi: 10.11895/j.issn.0253-3820.171228
Abstract:
A sensitive and rapid method using liquid chromatography-hydride generation atomic fluorescence spectrometry (HPLC-HG-AFS) was developed for the simultaneous determination of seven arsenic species As3+, As5+, MMA, DMA, p-ASA, 4-OH and ROX in feeds. The isolation of the analytes from feed samples was accomplished using methanol water (1:1, V/V). The target compounds were separated on a PRP-X100 anion exchange column and then analyzed by HG-AFS. The mobile phase was 15 mmol/L (NH4)2HPO4 and 10 mmol/L potassium acid phthalate. Good linearity was obtained for all of the seven arsenic species, with linear coefficients higher than 0.9964. The LODs of the seven arsenic species were between 5 and 30 μg/kg. Average recoveries for the seven analytes were in the ranges of 76.3%-108.1%, with intra-and inter-day repeatability lower than 7.7% and 17.4%, respectively. This validated method was successively applied to the determination of arsenic species in feed. This method was sensitive, simple, cheap and low operation cost, and could be used for the determination of the arsenicspecies in feeds.
A sensitive and rapid method using liquid chromatography-hydride generation atomic fluorescence spectrometry (HPLC-HG-AFS) was developed for the simultaneous determination of seven arsenic species As3+, As5+, MMA, DMA, p-ASA, 4-OH and ROX in feeds. The isolation of the analytes from feed samples was accomplished using methanol water (1:1, V/V). The target compounds were separated on a PRP-X100 anion exchange column and then analyzed by HG-AFS. The mobile phase was 15 mmol/L (NH4)2HPO4 and 10 mmol/L potassium acid phthalate. Good linearity was obtained for all of the seven arsenic species, with linear coefficients higher than 0.9964. The LODs of the seven arsenic species were between 5 and 30 μg/kg. Average recoveries for the seven analytes were in the ranges of 76.3%-108.1%, with intra-and inter-day repeatability lower than 7.7% and 17.4%, respectively. This validated method was successively applied to the determination of arsenic species in feed. This method was sensitive, simple, cheap and low operation cost, and could be used for the determination of the arsenicspecies in feeds.
2018, 46(4): 543-549
doi: 10.11895/j.issn.0253-3820.171230
Abstract:
The fatty acid contents in soybean oil, corn oil, coconut oil, sunflower seed oil and fish oil were detected by gas chromatography. According to the characteristics of fatty acids of raw oil and the relevant regulations of GB 10765-2010, the formula of 6 kinds of human milk lipid substitutes was designed by Matlab software and Excel linear programming. At the same time, the Schaal oven accelerated oxidation method was used to study the oxidation process of 6 formulations using synchronous fluorescence technique combined with traditional chemical reagents (oxidation index:peroxide value, value of fennel and total oxidation value). By statistical analysis of data, the statistical relationship between fluorescence intensity and oxidation index was explored. The results showed that the main fatty acids of coconut oil were lauric acid and myristic acid, and its saturated fatty acid content was the highest 93.75%±0.06%; while all the other oils were mainly composed of palmitic acid, linoleic acid and other components, wherein the fish oil had the highest content of unsaturated fatty acid. With the increase of oxidation time, the fluorescence intensity decreased gradually and the oxidation index value increased continuously. The correlation analysis and regression analysis results showed that the change of oxidation index and the fluorescence intensity of 6 samples had negative correlation, and the fluorescence intensity and the peroxide value and total oxidation value was quadratic linear correlation, and anisidine value as a linear correlation had strong correlation.
The fatty acid contents in soybean oil, corn oil, coconut oil, sunflower seed oil and fish oil were detected by gas chromatography. According to the characteristics of fatty acids of raw oil and the relevant regulations of GB 10765-2010, the formula of 6 kinds of human milk lipid substitutes was designed by Matlab software and Excel linear programming. At the same time, the Schaal oven accelerated oxidation method was used to study the oxidation process of 6 formulations using synchronous fluorescence technique combined with traditional chemical reagents (oxidation index:peroxide value, value of fennel and total oxidation value). By statistical analysis of data, the statistical relationship between fluorescence intensity and oxidation index was explored. The results showed that the main fatty acids of coconut oil were lauric acid and myristic acid, and its saturated fatty acid content was the highest 93.75%±0.06%; while all the other oils were mainly composed of palmitic acid, linoleic acid and other components, wherein the fish oil had the highest content of unsaturated fatty acid. With the increase of oxidation time, the fluorescence intensity decreased gradually and the oxidation index value increased continuously. The correlation analysis and regression analysis results showed that the change of oxidation index and the fluorescence intensity of 6 samples had negative correlation, and the fluorescence intensity and the peroxide value and total oxidation value was quadratic linear correlation, and anisidine value as a linear correlation had strong correlation.
2018, 46(4): 550-555
doi: 10.11895/j.issn.0253-3820.181009
Abstract:
The research for efficient and low-cost electrocatalysts for water splitting are essential for the exploitation and application of hydrogen energy. Transitional metal phosphides are considered as one of the most promising bifunctional water splitting electrocatalysts. Herein, we reported a facile two-step method (firstly hydrothermal preparation, then phosphorization under low temperature) to synthesize the bead-chain like nanoarrays of CoP supported on three dimensional Nickel foam (CoP/NF). The as-prepared CoP/NF could act as an efficient bifunctional catalyst for overall water splitting. The catalyst exhibited remarkable activity for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline media, delivering a current density of 10 mA/cm2 at an overpotential of 281 mV for OER and 95 mV for HER, respectively. Efficient water splitting in alkaline system was realized by applying a two-electrode system with the CoP/NF acting as both the anode and cathode. The applied potential was 1.63 V to obtain the current density of 10 mA/cm2, and good stability was also testified.
The research for efficient and low-cost electrocatalysts for water splitting are essential for the exploitation and application of hydrogen energy. Transitional metal phosphides are considered as one of the most promising bifunctional water splitting electrocatalysts. Herein, we reported a facile two-step method (firstly hydrothermal preparation, then phosphorization under low temperature) to synthesize the bead-chain like nanoarrays of CoP supported on three dimensional Nickel foam (CoP/NF). The as-prepared CoP/NF could act as an efficient bifunctional catalyst for overall water splitting. The catalyst exhibited remarkable activity for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline media, delivering a current density of 10 mA/cm2 at an overpotential of 281 mV for OER and 95 mV for HER, respectively. Efficient water splitting in alkaline system was realized by applying a two-electrode system with the CoP/NF acting as both the anode and cathode. The applied potential was 1.63 V to obtain the current density of 10 mA/cm2, and good stability was also testified.
2018, 46(4): 556-562
doi: 10.11895/j.issn.0253-3820.171479
Abstract:
Differences of protonated and lithiated leucine-enkephalin(LE) were investigated by hydrogen deuterium exchange-mass spectrometry (HDX-MS) combined with quantum chemistry calculation. The results revealed that the protonated ions possessed very high product yield with all hydrogen atoms being exchanged, while the reaction of lithiated LE stopped after exchanging five hydrogen atoms in the same experimental conditions. The different HDX behaviours probably indicated their conformational differences. To further clarify the experimental results, the most stable conformations of protonated and lithiated leucine-enkephalin were calculated by density functional theory. It was found that terminal amino group was the most thermodynamically stable protonation site, while Li+ in coordination of four carbonyl oxygen atoms formed the most favourable lithiated LE. The reaction field reduction of lithium LE was probably due to the less acidity of hydrogen atoms and the increasing rigid conformation change induced by lithium ion.
Differences of protonated and lithiated leucine-enkephalin(LE) were investigated by hydrogen deuterium exchange-mass spectrometry (HDX-MS) combined with quantum chemistry calculation. The results revealed that the protonated ions possessed very high product yield with all hydrogen atoms being exchanged, while the reaction of lithiated LE stopped after exchanging five hydrogen atoms in the same experimental conditions. The different HDX behaviours probably indicated their conformational differences. To further clarify the experimental results, the most stable conformations of protonated and lithiated leucine-enkephalin were calculated by density functional theory. It was found that terminal amino group was the most thermodynamically stable protonation site, while Li+ in coordination of four carbonyl oxygen atoms formed the most favourable lithiated LE. The reaction field reduction of lithium LE was probably due to the less acidity of hydrogen atoms and the increasing rigid conformation change induced by lithium ion.
2018, 46(4): 563-569
doi: 10.11895/j.issn.0253-3820.171322
Abstract:
Nanocomposites of magnetic attapulgite-resin (MPR) were prepared for adsorption of humic acid (HA). This nano adsorbent was characterized by X-ray diffractometer (XRD), Fourier Transform Infrared (FTIR) spectroscopy and Scanning Electron Microscope (SEM). The adsorption property of HA onto MPR was investigated. Experimental results indicated that MPR prepared by the ultrasonic dispersion exhibited a much better adsorption capacity than that of the resin and attapulgite. The effective specific surface area of the MPR was illustrated to be 674.31 m2/g. With a initial concentration of HA of 14.87 mg/L, the adsorption capacity reached 13 mg/g. Besides, it was found that the adsorption capacity increased with the contact time, and it reached the equilibrium at 233 min. The adsorption kinetics and isotherms could be well described by pseudo-second-order model and Langmuir isotherm model, respectively. Thermodynamic parameters (ΔHθ, ΔSθ, and ΔGθ) indicated that the adsorption was spontaneous and exothermic. Acetic acid had obvious influence on the adsorption of HA on this complex resin. The adsorbent could be reused six times without obvious decrease of adsorption performance.
Nanocomposites of magnetic attapulgite-resin (MPR) were prepared for adsorption of humic acid (HA). This nano adsorbent was characterized by X-ray diffractometer (XRD), Fourier Transform Infrared (FTIR) spectroscopy and Scanning Electron Microscope (SEM). The adsorption property of HA onto MPR was investigated. Experimental results indicated that MPR prepared by the ultrasonic dispersion exhibited a much better adsorption capacity than that of the resin and attapulgite. The effective specific surface area of the MPR was illustrated to be 674.31 m2/g. With a initial concentration of HA of 14.87 mg/L, the adsorption capacity reached 13 mg/g. Besides, it was found that the adsorption capacity increased with the contact time, and it reached the equilibrium at 233 min. The adsorption kinetics and isotherms could be well described by pseudo-second-order model and Langmuir isotherm model, respectively. Thermodynamic parameters (ΔHθ, ΔSθ, and ΔGθ) indicated that the adsorption was spontaneous and exothermic. Acetic acid had obvious influence on the adsorption of HA on this complex resin. The adsorbent could be reused six times without obvious decrease of adsorption performance.
2018, 46(4): 570-577
doi: 10.11895/j.issn.0253-3820.171204
Abstract:
Epsilon 3x energy dispersive X-ray fluorescence spectrometer (EDXRF) was used to analyze the major and minor elements in marine sediments collected from the Indian Ocean on-site. Results obtained by EDXRF were compared with those by inductively coupled plasma-mass spectrometry (ICP-MS) and inductively coupled plasma-optical emission spectrometry (ICP-OES) in the laboratory A total of 24 elements in marine sediment samples, namely Al2O3, MgO, Fe2O3, Na2O, K2O, CaO, Mn, P, Ti, Ba, Sr, V, Zn, Zr, Co, Ni, Cu, Ga, Rb, Y, Nb, Mo, Nd, Pb and Th were measured, and a good agreement was found for these elements (R2>0.9), except for Al2O3, and Ga, Nb and Th with content lower than 30 μg/g. The mean relative deviations of EDXRF method were less than 10% for all of the above mentioned major elements, except for MgO in low concentration and P in high concentration. The mean relative deviations were less than 25% for all of the above mentioned trace elements, except for Sr (>700 μg/g), Mo (<20 μg/g) and Nb. In general, precision and accuracy of EDXRF method were good enough for detection of marine sediments. Taking into account all these facts, the EDXRF method proposed here was proved to be an effective tool for element determination in marine sediment on-site, and it would provide a new technical support to investigate the spatial distribution of mineral resources in marine geological survey.
Epsilon 3x energy dispersive X-ray fluorescence spectrometer (EDXRF) was used to analyze the major and minor elements in marine sediments collected from the Indian Ocean on-site. Results obtained by EDXRF were compared with those by inductively coupled plasma-mass spectrometry (ICP-MS) and inductively coupled plasma-optical emission spectrometry (ICP-OES) in the laboratory A total of 24 elements in marine sediment samples, namely Al2O3, MgO, Fe2O3, Na2O, K2O, CaO, Mn, P, Ti, Ba, Sr, V, Zn, Zr, Co, Ni, Cu, Ga, Rb, Y, Nb, Mo, Nd, Pb and Th were measured, and a good agreement was found for these elements (R2>0.9), except for Al2O3, and Ga, Nb and Th with content lower than 30 μg/g. The mean relative deviations of EDXRF method were less than 10% for all of the above mentioned major elements, except for MgO in low concentration and P in high concentration. The mean relative deviations were less than 25% for all of the above mentioned trace elements, except for Sr (>700 μg/g), Mo (<20 μg/g) and Nb. In general, precision and accuracy of EDXRF method were good enough for detection of marine sediments. Taking into account all these facts, the EDXRF method proposed here was proved to be an effective tool for element determination in marine sediment on-site, and it would provide a new technical support to investigate the spatial distribution of mineral resources in marine geological survey.
2018, 46(4): 578-585
doi: 10.11895/j.issn.0253-3820.171305
Abstract:
Three kinds of glass sharp electrospray ionization devices were built for direct mass spectrometry (MS) analysis using sharp slide, slender capillary and sharp dropper. Through the simulation experiment and mass spectrometry experimental investigation, the influence of the experimental conditions was studied. Under the optimum working conditions such as the electrospray tip diameter was less than 0.24 mm, the distance between the electrospray tip and the MS sample inlet was 10 mm, the electrospray voltage was 4.5 kV, the electrospray capillary angle was about 5.0°-7.5° (upper at back) and the left and right angles were 0°, 0.1 mg/mL sample solution (containing 1% formic acid for positive ion detection, or ammonium hydroxide for negative ion detection) could be well analyzed by MS. In positive or negative ion modes, the quinine, mandelic acid, benzoin, phenylalanine and other different types of sample solutions were analyzed by MS. The result showed that quinine, mandelic acid, benzoin, phenylalanine, tartaric acid, 2,5-dihydroxybenzoic acid (DHB) and tangeretin could be detected in positive ion mode using sharp dropper electrospray. DHB, phenylalanine, tartaric acid and mandelic acid were detected in negative ion mode. Sharp slide electrospray was suitable for measuring the stable sample in the air, capillary electrospray and sharp dropper electrospray were suitable for detecting many low viscosity sample solution even instable sample. Using the method, the extraction solution of propranolol hydrochloride tablet and berberine hydrochloride tablet was directly analyzed by MS. The results showed that the glass sharp electrospray method had the advantages such as without carrier gas, simple structure, easy to build and operate, rapid analysis, anti-cross pollution, and could be conveniently used for MS analysis.
Three kinds of glass sharp electrospray ionization devices were built for direct mass spectrometry (MS) analysis using sharp slide, slender capillary and sharp dropper. Through the simulation experiment and mass spectrometry experimental investigation, the influence of the experimental conditions was studied. Under the optimum working conditions such as the electrospray tip diameter was less than 0.24 mm, the distance between the electrospray tip and the MS sample inlet was 10 mm, the electrospray voltage was 4.5 kV, the electrospray capillary angle was about 5.0°-7.5° (upper at back) and the left and right angles were 0°, 0.1 mg/mL sample solution (containing 1% formic acid for positive ion detection, or ammonium hydroxide for negative ion detection) could be well analyzed by MS. In positive or negative ion modes, the quinine, mandelic acid, benzoin, phenylalanine and other different types of sample solutions were analyzed by MS. The result showed that quinine, mandelic acid, benzoin, phenylalanine, tartaric acid, 2,5-dihydroxybenzoic acid (DHB) and tangeretin could be detected in positive ion mode using sharp dropper electrospray. DHB, phenylalanine, tartaric acid and mandelic acid were detected in negative ion mode. Sharp slide electrospray was suitable for measuring the stable sample in the air, capillary electrospray and sharp dropper electrospray were suitable for detecting many low viscosity sample solution even instable sample. Using the method, the extraction solution of propranolol hydrochloride tablet and berberine hydrochloride tablet was directly analyzed by MS. The results showed that the glass sharp electrospray method had the advantages such as without carrier gas, simple structure, easy to build and operate, rapid analysis, anti-cross pollution, and could be conveniently used for MS analysis.
2018, 46(4): 586-593
doi: 10.11895/j.issn.0253-3820.171472
Abstract:
A rapid Liquid chromatography-tandem mass spectrometry method was developed for the simultaneous determination of six neurotransmitters in rat plasma, adrenal gland and hypothalamus, including γ-aminobutyric acid (GABA), serotonin(5-HT), tyrosine(L-Tyr), dopamine(DA), norepinephrine(NE) and epinephrine(E). This method was used for the neurotransmitters detection in rat adrenal, blood and hypothalamus. The samples were pre-column derivatized with dansyl chloride, and 5-HTP and CA were used as internal standards. A Thermo C18 column (50 mm×3 mm, 2.7 μm) was used for sample separation with 0.1% aqueous formic acid solution as phase A and methanol as phase B at a flow rate of 0.2 mL/min, and the injection volume was set at 2 μL. The detection was carried out with multi-reaction monitoring (MRM) in electron spray ionization (ESI) positive mode. The linear ranges for detection of GABA, 5-HT, L-Tyr, DA, NE and E were 0.26-620.80 μmol/L, 0.03-11.20 μmol/L, 1.20-88.00 μmol/L, 0.03-41.02 μmol/L, 0.01-47.20 μmol/L, 0.01-90.24 μmol/L, respectively, with recoveries varying from 91.16% to 116.20%. This method can detect the neurotransmitters rapidly and accurately, providing a platform for the determination of neurotransmitters in rat plasma, adrenal gland and hypothalamus in pharmacological experiments.
A rapid Liquid chromatography-tandem mass spectrometry method was developed for the simultaneous determination of six neurotransmitters in rat plasma, adrenal gland and hypothalamus, including γ-aminobutyric acid (GABA), serotonin(5-HT), tyrosine(L-Tyr), dopamine(DA), norepinephrine(NE) and epinephrine(E). This method was used for the neurotransmitters detection in rat adrenal, blood and hypothalamus. The samples were pre-column derivatized with dansyl chloride, and 5-HTP and CA were used as internal standards. A Thermo C18 column (50 mm×3 mm, 2.7 μm) was used for sample separation with 0.1% aqueous formic acid solution as phase A and methanol as phase B at a flow rate of 0.2 mL/min, and the injection volume was set at 2 μL. The detection was carried out with multi-reaction monitoring (MRM) in electron spray ionization (ESI) positive mode. The linear ranges for detection of GABA, 5-HT, L-Tyr, DA, NE and E were 0.26-620.80 μmol/L, 0.03-11.20 μmol/L, 1.20-88.00 μmol/L, 0.03-41.02 μmol/L, 0.01-47.20 μmol/L, 0.01-90.24 μmol/L, respectively, with recoveries varying from 91.16% to 116.20%. This method can detect the neurotransmitters rapidly and accurately, providing a platform for the determination of neurotransmitters in rat plasma, adrenal gland and hypothalamus in pharmacological experiments.
2018, 46(4): 594-600
doi: 10.11895/j.issn.0253-3820.171117
Abstract:
A new ultrasonic-assisted extraction (UANE) method coupled with solid phase extraction (SPE) using ultrasonic fountain was established for the extraction of eight common ginsenosides from leaves of Panax quinquefolium L. The extraction system has been designed and several experimental parameters, including the type and volume of extraction solvent, pH value and salt concentration of extraction solvent,type and volume of elution solvent,and amount of C18, extraction time were examined and optimized. Under the optimal conditions, the recoveries of ginsenosides were in the range of 96.3%-110.6%, the relative standard deviations (RSDs) were in the range of 2.8%-4.3%, indicating that the method has a good performance for the extraction of these ginsenosides. Compared with traditional UANE-SPE method, the modified method simplified the extraction device, shortened the extraction time and improved the extraction efficiency.
A new ultrasonic-assisted extraction (UANE) method coupled with solid phase extraction (SPE) using ultrasonic fountain was established for the extraction of eight common ginsenosides from leaves of Panax quinquefolium L. The extraction system has been designed and several experimental parameters, including the type and volume of extraction solvent, pH value and salt concentration of extraction solvent,type and volume of elution solvent,and amount of C18, extraction time were examined and optimized. Under the optimal conditions, the recoveries of ginsenosides were in the range of 96.3%-110.6%, the relative standard deviations (RSDs) were in the range of 2.8%-4.3%, indicating that the method has a good performance for the extraction of these ginsenosides. Compared with traditional UANE-SPE method, the modified method simplified the extraction device, shortened the extraction time and improved the extraction efficiency.
2018, 46(4): 601-608
doi: 10.11895/j.issn.0253-3820.171421
Abstract:
Reversed phase liquid chromatography-tandem mass spectrometry (RPLC-MS/MS) was utilized to investigate peptide profiling and bioactivities of antler aqueous extract (AAE), digested antler aqueous extract (AED) and powder (PD). A total of 23, 417 and 389 peptides, as well as 15, 146 and 75 collagen peptides were identified from AAE, AED and PD, respectively. Angiotensin converting enzyme (ACE) inhibitory activity, dipeptidyl peptidase IV (DPP-IV) inhibitory activity, prolyl endopeptidase (PEP) inhibitory activity and antioxidant activity were used to evaluate the bioactivities of AAE, AED and PD, and it was found that the sequence of their bioactivities was AAE < AED < PD. All the results above proved that AED released more collagen peptides and PD possessed better biological activities. It suggests that the two edible ways of antler are complemented each other and have their own advantages.
Reversed phase liquid chromatography-tandem mass spectrometry (RPLC-MS/MS) was utilized to investigate peptide profiling and bioactivities of antler aqueous extract (AAE), digested antler aqueous extract (AED) and powder (PD). A total of 23, 417 and 389 peptides, as well as 15, 146 and 75 collagen peptides were identified from AAE, AED and PD, respectively. Angiotensin converting enzyme (ACE) inhibitory activity, dipeptidyl peptidase IV (DPP-IV) inhibitory activity, prolyl endopeptidase (PEP) inhibitory activity and antioxidant activity were used to evaluate the bioactivities of AAE, AED and PD, and it was found that the sequence of their bioactivities was AAE < AED < PD. All the results above proved that AED released more collagen peptides and PD possessed better biological activities. It suggests that the two edible ways of antler are complemented each other and have their own advantages.
2018, 46(4): 609-615,622
doi: 10.11895/j.issn.0253-3820.171084
Abstract:
A rapid quantitative component analysis method for biochar based on near infrared spectroscopy (NIRS) technology was established in this study. Near infrared spectra of 163 samples in 10000-3800 cm-1 (1000-2632 nm) range were collected, and the contents of fixed carbon (FC), volatile matter (VM) and ash of samples were analyzed. A partial least square (PLS) model for FC, VM and Ash was established in the optimized model spectral ranges. The factors were optimized and the raw spectra were pretreated by multiple scatter correction and second derivative (MSC+SD) method. Finally, the prediction performance of predictive model was evaluated. The results showed that the PLS model had a good prediction ability, and the predicted coefficient Rp2 of actual values vs prediction values for FC, VM and Ash were 0.9423, 0.9517 and 0.9265, respectively. Root mean square errors of prediction (RMSEP) were 0.1074, 0.1201 and 0.1243, and ratios of prediction to deviation (RPD) were 3.51, 4.28 and 2.03, respectively. The PLS model has good accuracy and precision for both of FC and VM, and can be used as a quantitative method for FC and VM contents analysis. Nevertheless, PLS model needs to improve the precision for Ash analysis according to RPD value. The method provides a fast and effective technical means for the quantitative analysis of biochar components.
A rapid quantitative component analysis method for biochar based on near infrared spectroscopy (NIRS) technology was established in this study. Near infrared spectra of 163 samples in 10000-3800 cm-1 (1000-2632 nm) range were collected, and the contents of fixed carbon (FC), volatile matter (VM) and ash of samples were analyzed. A partial least square (PLS) model for FC, VM and Ash was established in the optimized model spectral ranges. The factors were optimized and the raw spectra were pretreated by multiple scatter correction and second derivative (MSC+SD) method. Finally, the prediction performance of predictive model was evaluated. The results showed that the PLS model had a good prediction ability, and the predicted coefficient Rp2 of actual values vs prediction values for FC, VM and Ash were 0.9423, 0.9517 and 0.9265, respectively. Root mean square errors of prediction (RMSEP) were 0.1074, 0.1201 and 0.1243, and ratios of prediction to deviation (RPD) were 3.51, 4.28 and 2.03, respectively. The PLS model has good accuracy and precision for both of FC and VM, and can be used as a quantitative method for FC and VM contents analysis. Nevertheless, PLS model needs to improve the precision for Ash analysis according to RPD value. The method provides a fast and effective technical means for the quantitative analysis of biochar components.
2018, 46(4): 616-622
doi: 10.11895/j.issn.0253-3820.171100
Abstract:
Fourier transform mid-infrared spectroscopy (FTIR) method was used to analyze the soil organic matter (SOM) composition of a black soil under different management types. Spectral subtraction method was used for eliminating the interference of soil mineral to the absorption peak. Peaks at 2920, 2850, 1630 and 1420 cm-1 were selected as a range of organic functional groups, and relative areas of these peaks were calculated by integral method. The correlation between peak areas and the content of SOM fractions were analyzed. Positive correlations between carbon (C) in fractions representing labile SOM (water-soluble organic carbon, hot water-soluble organic carbon, free light fraction carbon, occluded light fraction carbon) and the peak area at 2920 cm-1 in the bulk soil indicated that this aliphatic peak corresponded to the more labile C compounds. Negative correlations between the same fractions and the area of the predominantly aromatic peak at 1630 cm-1 in the bulk soil suggested a relationship with more stable SOM compounds. The ratio of the peaks at 1630 and 2920 cm-1 was positively correlated with the ratio of stable C (heavy fraction) to labile C (light fraction) and thus taken as an indicator of SOM stability. This method was convenient, low cost and less sample usage, and could be used to analyze the organic carbon composition of soils which has the same mineral composition.
Fourier transform mid-infrared spectroscopy (FTIR) method was used to analyze the soil organic matter (SOM) composition of a black soil under different management types. Spectral subtraction method was used for eliminating the interference of soil mineral to the absorption peak. Peaks at 2920, 2850, 1630 and 1420 cm-1 were selected as a range of organic functional groups, and relative areas of these peaks were calculated by integral method. The correlation between peak areas and the content of SOM fractions were analyzed. Positive correlations between carbon (C) in fractions representing labile SOM (water-soluble organic carbon, hot water-soluble organic carbon, free light fraction carbon, occluded light fraction carbon) and the peak area at 2920 cm-1 in the bulk soil indicated that this aliphatic peak corresponded to the more labile C compounds. Negative correlations between the same fractions and the area of the predominantly aromatic peak at 1630 cm-1 in the bulk soil suggested a relationship with more stable SOM compounds. The ratio of the peaks at 1630 and 2920 cm-1 was positively correlated with the ratio of stable C (heavy fraction) to labile C (light fraction) and thus taken as an indicator of SOM stability. This method was convenient, low cost and less sample usage, and could be used to analyze the organic carbon composition of soils which has the same mineral composition.
2018, 46(4): 623-629
doi: 10.11895/j.issn.0253-3820.170278
Abstract:
The feature of gasoline Raman spectra which were used to study the quantitative analysis of the research octane number (RON) were extracted for the first time using backward interval partial least squares (BiPLS). In the experiment, the sample set partitioning based on joint x-y distances (SPXY) method was used to divide the training set, the cross validation set and the test set. And the robust regression algorithm was used to remove the abnormal sample. The partial least squares model was established using feature selected by the BiPLS algorithm. Compared with the model without feature selection, it was shown that the backward interval partial least squares algorithm could reduce the input dimension by 50.00%, and the root mean square error of cross validation(RMSECV) by 18.92% and the root mean square error of prediction (RMSEP) by 13.86%. The backward interval partial least squares algorithm can effectively extract the feature from gasoline Raman spectrum, reduce the model complexity, and improve the prediction accuracy of the model, and has great application prospect in the quantitative analysis of research octane number.
The feature of gasoline Raman spectra which were used to study the quantitative analysis of the research octane number (RON) were extracted for the first time using backward interval partial least squares (BiPLS). In the experiment, the sample set partitioning based on joint x-y distances (SPXY) method was used to divide the training set, the cross validation set and the test set. And the robust regression algorithm was used to remove the abnormal sample. The partial least squares model was established using feature selected by the BiPLS algorithm. Compared with the model without feature selection, it was shown that the backward interval partial least squares algorithm could reduce the input dimension by 50.00%, and the root mean square error of cross validation(RMSECV) by 18.92% and the root mean square error of prediction (RMSEP) by 13.86%. The backward interval partial least squares algorithm can effectively extract the feature from gasoline Raman spectrum, reduce the model complexity, and improve the prediction accuracy of the model, and has great application prospect in the quantitative analysis of research octane number.
