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2017 Volume 45 Issue 2
2017, 45(2): 151-156
doi: 10.11895/j.issn.0253-3820.160790
Abstract:
A valve-free continuous flow method and instrument were established, with only a multi-channel pump for delivering the sample and reagent, and without any injection or solenoid valves and sample loop for selecting and adding the sample or reagent. Nitrate was reduced to nitrite with Cu-Cd reductant column, and then detected with spectrophotometric detector. The proposed method was suitable for determination of nitrate at normal level in most of estuary and coastal seawaters. With the optimum parameters, the linear range and detection limit were 5-180 μmol/L and 0.27 μmol/L, respectively. The samples of 10 and 80 μmol/L nitrate were continually measured for 11 times, and the relative standard deviations were 1.4% and 1.3%, respectively. The recovery of real samples at different salinity ranged between 99.4% and 106.1%. There was no significant difference in the analytical results between the proposed method and the flow injection analysis (FIA). In comparison with FIA, the method and instrument were less cost and easy to operate, and was suitable to be applied in general laboratories and field for continuous monitoring. The method was successfully used to measure the nitrate in seawater samples in Xiamen's Western Harbor and monitor nitrate in Jiulongjiang estuary.
A valve-free continuous flow method and instrument were established, with only a multi-channel pump for delivering the sample and reagent, and without any injection or solenoid valves and sample loop for selecting and adding the sample or reagent. Nitrate was reduced to nitrite with Cu-Cd reductant column, and then detected with spectrophotometric detector. The proposed method was suitable for determination of nitrate at normal level in most of estuary and coastal seawaters. With the optimum parameters, the linear range and detection limit were 5-180 μmol/L and 0.27 μmol/L, respectively. The samples of 10 and 80 μmol/L nitrate were continually measured for 11 times, and the relative standard deviations were 1.4% and 1.3%, respectively. The recovery of real samples at different salinity ranged between 99.4% and 106.1%. There was no significant difference in the analytical results between the proposed method and the flow injection analysis (FIA). In comparison with FIA, the method and instrument were less cost and easy to operate, and was suitable to be applied in general laboratories and field for continuous monitoring. The method was successfully used to measure the nitrate in seawater samples in Xiamen's Western Harbor and monitor nitrate in Jiulongjiang estuary.
2017, 45(2): 157-162
doi: 10.11895/j.issn.0253-3820.160688
Abstract:
Thiamin pyrophosphate (TPP) is a thiamine (vitamin B1) derivative and an essential cofactor in oxidative metabolism of the sugars, fatty acids and amino acids in living cells. By now, numerous TPP-dependent artificial riboswitch systems have been developed to regulate target gene expression but limited in bacteria, fungi or plant cells. Herein, the activating (switch-on) and inhibiting (switch-off) TPP-depended hammerhead ribozyme switches, which are from previous reported structures of prokaryotes screening, were investigated in mammalian cells. These ribozyme switches were inserted into the 3'UTR of the enhanced green fluorescence protein (EGFP) gene to construct the efficient ribozyme-based artificial switches through overlap extension PCR cloning. The HEK293 cells were transfected with the engineered ribozyme switches at increasing concentration of TPP. The EGFP gene-regulatory ability was analyzed with fluorescent microscope and flow cytometry. These TPP-inducible gene regulation devices showed the obvious ligand dose-dependency and excellent specificity. Two "switch-on" and one "switch-off" constructs demonstrated 3.1-fold or 1.9-fold increment and 2.3-fold reduction of EGFP level respectively with 150 μmol/L TPP. The ligand-responsive ribozyme switches, by tuning the change of TPP concentration into the visual reporter genetic expression in cells, enable an efficient development of label-free, noninvasive and high-specific biosensors in living mammalian cells.
Thiamin pyrophosphate (TPP) is a thiamine (vitamin B1) derivative and an essential cofactor in oxidative metabolism of the sugars, fatty acids and amino acids in living cells. By now, numerous TPP-dependent artificial riboswitch systems have been developed to regulate target gene expression but limited in bacteria, fungi or plant cells. Herein, the activating (switch-on) and inhibiting (switch-off) TPP-depended hammerhead ribozyme switches, which are from previous reported structures of prokaryotes screening, were investigated in mammalian cells. These ribozyme switches were inserted into the 3'UTR of the enhanced green fluorescence protein (EGFP) gene to construct the efficient ribozyme-based artificial switches through overlap extension PCR cloning. The HEK293 cells were transfected with the engineered ribozyme switches at increasing concentration of TPP. The EGFP gene-regulatory ability was analyzed with fluorescent microscope and flow cytometry. These TPP-inducible gene regulation devices showed the obvious ligand dose-dependency and excellent specificity. Two "switch-on" and one "switch-off" constructs demonstrated 3.1-fold or 1.9-fold increment and 2.3-fold reduction of EGFP level respectively with 150 μmol/L TPP. The ligand-responsive ribozyme switches, by tuning the change of TPP concentration into the visual reporter genetic expression in cells, enable an efficient development of label-free, noninvasive and high-specific biosensors in living mammalian cells.
2017, 45(2): 163-168
doi: 10.11895/j.issn.0253-3820.160620
Abstract:
A simple, fast and highly sensitive fluorescence analysis method for detection of mercury ion was developed based on N-methyl-mesoporphyrin IX(NMM)/G-quadruplex DNA system and specific T-Hg(Ⅱ)-T mismatches. In this strategy, a large number of thymine was introduced into guanine-rich oigonucleotides which could form G-quadruplex. In the presence of Hg2+, guanine-rich oigonucleotides and complementary strand could form double-stranded DNA molecule by specific T-Hg(Ⅱ)-T mismatch pair, leading to destruction of G-quadruplex DNA structure. In the absence of Hg2+, guanine-rich oigonucleotides spontaneously formed G-quadruplex DNA structure that could bound NMM to generate intense fluorescence. Based on the above facts, a sensitive fluorescence biosensor for determination of Hg2+ was fabricated. And the optimal conditions for Hg2+ determination were as follows:buffer solution pH of 6.7, 20 mmol/L KCl and 2.5 μmol/L NMM in buffer and incubation for 2 h. Under the optimal conditions, the fluorescence intensity signal change (F0-F) and the Hg2+ concentration exhibited a linear correlation within 50 nmol/L to 1000 nmol/L range with a low detection limit of 22.8 nmol/L (3σ). The biosensor exhibited good selectivity toward common metal ions. The developed method was successfully employed to detect Hg2+ in tap water with recovery of 106.1%-107.8%.
A simple, fast and highly sensitive fluorescence analysis method for detection of mercury ion was developed based on N-methyl-mesoporphyrin IX(NMM)/G-quadruplex DNA system and specific T-Hg(Ⅱ)-T mismatches. In this strategy, a large number of thymine was introduced into guanine-rich oigonucleotides which could form G-quadruplex. In the presence of Hg2+, guanine-rich oigonucleotides and complementary strand could form double-stranded DNA molecule by specific T-Hg(Ⅱ)-T mismatch pair, leading to destruction of G-quadruplex DNA structure. In the absence of Hg2+, guanine-rich oigonucleotides spontaneously formed G-quadruplex DNA structure that could bound NMM to generate intense fluorescence. Based on the above facts, a sensitive fluorescence biosensor for determination of Hg2+ was fabricated. And the optimal conditions for Hg2+ determination were as follows:buffer solution pH of 6.7, 20 mmol/L KCl and 2.5 μmol/L NMM in buffer and incubation for 2 h. Under the optimal conditions, the fluorescence intensity signal change (F0-F) and the Hg2+ concentration exhibited a linear correlation within 50 nmol/L to 1000 nmol/L range with a low detection limit of 22.8 nmol/L (3σ). The biosensor exhibited good selectivity toward common metal ions. The developed method was successfully employed to detect Hg2+ in tap water with recovery of 106.1%-107.8%.
2017, 45(2): 169-174
doi: 10.11895/j.issn.0253-3820.160778
Abstract:
Based on the high solubility of azodicarbonamide (ADC) in hot solution and its electrostatic interaction with Nafion film, a new electroanalytical method was developed for the determination of ADC by using Nafion film electrode. The effect of temperature on the solubility of ADC and the mechanism of the reduction reaction of ADC on Nafion film electrode were investigated. Under the experimental conditions such as water bath at a constant temperature of 80℃, pH 6.0 and optimal test parameters, the differential pulse voltammetric response was proportional to the concentration of ADC in the range of 0.93-10.5 μg/L, and the detection limit was estimated to 0.58 μg/L. The relative standard deviation was less than 5.86% and the recovery was 95.8%-104.0% for the determination of the ADC in flour samples. The semicarbazide and nitrofurazone did not interfere with the determination of ADC.
Based on the high solubility of azodicarbonamide (ADC) in hot solution and its electrostatic interaction with Nafion film, a new electroanalytical method was developed for the determination of ADC by using Nafion film electrode. The effect of temperature on the solubility of ADC and the mechanism of the reduction reaction of ADC on Nafion film electrode were investigated. Under the experimental conditions such as water bath at a constant temperature of 80℃, pH 6.0 and optimal test parameters, the differential pulse voltammetric response was proportional to the concentration of ADC in the range of 0.93-10.5 μg/L, and the detection limit was estimated to 0.58 μg/L. The relative standard deviation was less than 5.86% and the recovery was 95.8%-104.0% for the determination of the ADC in flour samples. The semicarbazide and nitrofurazone did not interfere with the determination of ADC.
2017, 45(2): 175-182
doi: 10.11895/j.issn.0253-3820.160660
Abstract:
A thermal desorption low temperature plasma (TD-LTP) ionization was developed for rapid and sensitive detection of pesticides by direct mass spectrometry. The thermal desorption sampler was added in fount of the plasma generator. The sample was desorbed in the thermal desorption sampler firstly, and then the gas molecules were transported to the plasma generator by the carrier gas to be ionized. The utilization of thermal desorption sampler helps to shift the interaction of the gas phase plasma with the sample form gas-solid or gas-liquid to gas-gas, which increases the sensitivity and stability especially for non-volatile sample (e.g. pesticides) greatly compared with the traditional LTP ionization source. Under the optimal parameters of the thermal desorption LTP ionization source, the characteristic ions of 12 kinds of pesticides were investigated. Then the thermal desorption LTP ionization source was connected with the commercial ACQUITY TQD mass spectrometer to evaluate the pesticide residue level in broomcorn.
A thermal desorption low temperature plasma (TD-LTP) ionization was developed for rapid and sensitive detection of pesticides by direct mass spectrometry. The thermal desorption sampler was added in fount of the plasma generator. The sample was desorbed in the thermal desorption sampler firstly, and then the gas molecules were transported to the plasma generator by the carrier gas to be ionized. The utilization of thermal desorption sampler helps to shift the interaction of the gas phase plasma with the sample form gas-solid or gas-liquid to gas-gas, which increases the sensitivity and stability especially for non-volatile sample (e.g. pesticides) greatly compared with the traditional LTP ionization source. Under the optimal parameters of the thermal desorption LTP ionization source, the characteristic ions of 12 kinds of pesticides were investigated. Then the thermal desorption LTP ionization source was connected with the commercial ACQUITY TQD mass spectrometer to evaluate the pesticide residue level in broomcorn.
2017, 45(2): 183-190
doi: 10.11895/j.issn.0253-3820.160538
Abstract:
An atmospheric pressure chemical ionization mass spectrometry (APCI-MS) method was developed for the direct analysis of triglycerides in edible oils. The edible oil sample was dissolved in acetonitrile. Under the optimal conditions such as positive ion detection, 800 μL/h of sample flow rate, 250℃ of vaporizer temperature and 5000 nA of corona needle current, the repeatability (RSD) of peak intensity rate of m/z 857.76 to m/z 881.76 was less than 5%. Then, different kinds of oil from different manufacturers were analyzed by the proposed method. After a principal component analysis for the analytical results, the peak intensity rate of m/z 857.76 and m/z 881.76 was selected for oil identification. The adulteration of 5% lard in corn oil could be recognized directly using the peak intensity rate. Three characteristic triglycerides in edible oil were preliminarily identified by collision induced dissociation (CID) experiments. The method was applied to analyze the swill oil and fried oil samples, and the results showed that the swill oil contained both vegetable oil and animal fat, and the fried oil was also different with commercial vegetable oil.
An atmospheric pressure chemical ionization mass spectrometry (APCI-MS) method was developed for the direct analysis of triglycerides in edible oils. The edible oil sample was dissolved in acetonitrile. Under the optimal conditions such as positive ion detection, 800 μL/h of sample flow rate, 250℃ of vaporizer temperature and 5000 nA of corona needle current, the repeatability (RSD) of peak intensity rate of m/z 857.76 to m/z 881.76 was less than 5%. Then, different kinds of oil from different manufacturers were analyzed by the proposed method. After a principal component analysis for the analytical results, the peak intensity rate of m/z 857.76 and m/z 881.76 was selected for oil identification. The adulteration of 5% lard in corn oil could be recognized directly using the peak intensity rate. Three characteristic triglycerides in edible oil were preliminarily identified by collision induced dissociation (CID) experiments. The method was applied to analyze the swill oil and fried oil samples, and the results showed that the swill oil contained both vegetable oil and animal fat, and the fried oil was also different with commercial vegetable oil.
2017, 45(2): 191-198
doi: 10.11895/j.issn.0253-3820.160684
Abstract:
A rapid resolution liquid chromatography coupled with quadrupole-time-of-flight mass spectrometric (RRLC-Q-TOF-MS) method was established and optimized for the analysis of pharmacokinetic behavior of ginsenoside Rb2 in rats by intravenous injection administration. The metabolism of ginsenosides Rb2 in vivo rat was also explored. In the experiment, Agilent SB C18 column was selected for the sample separation with 0.1% aqueous formic acid solution as mobile phase (A) and acetonitrile as mobile phase (B) at a flow rate of 0.2 mL/min, and the injection volume was set to 5 μL. Q-TOF-MS was carried out in electron pray ionization (ESI) negative ion mode. The limit of quantification (LOQ, S/N=10) and limit of detection (LOD, S/N=3) were 0.10 and 0.08 μg/mL, respectively, and the linear range was 0.1-1.26 μg/mL. The experiment results showed that the concentration-time profile of ginsenoside Rb2 conformed to a two-compartment pharmacokinetic model after intravenous administration for rats. The mean plasma elimination half-lives were (23.58±1.10) min (t1/2α), (1306.55±147.23) min (t1/2β) for Rb2. By analyzing the urine of rats after intravenous administration and the fecal samples after oral administration of ginsenoside Rb2, it was found that the metabolites were M6, M2(CY), F2, and C-K.
A rapid resolution liquid chromatography coupled with quadrupole-time-of-flight mass spectrometric (RRLC-Q-TOF-MS) method was established and optimized for the analysis of pharmacokinetic behavior of ginsenoside Rb2 in rats by intravenous injection administration. The metabolism of ginsenosides Rb2 in vivo rat was also explored. In the experiment, Agilent SB C18 column was selected for the sample separation with 0.1% aqueous formic acid solution as mobile phase (A) and acetonitrile as mobile phase (B) at a flow rate of 0.2 mL/min, and the injection volume was set to 5 μL. Q-TOF-MS was carried out in electron pray ionization (ESI) negative ion mode. The limit of quantification (LOQ, S/N=10) and limit of detection (LOD, S/N=3) were 0.10 and 0.08 μg/mL, respectively, and the linear range was 0.1-1.26 μg/mL. The experiment results showed that the concentration-time profile of ginsenoside Rb2 conformed to a two-compartment pharmacokinetic model after intravenous administration for rats. The mean plasma elimination half-lives were (23.58±1.10) min (t1/2α), (1306.55±147.23) min (t1/2β) for Rb2. By analyzing the urine of rats after intravenous administration and the fecal samples after oral administration of ginsenoside Rb2, it was found that the metabolites were M6, M2(CY), F2, and C-K.
2017, 45(2): 199-204
doi: 10.11895/j.issn.0253-3820.160563
Abstract:
Nitrogen-doped carbon nanoparticles (N-CNPs) with a fluorescence quantum yield of 15.1% were prepared from sucrose and urea in oleic acid medium by a one-pot solvothermal method. A new approach for quick, sensitive, and selective determination of free chlorine in water was developed based on fluorescence quenching of N-CNPs. There existed a good linear correlation between the fluorescence quenching and the concentration of ClO- in the range of 0.05-25.00 μmol/L. The limit of detection (LOD, S/N=3) was estimated to be 23 nmol/L. This method can be applied to the determination of free chlorine in real water samples.
Nitrogen-doped carbon nanoparticles (N-CNPs) with a fluorescence quantum yield of 15.1% were prepared from sucrose and urea in oleic acid medium by a one-pot solvothermal method. A new approach for quick, sensitive, and selective determination of free chlorine in water was developed based on fluorescence quenching of N-CNPs. There existed a good linear correlation between the fluorescence quenching and the concentration of ClO- in the range of 0.05-25.00 μmol/L. The limit of detection (LOD, S/N=3) was estimated to be 23 nmol/L. This method can be applied to the determination of free chlorine in real water samples.
2017, 45(2): 205-210
doi: 10.11895/j.issn.0253-3820.160491
Abstract:
The samples of muscular tissue from pork, beef and lamb which were closely related in the genetic relationship were analyzed by ultra performance liquid chromatography-tandem mass spectrometric (UPLC-MS) technique. The specific peptide biomarkers of pig meat species were found and confirmed. Proteins from three pure meat samples were extracted and digested using trypsin, the digested proteins were identified by UPLC-triple time-of-flight (TOF)-MS, and the total ion chromatogram (TIC) was searched and analyzed against the UniProt database. Three high abundant homologous proteins of three species and 8 potential peptide biomarkers of pork were found. A multiple reaction monitoring (MRM) QTRAP-MS method was established to confirm the specificity of potential peptide biomarkers. As a result, five peptide biomarkers of pig species meat were confirmed, three of which were not reported.
The samples of muscular tissue from pork, beef and lamb which were closely related in the genetic relationship were analyzed by ultra performance liquid chromatography-tandem mass spectrometric (UPLC-MS) technique. The specific peptide biomarkers of pig meat species were found and confirmed. Proteins from three pure meat samples were extracted and digested using trypsin, the digested proteins were identified by UPLC-triple time-of-flight (TOF)-MS, and the total ion chromatogram (TIC) was searched and analyzed against the UniProt database. Three high abundant homologous proteins of three species and 8 potential peptide biomarkers of pork were found. A multiple reaction monitoring (MRM) QTRAP-MS method was established to confirm the specificity of potential peptide biomarkers. As a result, five peptide biomarkers of pig species meat were confirmed, three of which were not reported.
2017, 45(2): 211-216
doi: 10.11895/j.issn.0253-3820.160460
Abstract:
A target molecule affinity-ultrafiltration liquid chromatography-electrospray ionization tandem mass spectrometric (LC-ESI-MSn) method was established for rapid screening acetylcholinesterase (AChE) inhibitors from total alkaloids of fibraurea recisa Pierre. A total of 12 potential inhibitors were screened from Fibraurea recisa Pierre. and 6 compounds were identified including palmatine, berberine, jatrorrhizine, palmatrubine, 7,8-dihydro-8-hydroxyberberine and groenlandicine. The AChE inhibitory activity of these 6 compounds was validated in vitro. Palmatine showed the strongest inhibitory activity for AChE, which was stronger than that of donepezil hydrochloride, demonstrating the potential of palmatine as anti-Alzheimer's drug. This method is simple, rapid, and accurate for directly screening active ingredients which can inhibit AChE from complex extract of traditional Chinese medicines.
A target molecule affinity-ultrafiltration liquid chromatography-electrospray ionization tandem mass spectrometric (LC-ESI-MSn) method was established for rapid screening acetylcholinesterase (AChE) inhibitors from total alkaloids of fibraurea recisa Pierre. A total of 12 potential inhibitors were screened from Fibraurea recisa Pierre. and 6 compounds were identified including palmatine, berberine, jatrorrhizine, palmatrubine, 7,8-dihydro-8-hydroxyberberine and groenlandicine. The AChE inhibitory activity of these 6 compounds was validated in vitro. Palmatine showed the strongest inhibitory activity for AChE, which was stronger than that of donepezil hydrochloride, demonstrating the potential of palmatine as anti-Alzheimer's drug. This method is simple, rapid, and accurate for directly screening active ingredients which can inhibit AChE from complex extract of traditional Chinese medicines.
2017, 45(2): 217-223
doi: 10.11895/j.issn.0253-3820.160572
Abstract:
Immunomagnetic separation (IMS) was coupled with fluorescent microspheres lateral flow assay (FM-LFA) for rapid detection of S. choleraesuis in this study. The target bacteria were firstly enriched from sample by immunomagnetic beads (IMBs), then eluted by heat treatment and detected by fluorescent microspheres lateral flow test strip. The IMBs was labeled with 30 μg/mg antibody, and the capture efficiency was greater than 90% against 102-106 CFU/mL of S. choleraesuis with great specificity. The immunofluorescent microspheres were prepared by coupling 300 μg of 11D8-D4 monoclonal antibody with 1 mg of fluorescent microspheres at pH 6. Monoclonal antibody 5F11-B11 (2.0 mg/mL) and donkey anti-mouse IgG (1.0 mg/mL) were sprayed on nitrocellulose membrane as test line and control line, respectively. The FM-LFA based on IMS was used to detect S. choleraesuis in PBS and milk. The limits of detection in PBS buffer and milk were 1.5×105 CFU/mL and 7.6×105 CFU/mL respectively, which were 10 and 200 times lower than that of traditional fluorescent microspheres lateral flow assay, respectively. The results showed that the method, which could enrich S. choleraesuis in milk effectively, could avoid matrix interference and improve the detection sensitivity, thus had a good application prospect.
Immunomagnetic separation (IMS) was coupled with fluorescent microspheres lateral flow assay (FM-LFA) for rapid detection of S. choleraesuis in this study. The target bacteria were firstly enriched from sample by immunomagnetic beads (IMBs), then eluted by heat treatment and detected by fluorescent microspheres lateral flow test strip. The IMBs was labeled with 30 μg/mg antibody, and the capture efficiency was greater than 90% against 102-106 CFU/mL of S. choleraesuis with great specificity. The immunofluorescent microspheres were prepared by coupling 300 μg of 11D8-D4 monoclonal antibody with 1 mg of fluorescent microspheres at pH 6. Monoclonal antibody 5F11-B11 (2.0 mg/mL) and donkey anti-mouse IgG (1.0 mg/mL) were sprayed on nitrocellulose membrane as test line and control line, respectively. The FM-LFA based on IMS was used to detect S. choleraesuis in PBS and milk. The limits of detection in PBS buffer and milk were 1.5×105 CFU/mL and 7.6×105 CFU/mL respectively, which were 10 and 200 times lower than that of traditional fluorescent microspheres lateral flow assay, respectively. The results showed that the method, which could enrich S. choleraesuis in milk effectively, could avoid matrix interference and improve the detection sensitivity, thus had a good application prospect.
2017, 45(2): 224-230
doi: 10.11895/j.issn.0253-3820.160751
Abstract:
The peptides, proteins and other biological molecules in transudative pleural effusion correlate directly or indirectly with specific physiological and pathological state, reflecting the information regarding the lungs or other parts of the body. In the present study, the peptide fraction in transudative pleural effusion was isolated by ultrafiltration. After desalted and enriched by C18 tips, the peptide mixture was analyzed by nano LC-MS/MS. The results showed that 314 peptides, which were originated from 52 proteins, in pleural transudate were identified. More than half of the peptides were derived from fibrinogen. Many peptides were characterized as displaying ladder sequences. In addition, a large number of proline oxidation modifications were detected in the peptides derived from collagen and fibrinogen. Gene ontology enrichment analysis showed that the most of the proteins extracellular properties of pleural transudate polypeptide components were protein with exocytosis. The study provided a rapid and efficient separation and analysis methods for lung disease markers related peptide compounds in pleural fluid leakage. Also this research provided a rapid and effective method for screening peptide biomarkers related to lung diseases from transudative pleural effusion.
The peptides, proteins and other biological molecules in transudative pleural effusion correlate directly or indirectly with specific physiological and pathological state, reflecting the information regarding the lungs or other parts of the body. In the present study, the peptide fraction in transudative pleural effusion was isolated by ultrafiltration. After desalted and enriched by C18 tips, the peptide mixture was analyzed by nano LC-MS/MS. The results showed that 314 peptides, which were originated from 52 proteins, in pleural transudate were identified. More than half of the peptides were derived from fibrinogen. Many peptides were characterized as displaying ladder sequences. In addition, a large number of proline oxidation modifications were detected in the peptides derived from collagen and fibrinogen. Gene ontology enrichment analysis showed that the most of the proteins extracellular properties of pleural transudate polypeptide components were protein with exocytosis. The study provided a rapid and efficient separation and analysis methods for lung disease markers related peptide compounds in pleural fluid leakage. Also this research provided a rapid and effective method for screening peptide biomarkers related to lung diseases from transudative pleural effusion.
2017, 45(2): 231-237
doi: 10.11895/j.issn.0253-3820.160526
Abstract:
A novel method for simultaneous detection of mycotoxins (e.g., aflatoxin B1) or their metabolic residues in animal plasma with impurity adsorption purification followed ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed. Extraction of mycotoxins and their metabolites from animal plasma sample was performed with 0.1% formic acid-acetonitrile solution after addition of sodium chloride and hydrous magnesium sulfate. The extract was then dehydrated and purified with hydrous magnesium sulfate, C18, primary secondary amine, and alumina-A. 3 mL of the supernatant was evaporated and re-dissolved with 0.5 mL of 0.1% formic acid aqueous solution/acetonitrile (70:30, V/V) for UPLC-MS/MS detection. The analytes were separated by a C18 column utilizing gradient elution with 0.1% formic acid aqueous solution containing 0.5 mmol of ammonium acetate and 0.1% formic acid-methanol solution, and finally detected by tandem mass spectrometry in positive/negative ESI mode. Identification and quantification were achieved by LC-MS/MS with multi-reaction monitoring (MRM). Good linearity in response was obtained in the analytes concentration range of 0.05-100 ng/mL with correlation coefficients larger than 0.99. The limits of quantification (S/N=10) were around 0.05-0.5 ng/mL. The recoveries of mycotoxins and their metabolites spiked in blank plasma samples were in the range of 62.0%-116.4%, with relative standard deviations (RSDs) less than 19.0%.
A novel method for simultaneous detection of mycotoxins (e.g., aflatoxin B1) or their metabolic residues in animal plasma with impurity adsorption purification followed ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed. Extraction of mycotoxins and their metabolites from animal plasma sample was performed with 0.1% formic acid-acetonitrile solution after addition of sodium chloride and hydrous magnesium sulfate. The extract was then dehydrated and purified with hydrous magnesium sulfate, C18, primary secondary amine, and alumina-A. 3 mL of the supernatant was evaporated and re-dissolved with 0.5 mL of 0.1% formic acid aqueous solution/acetonitrile (70:30, V/V) for UPLC-MS/MS detection. The analytes were separated by a C18 column utilizing gradient elution with 0.1% formic acid aqueous solution containing 0.5 mmol of ammonium acetate and 0.1% formic acid-methanol solution, and finally detected by tandem mass spectrometry in positive/negative ESI mode. Identification and quantification were achieved by LC-MS/MS with multi-reaction monitoring (MRM). Good linearity in response was obtained in the analytes concentration range of 0.05-100 ng/mL with correlation coefficients larger than 0.99. The limits of quantification (S/N=10) were around 0.05-0.5 ng/mL. The recoveries of mycotoxins and their metabolites spiked in blank plasma samples were in the range of 62.0%-116.4%, with relative standard deviations (RSDs) less than 19.0%.
2017, 45(2): 238-244
doi: 10.11895/j.issn.0253-3820.160679
Abstract:
Heavy metal residue in vegetables is a big concern in the whole world. The aim of this work is to explore the effect of multivariable selection on analyzing Cd in Chinese cabbage polluted in lab by collecting the spectra of laser induced breakdown spectroscopy (LIBS) from the samples. At the same time, the actual Cd content in samples was obtained by anodic stripping voltammetry (ASV). The LIBS spectral range in partial least square (PLS) model was screened by standard normal variable transformation (SNV), first derivative (FD), second derivative (SD) and center treatment (CT) for preprocessing spectra and the optimized method was used for the analysis of interval partial least square (iPLS) and synergy interval partial least square (SiPLS). The results indicated that the method of CT was the best as a comparison with PLS, iPLS and SiPLS. And the intervals of wavelength were 214.72-215.82 nm, 215.88-216.97 nm and 225.08-226.35 nm by utilizing the optimized SiPLS. Here the root mean square error of cross validation (RMSECV) between real content and predicted ones was 1.487, the root mean squared error of prediction (RMSEP) was 1.094, the correlation coefficient (R) was 0.9942, and the average relative error (ARE) was 11.60%. The results displayed that LIBS could predict Cd in vegetables by multivariable selection of SiPLS and the accuracy could meet the requirement of rapid and green analysis of Cd in vegetables.
Heavy metal residue in vegetables is a big concern in the whole world. The aim of this work is to explore the effect of multivariable selection on analyzing Cd in Chinese cabbage polluted in lab by collecting the spectra of laser induced breakdown spectroscopy (LIBS) from the samples. At the same time, the actual Cd content in samples was obtained by anodic stripping voltammetry (ASV). The LIBS spectral range in partial least square (PLS) model was screened by standard normal variable transformation (SNV), first derivative (FD), second derivative (SD) and center treatment (CT) for preprocessing spectra and the optimized method was used for the analysis of interval partial least square (iPLS) and synergy interval partial least square (SiPLS). The results indicated that the method of CT was the best as a comparison with PLS, iPLS and SiPLS. And the intervals of wavelength were 214.72-215.82 nm, 215.88-216.97 nm and 225.08-226.35 nm by utilizing the optimized SiPLS. Here the root mean square error of cross validation (RMSECV) between real content and predicted ones was 1.487, the root mean squared error of prediction (RMSEP) was 1.094, the correlation coefficient (R) was 0.9942, and the average relative error (ARE) was 11.60%. The results displayed that LIBS could predict Cd in vegetables by multivariable selection of SiPLS and the accuracy could meet the requirement of rapid and green analysis of Cd in vegetables.
2017, 45(2): 245-252
doi: 10.11895/j.issn.0253-3820.160653
Abstract:
To screen the illegal substances in fishery inputs, we established the database including the precursor and the daughter ions for these possible components by the quadrupole/orbit-trap mass spectrometer, and the retention time of each drug on the same chromatographic column. And then, the extracted and diluted samples were analyzed and the components in the real samples were identified under the same conditions. Chromatographic analysis was performed on an Accucore RP-MS column (100 mm×2.1 mm, 2.6 μm) using gradient elution with 0.1% formic acid in water and 0.1% formic acid in acetonitrile as mobile phase. Elutes were ionized through heatable electrospray ionization (HESI) in both positive and negative mode simultaneously. Data acquisition was conducted by Full-scan ddMS2 (TopN) mode, in which the full mass profile for a continuous precursor ion injection and the fragments of each high abundant precursor of targeted were acquired with excellent time and mass resolution. Screening was carried out through comparison of the information of real samples with that of standards in the database, which were processed by software (Tracefinder). The Quantification of each component was analyzed based on the precursor ion chromatography acquired by orbit-trap mass spectroscopy, which showed a good linearity between 0.01-1 μg/mL, with R>0.98. The method was validated by checking its minimum screening concentration (0.5 mg/L for drugs and 5 mg/L for feedstuffs) and evaluating the recovery after addition of the standard mixture in real samples (>50%, under the addition of 10 and 100 mg/kg). The results for 68 practical samples demonstrated the effective performance of this method for screening with high-throughput, rapidness and acceptable minimum screening concentration and accuracy, in which 15 of 29 fishery drug samples were screened out for positive components that were not indicated in their labels.
To screen the illegal substances in fishery inputs, we established the database including the precursor and the daughter ions for these possible components by the quadrupole/orbit-trap mass spectrometer, and the retention time of each drug on the same chromatographic column. And then, the extracted and diluted samples were analyzed and the components in the real samples were identified under the same conditions. Chromatographic analysis was performed on an Accucore RP-MS column (100 mm×2.1 mm, 2.6 μm) using gradient elution with 0.1% formic acid in water and 0.1% formic acid in acetonitrile as mobile phase. Elutes were ionized through heatable electrospray ionization (HESI) in both positive and negative mode simultaneously. Data acquisition was conducted by Full-scan ddMS2 (TopN) mode, in which the full mass profile for a continuous precursor ion injection and the fragments of each high abundant precursor of targeted were acquired with excellent time and mass resolution. Screening was carried out through comparison of the information of real samples with that of standards in the database, which were processed by software (Tracefinder). The Quantification of each component was analyzed based on the precursor ion chromatography acquired by orbit-trap mass spectroscopy, which showed a good linearity between 0.01-1 μg/mL, with R>0.98. The method was validated by checking its minimum screening concentration (0.5 mg/L for drugs and 5 mg/L for feedstuffs) and evaluating the recovery after addition of the standard mixture in real samples (>50%, under the addition of 10 and 100 mg/kg). The results for 68 practical samples demonstrated the effective performance of this method for screening with high-throughput, rapidness and acceptable minimum screening concentration and accuracy, in which 15 of 29 fishery drug samples were screened out for positive components that were not indicated in their labels.
2017, 45(2): 253-260
doi: 10.11895/j.issn.0253-3820.160761
Abstract:
A new method was proposed for analysis of the organic compounds in cigarette smoke by high resolution Orbitrap mass spectrometry based on polyacrylonitrile-silica (PAN-SiO2) nanofiber membrane extraction and methanol elution. Hydrophobic PAN-SiO2 nanofiber membrane which was used to enrich small molecular organic compounds in cigarette smoke was prepared by the technology of electrospinning. Several parameters including the concentrations of PAN and SiO2 nanopartical, elecrospining voltage, needle aperture and flow rate of spinning solution were optimized. Under the optimal conditions, a PAN-SiO2 nanofiber membrane with good adsorption performance and great physical strength was obtained. A total of 21 compounds including acetone, styrene, acrolein, isoprene, and acrylonitrile were identified by analyzing the cigarette smoke with Orbitrap MS spectrometry in the positive ion mode. Six organic acids including salicylic acid, malic acid and lactic acid were detected in negative ion mode. The limits of detection and quantification for nicotine were 0.071 ng/L and 0.236 ng/L, respectively.
A new method was proposed for analysis of the organic compounds in cigarette smoke by high resolution Orbitrap mass spectrometry based on polyacrylonitrile-silica (PAN-SiO2) nanofiber membrane extraction and methanol elution. Hydrophobic PAN-SiO2 nanofiber membrane which was used to enrich small molecular organic compounds in cigarette smoke was prepared by the technology of electrospinning. Several parameters including the concentrations of PAN and SiO2 nanopartical, elecrospining voltage, needle aperture and flow rate of spinning solution were optimized. Under the optimal conditions, a PAN-SiO2 nanofiber membrane with good adsorption performance and great physical strength was obtained. A total of 21 compounds including acetone, styrene, acrolein, isoprene, and acrylonitrile were identified by analyzing the cigarette smoke with Orbitrap MS spectrometry in the positive ion mode. Six organic acids including salicylic acid, malic acid and lactic acid were detected in negative ion mode. The limits of detection and quantification for nicotine were 0.071 ng/L and 0.236 ng/L, respectively.
2017, 45(2): 261-267
doi: 10.11895/j.issn.0253-3820.160221
Abstract:
Super hydrophobic interface modified with silver nanoparticles was fabricated for the detection of pesticide residues. By using a chemical reduction method, silver nanoparticles were deposited on the substrate surfaces with different microscopic pore structures. Two kinds of composite substrates, including regular stainless steel mesh and cellulose polyester film, were used. The pre-treatment of the substrate with fluoridated reagents was used to form a super hydrophobic interface, which made the target molecules on the surface concentrate effectively. The surface with the cellulose polyester substrate was used to detect Rhodamine 6G (R 6G) effectively with surface enhanced Raman scattering (SERS) technique. The results showed that the detection limit was 10-16 mol/L. In addition, the surfaces based on the stainless steel mesh and cellulose polyester substrate were used to detect trichlorfon pesticide with detection limits of 1×10-15 mol/L and 1×10-16 mol/L, respectively.
Super hydrophobic interface modified with silver nanoparticles was fabricated for the detection of pesticide residues. By using a chemical reduction method, silver nanoparticles were deposited on the substrate surfaces with different microscopic pore structures. Two kinds of composite substrates, including regular stainless steel mesh and cellulose polyester film, were used. The pre-treatment of the substrate with fluoridated reagents was used to form a super hydrophobic interface, which made the target molecules on the surface concentrate effectively. The surface with the cellulose polyester substrate was used to detect Rhodamine 6G (R 6G) effectively with surface enhanced Raman scattering (SERS) technique. The results showed that the detection limit was 10-16 mol/L. In addition, the surfaces based on the stainless steel mesh and cellulose polyester substrate were used to detect trichlorfon pesticide with detection limits of 1×10-15 mol/L and 1×10-16 mol/L, respectively.
2017, 45(2): 268-274
doi: 10.11895/j.issn.0253-3820.160625
Abstract:
A method for the simultaneous determination of nine perfluorocarboxylic acids (PFCAs) in water by precolumn derivatization-gas chromatography-electron capture detector (GC-ECD) was established. PFCAs were firstly converted to amide derivative products using 2,4-difluoroaniline (2,4-DFA) as derivatizing agent and N,N'-dicyclohexylcarbodiimide (DCC) as dehydrating agent. Then the amide derivative products were determined by ECD after separation with TR-5 capillary-column chromatography. The experimental conditions in derivatization of PFCAs were optimized, including the dosage of 2,4-DFA and DCC, reaction solvent, reaction temperature and reaction time. The optimal derivatization parameters were obtained. The results showed that the linear correlation coefficients of nine derivative products of PFCAs were higher than 0.99 under the optimized experimental conditions. The limits of detection were 0.62-1.38 μg/L, while the relative standard derivations RSDs were 1.3%-7.5%. The proposed method was applied to the analysis of PFCAs in municipal sewage. It was found that the municipal sewage contained trace PFCAs which mainly existed in the form of perfluoropentanoic acid (PFPeA), perfloroheptanoic acid (PFHpA) and pentadecafluorooctanoic acid (PFOA). The recoveries of actual samples were between 84.4% and 120.9%. The method was stable and reliable with low cost, and it could meet the simultaneous determination of several PFCAs in water samples. This study provided technical support for the pollution assessment of perfluorinated compounds in water.
A method for the simultaneous determination of nine perfluorocarboxylic acids (PFCAs) in water by precolumn derivatization-gas chromatography-electron capture detector (GC-ECD) was established. PFCAs were firstly converted to amide derivative products using 2,4-difluoroaniline (2,4-DFA) as derivatizing agent and N,N'-dicyclohexylcarbodiimide (DCC) as dehydrating agent. Then the amide derivative products were determined by ECD after separation with TR-5 capillary-column chromatography. The experimental conditions in derivatization of PFCAs were optimized, including the dosage of 2,4-DFA and DCC, reaction solvent, reaction temperature and reaction time. The optimal derivatization parameters were obtained. The results showed that the linear correlation coefficients of nine derivative products of PFCAs were higher than 0.99 under the optimized experimental conditions. The limits of detection were 0.62-1.38 μg/L, while the relative standard derivations RSDs were 1.3%-7.5%. The proposed method was applied to the analysis of PFCAs in municipal sewage. It was found that the municipal sewage contained trace PFCAs which mainly existed in the form of perfluoropentanoic acid (PFPeA), perfloroheptanoic acid (PFHpA) and pentadecafluorooctanoic acid (PFOA). The recoveries of actual samples were between 84.4% and 120.9%. The method was stable and reliable with low cost, and it could meet the simultaneous determination of several PFCAs in water samples. This study provided technical support for the pollution assessment of perfluorinated compounds in water.
2017, 45(2): 275-281
doi: 10.11895/j.issn.0253-3820.160564
Abstract:
A novel method for accurate, fast and sensitive detection of pesticides such as imidacloprid, isocarbophos, phoxim, dursban, imidacloprid, pyridaben and avermectin in environmental water samples has been developed by using ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) coupled with high performance liquid chromatography with ultraviolet detection (HPLC-UV). The UA-DLLME parameters such as types/volumes of extraction/dispersion solvents, ultrasonic time, ionic strength and extraction time were investigated. Under the optimized extraction conditions, the linearity for the detection of six pesticides in the concentration range of 10-600 μg/L was obtained with limits of detections (LODs) of 0.8-3.1 μg/L and relative standard deviations (RSDs) of 4.7%-11.3%. UA-DLLME method exhibited strong enrichment ability for the six pesticides, and the enrichment factor (EFs) were ranged from 58 to 187. This method had perfect linearity, precision and recovery results, and showed obvious advantages and practicality comparing the previously reported methods.
A novel method for accurate, fast and sensitive detection of pesticides such as imidacloprid, isocarbophos, phoxim, dursban, imidacloprid, pyridaben and avermectin in environmental water samples has been developed by using ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) coupled with high performance liquid chromatography with ultraviolet detection (HPLC-UV). The UA-DLLME parameters such as types/volumes of extraction/dispersion solvents, ultrasonic time, ionic strength and extraction time were investigated. Under the optimized extraction conditions, the linearity for the detection of six pesticides in the concentration range of 10-600 μg/L was obtained with limits of detections (LODs) of 0.8-3.1 μg/L and relative standard deviations (RSDs) of 4.7%-11.3%. UA-DLLME method exhibited strong enrichment ability for the six pesticides, and the enrichment factor (EFs) were ranged from 58 to 187. This method had perfect linearity, precision and recovery results, and showed obvious advantages and practicality comparing the previously reported methods.
2017, 45(2): 282-296
doi: 10.11895/j.issn.0253-3820.160498
Abstract:
Micro-droplets are widely used in the fields of drug controlled release, virus detection, synthetic of particulate materials, catalysts and so on due to their small size, large surface area, high speed, high throughput, uniform size, closed system, internal stability and other characteristics. The emergence and development of microfluidics technology provide a new platform for the generation and precise manipulation of size-controlled microdroplets with different structures and functional characteristics. The fundamentals, generation and manipulation of droplet-based microfluidics technology are introduced. Similarities and differences of droplets' conventional preparation methods and droplet-based microfluidics technology are compared and analyzed. Finally, the applications of droplet-based microfluidics for the synthesis of functional materials, bio-medicine and design of food structure etc. are comprehensively presented. In addition, the potential value and development direction of drop-based microfluidics are discussed and forecasted.
Micro-droplets are widely used in the fields of drug controlled release, virus detection, synthetic of particulate materials, catalysts and so on due to their small size, large surface area, high speed, high throughput, uniform size, closed system, internal stability and other characteristics. The emergence and development of microfluidics technology provide a new platform for the generation and precise manipulation of size-controlled microdroplets with different structures and functional characteristics. The fundamentals, generation and manipulation of droplet-based microfluidics technology are introduced. Similarities and differences of droplets' conventional preparation methods and droplet-based microfluidics technology are compared and analyzed. Finally, the applications of droplet-based microfluidics for the synthesis of functional materials, bio-medicine and design of food structure etc. are comprehensively presented. In addition, the potential value and development direction of drop-based microfluidics are discussed and forecasted.
2017, 45(2): 297-302
doi: 10.11895/j.issn.0253-3820.160715
Abstract:
Printed-circuit-board ion trap (PCBIT) is a novel ion trap mass analyzer, which is capable of optimizing its internal electric field distributions by adjusting the radio frequency (RF) voltage-divided ratio to improve its analytical performance. This work introduced odd electric field components into the trapping volume to achieve unidirectional ion ejection by applying asymmetric RF voltages to x electrode pairs of PCBIT. In this case, the center of ion vibration was displaced away from the geometrical center of PCBIT and ions were ejected predominantly through one of x electrode pairs. The relationship between asymmetric voltage-divided ratio (ΔV) and internal electric field distributions was investigated by simulation software SIMION and AXSIM. At the same time, the ion trajectories and simulated mass spectrum peaks were calculated. The results showed that, for ions with m/z 609 Th, a mass resolution over 2500 and an ion unidirectional ejection efficiency of over 90% were achieved in PCBIT with ΔV=20% at an appropriate frequency of AC. Using this method, ion unidirectional ejection efficiency of PCBIT can be significantly improved while maintaining a high mass resolution, which makes the PCBIT more suitable for developing miniaturized mass spectrometer.
Printed-circuit-board ion trap (PCBIT) is a novel ion trap mass analyzer, which is capable of optimizing its internal electric field distributions by adjusting the radio frequency (RF) voltage-divided ratio to improve its analytical performance. This work introduced odd electric field components into the trapping volume to achieve unidirectional ion ejection by applying asymmetric RF voltages to x electrode pairs of PCBIT. In this case, the center of ion vibration was displaced away from the geometrical center of PCBIT and ions were ejected predominantly through one of x electrode pairs. The relationship between asymmetric voltage-divided ratio (ΔV) and internal electric field distributions was investigated by simulation software SIMION and AXSIM. At the same time, the ion trajectories and simulated mass spectrum peaks were calculated. The results showed that, for ions with m/z 609 Th, a mass resolution over 2500 and an ion unidirectional ejection efficiency of over 90% were achieved in PCBIT with ΔV=20% at an appropriate frequency of AC. Using this method, ion unidirectional ejection efficiency of PCBIT can be significantly improved while maintaining a high mass resolution, which makes the PCBIT more suitable for developing miniaturized mass spectrometer.
