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2012 Volume 40 Issue 10
2012, 40(10): 1471-1476
doi: 10.3724/SP.J.1096.2012.20095
Abstract:
The complex of G-quadruplex-hemin, also named peroxidase-mimicking DNAzyme, shows a catalytic activity towards hydrogen peroxide, which is rarely used as a catalyst in the assembly of electrochemical biosensors. Meanwhile, it is of significance to develop novel method in immobilizing DNA for the purpose of fabrication of DNA-based biosensors. Dopamine can form polydopamine film via self-polymerization. In this study, an electrochemical hydrogen peroxide biosensor was successfully constructed using polydopamine-entrapped G-quadruplex-hemin DNAzyme. The mixture of DNA and hemin achieved the formation of G-quadruplex-hemin complex. After the physical adsorption of DNAzyme on the glassy carbon electrode, a droplet containing 5 g/L dopamine in PBS (pH 8.0) was cast onto the surface. Ambient oxygen in the air oxidized dopamine for the formation of polydopamine to retain DNAzyme. The influence of DNA sequence to electrochemistry was investigated, showing a different phenomenon to optical sensors. The proposed biosensor was sensitive to hydrogen peroxide with the linear range spans the concentration from 10 μmol/L to 1.5 mmol/L and the limit of detection of 2.2 μmol/L. The results demonstrated the possibility of enzyme immobilization on the electrode through polydopamine and the substitution of G-quadruplex-hemin DNAzyme for natural enzyme.
The complex of G-quadruplex-hemin, also named peroxidase-mimicking DNAzyme, shows a catalytic activity towards hydrogen peroxide, which is rarely used as a catalyst in the assembly of electrochemical biosensors. Meanwhile, it is of significance to develop novel method in immobilizing DNA for the purpose of fabrication of DNA-based biosensors. Dopamine can form polydopamine film via self-polymerization. In this study, an electrochemical hydrogen peroxide biosensor was successfully constructed using polydopamine-entrapped G-quadruplex-hemin DNAzyme. The mixture of DNA and hemin achieved the formation of G-quadruplex-hemin complex. After the physical adsorption of DNAzyme on the glassy carbon electrode, a droplet containing 5 g/L dopamine in PBS (pH 8.0) was cast onto the surface. Ambient oxygen in the air oxidized dopamine for the formation of polydopamine to retain DNAzyme. The influence of DNA sequence to electrochemistry was investigated, showing a different phenomenon to optical sensors. The proposed biosensor was sensitive to hydrogen peroxide with the linear range spans the concentration from 10 μmol/L to 1.5 mmol/L and the limit of detection of 2.2 μmol/L. The results demonstrated the possibility of enzyme immobilization on the electrode through polydopamine and the substitution of G-quadruplex-hemin DNAzyme for natural enzyme.
2012, 40(10): 1477-1481
doi: 10.3724/SP.J.1096.2012.20281
Abstract:
We demonstrate a novel method to synthesize the graphene-supported AgPd alloy nanocrystals (AgPd/GO) which exhibits unique hollow structure and excellent electrocatalytic activity for H2O2 reduction. The hybrid nanomaterials were synthesized via a two-step method. The graphene supported Ag nanoparticles (Ag/GO) were first synthesized by using sodium citrate as both reducing and stabilizing agents. AgPd alloy nanoparticles supported on graphene (AgPd/GO) were then prepared through a galvanic displacement reaction at 100 ℃. The structure of the prepared materials was characterized with UV-visible spectroscopy and transmission electron microscopy (TEM). The electrochemical measurements showed that AgPd/GO had excellent electrocatalytic activity toward the reduction of hydrogen peroxide. Such hollow Ag/Pd alloy nanoparticles supported on graphene exhibited a low detection limit (1.4 μmol/L) and good linear ranges (0.01 mmol/L-1.4 mmol/L) for H2O2 detection, which render them the suitable electrochemical sensors for hydrogen peroxide detection in practical applications.
We demonstrate a novel method to synthesize the graphene-supported AgPd alloy nanocrystals (AgPd/GO) which exhibits unique hollow structure and excellent electrocatalytic activity for H2O2 reduction. The hybrid nanomaterials were synthesized via a two-step method. The graphene supported Ag nanoparticles (Ag/GO) were first synthesized by using sodium citrate as both reducing and stabilizing agents. AgPd alloy nanoparticles supported on graphene (AgPd/GO) were then prepared through a galvanic displacement reaction at 100 ℃. The structure of the prepared materials was characterized with UV-visible spectroscopy and transmission electron microscopy (TEM). The electrochemical measurements showed that AgPd/GO had excellent electrocatalytic activity toward the reduction of hydrogen peroxide. Such hollow Ag/Pd alloy nanoparticles supported on graphene exhibited a low detection limit (1.4 μmol/L) and good linear ranges (0.01 mmol/L-1.4 mmol/L) for H2O2 detection, which render them the suitable electrochemical sensors for hydrogen peroxide detection in practical applications.
2012, 40(10): 1482-1487
doi: 10.3724/SP.J.1096.2012.20012
Abstract:
To explore the plasma metabolite profiles in patients with dyslipidemia and seek for the metabolic biomarkers of the disease, the plasma metabolite profiles of 37 patients and 10 healthy people were analyzed by gas chromatography-mass spectrometry (GC-MS). Partial least squares-discriminant analysis (PLS-DA) was employed to perform the pattern recognition analysis of the data. The concentrations in plasma of 9 metabolites were found out with significant differences between patients with dyslipidemia and healthy people (p＜0.05) .They were identified as valine, glycine, alanine, pyroglutamic acid, glucuronic acid, galactose, mannose, linoleic acid and glycerol by searching in NIST database. The concentrations of 8 metabolites in plasma of patients with dyslipidemia were less than those of healthy people, while the glycerol`s was higher. The plasma metabolic biomarkers showed good correlation with the diagnostic criteria of dyslipidemia analyzed graphical models. Compared with healthy people, these 9 metabolites showing abnormal assembling in patients with dyslipidemia, and they might be the diagnostic and prognostic special metabolic biomarkers.
To explore the plasma metabolite profiles in patients with dyslipidemia and seek for the metabolic biomarkers of the disease, the plasma metabolite profiles of 37 patients and 10 healthy people were analyzed by gas chromatography-mass spectrometry (GC-MS). Partial least squares-discriminant analysis (PLS-DA) was employed to perform the pattern recognition analysis of the data. The concentrations in plasma of 9 metabolites were found out with significant differences between patients with dyslipidemia and healthy people (p＜0.05) .They were identified as valine, glycine, alanine, pyroglutamic acid, glucuronic acid, galactose, mannose, linoleic acid and glycerol by searching in NIST database. The concentrations of 8 metabolites in plasma of patients with dyslipidemia were less than those of healthy people, while the glycerol`s was higher. The plasma metabolic biomarkers showed good correlation with the diagnostic criteria of dyslipidemia analyzed graphical models. Compared with healthy people, these 9 metabolites showing abnormal assembling in patients with dyslipidemia, and they might be the diagnostic and prognostic special metabolic biomarkers.
2012, 40(10): 1488-1493
doi: 10.3724/SP.J.1096.2012.11387
Abstract:
The Composition-activity relationship (CAR) model of curcuma volatile oil based on GC-MS analysis was established to recognize the active compounds. 31 batches of curcuma volatile oil were prepared using steam distillation with the extraction rate ranging from 1.63% to 4.52%, and quantitatively analyzed by GC-MS. Anti-tumor activity was investigated by MTT assays on Hela cell line. The orthogonal partial least squares (OPLS) and bivariate correlation analysis was respectively performed on SIMCA-P 11.5 and SPSS 18.0 software to construct the CAR model of curcuma volatile oil. The results showed that 9 peaks including Peaks 11, 15, 7, 19, 3, 6, 12, 14 and 9 were significantly related to anti-tumor activity according to scores plot, variable importance in projection (VIP) values in OPLS and Pearson correlation coefficient in bivariate correlation analysis; Peaks 11, 15, 7, 3, 6, 12, 14 and 9 were identified as ar-tumerone, β-tumerone, zingiberene, β-elemene, α-curcumene, α-tumerone, germacrone, β-sesquiphellandrene, respectively.
The Composition-activity relationship (CAR) model of curcuma volatile oil based on GC-MS analysis was established to recognize the active compounds. 31 batches of curcuma volatile oil were prepared using steam distillation with the extraction rate ranging from 1.63% to 4.52%, and quantitatively analyzed by GC-MS. Anti-tumor activity was investigated by MTT assays on Hela cell line. The orthogonal partial least squares (OPLS) and bivariate correlation analysis was respectively performed on SIMCA-P 11.5 and SPSS 18.0 software to construct the CAR model of curcuma volatile oil. The results showed that 9 peaks including Peaks 11, 15, 7, 19, 3, 6, 12, 14 and 9 were significantly related to anti-tumor activity according to scores plot, variable importance in projection (VIP) values in OPLS and Pearson correlation coefficient in bivariate correlation analysis; Peaks 11, 15, 7, 3, 6, 12, 14 and 9 were identified as ar-tumerone, β-tumerone, zingiberene, β-elemene, α-curcumene, α-tumerone, germacrone, β-sesquiphellandrene, respectively.
2012, 40(10): 1494-1499
doi: 10.3724/SP.J.1096.2012.20168
Abstract:
Raman spectra had been used to image the spatial distribution of chemical composition by scanning the laser spot across some parts of mice ear at different depth. Selecting the bands at 1125 cm-1(blood sugar), 1300 cm-1(lipids), 1549 cm-1 (hemoglobin), 1660 cm-1 (protein) to calculate their peak areas, and using these data to generate 2D, and 3D images, we have demonstrated that Raman imaging can yield 3D spatially biochemical information from a living tissue. This technique provides a new way to study the biochemical molecule's distribution in vivo.
Raman spectra had been used to image the spatial distribution of chemical composition by scanning the laser spot across some parts of mice ear at different depth. Selecting the bands at 1125 cm-1(blood sugar), 1300 cm-1(lipids), 1549 cm-1 (hemoglobin), 1660 cm-1 (protein) to calculate their peak areas, and using these data to generate 2D, and 3D images, we have demonstrated that Raman imaging can yield 3D spatially biochemical information from a living tissue. This technique provides a new way to study the biochemical molecule's distribution in vivo.
2012, 40(10): 1500-1506
doi: 10.3724/SP.J.1096.2012.20027
Abstract:
The phosphorylation modification of talin, especially the phosphorylation state of talin in pathological environment such as carcinoma, is closely relevant to carcinogenesis and metastasis process. In this study, talin protein was isolated from human colorectal carcinoma tissues by salt fractionation and ion exchange chromatography, followed by further purification by electrophoresis. The purified talin was subject to tryptic digestion. Either immobilized Fe3+ affinity chromatography or TiO2 affinity chromatography was used to absorb the phosphorylated peptides under acidic condition, which were then eluted with 1% ammonium hydroxide. The separation was performed on a Michrom Magic C18 column with gradient elution using two mobile phase solutions (A:99% water+1% ACN+0.1% formic acid; B:99% ACN+1% water+0.1% formic acid). ESI mass spectrometer was used to detect the product ions of the eluted peaks under data-dependent acquisition mode. The results indicated that 8 phosphorylated peptides were captured by the immobilized Fe3+ affinity chromatography, whereas 9 phosphorylated peptides were captured by TiO2 affinity chromatography. The present study provides a rapid, accurate method for characterizing talin protein isolated from human colorectal carcinoma tissues.
The phosphorylation modification of talin, especially the phosphorylation state of talin in pathological environment such as carcinoma, is closely relevant to carcinogenesis and metastasis process. In this study, talin protein was isolated from human colorectal carcinoma tissues by salt fractionation and ion exchange chromatography, followed by further purification by electrophoresis. The purified talin was subject to tryptic digestion. Either immobilized Fe3+ affinity chromatography or TiO2 affinity chromatography was used to absorb the phosphorylated peptides under acidic condition, which were then eluted with 1% ammonium hydroxide. The separation was performed on a Michrom Magic C18 column with gradient elution using two mobile phase solutions (A:99% water+1% ACN+0.1% formic acid; B:99% ACN+1% water+0.1% formic acid). ESI mass spectrometer was used to detect the product ions of the eluted peaks under data-dependent acquisition mode. The results indicated that 8 phosphorylated peptides were captured by the immobilized Fe3+ affinity chromatography, whereas 9 phosphorylated peptides were captured by TiO2 affinity chromatography. The present study provides a rapid, accurate method for characterizing talin protein isolated from human colorectal carcinoma tissues.
2012, 40(10): 1507-1513
doi: 10.3724/SP.J.1096.2012.20120
Abstract:
An impedance immunosensor was developed for the rapid detection of H5 subtype avian influenza virus (AIV). Monoclonal antibodies against AIV H5N1 surface antigen hemagglutinin (HA) were immobilized on the surface of gold interdigitated array microelectrodes through protein A for capturing AIV H5N1 in sample solutions. Electrochemical impedance spectroscopy in the presence of [Fe(CN)6]3-/4- as a redox probe was used to describe the surface modification of microelectrodes and the binding of viruses. A linear relationship between the logarithmic value of concentration of AIV H5N1 and the change of electron transfer resistance was found in the concentration range of 21-26 HA unit per 50 μL, and its correlation coefficient was 0.9885. The detection limit was 20 HA unit per 50 μL, and the detection time was 1 h. This immunosensor could be used repeatedly with good specificity and high sensitivity, and it is promising for rapid detection of pathogenic microorganisms.
An impedance immunosensor was developed for the rapid detection of H5 subtype avian influenza virus (AIV). Monoclonal antibodies against AIV H5N1 surface antigen hemagglutinin (HA) were immobilized on the surface of gold interdigitated array microelectrodes through protein A for capturing AIV H5N1 in sample solutions. Electrochemical impedance spectroscopy in the presence of [Fe(CN)6]3-/4- as a redox probe was used to describe the surface modification of microelectrodes and the binding of viruses. A linear relationship between the logarithmic value of concentration of AIV H5N1 and the change of electron transfer resistance was found in the concentration range of 21-26 HA unit per 50 μL, and its correlation coefficient was 0.9885. The detection limit was 20 HA unit per 50 μL, and the detection time was 1 h. This immunosensor could be used repeatedly with good specificity and high sensitivity, and it is promising for rapid detection of pathogenic microorganisms.
2012, 40(10): 1514-1518
doi: 10.3724/SP.J.1096.2012.11447
Abstract:
A novel ultra-sensitive immunoassay for Hepatitis B surface antigen (HBsAg) was proposed. Magnetic nanosphere functionalized with carboxyl group was activated with 1-ethyl-3-(3-dimethylamino-propyl) carbodiimide hydrochloride/N-hydroxy-succinimimide (EDC/NHS), and then Hepatitis B surface antibody (HBsAb) was covalently immobilized on the surface. Hepatitis B secondary antibody labeled with horseradish peroxide (HRP) was covalently linked to the hyperbranched polymer(HBP). The antibody could capture the HBsAg when the antibody-modified magnetic nanosphere was incubated with HBsAg. Then the HBP conjugate was added, and a sandwich immunocomplex formed on the surface of magnetic nanospheres. The nanosphere with sandwich complex was separated magnetically from sample solution, and then incubated in the buffer solution containing 2-amino hydroxy benzene and hydrogen peroxide. The HRP could catalyze the reaction between 2-amino hydroxy benzene and hydrogen peroxide to produce electroactive product 2-hydroxy-3-amino phenoxazine. When using differential pulse voltammetry. the peak current was linear with the concentration of HBsAg in the range of 0.05 to 10 μg/L under the optimum conditions. The detection limit was found to be 0.008 μg/L, and the linear regression equation was I(μA)＝0.140+16.80C(μg/L) with r＝0.9995. This method was applied to analyze real samples.
A novel ultra-sensitive immunoassay for Hepatitis B surface antigen (HBsAg) was proposed. Magnetic nanosphere functionalized with carboxyl group was activated with 1-ethyl-3-(3-dimethylamino-propyl) carbodiimide hydrochloride/N-hydroxy-succinimimide (EDC/NHS), and then Hepatitis B surface antibody (HBsAb) was covalently immobilized on the surface. Hepatitis B secondary antibody labeled with horseradish peroxide (HRP) was covalently linked to the hyperbranched polymer(HBP). The antibody could capture the HBsAg when the antibody-modified magnetic nanosphere was incubated with HBsAg. Then the HBP conjugate was added, and a sandwich immunocomplex formed on the surface of magnetic nanospheres. The nanosphere with sandwich complex was separated magnetically from sample solution, and then incubated in the buffer solution containing 2-amino hydroxy benzene and hydrogen peroxide. The HRP could catalyze the reaction between 2-amino hydroxy benzene and hydrogen peroxide to produce electroactive product 2-hydroxy-3-amino phenoxazine. When using differential pulse voltammetry. the peak current was linear with the concentration of HBsAg in the range of 0.05 to 10 μg/L under the optimum conditions. The detection limit was found to be 0.008 μg/L, and the linear regression equation was I(μA)＝0.140+16.80C(μg/L) with r＝0.9995. This method was applied to analyze real samples.
2012, 40(10): 1519-1523
doi: 10.3724/SP.J.1096.2012.20364
Abstract:
A gel permeation chromatography-gas chromatography-negative chemical ionization-mass spectrometry method (GPC-GC-NCI-MS) was developed for the determination of 2,2',4,4',5,5'-hexabromobiphenyl (BB-153), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) and Dechlorane plus (DP) in human serum sample. The serum samples were spiked with 13C12BB-153 and 13C10syn-DP as surrogate internal standard before extracting, and the serum lipid was extracted and mostly removed by gel permeation chromatography. Samples were further cleaned up with a silica/sulfuric acid column. Identification and quantification of BB-153, BTBPE, syn-DP and anti-DP were performed by Gas chromatography-Negative chemical ionization-Mass spectrometry. The monitored ions were as follows: m/z 627.5 and 629.5 for BB-153; m/z 79 and 81 for BTBPE; m/z 652 and 654 for DP. The recoveries of 13C12BB-153 and 13C10syn-DP in serum samples were 91.5%±8.9% and 92.3%±8.1%, respectively. The limits of detection were from 0.6 to 1.2 ng/g lipid. BB-153 and BTBPE were not detected in all serum samples, and the concentrations of syn-DP and anti-DP were 0.7-9.2 ng/g lipid and 0.6-2.0 ng/g lipid, respectively.
A gel permeation chromatography-gas chromatography-negative chemical ionization-mass spectrometry method (GPC-GC-NCI-MS) was developed for the determination of 2,2',4,4',5,5'-hexabromobiphenyl (BB-153), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) and Dechlorane plus (DP) in human serum sample. The serum samples were spiked with 13C12BB-153 and 13C10syn-DP as surrogate internal standard before extracting, and the serum lipid was extracted and mostly removed by gel permeation chromatography. Samples were further cleaned up with a silica/sulfuric acid column. Identification and quantification of BB-153, BTBPE, syn-DP and anti-DP were performed by Gas chromatography-Negative chemical ionization-Mass spectrometry. The monitored ions were as follows: m/z 627.5 and 629.5 for BB-153; m/z 79 and 81 for BTBPE; m/z 652 and 654 for DP. The recoveries of 13C12BB-153 and 13C10syn-DP in serum samples were 91.5%±8.9% and 92.3%±8.1%, respectively. The limits of detection were from 0.6 to 1.2 ng/g lipid. BB-153 and BTBPE were not detected in all serum samples, and the concentrations of syn-DP and anti-DP were 0.7-9.2 ng/g lipid and 0.6-2.0 ng/g lipid, respectively.
2012, 40(10): 1524-1529
doi: 10.3724/SP.J.1096.2012.20046
Abstract:
Based on direct competitive immunoassay principle and giant magnetoresistance (GMR) effect, a novel method for detecting chloramphenicol (CAP) by magnetic biosensor has been developed. The sample, biotinylated anti-CAP monoclonal antibody, and streptavidin-beads conjugate were added onto the prepared CAP hapten chips one by one. Subsequently, competitive immune reaction happened and the number of beads bonded on chips was detected by magnetic biosensor. The standard curve was established by optimizing the detection condition. This method can be used to detect CAP in a range of 0.05-100.0 μg/L, detection limit of 50 ng/L. The analyte recoveries in milk samples ranged from 95.97% to 99.36%. The relative standard deviations ranged from 0.8% to 3.9% for intra-assay and 1.1% to 1.7% for inter-assay. The correlation coefficient between this method and ELISA was 0.98. Rapid quantitative detection could be accomplished within 30 minutes using this method. It provides feasibility for the establishment of rapid multi-target magnetic competitive immunoassay system.
Based on direct competitive immunoassay principle and giant magnetoresistance (GMR) effect, a novel method for detecting chloramphenicol (CAP) by magnetic biosensor has been developed. The sample, biotinylated anti-CAP monoclonal antibody, and streptavidin-beads conjugate were added onto the prepared CAP hapten chips one by one. Subsequently, competitive immune reaction happened and the number of beads bonded on chips was detected by magnetic biosensor. The standard curve was established by optimizing the detection condition. This method can be used to detect CAP in a range of 0.05-100.0 μg/L, detection limit of 50 ng/L. The analyte recoveries in milk samples ranged from 95.97% to 99.36%. The relative standard deviations ranged from 0.8% to 3.9% for intra-assay and 1.1% to 1.7% for inter-assay. The correlation coefficient between this method and ELISA was 0.98. Rapid quantitative detection could be accomplished within 30 minutes using this method. It provides feasibility for the establishment of rapid multi-target magnetic competitive immunoassay system.
2012, 40(10): 1530-1535
doi: 10.3724/SP.J.1096.2012.20160
Abstract:
The content of semicarbazide in crustaceans had been determined by LC/MS/MS. Samples were hydrolyzed by hydrochloric acid and derivatized with 2-nitrobenzaidehyde. After extraction with ethyl acetate, chromatographic separation was achieved by HPLC and the target compound was detected by tandem mass spectrometry using internal standard as quantification method. The qualitative limit was 0.25 μg/kg(S/N＞3)and the quantitative limit was 0.5 μg/kg(S/N＞10). Crustacean species were from natural water and free market of agricultural products including oriental river prawn, giant tiger prawn, giant freshwater prawn, white-leg shrimp, red swamp crayfish, mud crab, dungeness crab, swimming crab, mitten crab and horse shoe crab. Concentrations of semicarbazide in shrimp and in crab were from not detected to 370.4 μg/kg and not detected to 87.5 μg/kg and concentrations of semicarbazide varied from tissues with highest in carapace and lowest in muscle. In the present study, the results revealed that semicarbazide was an endogenous substance existing in crustaceans.
The content of semicarbazide in crustaceans had been determined by LC/MS/MS. Samples were hydrolyzed by hydrochloric acid and derivatized with 2-nitrobenzaidehyde. After extraction with ethyl acetate, chromatographic separation was achieved by HPLC and the target compound was detected by tandem mass spectrometry using internal standard as quantification method. The qualitative limit was 0.25 μg/kg(S/N＞3)and the quantitative limit was 0.5 μg/kg(S/N＞10). Crustacean species were from natural water and free market of agricultural products including oriental river prawn, giant tiger prawn, giant freshwater prawn, white-leg shrimp, red swamp crayfish, mud crab, dungeness crab, swimming crab, mitten crab and horse shoe crab. Concentrations of semicarbazide in shrimp and in crab were from not detected to 370.4 μg/kg and not detected to 87.5 μg/kg and concentrations of semicarbazide varied from tissues with highest in carapace and lowest in muscle. In the present study, the results revealed that semicarbazide was an endogenous substance existing in crustaceans.
2012, 40(10): 1536-1542
doi: 10.3724/SP.J.1096.2012.20197
Abstract:
A fast method based on the Quick Easy Cheap Effective Rugged and Safe (QuEChERS) sample preparation method and gas chromatography-tandem mass spectrometry (GC-MS/MS) for the analysis of eight photoinitiator residues in various soft drinks including orange juice, cider, peach juice, pineapple juice and herb tea was developed. The procedure involved the quick extraction of the sample with acetonitrile, followed by adding NaCl plus anhydrous MgSO4. Then the extract was purified by primary secondary amine (PSA) sorbent plus C18 power. The ultimate solution was detected by GC-MS/MS under multiple reaction monitoring mode. The recoveries of eight photoinitiators were in the range from 60.4% to 99.1% at three spike levels of 0.01, 0.1 and 0.5 mg/kg into five soft drinks matrices, the relative standard deviations (RSDs) were between 1.2% and 15.9% and the limits of detection were between 0.2 μg/L and 0.8 μg/L. The method is simple, quick, safe, cheap and reproducible, and applicable to confirm photoinitiator residues in the real sample.
A fast method based on the Quick Easy Cheap Effective Rugged and Safe (QuEChERS) sample preparation method and gas chromatography-tandem mass spectrometry (GC-MS/MS) for the analysis of eight photoinitiator residues in various soft drinks including orange juice, cider, peach juice, pineapple juice and herb tea was developed. The procedure involved the quick extraction of the sample with acetonitrile, followed by adding NaCl plus anhydrous MgSO4. Then the extract was purified by primary secondary amine (PSA) sorbent plus C18 power. The ultimate solution was detected by GC-MS/MS under multiple reaction monitoring mode. The recoveries of eight photoinitiators were in the range from 60.4% to 99.1% at three spike levels of 0.01, 0.1 and 0.5 mg/kg into five soft drinks matrices, the relative standard deviations (RSDs) were between 1.2% and 15.9% and the limits of detection were between 0.2 μg/L and 0.8 μg/L. The method is simple, quick, safe, cheap and reproducible, and applicable to confirm photoinitiator residues in the real sample.
2012, 40(10): 1543-1548
doi: 10.3724/SP.J.1096.2012.20208
Abstract:
A nano-cluster with highly efficient peroxide activity was constructed self-assembly based on nafion (NF) and cytochrome c (Cyt c), The UV-Vis spectrometry, Circular Dichroism (CD) and transmission electron microscopic (TEM) methods were utilized for additional characterization of the artificial peroxidase (AP). The nano-cluster was composed of chain-ball structure, with an average ball size of approximately 40 nm detected by TEM method. The Michaelis–Menten (Km) and catalytic rate (kcat) constants of the AP were determined to be (2.5±0.4) μmol/L and (0.069±0.001) s-1, respectively, in 50 mmol/L PBS at pH 7.0. The catalytic efficiency of AP was evaluated to be (0.028±0.005) μmol/L-1s-1, which was 39%±5% as efficient as the native HRP. AP generated here can be used in place of HRP with high stability and activity. The AP was also immobilized on a functional MWNCTs-gold nano-complex modified glassy carbon electrode. The cyclic voltammetry of AP on the nano complex modified glassy carbon electrode showed a pair of well-defined quasi-reversible redox peaks with the formal potential of (Eo') of (-45±2) mV (vs. Ag/AgCl) at scan rate of 0.05 V/s. The heterogeneous electron transfer rate constant was evaluated to be 0.65 s-1 in 50 mmol/L Na2HPO4-NaH2PO4 buffer solution at pH 7.0. The cathodic peak current of the modified electrode increased with increasing concentration of hydrogen peroxide(from 0.02 to 10 nmol/L) with a detection limit of 0.05 nmol/L. The apparent Michaelis-Menten constant (Kmapp) was 0.23 nmol/L.
A nano-cluster with highly efficient peroxide activity was constructed self-assembly based on nafion (NF) and cytochrome c (Cyt c), The UV-Vis spectrometry, Circular Dichroism (CD) and transmission electron microscopic (TEM) methods were utilized for additional characterization of the artificial peroxidase (AP). The nano-cluster was composed of chain-ball structure, with an average ball size of approximately 40 nm detected by TEM method. The Michaelis–Menten (Km) and catalytic rate (kcat) constants of the AP were determined to be (2.5±0.4) μmol/L and (0.069±0.001) s-1, respectively, in 50 mmol/L PBS at pH 7.0. The catalytic efficiency of AP was evaluated to be (0.028±0.005) μmol/L-1s-1, which was 39%±5% as efficient as the native HRP. AP generated here can be used in place of HRP with high stability and activity. The AP was also immobilized on a functional MWNCTs-gold nano-complex modified glassy carbon electrode. The cyclic voltammetry of AP on the nano complex modified glassy carbon electrode showed a pair of well-defined quasi-reversible redox peaks with the formal potential of (Eo') of (-45±2) mV (vs. Ag/AgCl) at scan rate of 0.05 V/s. The heterogeneous electron transfer rate constant was evaluated to be 0.65 s-1 in 50 mmol/L Na2HPO4-NaH2PO4 buffer solution at pH 7.0. The cathodic peak current of the modified electrode increased with increasing concentration of hydrogen peroxide(from 0.02 to 10 nmol/L) with a detection limit of 0.05 nmol/L. The apparent Michaelis-Menten constant (Kmapp) was 0.23 nmol/L.
Electrochemiluminescence Biosensor for Detection of Thrombin Using Enzyme-based Signal Amplification
2012, 40(10): 1549-1554
doi: 10.3724/SP.J.1096.2012.11394
Abstract:
Amino functionalized gold nanoparticles(GNP) were synthesized in this work. Electrochemiluminescence (ECL) probe was synthesized by covalently linking tris (2,2-bipyridyl) ruthenium (Ⅱ) and self-assembly of thiol DNA5 to this GNP. By using nicking endonuclease signal amplification technology, large amount of newly obtained DNA fragments was obtained to capture ECL probe. Thiol DNA probe was self-assembled on gold electrode surface, and then ECL biosensor was fabricated by sequentially hybridization of complementary DNA (newly obtained DNA fragment) and ECL probe to this modified gold electrode. Under optimized conditions, the ECL intensity of this biosensor exhibited linear relationship with thrombin concentration in the range of 3.0×10-13-6.0×10-11 mol/L, and the detection limit was 1.8×10-13 mol/L (3σ). The biosensor shows good application prospect in the field of biological samples analysis owing to its high sensitivity, good stability and reproducibility.
Amino functionalized gold nanoparticles(GNP) were synthesized in this work. Electrochemiluminescence (ECL) probe was synthesized by covalently linking tris (2,2-bipyridyl) ruthenium (Ⅱ) and self-assembly of thiol DNA5 to this GNP. By using nicking endonuclease signal amplification technology, large amount of newly obtained DNA fragments was obtained to capture ECL probe. Thiol DNA probe was self-assembled on gold electrode surface, and then ECL biosensor was fabricated by sequentially hybridization of complementary DNA (newly obtained DNA fragment) and ECL probe to this modified gold electrode. Under optimized conditions, the ECL intensity of this biosensor exhibited linear relationship with thrombin concentration in the range of 3.0×10-13-6.0×10-11 mol/L, and the detection limit was 1.8×10-13 mol/L (3σ). The biosensor shows good application prospect in the field of biological samples analysis owing to its high sensitivity, good stability and reproducibility.
2012, 40(10): 1555-1560
doi: 10.3724/SP.J.1096.2012.20064
Abstract:
A simple hydrophilic interaction liquid chromatographic (HILIC) method for the determination of acrylamide (AA), N,N-dimethylformamide (DMF), and N,N-dimethylacetamide (DMAC) in environmental water was developed. A cartridge containing graphitized carbon black was used for solid phase extraction (SPE) of the compounds in environmental water, the sample loaded was 1.0 mL, and then eluted with 1.0 mL acetonitrile, the elution was introduced into the instrument and determined by HPLC coupled with photo-diode array detector (PDA) at 200 nm. A good baseline separation of target compounds was obtained in 11 minutes under the optimum condition of determination. The calibration curves of 3 amides were linear in the concentration range of 0.05-100 mg/L with correlation coefficients of 0.9999. Overall recoveries were good (84.1%-106%), and the relative standard deviations ranged from 1.8% to 10.4% for the target compounds. The minimum detectable concentrations were 0.01 mg/L. This established method is convenient, sensitive and accurate, and was suitable for the routine detection of trace amide contaminants in environmental water.
A simple hydrophilic interaction liquid chromatographic (HILIC) method for the determination of acrylamide (AA), N,N-dimethylformamide (DMF), and N,N-dimethylacetamide (DMAC) in environmental water was developed. A cartridge containing graphitized carbon black was used for solid phase extraction (SPE) of the compounds in environmental water, the sample loaded was 1.0 mL, and then eluted with 1.0 mL acetonitrile, the elution was introduced into the instrument and determined by HPLC coupled with photo-diode array detector (PDA) at 200 nm. A good baseline separation of target compounds was obtained in 11 minutes under the optimum condition of determination. The calibration curves of 3 amides were linear in the concentration range of 0.05-100 mg/L with correlation coefficients of 0.9999. Overall recoveries were good (84.1%-106%), and the relative standard deviations ranged from 1.8% to 10.4% for the target compounds. The minimum detectable concentrations were 0.01 mg/L. This established method is convenient, sensitive and accurate, and was suitable for the routine detection of trace amide contaminants in environmental water.
2012, 40(10): 1561-1566
doi: 10.3724/SP.J.1096.2012.11297
Abstract:
The molecularly imprinted colloidal microspheres with good monodispersity were prepared by using trinitrotoluene (TNT) as template, and acrylamide as monomer and polymerizing by emulsion polymerization. The colloidal microspheres were self-assembled into array by vertical deposition method on a quartz slide, and then molecularly-imprinted colloidal array (MICA) which had opal structure was peeled off and immobilized on glue tape. In this research, the influence of different detection environments on optical response of MICA was discussed, as well as the specific adsorption capacity in response of the optimum testing environment. The results showed that the response of TNT at the concentration of 20 mmol/L in methanol-aqueous (7∶3, V/V) solution reached a redshift of 24 nm, which was 1.4 times of non-molecularly-imprinted colloidal array and 23 times of its analogues. MICA simplified the preparation process of photonic crystals sensor, and represented a noval highly selective, real-time "naked-eye" detection method for explosive.
The molecularly imprinted colloidal microspheres with good monodispersity were prepared by using trinitrotoluene (TNT) as template, and acrylamide as monomer and polymerizing by emulsion polymerization. The colloidal microspheres were self-assembled into array by vertical deposition method on a quartz slide, and then molecularly-imprinted colloidal array (MICA) which had opal structure was peeled off and immobilized on glue tape. In this research, the influence of different detection environments on optical response of MICA was discussed, as well as the specific adsorption capacity in response of the optimum testing environment. The results showed that the response of TNT at the concentration of 20 mmol/L in methanol-aqueous (7∶3, V/V) solution reached a redshift of 24 nm, which was 1.4 times of non-molecularly-imprinted colloidal array and 23 times of its analogues. MICA simplified the preparation process of photonic crystals sensor, and represented a noval highly selective, real-time "naked-eye" detection method for explosive.
2012, 40(10): 1567-1572
doi: 10.3724/SP.J.1096.2012.20249
Abstract:
A method based on isotope dilution-liquid chromatography tandem mass spectrometry (HPLC-MS/MS) was developed and validated to simultaneously quantify metabolites of sulfur mustard, thioglycol (TDG) and thioglycol sulfoxide (TDGO), in rat plasma. Plasma samples were pretreated with the mixed solvent of methanol and acetonitrile to precipitate proteins. The separation of TDG and TDGO was achieved on a ZORBAX-C18 column (3.0 mm×100 mm, 3.5 μm) by gradient elution with mobile phase consisting of methanol and 5 mmol/L ammonium formate aqueous solution. The mass spectrometric identification and quantification were performed using positive electrospray ionization and multiple reactions monitoring mode. An isotopic labeled TDG (d8-TDG) was used as internal standard. The calibration curves for TDG and TDGO were linear (R2＞0.991) over the range from 5-800 μg/L, and 0.5-80 μg/L, with the lower limit of quantification at 5 and 0.5 μg/L. The recovery of the analytes ranged from 101% to 118%. The intra- and inter-day precisions (RSD) were all within 10%. The plasma was collected and analyzed from HD-exposure rats after subcutaneous administration, and the kinetics parameters of TDG and TDGO were calculated and demonstrated as follow: tmax 30 min and 60 min, cmax (1724±227) μg/L and (301±115) μg/L, AUC (3286±249) μg·h/L and (1010±363) μg·h/L, respectively.
A method based on isotope dilution-liquid chromatography tandem mass spectrometry (HPLC-MS/MS) was developed and validated to simultaneously quantify metabolites of sulfur mustard, thioglycol (TDG) and thioglycol sulfoxide (TDGO), in rat plasma. Plasma samples were pretreated with the mixed solvent of methanol and acetonitrile to precipitate proteins. The separation of TDG and TDGO was achieved on a ZORBAX-C18 column (3.0 mm×100 mm, 3.5 μm) by gradient elution with mobile phase consisting of methanol and 5 mmol/L ammonium formate aqueous solution. The mass spectrometric identification and quantification were performed using positive electrospray ionization and multiple reactions monitoring mode. An isotopic labeled TDG (d8-TDG) was used as internal standard. The calibration curves for TDG and TDGO were linear (R2＞0.991) over the range from 5-800 μg/L, and 0.5-80 μg/L, with the lower limit of quantification at 5 and 0.5 μg/L. The recovery of the analytes ranged from 101% to 118%. The intra- and inter-day precisions (RSD) were all within 10%. The plasma was collected and analyzed from HD-exposure rats after subcutaneous administration, and the kinetics parameters of TDG and TDGO were calculated and demonstrated as follow: tmax 30 min and 60 min, cmax (1724±227) μg/L and (301±115) μg/L, AUC (3286±249) μg·h/L and (1010±363) μg·h/L, respectively.
2012, 40(10): 1573-1578
doi: 10.3724/SP.J.1096.2012.11135
Abstract:
This study aims to develop an LC-MS/MS method for the determination of drugs contained immunodepressants and other drugs in human plasma. The drugs and the internal standard were treated by methanol precipitation to remove protein component from human plasma, and then separated on a Kromasil-C18 column (5 μm, 50 mm×4.6 mm) with a gradient elution. The mobile phase consisted of methanol-acetonitrile-1 mmol/L ammonium acetate was maintained at 35 ℃. The flow rate was 1.1 mL/min and 20 μL aliquot of residues was injected into the LC-MS/MS system. Detection was carried out by multiple reaction monitoring on a 3200 QTrap LC-MS/MS system. The assay was linear over the range of 0.2-1000 μg/L with a lower limit of quantitation of 0.2 μg/L. Intra-and inter-day precisions were both less than 15%. The relative deviation was in the range of -13%-9.33%. The stabilities of the method were good. It is a rapid, sensitive, selective and reliable method for the determination of the drugs which contain immunodepressants and other drugs in human plasma. The assay can be applied for the determination of these drugs in human plasma.
This study aims to develop an LC-MS/MS method for the determination of drugs contained immunodepressants and other drugs in human plasma. The drugs and the internal standard were treated by methanol precipitation to remove protein component from human plasma, and then separated on a Kromasil-C18 column (5 μm, 50 mm×4.6 mm) with a gradient elution. The mobile phase consisted of methanol-acetonitrile-1 mmol/L ammonium acetate was maintained at 35 ℃. The flow rate was 1.1 mL/min and 20 μL aliquot of residues was injected into the LC-MS/MS system. Detection was carried out by multiple reaction monitoring on a 3200 QTrap LC-MS/MS system. The assay was linear over the range of 0.2-1000 μg/L with a lower limit of quantitation of 0.2 μg/L. Intra-and inter-day precisions were both less than 15%. The relative deviation was in the range of -13%-9.33%. The stabilities of the method were good. It is a rapid, sensitive, selective and reliable method for the determination of the drugs which contain immunodepressants and other drugs in human plasma. The assay can be applied for the determination of these drugs in human plasma.
2012, 40(10): 1579-1583
doi: 10.3724/SP.J.1096.2012.11380
Abstract:
A novel polypyrrole-ionic liquid (PPY-IL) film coated steel wire was prepared by electrodeposition in 0.1 mol/L pyrrole+0.1 mol/L p-methyl benzene sulfonate acid+4 g/L 1-butyl-3-methylimidazolium tetrafluoroborate aqueous solution. The PPY-IL coating showed cauliflower structure, with smaller particle size than that of polypyrrole. Taking five benzene derivatives as models, the analytical performance of the resulting fiber was explored. Under the optimized conditions (i.e. extraction temperature: 50 ℃; extraction time: 40 min; stirring rate: 600 r/min; NaCl concentration: 0.2 g/mL), when the benzene derivatives were determined by GC after headspace solid-phase microextraction with the PPY-IL fiber, the linear ranges were 0.6-800 μg/L with correlation coefficients above 0.99. The relative standard deviations (RSD) of chromatographic peak areas were smaller than 4.5% for five successive extraction with single fiber, and the RSDs for fiber-to-fiber were 4.5-12.4% (n＝5) for different benzene derivatives. The fiber also presented good stability and it still had high extraction efficiency after being used for about 150 times; when the temperature was up to 290 ℃ it did not decompose. In comparison with PPY and polydimethylsiloxane fibers, the PPY-IL fiber showed higher extraction capability and durability.
A novel polypyrrole-ionic liquid (PPY-IL) film coated steel wire was prepared by electrodeposition in 0.1 mol/L pyrrole+0.1 mol/L p-methyl benzene sulfonate acid+4 g/L 1-butyl-3-methylimidazolium tetrafluoroborate aqueous solution. The PPY-IL coating showed cauliflower structure, with smaller particle size than that of polypyrrole. Taking five benzene derivatives as models, the analytical performance of the resulting fiber was explored. Under the optimized conditions (i.e. extraction temperature: 50 ℃; extraction time: 40 min; stirring rate: 600 r/min; NaCl concentration: 0.2 g/mL), when the benzene derivatives were determined by GC after headspace solid-phase microextraction with the PPY-IL fiber, the linear ranges were 0.6-800 μg/L with correlation coefficients above 0.99. The relative standard deviations (RSD) of chromatographic peak areas were smaller than 4.5% for five successive extraction with single fiber, and the RSDs for fiber-to-fiber were 4.5-12.4% (n＝5) for different benzene derivatives. The fiber also presented good stability and it still had high extraction efficiency after being used for about 150 times; when the temperature was up to 290 ℃ it did not decompose. In comparison with PPY and polydimethylsiloxane fibers, the PPY-IL fiber showed higher extraction capability and durability.
2012, 40(10): 1584-1588
doi: 10.3724/SP.J.1096.2012.20329
Abstract:
A novel C18 open-tubular column (C18 capillary) for capillary electrochromatography was prepared based on thiol-ene click chemistry between n-octadecanethiol and vinyl-functionalized capillary (Vinyl capillary). The inner wall of capillary was chemically modified with vinyltrimethoxysilane to provide ene-functionality. Then n-octadecanethiol was chemically bonded on surface of Vinyl capillary via thiol-ene click chemistry. The surface features of the prepared C18 capillary were determined using scanning electron microscopy. The effects of buffer pH on the electroosmotic flow (EOF) of C18 capillary, Vinyl capillary and bare capillary were investigated. The experiment results indicated that the lowest EOF profile was obtained on the C18 capillary under the same experimental conditions compared to Vinyl capillary and bare capillary. To evaluate the column performance, test mixture of three polycyclic aromatic hydrocarbons (PAHs) was electrochromatographic separation on the C18 capillary, Vinyl capillary and bare capillary. The electrochromatographic retention behavior of the selected model PAHs on C18 capillary was also investigated. The experiment results showed that C18 capillary exhibited typical reversed phase electrochromatographic behavior toward PAHs. Compared with Vinyl capillary, the relatively good peak shape and no peak tailing were observed for the separation of basic model analytes on C18 capillary, which may be attributed to embedded polar sulphur groups on the surface of the C18 capillary that effectively shielded the adsorption of basic analytes onto the residual silanol groups.
A novel C18 open-tubular column (C18 capillary) for capillary electrochromatography was prepared based on thiol-ene click chemistry between n-octadecanethiol and vinyl-functionalized capillary (Vinyl capillary). The inner wall of capillary was chemically modified with vinyltrimethoxysilane to provide ene-functionality. Then n-octadecanethiol was chemically bonded on surface of Vinyl capillary via thiol-ene click chemistry. The surface features of the prepared C18 capillary were determined using scanning electron microscopy. The effects of buffer pH on the electroosmotic flow (EOF) of C18 capillary, Vinyl capillary and bare capillary were investigated. The experiment results indicated that the lowest EOF profile was obtained on the C18 capillary under the same experimental conditions compared to Vinyl capillary and bare capillary. To evaluate the column performance, test mixture of three polycyclic aromatic hydrocarbons (PAHs) was electrochromatographic separation on the C18 capillary, Vinyl capillary and bare capillary. The electrochromatographic retention behavior of the selected model PAHs on C18 capillary was also investigated. The experiment results showed that C18 capillary exhibited typical reversed phase electrochromatographic behavior toward PAHs. Compared with Vinyl capillary, the relatively good peak shape and no peak tailing were observed for the separation of basic model analytes on C18 capillary, which may be attributed to embedded polar sulphur groups on the surface of the C18 capillary that effectively shielded the adsorption of basic analytes onto the residual silanol groups.
2012, 40(10): 1589-1592
doi: 10.3724/SP.J.1096.2012.20324
Abstract:
A headspace solid phase microextraction (HS-SPME), followed by gas chromatographic method was established for the detection of three pyrazine compounds (2,5-dimethyl pyrazine, 2,3,5-trimethyl pyrazine and 2,3,5,6-tetramethyl pyrazine) in cocoa wort. Equilibrium temperature and equilibrium time were optimized by using different SPME heads. According to the results of the optimization experiments, the following conclusion can be drawn:The cocoa wort sample was efficiently extracted under 40℃ for 40 min with 75 μm CAR/PDMS SPME head. The method had linear response within 1-500 mg/L, and the detection limits (S/N＝3) were below 0.023 μg/L. The relative standard deviations were from 3.6%-6.4% and the recoveries were from 95.4% to 102.7%. This method is characterized by rapidly, high sensitivity, good linearity and repeatability for the analysis of cocoa wort samples.
A headspace solid phase microextraction (HS-SPME), followed by gas chromatographic method was established for the detection of three pyrazine compounds (2,5-dimethyl pyrazine, 2,3,5-trimethyl pyrazine and 2,3,5,6-tetramethyl pyrazine) in cocoa wort. Equilibrium temperature and equilibrium time were optimized by using different SPME heads. According to the results of the optimization experiments, the following conclusion can be drawn:The cocoa wort sample was efficiently extracted under 40℃ for 40 min with 75 μm CAR/PDMS SPME head. The method had linear response within 1-500 mg/L, and the detection limits (S/N＝3) were below 0.023 μg/L. The relative standard deviations were from 3.6%-6.4% and the recoveries were from 95.4% to 102.7%. This method is characterized by rapidly, high sensitivity, good linearity and repeatability for the analysis of cocoa wort samples.
2012, 40(10): 1593-1597
doi: 10.3724/SP.J.1096.2012.20115
Abstract:
Connecting the hydroxyl of acid red 73 (AR73) molecule with a "spacer arm" containing a carboxyl as hapten, and the hapten was conjugated to bovine serum albumin (BSA) or ovalbumin (OA) by using N-hydroxysuccinimide active ester method as immunogen and coating antigen respectively, the polyclonal antibody titer was 2.56×105 through immunization of New zealand white rabbits, then an indirect ELISA procedure for the determination of acid red 73 was established. The half of inhibition concentration (IC50) was 181.2 μg/L, the limit of detection for acid red 73 was 7.9 μg/L, and the cross-reactivity study showed that the polyclonal antiserum was highly specific to AR73, and no cross-reactivity was detected between the obtained polyclonal antiserum and the other competitors except to Sudan red Ⅲ (1.13%). The recoveries from the standards fortified blank samples were in the range of 63.5%-90.7% with RSD lower than 6.8%. The developed method can be used to determine the acid red 73 residue in shrimps, and can help to prepare the monoclonal antibody and develop the rapid test kits for acid red 73.
Connecting the hydroxyl of acid red 73 (AR73) molecule with a "spacer arm" containing a carboxyl as hapten, and the hapten was conjugated to bovine serum albumin (BSA) or ovalbumin (OA) by using N-hydroxysuccinimide active ester method as immunogen and coating antigen respectively, the polyclonal antibody titer was 2.56×105 through immunization of New zealand white rabbits, then an indirect ELISA procedure for the determination of acid red 73 was established. The half of inhibition concentration (IC50) was 181.2 μg/L, the limit of detection for acid red 73 was 7.9 μg/L, and the cross-reactivity study showed that the polyclonal antiserum was highly specific to AR73, and no cross-reactivity was detected between the obtained polyclonal antiserum and the other competitors except to Sudan red Ⅲ (1.13%). The recoveries from the standards fortified blank samples were in the range of 63.5%-90.7% with RSD lower than 6.8%. The developed method can be used to determine the acid red 73 residue in shrimps, and can help to prepare the monoclonal antibody and develop the rapid test kits for acid red 73.
2012, 40(10): 1598-1601
doi: 10.3724/SP.J.1096.2012.20143
Abstract:
A technique for separation of Mg, with 101.6%±1.2% yield from wine has been developed for high precision analysis of Mg isotopes by multiple-collector inductively coupled plasma mass spectrometry. One separate stage of ion-exchange chromatography was carried out using cation exchange resin, AG50W-X8 and elution with 1 mol/L HNO3. A mixture of H2 (2.1 mL/min) and He (7.0 mL/min) was performed to decrease isobars of 12C12C+, 12C21H+ during Mg isotope analysis by MC-ICP-MS technique along with SSB method. 40 wines were analyzed then. 26Mg/24Mg and 25Mg/24Mg show significant variation, this implies that Mg can be a good tracer to tracing geographical origin of wine with good geographical resolution. The samples with similar Mg isotopic compositions can be distinguished by the combined technique of Mg isotope analysis with inorganic elements analysis.
A technique for separation of Mg, with 101.6%±1.2% yield from wine has been developed for high precision analysis of Mg isotopes by multiple-collector inductively coupled plasma mass spectrometry. One separate stage of ion-exchange chromatography was carried out using cation exchange resin, AG50W-X8 and elution with 1 mol/L HNO3. A mixture of H2 (2.1 mL/min) and He (7.0 mL/min) was performed to decrease isobars of 12C12C+, 12C21H+ during Mg isotope analysis by MC-ICP-MS technique along with SSB method. 40 wines were analyzed then. 26Mg/24Mg and 25Mg/24Mg show significant variation, this implies that Mg can be a good tracer to tracing geographical origin of wine with good geographical resolution. The samples with similar Mg isotopic compositions can be distinguished by the combined technique of Mg isotope analysis with inorganic elements analysis.
2012, 40(10): 1602-1606
doi: 10.3724/SP.J.1096.2012.20111
Abstract:
A new method for the determination of detecting β-fructofruanosidase in honey was developed by liquid chromatography with refractive index detector (HPLC-RID). The method was based on the changes of product concentration of melibiose by the reaction of β-fructofruanosidase enzyme with raffinose in the medium of citric acid-sodium hydroxide solution (pH＝4.50) for 16 h in water bath at 50℃. Agilent Carbohydrate was chosen as the separation column, acetonitrile-water (78:22, V/V) was selected as mobile phase with flow rate of 1.4 mL/min. The column temperature and detector temperature was 35℃. The results showed that the numbers of peaks were simplified and the sensitivity of this proposed method was improved 1.3 fold as well by using polyacrylamide gel column for pre-separation. A good linear fit was received for the concentration of β-fructofruanosidase enzyme from 10 U/kg to 200 U/kg with the detection limit of 10 U/kg. Recovery was obtained between 81.3% and 112.4% with the relative standard deviation of 3.7% to 9.7% (n＝6). It is judged to be adulteration honey if β-fructofruanosidase concentration is more than 20 U/kg,
A new method for the determination of detecting β-fructofruanosidase in honey was developed by liquid chromatography with refractive index detector (HPLC-RID). The method was based on the changes of product concentration of melibiose by the reaction of β-fructofruanosidase enzyme with raffinose in the medium of citric acid-sodium hydroxide solution (pH＝4.50) for 16 h in water bath at 50℃. Agilent Carbohydrate was chosen as the separation column, acetonitrile-water (78:22, V/V) was selected as mobile phase with flow rate of 1.4 mL/min. The column temperature and detector temperature was 35℃. The results showed that the numbers of peaks were simplified and the sensitivity of this proposed method was improved 1.3 fold as well by using polyacrylamide gel column for pre-separation. A good linear fit was received for the concentration of β-fructofruanosidase enzyme from 10 U/kg to 200 U/kg with the detection limit of 10 U/kg. Recovery was obtained between 81.3% and 112.4% with the relative standard deviation of 3.7% to 9.7% (n＝6). It is judged to be adulteration honey if β-fructofruanosidase concentration is more than 20 U/kg,
2012, 40(10): 1607-1615
doi: 10.3724/SP.J.1096.2012.20380
Abstract:
Paramagnetic gadofullerenes and their derivatives exhibit much higher relaxivity than commercial MagnevistTM (Gd-DTPA), therefore have become competitive candidates for magnetic (MR) imaging probes. More prominently, the stable fullerene cages are believed to hinder both chemical attack on the inner clusters and the escape of the toxic lanthanide ions, which should effectively suppress the toxicity of naked Gd3+ ions. Some functionalized gadofullerides also available for further conjugation to fabricate multifunctional probes. This review presents the latest finding of magnetic resonance imaging (MRI) probes based on various gadofullerenes, including Gd@C60, Gd@C82 and Gd3N@C80. The derivative strategy dependent relaxivity properties and biodistributions as well as their potential application as nanoplatform for multifunctional probe are reviewed and discussed.
Paramagnetic gadofullerenes and their derivatives exhibit much higher relaxivity than commercial MagnevistTM (Gd-DTPA), therefore have become competitive candidates for magnetic (MR) imaging probes. More prominently, the stable fullerene cages are believed to hinder both chemical attack on the inner clusters and the escape of the toxic lanthanide ions, which should effectively suppress the toxicity of naked Gd3+ ions. Some functionalized gadofullerides also available for further conjugation to fabricate multifunctional probes. This review presents the latest finding of magnetic resonance imaging (MRI) probes based on various gadofullerenes, including Gd@C60, Gd@C82 and Gd3N@C80. The derivative strategy dependent relaxivity properties and biodistributions as well as their potential application as nanoplatform for multifunctional probe are reviewed and discussed.
2012, 40(10): 1616-1621
doi: 10.3724/SP.J.1096.2012.20403
Abstract:
Since gas analysis mass spectrometers usually use quadrupole as the mass analyzer, the resolution is typically less than 300, and the same mass ions interference problem cannot be solved. This study developed a high resolution gas analysis mass spectrometer. Electron impact ion source reflection time-of-flight mass analyzer has been designed and tested. The length of vacuum chamber is only 45 cm. Mass resolution of 3,000 (Full width at half maximum, FWHM) has been achieved at m/z 28, as a result, CO and N2 can be separated at the half peak height. The best resolution of instrument can reach 5000 (FWHM) at m/z 69. At the condition of direct ambient air sampling, 136Xe (7.8 μg/m3) and 80Kr (2.8 μg/m3) can be detected. The dynamic range is up to 106 with fast ADC acquiring system. This instrument can be used as a high-end gas mass spectrometer and applied to on-line gas analysis for process monitoring, environmental organic volatile compounds research, thermal analysis mass spectrometry and catalytic reaction monitoring.
Since gas analysis mass spectrometers usually use quadrupole as the mass analyzer, the resolution is typically less than 300, and the same mass ions interference problem cannot be solved. This study developed a high resolution gas analysis mass spectrometer. Electron impact ion source reflection time-of-flight mass analyzer has been designed and tested. The length of vacuum chamber is only 45 cm. Mass resolution of 3,000 (Full width at half maximum, FWHM) has been achieved at m/z 28, as a result, CO and N2 can be separated at the half peak height. The best resolution of instrument can reach 5000 (FWHM) at m/z 69. At the condition of direct ambient air sampling, 136Xe (7.8 μg/m3) and 80Kr (2.8 μg/m3) can be detected. The dynamic range is up to 106 with fast ADC acquiring system. This instrument can be used as a high-end gas mass spectrometer and applied to on-line gas analysis for process monitoring, environmental organic volatile compounds research, thermal analysis mass spectrometry and catalytic reaction monitoring.
2012, 40(10): 1622-1626
doi: 10.3724/SP.J.1096.2012.20373
Abstract:
A novel micro-flow evaporative light scattering detector (μELSD), suitable for capillary liquid chromatography (cLC) system, was constructed and eveluated. The main parameters of detector, such as the aperture of nebulizer, inner diameter of capillary, specification of the evaporative tube and scattering cell, were optimized. Under the optimal experimental conditions:nebulizer 410 μm I.D., nebulized capillary 50 μm I.D.×360 μm O.D., evaporative tube 15 cm×4.6 mm I.D., scattering cell 60 mm×33 mm I.D., the detection limitation of glucose (S/N＞10) was 1 ng with a linear range of 0.01-1 μg. Good reproducibility has been achieved in peak area and peak height with the RSD (n=6) of 0.4% and 0.3% (n=6), respectively. The detector was successfully coupled to a cLC system and applied to the separation and detection of three kinds of sweeteners, in the condition of capillary column ( C18, 250 μm I.D.) and 0.1% (V/V) ammonium formate (pH=4.5): methanol (60:40, V/V) as mobile phase. The cLC-μELSD system has the advantages in universal applicability, high column efficiency, and less solvent and sample consumptions compare with a common HPLC-ELSD system, and is suitable for separation and analysis of real samples.
A novel micro-flow evaporative light scattering detector (μELSD), suitable for capillary liquid chromatography (cLC) system, was constructed and eveluated. The main parameters of detector, such as the aperture of nebulizer, inner diameter of capillary, specification of the evaporative tube and scattering cell, were optimized. Under the optimal experimental conditions:nebulizer 410 μm I.D., nebulized capillary 50 μm I.D.×360 μm O.D., evaporative tube 15 cm×4.6 mm I.D., scattering cell 60 mm×33 mm I.D., the detection limitation of glucose (S/N＞10) was 1 ng with a linear range of 0.01-1 μg. Good reproducibility has been achieved in peak area and peak height with the RSD (n=6) of 0.4% and 0.3% (n=6), respectively. The detector was successfully coupled to a cLC system and applied to the separation and detection of three kinds of sweeteners, in the condition of capillary column ( C18, 250 μm I.D.) and 0.1% (V/V) ammonium formate (pH=4.5): methanol (60:40, V/V) as mobile phase. The cLC-μELSD system has the advantages in universal applicability, high column efficiency, and less solvent and sample consumptions compare with a common HPLC-ELSD system, and is suitable for separation and analysis of real samples.
2012, 40(10): 1627-1631
doi: 10.3724/SP.J.1096.2012.11361
Abstract:
A control system for an electrochemistry/electrospray ionization source (EC/ESI source) was designed and fabricated. The system includes two parts, a homemade embedded potentiostat floated on electrospray high voltage, and a remote computer, which communicates with the potentiostat through a Bluetooth wireless interface. The accuracy of potential is controlled in the range of ±1 mV, and the accuracies of the current measurements are ±0.1 μA (gain=0.01 V/μA) and ±0.01 μA (gain=0.1 V/μA). The performance of the control system was tested by cyclic voltammetry and online electrochemistry/electrospray ionization mass spectrometry (online EC/ESI-MS) using 9,10-diphenylanthrance as a model compound. Accurate potential control was achieved and most importantly, 9,10-diphenylanthrance, a non-polar compound usually undetectable by electrospray ionization mass spectrometry, was detected in high abundance.
A control system for an electrochemistry/electrospray ionization source (EC/ESI source) was designed and fabricated. The system includes two parts, a homemade embedded potentiostat floated on electrospray high voltage, and a remote computer, which communicates with the potentiostat through a Bluetooth wireless interface. The accuracy of potential is controlled in the range of ±1 mV, and the accuracies of the current measurements are ±0.1 μA (gain=0.01 V/μA) and ±0.01 μA (gain=0.1 V/μA). The performance of the control system was tested by cyclic voltammetry and online electrochemistry/electrospray ionization mass spectrometry (online EC/ESI-MS) using 9,10-diphenylanthrance as a model compound. Accurate potential control was achieved and most importantly, 9,10-diphenylanthrance, a non-polar compound usually undetectable by electrospray ionization mass spectrometry, was detected in high abundance.
