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2016 Volume 44 Issue 1
2016, 44(1): 1-7
doi: 10.11895/j.issn.0253-3820.150564
Abstract:
A novel ordered mesoporous carbon (OMC) coating supported on graphite fiber for solid phase microextraction (SPME) was prepared by combining evaporation-induced self-assembly process with dip-coating method for determination of chlorobenzenes in aqueous media. Scanning electron microscopy (SEM) studies showed that the obtained OMC film was defect free and well integrated with the substrate. The thickness of the film was about 7.0 μm. Transmission electron microscopy (TEM), X-ray diffraction (XRD), and nitrogen isothermal adsorption results indicated that the resultant OMC film possessed well-ordered two dimensional hexagonal mesostructure with pore volume of 0.28 cm3/g and BET surfaces of 369.7 m2/g. The SPME performance of the OMC coating was evaluated by analysis of four kinds of chlorobenzenes from water samples with gas chromatography-flame ionization detection (GC-FID). The analysis conditions, including extraction time and temperature, desorption time, stirring rate, ionic strength and headspace volume, were optimized. Moreover, the SPME performance home-made coating was compared with the commercial coatings. The analysis results indicated that the optimum extraction conditions were extraction time of 30 min, extraction temperature of 50℃, desorption time of 2 min, ionic strength of 0.35 g/mL, headspace volume of 15 mL. The prepared OMC fiber demonstrated wide linear ranges (1-1000 μg/L) and low detection limits (0.05-0.15 μg/L) under the optimal conditions. The relative standard deviations were 4.1%-6.4% for seven parallel samples. The peak areas of the OMC coating were 2 times more than those of polydimethylsiloxane/divinylbenzene (PDMS/DVB) coating and 18 times those of more than polyacrylate (PA) coating. The OMC coating was applied to analysis of two real water, and four chlorobenzenes were not detected. The recoveries of two samples spiked at 20 μg/L were in the range of 99.4%-114.5% and 92.3%-97.0%, respectively.
A novel ordered mesoporous carbon (OMC) coating supported on graphite fiber for solid phase microextraction (SPME) was prepared by combining evaporation-induced self-assembly process with dip-coating method for determination of chlorobenzenes in aqueous media. Scanning electron microscopy (SEM) studies showed that the obtained OMC film was defect free and well integrated with the substrate. The thickness of the film was about 7.0 μm. Transmission electron microscopy (TEM), X-ray diffraction (XRD), and nitrogen isothermal adsorption results indicated that the resultant OMC film possessed well-ordered two dimensional hexagonal mesostructure with pore volume of 0.28 cm3/g and BET surfaces of 369.7 m2/g. The SPME performance of the OMC coating was evaluated by analysis of four kinds of chlorobenzenes from water samples with gas chromatography-flame ionization detection (GC-FID). The analysis conditions, including extraction time and temperature, desorption time, stirring rate, ionic strength and headspace volume, were optimized. Moreover, the SPME performance home-made coating was compared with the commercial coatings. The analysis results indicated that the optimum extraction conditions were extraction time of 30 min, extraction temperature of 50℃, desorption time of 2 min, ionic strength of 0.35 g/mL, headspace volume of 15 mL. The prepared OMC fiber demonstrated wide linear ranges (1-1000 μg/L) and low detection limits (0.05-0.15 μg/L) under the optimal conditions. The relative standard deviations were 4.1%-6.4% for seven parallel samples. The peak areas of the OMC coating were 2 times more than those of polydimethylsiloxane/divinylbenzene (PDMS/DVB) coating and 18 times those of more than polyacrylate (PA) coating. The OMC coating was applied to analysis of two real water, and four chlorobenzenes were not detected. The recoveries of two samples spiked at 20 μg/L were in the range of 99.4%-114.5% and 92.3%-97.0%, respectively.
2016, 44(1): 8-12
doi: 10.11895/j.issn.0253-3820.150787
Abstract:
To evaluate the ability of microfabricated glow discharge plasma (MFGDP) as ion source used for mass spectrometry imaging, the different handwritings with urea added were analyzed, and the spatial distribution of stearic acid and the ramification of quercetin in a slice of winter jujube were explored. The MFGDP was independently researched and developed by our lab, and acted as ion source to absorb and ionize the sample. The mass spectra of the excited sample ions entered into mass spectrometer were converted into corresponding image by special software. The results showed that the MFGDP source was feasible and valuable for mass spectrometry imaging. The method proposed here has remarkable features such as simple device, easy operation, low temperature plasma and time saving (<20 min) and it could be used to locate the distribution of the different substances in a sample. The factors influenced the definition of image were discussed and the experimental conditions were optimized, and the resolution was about 300 μm under the optimum conditions. The technology can distinguish different handwritings according to the
To evaluate the ability of microfabricated glow discharge plasma (MFGDP) as ion source used for mass spectrometry imaging, the different handwritings with urea added were analyzed, and the spatial distribution of stearic acid and the ramification of quercetin in a slice of winter jujube were explored. The MFGDP was independently researched and developed by our lab, and acted as ion source to absorb and ionize the sample. The mass spectra of the excited sample ions entered into mass spectrometer were converted into corresponding image by special software. The results showed that the MFGDP source was feasible and valuable for mass spectrometry imaging. The method proposed here has remarkable features such as simple device, easy operation, low temperature plasma and time saving (<20 min) and it could be used to locate the distribution of the different substances in a sample. The factors influenced the definition of image were discussed and the experimental conditions were optimized, and the resolution was about 300 μm under the optimum conditions. The technology can distinguish different handwritings according to the
2016, 44(1): 13-18
doi: 10.11895/j.issn.0253-3820.150480
Abstract:
A biosensor for detection of T4 polynucleotide kinase (PNK) activity was fabricated by using a split-to-intact DNAzyme conversion strategy. G-quadrplex-forming G-rich sequence PS5.M was chosen as a model DNAzyme and splitted into two short parts of S1OH and S2OH, which both had hydroxyl groups at 3' and 5'terminals, and could hybridize to another sequence, helper DNA (SH), to form a duplex structure. In the presence of T4 PNK, 5'-end of S2OH was phophorylated to obtain S2P. Then S1OH and S2P could be linked by T4 DNA ligase to intact PS5.M. In the presence of exonuclease Ⅲ (Exo Ⅲ), SH chain in the duplex of PS5.M-SH could be cleaved into nucleotides, releasing free PS5.M. The released PS5.M could form catalytically active G-quadruplex DNAzyme upon binding hemin in the presence of K+, which could catalyze the oxidation of 2,2'-azino bis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) by H2O2. Quantitative detection of T4 PNK activity could be achieved by measuring the maximal absorbance of product at 418 nm. The absorbance of the sensing system at 418 nm exhibited a linear relationship with T4 PNK activity in the range of 0.02-0.3 U/mL with a detection limit of 0.014 U/mL (S/N=3). The biosensor was also applied to the determination of PNK activity in Hela cell and HEK 293 cell, and good recoveries of 95.6%-105.7% were obtained at three spiked levels.
A biosensor for detection of T4 polynucleotide kinase (PNK) activity was fabricated by using a split-to-intact DNAzyme conversion strategy. G-quadrplex-forming G-rich sequence PS5.M was chosen as a model DNAzyme and splitted into two short parts of S1OH and S2OH, which both had hydroxyl groups at 3' and 5'terminals, and could hybridize to another sequence, helper DNA (SH), to form a duplex structure. In the presence of T4 PNK, 5'-end of S2OH was phophorylated to obtain S2P. Then S1OH and S2P could be linked by T4 DNA ligase to intact PS5.M. In the presence of exonuclease Ⅲ (Exo Ⅲ), SH chain in the duplex of PS5.M-SH could be cleaved into nucleotides, releasing free PS5.M. The released PS5.M could form catalytically active G-quadruplex DNAzyme upon binding hemin in the presence of K+, which could catalyze the oxidation of 2,2'-azino bis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) by H2O2. Quantitative detection of T4 PNK activity could be achieved by measuring the maximal absorbance of product at 418 nm. The absorbance of the sensing system at 418 nm exhibited a linear relationship with T4 PNK activity in the range of 0.02-0.3 U/mL with a detection limit of 0.014 U/mL (S/N=3). The biosensor was also applied to the determination of PNK activity in Hela cell and HEK 293 cell, and good recoveries of 95.6%-105.7% were obtained at three spiked levels.
2016, 44(1): 19-24
doi: 10.11895/j.issn.0253-3820.150404
Abstract:
A method using high performance liquid chromatography (HPLC) coupled with tandem mass spectrometry for quantitative determination of bisphenol A (BPA), tetrabromobisphenol A (TBBPA) and 4-tert-octylphenol (OP) in urine samples of children and adults was developed. The frozen urinary samples were unfrozen at room temperature, extracted by liquid-liquid extraction, evaporated to dryness, and dissolved by methanol so as to be analyzed by LC-MS/MS. The calibration curves for the determination of the three target compounds were linear in the concentration range of 0.2-50 μg/L, correlation coefficients (R) were greater than 0.99, and the quantitative limits (LOQ) were 0.05-0.27 μg/L. The recoveries of different concentration levels (5, 10 and 50 μg/L) were in the range of 85.7%-118.6% and the relative standard deviation (RSD) was 4.1%-10.5%. This method was successfully applied to the determination of BPA, TBBPA and OP in urine samples from 20 groups of children and adults. The results showed that exposure concentrations of TBBPA and OP in urine samples of children and adults were basically same, but exposure levels of BPA had significant difference (children >adults (Father or Mother)).
A method using high performance liquid chromatography (HPLC) coupled with tandem mass spectrometry for quantitative determination of bisphenol A (BPA), tetrabromobisphenol A (TBBPA) and 4-tert-octylphenol (OP) in urine samples of children and adults was developed. The frozen urinary samples were unfrozen at room temperature, extracted by liquid-liquid extraction, evaporated to dryness, and dissolved by methanol so as to be analyzed by LC-MS/MS. The calibration curves for the determination of the three target compounds were linear in the concentration range of 0.2-50 μg/L, correlation coefficients (R) were greater than 0.99, and the quantitative limits (LOQ) were 0.05-0.27 μg/L. The recoveries of different concentration levels (5, 10 and 50 μg/L) were in the range of 85.7%-118.6% and the relative standard deviation (RSD) was 4.1%-10.5%. This method was successfully applied to the determination of BPA, TBBPA and OP in urine samples from 20 groups of children and adults. The results showed that exposure concentrations of TBBPA and OP in urine samples of children and adults were basically same, but exposure levels of BPA had significant difference (children >adults (Father or Mother)).
2016, 44(1): 25-31
doi: 10.11895/j.issn.0253-3820.150188
Abstract:
Liquid-assisted surface desorption atmospheric pressure chemical ionization source (LA-DAPCI) technique shows good potential in complex matrix mass spectrometry imaging. Due to primary ions and high density charged droplets of solvent generated by corona discharge, analytes on sample surface are extracted and ionized efficiently. However, direct application of the DAPCI ionization for mass spectrometry imaging of complex matrix analytes usually tends to be challenging because of low spatial resolution. To resolve this problem, several ion source parameters and experiment conditions were optimized in the present work, including ion source configuration, chemical composition of the extraction solvent, geometry parameters, solvent flow rate and pressure of nebulizing gas. The results presented here confirmed that the spatial resolution of LA-DAPCI was improved (from (441±14) μm to (58±7) μm). The proposed LA-DAPCI-MS/MS method was then successfully used to profile the distribution of Rhodamine 6G with a limit of detection of 0.01 ng/cm2.
Liquid-assisted surface desorption atmospheric pressure chemical ionization source (LA-DAPCI) technique shows good potential in complex matrix mass spectrometry imaging. Due to primary ions and high density charged droplets of solvent generated by corona discharge, analytes on sample surface are extracted and ionized efficiently. However, direct application of the DAPCI ionization for mass spectrometry imaging of complex matrix analytes usually tends to be challenging because of low spatial resolution. To resolve this problem, several ion source parameters and experiment conditions were optimized in the present work, including ion source configuration, chemical composition of the extraction solvent, geometry parameters, solvent flow rate and pressure of nebulizing gas. The results presented here confirmed that the spatial resolution of LA-DAPCI was improved (from (441±14) μm to (58±7) μm). The proposed LA-DAPCI-MS/MS method was then successfully used to profile the distribution of Rhodamine 6G with a limit of detection of 0.01 ng/cm2.
2016, 44(1): 32-40
doi: 10.11895/j.issn.0253-3820.150309
Abstract:
The metabolism of pyrimethamine (PYR) after a single oral administration at a dose of 5 mg/kg in rats was investigated. In vivo samples including rat plasma, urine and feces were collected respectively at different times. We performed liquid chromatography tandem two-dimensional linear ion trapped orbitrap mass spectrometry spectrometer (LC-LTQ-Orbitrap MS) to identify the unknown metabolites of PYR. Then 10 metabolites of PYR were found in rats with this approach, which indicates that hydroxylation on benzene ring, N-oxidation, dioxidation, N-glucuronidation, methylation+glucuronidation, hydroxylation+glucuronidation and N-oxidation+glucuronidation were the major metabolic pathways of PYR in rats. 9 of these metabolites were identified in vivo for the first time while the PYR 3-N-oxide was ever detected in vitro metabolism of PYR in isolated rat liver. We identified the structure of the metabolites according to their accurate mass data and the characteristic MSn product ions. Based on the above analyses, we proposed the phase I and II metabolic pathways for PYR in rat. The major phase I metabolites were formed via hydroxylation and N-oxidation pathways, and the major phase II metabolites were methylation and glucuronidation.
The metabolism of pyrimethamine (PYR) after a single oral administration at a dose of 5 mg/kg in rats was investigated. In vivo samples including rat plasma, urine and feces were collected respectively at different times. We performed liquid chromatography tandem two-dimensional linear ion trapped orbitrap mass spectrometry spectrometer (LC-LTQ-Orbitrap MS) to identify the unknown metabolites of PYR. Then 10 metabolites of PYR were found in rats with this approach, which indicates that hydroxylation on benzene ring, N-oxidation, dioxidation, N-glucuronidation, methylation+glucuronidation, hydroxylation+glucuronidation and N-oxidation+glucuronidation were the major metabolic pathways of PYR in rats. 9 of these metabolites were identified in vivo for the first time while the PYR 3-N-oxide was ever detected in vitro metabolism of PYR in isolated rat liver. We identified the structure of the metabolites according to their accurate mass data and the characteristic MSn product ions. Based on the above analyses, we proposed the phase I and II metabolic pathways for PYR in rat. The major phase I metabolites were formed via hydroxylation and N-oxidation pathways, and the major phase II metabolites were methylation and glucuronidation.
2016, 44(1): 41-48
doi: 10.11895/j.issn.0253-3820.150568
Abstract:
Graphene quantum dots/Ag nanoparticles nanocomposite (GQDs/AgNPs) was prepared via in-situ growth of AgNPs on the surface of GQDs, in which GQDs served as both reducing agent and stabilizer. The as-prepared nanocomposites were mono-dispersed with an average diameter of less than 30 nm. The obtained GQDs@AgNPs nanocomposites exhibited excellent intrinsic peroxidese-like activity, which could catalyze the oxidization of 3,3',5,5'-tetramethylbenzidine (TMB) by H2O2 to produce a colour product. Steady-state kinetic assays showed that the catalytic activity of GQDs/AgNPs towards H2O2 fitted well with typical Michaelis-Menten kinetic model, followed by the ping-pong mechanism. Compared with the horseradish peroxidase (HRP), GQDs/AgNPs showed higher affinity towards TMB and H2O2 substrate. Based on the intrinsic peroxidese-like activity of GQDs/AgNPs nanocomposites and the production of H2O2 after the oxidation of glucose, a colorimetric method was developed for the detection of H2O2 and glucose, along with detection limit of 0.18 μmol/L and 1.6 μmol/L, respectively. The present method was applied to the detection of glucose in human serum, and the obtained results agreed with that obtained by reference method.
Graphene quantum dots/Ag nanoparticles nanocomposite (GQDs/AgNPs) was prepared via in-situ growth of AgNPs on the surface of GQDs, in which GQDs served as both reducing agent and stabilizer. The as-prepared nanocomposites were mono-dispersed with an average diameter of less than 30 nm. The obtained GQDs@AgNPs nanocomposites exhibited excellent intrinsic peroxidese-like activity, which could catalyze the oxidization of 3,3',5,5'-tetramethylbenzidine (TMB) by H2O2 to produce a colour product. Steady-state kinetic assays showed that the catalytic activity of GQDs/AgNPs towards H2O2 fitted well with typical Michaelis-Menten kinetic model, followed by the ping-pong mechanism. Compared with the horseradish peroxidase (HRP), GQDs/AgNPs showed higher affinity towards TMB and H2O2 substrate. Based on the intrinsic peroxidese-like activity of GQDs/AgNPs nanocomposites and the production of H2O2 after the oxidation of glucose, a colorimetric method was developed for the detection of H2O2 and glucose, along with detection limit of 0.18 μmol/L and 1.6 μmol/L, respectively. The present method was applied to the detection of glucose in human serum, and the obtained results agreed with that obtained by reference method.
2016, 44(1): 49-53
doi: 10.11895/j.issn.0253-3820.150393
Abstract:
A method was established for the determination of triptolide in rat synoviocytes by microemulsion electrokinetic chromatography (MEEKC). Synoviocytes were divided into control groups and treatment groups by the different administration time of triptolide, and the concentrations of triptolide in intercellular and extracellular fluid were determined. The determination of triptolide by MEEKC was performed at 25℃ under the conditions including running buffer of 5 mmol/L borate-10 mmol/L phosphate (96%, V/V, pH 9.0) with 1% SDS (w/V), 3% 1-butanol (V/V) and 1% ethyl acetate (V/V), 25 kV of running voltage, 3.45 kPa×6 s of inject pressure and 214 nm of test wavelength. The results showed that triptolide was baseline separation, and there was a good linearity for triptolide in intercellular and extracellular of synoviocytes and the correlation coefficients were 0.9995 and 0.9991, respectively. The concentrations of triptolide in intercellular and extracellular of synoviocytes were 0.736 μg/mL and 20.745 μg/mL, respectively. The present method is simple, accurate, sensitive and precise, and can be used to study dynamic change of the triptolide concentration in rat synoviocytes and provide methodology basis for further study the influence of effective compounds of TCM on synoviocytes' function and activity.
A method was established for the determination of triptolide in rat synoviocytes by microemulsion electrokinetic chromatography (MEEKC). Synoviocytes were divided into control groups and treatment groups by the different administration time of triptolide, and the concentrations of triptolide in intercellular and extracellular fluid were determined. The determination of triptolide by MEEKC was performed at 25℃ under the conditions including running buffer of 5 mmol/L borate-10 mmol/L phosphate (96%, V/V, pH 9.0) with 1% SDS (w/V), 3% 1-butanol (V/V) and 1% ethyl acetate (V/V), 25 kV of running voltage, 3.45 kPa×6 s of inject pressure and 214 nm of test wavelength. The results showed that triptolide was baseline separation, and there was a good linearity for triptolide in intercellular and extracellular of synoviocytes and the correlation coefficients were 0.9995 and 0.9991, respectively. The concentrations of triptolide in intercellular and extracellular of synoviocytes were 0.736 μg/mL and 20.745 μg/mL, respectively. The present method is simple, accurate, sensitive and precise, and can be used to study dynamic change of the triptolide concentration in rat synoviocytes and provide methodology basis for further study the influence of effective compounds of TCM on synoviocytes' function and activity.
2016, 44(1): 54-60
doi: 10.11895/j.issn.0253-3820.150657
Abstract:
Aflatoxin B1 (AFB1) is the most powerful cancer-causing mycotoxins, which is serious harmful to human and animal health. Human serum albumin has important physiological functions in the binding or transporting endogenous and exogenous ligands aspects. It's great significance in molecular toxicology of researching AFB1 and human serum albumin interaction mechanism. The interaction between AFB1 and human serum albumin (HSA) was investigated by fluorescence spectroscopy, circular dichroism and 3D fluorescence spectroscopy under the simulative physiological conditions (pH=7.4, Ionic strength 0.1 mol/L). Results showed that the main quenching mechanism between AFB1 and HSA was a static quenching process. At four different temperatures (298, 303, 308 and 313 K), all the magnitude binding constants (K) were 104 and the number of binding sites (n) in the binary system was approximate to 1. According to Van't Hoff equation, the negative enthalpy change (ΔHθ) and postive entropy change (ΔSθ) values indicated that hydrophobic interaction and hydrogen bonding were the mainly interaction and force in the binding process. The binding distance (r) between the AFB1 and HSA was calculated to be 3.31 nm based on the theory of F rster's non-radiation energy transfer. The site marker displacement experiments suggested the location of AFB1 binding to HSA was site I, closely Trp-214. The 3D florescence revealed that the microenvironment of amino acid residues and the conformation of HSA were changed during the binding reaction. CD spectra revealed that the conformations of HSA were changed during the binding reaction with increasing in α-helix.
Aflatoxin B1 (AFB1) is the most powerful cancer-causing mycotoxins, which is serious harmful to human and animal health. Human serum albumin has important physiological functions in the binding or transporting endogenous and exogenous ligands aspects. It's great significance in molecular toxicology of researching AFB1 and human serum albumin interaction mechanism. The interaction between AFB1 and human serum albumin (HSA) was investigated by fluorescence spectroscopy, circular dichroism and 3D fluorescence spectroscopy under the simulative physiological conditions (pH=7.4, Ionic strength 0.1 mol/L). Results showed that the main quenching mechanism between AFB1 and HSA was a static quenching process. At four different temperatures (298, 303, 308 and 313 K), all the magnitude binding constants (K) were 104 and the number of binding sites (n) in the binary system was approximate to 1. According to Van't Hoff equation, the negative enthalpy change (ΔHθ) and postive entropy change (ΔSθ) values indicated that hydrophobic interaction and hydrogen bonding were the mainly interaction and force in the binding process. The binding distance (r) between the AFB1 and HSA was calculated to be 3.31 nm based on the theory of F rster's non-radiation energy transfer. The site marker displacement experiments suggested the location of AFB1 binding to HSA was site I, closely Trp-214. The 3D florescence revealed that the microenvironment of amino acid residues and the conformation of HSA were changed during the binding reaction. CD spectra revealed that the conformations of HSA were changed during the binding reaction with increasing in α-helix.
2016, 44(1): 61-67
doi: 10.11895/j.issn.0253-3820.150450
Abstract:
The experiment of photocatalytic degradation on fluorescent substance core/shell CdSe/ZnS quantum dots by Nano-TiO2 (P25) under visible light-induced was investigated. The degradation rate was analyzed and evaluated by determining the absorbance of degradation substance to determine the degree of degradation and efficiency. The results of photocatalytic experiment showed a good linear relationship between fluorescence quenching degree (F/F0) and reaction time (t) on fluorescent substance of CdSe/ZnS quantum dot, according to the photocatalytic degradation kinetics equation of CdSe/ZnS quantum dots. The consistency of experimental results was also confirmed with fluorescence spectroscopy and conventional spectrophotometry. Based on this, a new sensitive method was established for efficient determination of photocatalytic degradation fluorescent substance. The present method was helpful to analyze the photocatalytic degradation mechanism of fluorescent substance and provided a theoretical basis and reference to study the photocatalytic degradation on other fluorescent substances.
The experiment of photocatalytic degradation on fluorescent substance core/shell CdSe/ZnS quantum dots by Nano-TiO2 (P25) under visible light-induced was investigated. The degradation rate was analyzed and evaluated by determining the absorbance of degradation substance to determine the degree of degradation and efficiency. The results of photocatalytic experiment showed a good linear relationship between fluorescence quenching degree (F/F0) and reaction time (t) on fluorescent substance of CdSe/ZnS quantum dot, according to the photocatalytic degradation kinetics equation of CdSe/ZnS quantum dots. The consistency of experimental results was also confirmed with fluorescence spectroscopy and conventional spectrophotometry. Based on this, a new sensitive method was established for efficient determination of photocatalytic degradation fluorescent substance. The present method was helpful to analyze the photocatalytic degradation mechanism of fluorescent substance and provided a theoretical basis and reference to study the photocatalytic degradation on other fluorescent substances.
2016, 44(1): 68-73
doi: 10.11895/j.issn.0253-3820.150501
Abstract:
The chrome concentration in soil was quantitatively analyzed by laser induced breakdown spectroscopy (LIBS). Due to the complexity of soil components, there is serious overlap interference spectral line, which leads to the unsatisfactory results for the monadic regression analysis. To obtain the more effective spectrum information, by using the spectral intensity of Cr Ⅰ 425.43 nm and Fe Ⅰ 425.07 nm as independent variables and Cr concentration as dependent variable, the methods of cross dimension reduction approximate multivariate nonlinear regression, multiple quadratic non-linear regression and square dimension reduction approximate multivariate nonlinear regression were established. The results showed that when the cross term for characteristic spectral intensity of Cr Ⅰ 425.43 nm and Fe Ⅰ 425.07 nm was used, the multiple quadratic nonlinear regression model was better than others. The correlation coefficients between predicted concentration and reference concentration reached 0.9943, and the relative error of four predicted sample was 3.57%, 0.76%, 7.66% and 2.24% respectively.
The chrome concentration in soil was quantitatively analyzed by laser induced breakdown spectroscopy (LIBS). Due to the complexity of soil components, there is serious overlap interference spectral line, which leads to the unsatisfactory results for the monadic regression analysis. To obtain the more effective spectrum information, by using the spectral intensity of Cr Ⅰ 425.43 nm and Fe Ⅰ 425.07 nm as independent variables and Cr concentration as dependent variable, the methods of cross dimension reduction approximate multivariate nonlinear regression, multiple quadratic non-linear regression and square dimension reduction approximate multivariate nonlinear regression were established. The results showed that when the cross term for characteristic spectral intensity of Cr Ⅰ 425.43 nm and Fe Ⅰ 425.07 nm was used, the multiple quadratic nonlinear regression model was better than others. The correlation coefficients between predicted concentration and reference concentration reached 0.9943, and the relative error of four predicted sample was 3.57%, 0.76%, 7.66% and 2.24% respectively.
2016, 44(1): 74-80
doi: 10.11895/j.issn.0253-3820.150561
Abstract:
A method was developed to determine cortisone, cortisol, prednisone and dexamethasone in muscle tissues by high performance liquid chromatography-tandem mass spectrometry (LC-ESI-MS/MS). Deconjugation of glucocorticoids was carried out by enzymatic hydrolysis. These preliminary steps were followed by ethyl acetate extraction and HLB solid phase extraction clean up step for all matrices. Chromatographic separation was achieved on C8 column and MS/MS data were obtained in the multiple reaction monitoring mode using negative electrospray ionization. Calibration graphs were prepared in the 0.5-50.0 μg/L range and good linearity was achieved (R2 ≥ 0.99).The limits of detection (LOQ) and the limits of quantification (LOD) were 0.13-0.25 μg/kg and 0.25-0.50 μg/kg, respectively. Spiking at the levels of 0.5, 5.0 and 10.0 μg/L, the average recovery for glucocorticoids ranged from 74.0% to 101.8%. The relative standard deviations (RSD) were between 0.7%-8.6%.
A method was developed to determine cortisone, cortisol, prednisone and dexamethasone in muscle tissues by high performance liquid chromatography-tandem mass spectrometry (LC-ESI-MS/MS). Deconjugation of glucocorticoids was carried out by enzymatic hydrolysis. These preliminary steps were followed by ethyl acetate extraction and HLB solid phase extraction clean up step for all matrices. Chromatographic separation was achieved on C8 column and MS/MS data were obtained in the multiple reaction monitoring mode using negative electrospray ionization. Calibration graphs were prepared in the 0.5-50.0 μg/L range and good linearity was achieved (R2 ≥ 0.99).The limits of detection (LOQ) and the limits of quantification (LOD) were 0.13-0.25 μg/kg and 0.25-0.50 μg/kg, respectively. Spiking at the levels of 0.5, 5.0 and 10.0 μg/L, the average recovery for glucocorticoids ranged from 74.0% to 101.8%. The relative standard deviations (RSD) were between 0.7%-8.6%.
2016, 44(1): 81-87
doi: 10.11895/j.issn.0253-3820.150497
Abstract:
A method for simultaneous determination of metabolites of benzene compounds and trichloroethylene in pregnant urine by isotope dilution-ultra performance liquid chromatography-tandem mass spectrometry was established. Urine samples were diluted 10 times with ammonium acetate buffer containing working mixed internal standard and the filtrate was injected into UPLC/MS/MS for analysis. UPLC-MS/MS was performed on Waters C18 column and the gradient elution was used for separation. The negative electrospray ionization (ESI) source under the multiple reaction monitoring (MRM) mode was used for quantitative analysis. The limits of detection (LOD) ranged from 0.0350 μg/L to 1.75 μg/L. The inter-day and intra-day precisions of method were 1.2%-9.1% and 2.0%-9.7%, respectively. The proposed method was applied on detecting 650 urine samples of pregnant women in different region and the results were analyzed by statistical method. The spiked recoveries were in the range of 85.0%-104%. The method was quick, sensitive and suitable for batch analysis of urine samples.
A method for simultaneous determination of metabolites of benzene compounds and trichloroethylene in pregnant urine by isotope dilution-ultra performance liquid chromatography-tandem mass spectrometry was established. Urine samples were diluted 10 times with ammonium acetate buffer containing working mixed internal standard and the filtrate was injected into UPLC/MS/MS for analysis. UPLC-MS/MS was performed on Waters C18 column and the gradient elution was used for separation. The negative electrospray ionization (ESI) source under the multiple reaction monitoring (MRM) mode was used for quantitative analysis. The limits of detection (LOD) ranged from 0.0350 μg/L to 1.75 μg/L. The inter-day and intra-day precisions of method were 1.2%-9.1% and 2.0%-9.7%, respectively. The proposed method was applied on detecting 650 urine samples of pregnant women in different region and the results were analyzed by statistical method. The spiked recoveries were in the range of 85.0%-104%. The method was quick, sensitive and suitable for batch analysis of urine samples.
2016, 44(1): 88-94
doi: 10.11895/j.issn.0253-3820.150544
Abstract:
A simple, rapid, efficient, sensitive and low matrix interference method for the determination of 7 specified polychlorinated biphenyls (PCBs) in soil or sediment samples using gas chromatography-electron capture detection (GC-ECD) combined with ultrasonic extraction and dispersive solid phase extraction (DSPE) cleanup was described. The step of concentrated sulfuric acid purification could be chosen flexibly according to the color of the extract, and the kinds and amounts of adsorbent were optimized. If the extract was basically colorless transparent, only 150 mg of primary secondary amine (PSA) was used for DSPE cleanup (one-step purification process), otherwise it needed a purification for the extract by concentrated sulfuric acid and 100 mg of PSA for the DSPE cleanup (two-step purification process). The whole DSPE cleanup process only needed less than 5 min, which significantly shortened the sample pretreatment time. The linearity of the method ranged from 1.25 μg/L to 100 μg/L for 7 PCBs, with correlation coefficients ranging from 0.9990 to 0.9999. The detection limits for 7 PCBs were 0.02-0.03 μg/kg. The recoveries of spiked PCBs at different concentration levels in samples with two-step purification process (concentrated sulfuric acid purification and DSPE cleanup) and one-step purification process (only DSPE cleanup) were 72%-107%, and 88%-115%, respectively, with relative standard deviations (RSDs) of 3.5%-5.8%, and 3.7%-6.9% (n=5), respectively. The performance of the proposed method was compared with national standard methods on the real water samples (i.e., soil samples in certain vegetable patch of Zhujiajian, Zhoushan, sediment samples in waters of Daiquyang, Zhoushan, etc.) and comparable efficiencies were obtained. It was concluded that this method could be successfully applied for the determination of PCBs in soil or sediment with good accuracy and precision.
A simple, rapid, efficient, sensitive and low matrix interference method for the determination of 7 specified polychlorinated biphenyls (PCBs) in soil or sediment samples using gas chromatography-electron capture detection (GC-ECD) combined with ultrasonic extraction and dispersive solid phase extraction (DSPE) cleanup was described. The step of concentrated sulfuric acid purification could be chosen flexibly according to the color of the extract, and the kinds and amounts of adsorbent were optimized. If the extract was basically colorless transparent, only 150 mg of primary secondary amine (PSA) was used for DSPE cleanup (one-step purification process), otherwise it needed a purification for the extract by concentrated sulfuric acid and 100 mg of PSA for the DSPE cleanup (two-step purification process). The whole DSPE cleanup process only needed less than 5 min, which significantly shortened the sample pretreatment time. The linearity of the method ranged from 1.25 μg/L to 100 μg/L for 7 PCBs, with correlation coefficients ranging from 0.9990 to 0.9999. The detection limits for 7 PCBs were 0.02-0.03 μg/kg. The recoveries of spiked PCBs at different concentration levels in samples with two-step purification process (concentrated sulfuric acid purification and DSPE cleanup) and one-step purification process (only DSPE cleanup) were 72%-107%, and 88%-115%, respectively, with relative standard deviations (RSDs) of 3.5%-5.8%, and 3.7%-6.9% (n=5), respectively. The performance of the proposed method was compared with national standard methods on the real water samples (i.e., soil samples in certain vegetable patch of Zhujiajian, Zhoushan, sediment samples in waters of Daiquyang, Zhoushan, etc.) and comparable efficiencies were obtained. It was concluded that this method could be successfully applied for the determination of PCBs in soil or sediment with good accuracy and precision.
2016, 44(1): 95-102
doi: 10.11895/j.issn.0253-3820.150611
Abstract:
This work fabricates four novel chiral stationary phases (CSPs) by tuning the functionality on cyclodextrin (CD) small mouth via click chemistry. Mono-6-deoxy-azido CD was anchored onto silica surface via ether linkage, followed by introducing tert-butyl, phenyl, ester and hydroxyl groups to the azido CD silica respectively. The as-prepared four novel CD CSPs were characterized by FTIR and elemental analysis. 16 enantiomer pairs including isoxazolines and dansyl amino acids could be baseline or partially separated on the current CD CSPs under reversed-phase separation mode. Ester functionalized CD CSP exhibited good chiral recognition towards isoxazolines and the resolution of 2-chlorphenyl-isoxazole(2ClPh-OPr)reached 1.62. The optimum pH for the separation of dansyl amino acids was 5.0. Among the prepared CSPs, Tert-butyl functionalized CD CSP had the best enantioseparation performance towards dansyl amino acids with most of the analytes baseline separated (Rs>1.5).
This work fabricates four novel chiral stationary phases (CSPs) by tuning the functionality on cyclodextrin (CD) small mouth via click chemistry. Mono-6-deoxy-azido CD was anchored onto silica surface via ether linkage, followed by introducing tert-butyl, phenyl, ester and hydroxyl groups to the azido CD silica respectively. The as-prepared four novel CD CSPs were characterized by FTIR and elemental analysis. 16 enantiomer pairs including isoxazolines and dansyl amino acids could be baseline or partially separated on the current CD CSPs under reversed-phase separation mode. Ester functionalized CD CSP exhibited good chiral recognition towards isoxazolines and the resolution of 2-chlorphenyl-isoxazole(2ClPh-OPr)reached 1.62. The optimum pH for the separation of dansyl amino acids was 5.0. Among the prepared CSPs, Tert-butyl functionalized CD CSP had the best enantioseparation performance towards dansyl amino acids with most of the analytes baseline separated (Rs>1.5).
2016, 44(1): 103-109
doi: 10.11895/j.issn.0253-3820.150180
Abstract:
A molecularly imprinted electrochemical sensor was prepared by electropolymerization using semicarbazide (SEM) as template molecule and o-phenylenediamine as functional monomer in 0.1 mol/L NaAc-HAc buffer solution (pH 5.2). The performance and surface feature of the proposed imprinted sensor was investigated using cyclic voltammetry (CV), differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS) and scanning electron microscope. The sensor had a rough and porous surface morphology, and showed good recognition and selectivity to SEM. The sensor performance was optimized by using DPV method in 0.5 mol/L KCl solution with 5 mmol/L K3[Fe(CN)6] as the electron transport medium. The optimized conditions were that the molar ratio of functional monomer to template molecule was 1:2, the elution liquid was 0.2 mol/L NaOH, and elution and incubation time was 15 and 12 min, respectively. The DPV peak current difference of the sensor had a linear relationship with the concentration of SEM in the range of 3.75-188 ng/L and the detection limit was 1.5 ng/L (S/N=3). The prepared imprinted sensor was used to detect SEM in commercially available fresh shrimp muscles as well as shrimp contaminated with drugs with satisfactory results, and the recoveries of SEM were in the range of 80%-97%.
A molecularly imprinted electrochemical sensor was prepared by electropolymerization using semicarbazide (SEM) as template molecule and o-phenylenediamine as functional monomer in 0.1 mol/L NaAc-HAc buffer solution (pH 5.2). The performance and surface feature of the proposed imprinted sensor was investigated using cyclic voltammetry (CV), differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS) and scanning electron microscope. The sensor had a rough and porous surface morphology, and showed good recognition and selectivity to SEM. The sensor performance was optimized by using DPV method in 0.5 mol/L KCl solution with 5 mmol/L K3[Fe(CN)6] as the electron transport medium. The optimized conditions were that the molar ratio of functional monomer to template molecule was 1:2, the elution liquid was 0.2 mol/L NaOH, and elution and incubation time was 15 and 12 min, respectively. The DPV peak current difference of the sensor had a linear relationship with the concentration of SEM in the range of 3.75-188 ng/L and the detection limit was 1.5 ng/L (S/N=3). The prepared imprinted sensor was used to detect SEM in commercially available fresh shrimp muscles as well as shrimp contaminated with drugs with satisfactory results, and the recoveries of SEM were in the range of 80%-97%.
2016, 44(1): 110-116
doi: 10.11895/j.issn.0253-3820.150316
Abstract:
A highly sensitive impedance aptamer biosensor was fabricated on the glassy carbon electrode surface by one-step electrochemical deposition synthesis of cobalt aluminium layered double hydroxides-gold nanoparticles (CoAl LDH-GNPs) composite nanomaterials, which were used as the immobilization matrix for aptamer. The composite nanomaterials of CoAl LDH-GNPs were characterized with scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The electrode assembly process was monitored by the cyclic voltammetry and electrochemical impedance spectroscopy, the performance of sensor was studied by electrochemical impedance spectroscopy. The sensor fabricated by LDH-GNPs nanomaterials showed a linear relationship to thrombin from 1.0 ng/L to 100.0 μg/L with a linear correlation coefficient R=0.995 and a detection limit of 0.3 ng/L(S/N=3).
A highly sensitive impedance aptamer biosensor was fabricated on the glassy carbon electrode surface by one-step electrochemical deposition synthesis of cobalt aluminium layered double hydroxides-gold nanoparticles (CoAl LDH-GNPs) composite nanomaterials, which were used as the immobilization matrix for aptamer. The composite nanomaterials of CoAl LDH-GNPs were characterized with scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The electrode assembly process was monitored by the cyclic voltammetry and electrochemical impedance spectroscopy, the performance of sensor was studied by electrochemical impedance spectroscopy. The sensor fabricated by LDH-GNPs nanomaterials showed a linear relationship to thrombin from 1.0 ng/L to 100.0 μg/L with a linear correlation coefficient R=0.995 and a detection limit of 0.3 ng/L(S/N=3).
2016, 44(1): 117-123
doi: 10.11895/j.issn.0253-3820.150411
Abstract:
A comparative study of the performance of ultrasound-assisted (UA), and temperature-controlled (TC) ionic liquid (IL) dispersive liquid-liquid microextraction (IL-DLLME) was presented. Various parameters that affected extraction efficiency were evaluated. UA-IL-DLLME was found to provide the better extraction efficiency. After adjustment of pH, the water sample was mixed with[C8MIM] [PF6] and acetonitrile, then was extracted under ultrasound-assisted/temperature-controlled conditions. The mixture was then centrifuged, separated, and analyzed by UPLC-MS/MS. Under the optimal conditions, the calibration curves were linear well with correlation coefficient ranged from 0.9969-0.9991, and the limits of detection of acrylamide, caprolactam, aniline and benzidine were in the range of 5.0-50 ng/L. At the spiked levels of three concentrations, the average recoveries were between 81.5% and 106.9%. The relative standard deviations of run-to-run and day-to-day were 7.6%-15.7% and 14.7%-22.9%, respectively. The developed method is simple and sensitive, and was suitable for rapid analysis of large quantities of samples.
A comparative study of the performance of ultrasound-assisted (UA), and temperature-controlled (TC) ionic liquid (IL) dispersive liquid-liquid microextraction (IL-DLLME) was presented. Various parameters that affected extraction efficiency were evaluated. UA-IL-DLLME was found to provide the better extraction efficiency. After adjustment of pH, the water sample was mixed with[C8MIM] [PF6] and acetonitrile, then was extracted under ultrasound-assisted/temperature-controlled conditions. The mixture was then centrifuged, separated, and analyzed by UPLC-MS/MS. Under the optimal conditions, the calibration curves were linear well with correlation coefficient ranged from 0.9969-0.9991, and the limits of detection of acrylamide, caprolactam, aniline and benzidine were in the range of 5.0-50 ng/L. At the spiked levels of three concentrations, the average recoveries were between 81.5% and 106.9%. The relative standard deviations of run-to-run and day-to-day were 7.6%-15.7% and 14.7%-22.9%, respectively. The developed method is simple and sensitive, and was suitable for rapid analysis of large quantities of samples.
2016, 44(1): 124-130
doi: 10.11895/j.issn.0253-3820.150585
Abstract:
A method of simultaneous determination of four kind of auxins (Indole-3-acetic acid, Indole-3-butyric acid, Abscisic acid, Zeatin) in sargassum by ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) was established. After extracted by 70% methanol, the samples were enriched by the PCX and PAX solid-phase column. Then the samples were purified by reversed phase C18 column using 5 mmol/L ammonium acetate (containing 0.01% formic acid) and methanol as a mobile phase in gradient elution. On the base of multiple reaction monitoring (MRM) analysis, the results showed that the correlation coefficient for all auxins examined exceeded 0.9990 in the range of 0.01-1.0 μg/mL. The recovery was from 84.3% to 102.1%, respectively. The relative standard deviation was less than 10%. Besides, the detection limit of this method was from 0.025 μg/kg to 0.2 μg/kg.
A method of simultaneous determination of four kind of auxins (Indole-3-acetic acid, Indole-3-butyric acid, Abscisic acid, Zeatin) in sargassum by ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) was established. After extracted by 70% methanol, the samples were enriched by the PCX and PAX solid-phase column. Then the samples were purified by reversed phase C18 column using 5 mmol/L ammonium acetate (containing 0.01% formic acid) and methanol as a mobile phase in gradient elution. On the base of multiple reaction monitoring (MRM) analysis, the results showed that the correlation coefficient for all auxins examined exceeded 0.9990 in the range of 0.01-1.0 μg/mL. The recovery was from 84.3% to 102.1%, respectively. The relative standard deviation was less than 10%. Besides, the detection limit of this method was from 0.025 μg/kg to 0.2 μg/kg.
2016, 44(1): 131-137
doi: 10.11895/j.issn.0253-3820.150630
Abstract:
A new extraction method, dicyclohexyl-18-crown-6 (DCH18C6)-dual cloud point extraction method (DCH18C6-DCPE), was developed for extraction and determination of Pb in environmental water and food samples. The DCH18C6-DCPE method included two cloud point extraction (CPE) steps. At the first CPE procedure, DCH18C6 was used as selective chelating agent of Pb2+, and the formed hydrophobic complex (Pb-DCH18C6) was entrapped in a thermoseparating triblock copolymer (L64) rich phase. At the second CPE stage, the L64-rich phase was treated with a certain amount of Ethylene Diamine Tetraacetic Acid (EDTA) solution, and Pb2+ was back extracted into the aqueous phase for analysis due to its stronger combining capacity with EDTA. The single factor experiment and response surface methodology design were used to obtain the optimal condition, namely 2.06% L64 (m/m), 8.13% K2HPO4(m/m), 207.23 μg/mL DCH18C6, 70℃ of extraction temperature, and 10 min of extraction time. Under the optimized conditions, the calibration curve was linear in the range of 0.05-0.3 μg/mL (R2=0.998), the extraction efficiency of Pb was 98.8%, and the limit of detection (LOD) was 2.8 μg/L. Besides, the precisions of inter-day RSD<4.6% and intra-day RSD<6.8% were obtained. Moreover, the proposed method was successfully applied to the determination of Pb2+ in water and food samples with the recoveries of 97.3%-102.2% and a relative standard deviation (RSD) lower than 3.7%. The results indicated that the proposed method was effective for the determination of Pb2+ in real samples.
A new extraction method, dicyclohexyl-18-crown-6 (DCH18C6)-dual cloud point extraction method (DCH18C6-DCPE), was developed for extraction and determination of Pb in environmental water and food samples. The DCH18C6-DCPE method included two cloud point extraction (CPE) steps. At the first CPE procedure, DCH18C6 was used as selective chelating agent of Pb2+, and the formed hydrophobic complex (Pb-DCH18C6) was entrapped in a thermoseparating triblock copolymer (L64) rich phase. At the second CPE stage, the L64-rich phase was treated with a certain amount of Ethylene Diamine Tetraacetic Acid (EDTA) solution, and Pb2+ was back extracted into the aqueous phase for analysis due to its stronger combining capacity with EDTA. The single factor experiment and response surface methodology design were used to obtain the optimal condition, namely 2.06% L64 (m/m), 8.13% K2HPO4(m/m), 207.23 μg/mL DCH18C6, 70℃ of extraction temperature, and 10 min of extraction time. Under the optimized conditions, the calibration curve was linear in the range of 0.05-0.3 μg/mL (R2=0.998), the extraction efficiency of Pb was 98.8%, and the limit of detection (LOD) was 2.8 μg/L. Besides, the precisions of inter-day RSD<4.6% and intra-day RSD<6.8% were obtained. Moreover, the proposed method was successfully applied to the determination of Pb2+ in water and food samples with the recoveries of 97.3%-102.2% and a relative standard deviation (RSD) lower than 3.7%. The results indicated that the proposed method was effective for the determination of Pb2+ in real samples.
2016, 44(1): 138-145
doi: 10.11895/j.issn.0253-3820.150785
Abstract:
Polypyrrole/Nylon 6 core-shell Nanofibers mat (PPy/Nylon 6-NFSM), prepared via situ polymerization on nylon6 electrospun nanofibers mat template, was used as an adsorbent to remove Pb2+ from aqueous solutions. To study the adsorption characteristics of PPy/Nylon 6-NFSM on Pb2+, the work focused on two parts, dynamic adsorption and static adsorption. The investigation explored the possibility of PPy/Nylon 6-NFSM as an efficient solid phase extraction (SPE) adsorbent for the separation and enrichment of trace Pb2+ in water samples. The experiment results showed that the maximum static adsorption capacity of PPy/Nylon 6-NFSM for Pb2+ was 542.1 mg/g at 298 K in pH=10 solution. The adsorption process could be well fitted with the pseudo-second-order kinetic model, the adsorption equilibrium data accorded with Freundlich isotherm model. Under the optimum conditions, PPy/Nylon 6-NFSM was used as adsorbent in SPE coupled with Flame atomic spectrophotometer (AA-7000) for the determination of Pb2+ in water samples. The limits of detection of the method were 1.2 μg/L (S/N=3), the recoveries of spiked water samples at concentration of 10 μg/L were 95.3%-100.4% with RSD of 1.6%. The method is accurate and sensitive in detection of trace concentrations of Pb2+ in water sample.
Polypyrrole/Nylon 6 core-shell Nanofibers mat (PPy/Nylon 6-NFSM), prepared via situ polymerization on nylon6 electrospun nanofibers mat template, was used as an adsorbent to remove Pb2+ from aqueous solutions. To study the adsorption characteristics of PPy/Nylon 6-NFSM on Pb2+, the work focused on two parts, dynamic adsorption and static adsorption. The investigation explored the possibility of PPy/Nylon 6-NFSM as an efficient solid phase extraction (SPE) adsorbent for the separation and enrichment of trace Pb2+ in water samples. The experiment results showed that the maximum static adsorption capacity of PPy/Nylon 6-NFSM for Pb2+ was 542.1 mg/g at 298 K in pH=10 solution. The adsorption process could be well fitted with the pseudo-second-order kinetic model, the adsorption equilibrium data accorded with Freundlich isotherm model. Under the optimum conditions, PPy/Nylon 6-NFSM was used as adsorbent in SPE coupled with Flame atomic spectrophotometer (AA-7000) for the determination of Pb2+ in water samples. The limits of detection of the method were 1.2 μg/L (S/N=3), the recoveries of spiked water samples at concentration of 10 μg/L were 95.3%-100.4% with RSD of 1.6%. The method is accurate and sensitive in detection of trace concentrations of Pb2+ in water sample.
2016, 44(1): 146-151
doi: 10.11895/j.issn.0253-3820.150443
Abstract:
A new method has been developed for the determination of tetracycline residues in milk by on-line restricted access material solid phase extraction-HPLC analysis. Restricted accessed poly(styrene-co-divinylbenzene) bonded silica, synthesized by atom transfer radical polymerization, was used as solid phase extraction material in the experiment. This material played both functions of tetracylines extraction and biomacromolecule exclusion. Tetracyclines extracted from milk sample were back-flushed into a reversed phase C18 analytical column and oxytetracycline, tetracycline and chlortetracycline were separated and quantified by HPLC analysis. The exclusion ratio of bovine serum albumin from the restricted access material column was 96.0%, which indicated that the restricted access material had the ability to exclude large biological molecules. The recoveries of three tetracylines in milk samples were 88.3%-101.5% with relative standard deviations <8.0%. The detection limits of 50-80 μg/L and the linear ranges from 0.05 μg/mL to 2.0 μg/mL for the analytes were obtained. The results demonstrated that the method could be used in the determination of tetracycline residues in milk samples with good sensitivity and efficiency.
A new method has been developed for the determination of tetracycline residues in milk by on-line restricted access material solid phase extraction-HPLC analysis. Restricted accessed poly(styrene-co-divinylbenzene) bonded silica, synthesized by atom transfer radical polymerization, was used as solid phase extraction material in the experiment. This material played both functions of tetracylines extraction and biomacromolecule exclusion. Tetracyclines extracted from milk sample were back-flushed into a reversed phase C18 analytical column and oxytetracycline, tetracycline and chlortetracycline were separated and quantified by HPLC analysis. The exclusion ratio of bovine serum albumin from the restricted access material column was 96.0%, which indicated that the restricted access material had the ability to exclude large biological molecules. The recoveries of three tetracylines in milk samples were 88.3%-101.5% with relative standard deviations <8.0%. The detection limits of 50-80 μg/L and the linear ranges from 0.05 μg/mL to 2.0 μg/mL for the analytes were obtained. The results demonstrated that the method could be used in the determination of tetracycline residues in milk samples with good sensitivity and efficiency.
2016, 44(1): 152-159
doi: 10.11895/j.issn.0253-3820.150523
Abstract:
Molecular imprinted technology has been maturely applied to analyze and detect small molecule organic compounds, also it has been increasingly applied in biological macromolecule assay. This review addresses the perspective of bio-macromolecular imprinted sensors and their applications, including optical molecular imprinted sensors, electrochemical molecular imprinted sensors and mass-sensitive molecular imprinted sensors. In addition, the opportunities, the challenges, and the further research orientations of molecular imprinted sensors for bio-macromolecule detection are prospected.
Molecular imprinted technology has been maturely applied to analyze and detect small molecule organic compounds, also it has been increasingly applied in biological macromolecule assay. This review addresses the perspective of bio-macromolecular imprinted sensors and their applications, including optical molecular imprinted sensors, electrochemical molecular imprinted sensors and mass-sensitive molecular imprinted sensors. In addition, the opportunities, the challenges, and the further research orientations of molecular imprinted sensors for bio-macromolecule detection are prospected.
2016, 44(1): 160-166
doi: 10.11895/j.issn.0253-3820.150546
Abstract:
Dielectric difference analysis is important for impedance spectroscopy, which is the basis of dielectric materials composition, structure and performance characteristics analysis. As for normal single channel impedance spectroscopy measurement technique, substrate signals resulting from sensor substrate and so on will weaken the dielectric difference dramatically. In this work, a new impedance spectroscopic technique has been proposed, which is characterized by two-channel and differential detection methods and based on AD5933 impedance converter chip. In the frequency range of 1-91 kHz, experiments have been performed with the excitation signal differences from 0 mV to 100 mV under the substrate signal of 200, 400 and 1000 mV for new two-channel and differential and normal single channel impedance spectroscopic methods. Seven oil samples including gasoline, diesel fuel, jet fuel and lubricating oils have also been tested by the methods of single channel detection, differential detection with the references of air and jet fuel under the excitation voltage of 18 Vpp. The results showed that the impedance response sensitivity of two-channel and differential detection was 1-2 orders of magnitude of the normal single channel detection and free from the influence of substrate signal. For the oil samples, the impedance response sensitivity of differential detection with reference by jet fuel was 5-10 times of differential detection reference by air and 9-12 times of single channel detection, respectively, which proved that the differential detection could improve impedance detection sensitivity and eliminate the effect of substrate signal significantly.
Dielectric difference analysis is important for impedance spectroscopy, which is the basis of dielectric materials composition, structure and performance characteristics analysis. As for normal single channel impedance spectroscopy measurement technique, substrate signals resulting from sensor substrate and so on will weaken the dielectric difference dramatically. In this work, a new impedance spectroscopic technique has been proposed, which is characterized by two-channel and differential detection methods and based on AD5933 impedance converter chip. In the frequency range of 1-91 kHz, experiments have been performed with the excitation signal differences from 0 mV to 100 mV under the substrate signal of 200, 400 and 1000 mV for new two-channel and differential and normal single channel impedance spectroscopic methods. Seven oil samples including gasoline, diesel fuel, jet fuel and lubricating oils have also been tested by the methods of single channel detection, differential detection with the references of air and jet fuel under the excitation voltage of 18 Vpp. The results showed that the impedance response sensitivity of two-channel and differential detection was 1-2 orders of magnitude of the normal single channel detection and free from the influence of substrate signal. For the oil samples, the impedance response sensitivity of differential detection with reference by jet fuel was 5-10 times of differential detection reference by air and 9-12 times of single channel detection, respectively, which proved that the differential detection could improve impedance detection sensitivity and eliminate the effect of substrate signal significantly.
