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2016 Volume 44 Issue 3
2016, 44(3): 329-334
doi: 10.11895/j.issn.0253-3820.160034
Abstract:
Phospholipids and their metabolites play an important role in a variety of cellular processes including cell-cell adhesion, cell growth and differentiation, apoptosis, phagocytosis as well as storage of energy. In this study, the phospholipid composition of cancer tissue and adjacent normal tissue from humans and animals were analyzed by internal extractive electrospray ionization mass spectrometry (iEESI-MS). Extractive solvent at high voltage (+5.5 kV) was injected into tissue samples using a fused silica capillary at a flow rate of 0.5-1 μL/min, producing fine charged droplets containing analytes of tissue samples at the tip of the sample. Charged droplets were directly sampled to the atmospheric inlet of a mass spectrometer. Out of 21 different ratios of CH3OH:H2O solvent mixture, the ratio CH3OH:H2O=30:70 (V/V) showed the optimal phospholipids extraction and visibility in MS. A large number of phospholipids from different tissue samples (such as cancer tissue and adjacent normal tissue of lung cancer, esophageal cancer tissue, pork, beef, porcine heart and porcine lung) were obtained simultaneously by iEESI-MS analysis. The experimental results demonstrated that iEESI-MS was characterized by minimal sample pretreatment, low sample consumption, and rapid analysis (the analysis time per sample was less than 1 min), and the selectivity and sensitivity of iEESI-MS could be improved by choosing proper solvent. Importantly, the experimental results provided new information for further studies of phospholipids in biological tissues.
Phospholipids and their metabolites play an important role in a variety of cellular processes including cell-cell adhesion, cell growth and differentiation, apoptosis, phagocytosis as well as storage of energy. In this study, the phospholipid composition of cancer tissue and adjacent normal tissue from humans and animals were analyzed by internal extractive electrospray ionization mass spectrometry (iEESI-MS). Extractive solvent at high voltage (+5.5 kV) was injected into tissue samples using a fused silica capillary at a flow rate of 0.5-1 μL/min, producing fine charged droplets containing analytes of tissue samples at the tip of the sample. Charged droplets were directly sampled to the atmospheric inlet of a mass spectrometer. Out of 21 different ratios of CH3OH:H2O solvent mixture, the ratio CH3OH:H2O=30:70 (V/V) showed the optimal phospholipids extraction and visibility in MS. A large number of phospholipids from different tissue samples (such as cancer tissue and adjacent normal tissue of lung cancer, esophageal cancer tissue, pork, beef, porcine heart and porcine lung) were obtained simultaneously by iEESI-MS analysis. The experimental results demonstrated that iEESI-MS was characterized by minimal sample pretreatment, low sample consumption, and rapid analysis (the analysis time per sample was less than 1 min), and the selectivity and sensitivity of iEESI-MS could be improved by choosing proper solvent. Importantly, the experimental results provided new information for further studies of phospholipids in biological tissues.
2016, 44(3): 335-341
doi: 10.11895/j.issn.0253-3820.150714
Abstract:
The particles suspended in seawater have great influence on pollutant migration and transformation in marine environment, while the lipophilic algae toxins enriched by the particles suspended in seawater will lead more serious toxicity to marine filter feeders. In this study, a new method was developed for the simultaneous determination of eight lipophilic algae toxins in suspended particles by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). After extracted with methanol by ultrasonic-assisted extraction, the sample was separated on an Acquity UPLC BEH C18 column (50 mm×2.1 mm, 1.7 μm) using gradient elution of acetonitrile and water containing 5 mmol/L ammonium acetate as eluent modifiers. The qualitative and quantitative analyses were carried out by electrospray ionization (ESI) tandem mass spectrometry in multiple reaction monitoring (MRM) mode. Under the optimal conditions, satisfactory precision (relative standard deviations (RSD≤14.1%), recoveries (83.8%-110.4%) and detection limits (2.9-103 pg/g) of the method were achieved. Good linearity (R2≥0.99) was also obtained for all studied analytes. Then, the method was applied to determine the amounts of the eight lipophilic marine toxins in authentic suspended particle samples collected from Qingdao near-shore area. Pectenotoxin 2 (PTX2) was detected in the samples from Shilaoren beach and No. 3 bathing beach with concentration ranges of 717 and 790 pg/g, respectively.
The particles suspended in seawater have great influence on pollutant migration and transformation in marine environment, while the lipophilic algae toxins enriched by the particles suspended in seawater will lead more serious toxicity to marine filter feeders. In this study, a new method was developed for the simultaneous determination of eight lipophilic algae toxins in suspended particles by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). After extracted with methanol by ultrasonic-assisted extraction, the sample was separated on an Acquity UPLC BEH C18 column (50 mm×2.1 mm, 1.7 μm) using gradient elution of acetonitrile and water containing 5 mmol/L ammonium acetate as eluent modifiers. The qualitative and quantitative analyses were carried out by electrospray ionization (ESI) tandem mass spectrometry in multiple reaction monitoring (MRM) mode. Under the optimal conditions, satisfactory precision (relative standard deviations (RSD≤14.1%), recoveries (83.8%-110.4%) and detection limits (2.9-103 pg/g) of the method were achieved. Good linearity (R2≥0.99) was also obtained for all studied analytes. Then, the method was applied to determine the amounts of the eight lipophilic marine toxins in authentic suspended particle samples collected from Qingdao near-shore area. Pectenotoxin 2 (PTX2) was detected in the samples from Shilaoren beach and No. 3 bathing beach with concentration ranges of 717 and 790 pg/g, respectively.
2016, 44(3): 342-347
doi: 10.11895/j.issn.0253-3820.150705
Abstract:
Chitosan-Ru(bpy)32+-SiO2 composite nanoparticles (CRuS NPs) were prepared by reverse microemulsion method, and based on the Nafion/MCNT composite membrane technology, CRuS NPs were effectively and steadily immobilize on the surface of a glassy carbon electrode to prepare the electrochemiluminescence sensor for uric acid determination. In 0.1 mol/L PBS (pH 7.4) buffer solution, when the actuation duration between uric acid and the modified electrode was 15 min, the electrochemiluminescence showed a good linear relationship to the negative logarithm of uric acid concentration in the range of 1.0 × 10-10-1.0 × 10-5 mol/L, the linear equation was IECL=-709.52-202.74lgC and the correlation coefficient was 0.9936 with a detection limit of 6.0 × 10-12 mol/L. The ECL sensor exhibited excellent repeatability and stability, and the RSD for 11 times determination of 1.0 × 10-8 mol/L uric acid was 2.9%. The recovery was 98.5%-103.5% in the determination of real Uric acid sample.
Chitosan-Ru(bpy)32+-SiO2 composite nanoparticles (CRuS NPs) were prepared by reverse microemulsion method, and based on the Nafion/MCNT composite membrane technology, CRuS NPs were effectively and steadily immobilize on the surface of a glassy carbon electrode to prepare the electrochemiluminescence sensor for uric acid determination. In 0.1 mol/L PBS (pH 7.4) buffer solution, when the actuation duration between uric acid and the modified electrode was 15 min, the electrochemiluminescence showed a good linear relationship to the negative logarithm of uric acid concentration in the range of 1.0 × 10-10-1.0 × 10-5 mol/L, the linear equation was IECL=-709.52-202.74lgC and the correlation coefficient was 0.9936 with a detection limit of 6.0 × 10-12 mol/L. The ECL sensor exhibited excellent repeatability and stability, and the RSD for 11 times determination of 1.0 × 10-8 mol/L uric acid was 2.9%. The recovery was 98.5%-103.5% in the determination of real Uric acid sample.
2016, 44(3): 348-354
doi: 10.11895/j.issn.0253-3820.150918
Abstract:
A novel molecularly imprinted sensor for Ni2+ detection was fabricated based on photocurrent method. CdTe quantum dot (QDs) was selected as photoelectric material and modified in ITO electrode, then the nickel-1-(2-pyridylazo)-2-naphthol molecularly imprinted film was formed on the QDs layer by photopolymerization. By using 365 nm ultraviolet light as excitation light, the QDs generated electron-hole, and the electron donor-ascorbic acid combined with electron to form the photocurrent signals. Based on this evidence, Ni2+ was detected according to "gate-effect". The complex was characterized by Fourier transform infrared spectrum and the CdTe QDs was characterized by ultraviolet absorption spectrum and fluorescence emission spectrum, the time for elution and rebinding and the concentration of ascorbic acid in base solution were optimized. The experiment showed that there was a liner relationship between the photocurrent and the concentration of Ni2+ at 5×10-11-5×10-8 mol/L, with the detection limit of 8.3×10-12 mol/L. The sensor also had good selectivity, and it was applied in real water samples analysis.
A novel molecularly imprinted sensor for Ni2+ detection was fabricated based on photocurrent method. CdTe quantum dot (QDs) was selected as photoelectric material and modified in ITO electrode, then the nickel-1-(2-pyridylazo)-2-naphthol molecularly imprinted film was formed on the QDs layer by photopolymerization. By using 365 nm ultraviolet light as excitation light, the QDs generated electron-hole, and the electron donor-ascorbic acid combined with electron to form the photocurrent signals. Based on this evidence, Ni2+ was detected according to "gate-effect". The complex was characterized by Fourier transform infrared spectrum and the CdTe QDs was characterized by ultraviolet absorption spectrum and fluorescence emission spectrum, the time for elution and rebinding and the concentration of ascorbic acid in base solution were optimized. The experiment showed that there was a liner relationship between the photocurrent and the concentration of Ni2+ at 5×10-11-5×10-8 mol/L, with the detection limit of 8.3×10-12 mol/L. The sensor also had good selectivity, and it was applied in real water samples analysis.
2016, 44(3): 355-360
doi: 10.11895/j.issn.0253-3820.150866
Abstract:
The content of bicarbonate (HCO3-) and carbonate (CO32-) ions in groundwater and lake water reflects a broad set of carbon cycling reactions associated with decomposition or synthesis of organic compounds with mineral dissolution or precipitation, which indicates the local geochemical environment. However, the content of HCO3- and CO32- changes easily under the influence of pH, temperature, atmosphere pressure in the process of sampling, transportation and storage, so it has been a worldwide problem to determine the real content of HCO3- and CO32- ions in groundwater and lake water. This article proposed a new way to solve the problem by fast field detection of HCO3- and CO32- ions through the use of pH electrode combined with carbon dioxide electrode. Studies showed in the base solution of pH=4.8 ± 0.1, the detection range of HCO3- ion was 0.027-570 mg/L and that of CO32- was 1.25×10-8-39.7 mg/L. In the most case, the coexisting ions and weak acid (K+, Na+, Mg2+, Cl-, SO42-<100 mg/L; HSO3-, NO2-, HOAc<50 mg/L) did not interfere with the analysis. The method was validated for real water samples and the recoveries were in the range of 95.2%-99.2% with the relative standard deviations (RSDs) of 2.6%-3.7%. Compared with the acid-base titration method, the accuracy of this method had proved to be good. However, the method could be affected by temperature, so the standard solution and samples should be measured at the same temperature. Above all, this method is suitable for fast field analysis for HCO3- and CO32- ions in the nature water as it is sensitive, fast, economical, and the electrodes are easy to carry and operate. It has been successfully applied in the determination of HCO3- and CO32- in groundwater and lake water in Qinghai Province. Experiment showed that the pH of the groundwater samples from Haidong district was 6.4-7.4, with 234-4096 mg/L HCO3- and 0.16-1.89 mg/L CO32-. The pH of the lake water samples was about 8.7, with 1.36-1.86 g/L HCO3- and 32.3-43.9 mg/L CO32-, which was consistent with the previous results.
The content of bicarbonate (HCO3-) and carbonate (CO32-) ions in groundwater and lake water reflects a broad set of carbon cycling reactions associated with decomposition or synthesis of organic compounds with mineral dissolution or precipitation, which indicates the local geochemical environment. However, the content of HCO3- and CO32- changes easily under the influence of pH, temperature, atmosphere pressure in the process of sampling, transportation and storage, so it has been a worldwide problem to determine the real content of HCO3- and CO32- ions in groundwater and lake water. This article proposed a new way to solve the problem by fast field detection of HCO3- and CO32- ions through the use of pH electrode combined with carbon dioxide electrode. Studies showed in the base solution of pH=4.8 ± 0.1, the detection range of HCO3- ion was 0.027-570 mg/L and that of CO32- was 1.25×10-8-39.7 mg/L. In the most case, the coexisting ions and weak acid (K+, Na+, Mg2+, Cl-, SO42-<100 mg/L; HSO3-, NO2-, HOAc<50 mg/L) did not interfere with the analysis. The method was validated for real water samples and the recoveries were in the range of 95.2%-99.2% with the relative standard deviations (RSDs) of 2.6%-3.7%. Compared with the acid-base titration method, the accuracy of this method had proved to be good. However, the method could be affected by temperature, so the standard solution and samples should be measured at the same temperature. Above all, this method is suitable for fast field analysis for HCO3- and CO32- ions in the nature water as it is sensitive, fast, economical, and the electrodes are easy to carry and operate. It has been successfully applied in the determination of HCO3- and CO32- in groundwater and lake water in Qinghai Province. Experiment showed that the pH of the groundwater samples from Haidong district was 6.4-7.4, with 234-4096 mg/L HCO3- and 0.16-1.89 mg/L CO32-. The pH of the lake water samples was about 8.7, with 1.36-1.86 g/L HCO3- and 32.3-43.9 mg/L CO32-, which was consistent with the previous results.
2016, 44(3): 361-366
doi: 10.11895/j.issn.0253-3820.150689
Abstract:
Artificial sweeteners (ASs) have gained more and more attention by environmental scientists because some of them such as acesulfame, have the potential to be the ideal tracers of domestic wastewater for environmental monitoring. In contrast to the existing methods of artificial sweeteners, the analytical method of ASs as a new tracer for environmental samples requires better sensitivity and selectivity to avoid matrix interference. A highly sensitive method for the simultaneous determination of four frequently-used artificial sweeteners in water samples using solid-phase extraction and ion chromatography triple quadrupole mass spectrometer with an electrospray ionization source (IC-MS/MS) in negative ion mode was developed. The separation effect of different separation columns was compared and a 2-mm ion chromatography column AS19 was chosen in the experiment. Chromatographic separation of all the 4 artificial sweeteners was carried out in 9 min in isocratic elution mode using 60 mmol/L sodium hydroxide as eluent. Different kinds of solid phase extraction cartridges were evaluated to obtain satisfactory recoveries of all of the analytes. Merk LiChrolut EN (200 mg, 3 mL) was preconditioned with 2 mL of methanol, followed by 2 mL of H2O. About 200 mL of sample (pH＜2.0) was passed through the cartridge at a flow rate of 4 mL/min, and then the cartridge was eluted using 2 mL of methanol. 2 mm suppresser (75 mA) was used to reduce the background noise and to remove the matrix interference. The limits of detection were below 5.0 ng/L for various artificial sweeteners based on 3-fold the S/N. The recoveries of different matrices in the samples were 65%-120%. The method described here is time-saving, accurate and precise, and is suitable for monitoring artificial sweeteners in different water matrices. The method has also the potential to trace other contaminants in groundwater.
Artificial sweeteners (ASs) have gained more and more attention by environmental scientists because some of them such as acesulfame, have the potential to be the ideal tracers of domestic wastewater for environmental monitoring. In contrast to the existing methods of artificial sweeteners, the analytical method of ASs as a new tracer for environmental samples requires better sensitivity and selectivity to avoid matrix interference. A highly sensitive method for the simultaneous determination of four frequently-used artificial sweeteners in water samples using solid-phase extraction and ion chromatography triple quadrupole mass spectrometer with an electrospray ionization source (IC-MS/MS) in negative ion mode was developed. The separation effect of different separation columns was compared and a 2-mm ion chromatography column AS19 was chosen in the experiment. Chromatographic separation of all the 4 artificial sweeteners was carried out in 9 min in isocratic elution mode using 60 mmol/L sodium hydroxide as eluent. Different kinds of solid phase extraction cartridges were evaluated to obtain satisfactory recoveries of all of the analytes. Merk LiChrolut EN (200 mg, 3 mL) was preconditioned with 2 mL of methanol, followed by 2 mL of H2O. About 200 mL of sample (pH＜2.0) was passed through the cartridge at a flow rate of 4 mL/min, and then the cartridge was eluted using 2 mL of methanol. 2 mm suppresser (75 mA) was used to reduce the background noise and to remove the matrix interference. The limits of detection were below 5.0 ng/L for various artificial sweeteners based on 3-fold the S/N. The recoveries of different matrices in the samples were 65%-120%. The method described here is time-saving, accurate and precise, and is suitable for monitoring artificial sweeteners in different water matrices. The method has also the potential to trace other contaminants in groundwater.
2016, 44(3): 367-376
doi: 10.11895/j.issn.0253-3820.150778
Abstract:
Silicon quantum dot has become an attractive nanomaterial due to their excellent biocompatibility and optical performance. However, poor water-solubility of the traditional silicon quantum dot limits its wide application. In this study, we reported the synthesis of water-soluble silicon quantum dots with imidazole groups by using hydrothermal method, in which N-trimethysilylimidazole was used as a precursor of silicon. Compared with sodium borohydride, ascorbic acid, bovine serum protein, cysteine and citric acid, the as-prepared silicon quantum dots offered the strongest fluorescence intensity when sodium citrate was used as the reducing agent and stabilizer for the synthesis. The reaction could complete within 2 h at 220℃. The obtained silicon quantum dots showed good water-solubility with an average particle size of 2.6 nm, and the result of infrared spectroscopic analysis verified the existence of free imidazole groups on the surface. By means of the investigation of the fluorescence quenching behavior of copper ions towards the silicon quantum dots at different temperatures, we found that the degree of fluorescence quenching increased with the increase of temperature. There results proved that the fluorescence decrease belongs to static quenching. Namely, the interaction of Cu2+ with imidazole groups on the surface of silicon quantum dots formed stable complex. In addition, the resonance light scattering analysis also showed that the fluorescence quenching process was accompanied by the agglomeration of particles. Based on the fluorescence quenching behavior of silicon quantum dots, we established a method for the fluorescent detection of Cu2+. When the concentration of Cu2+ was in the range of 0.04-2400 μmol/L, the fluorescence intensity would linearly decrease with the increase of Cu2+ concentration, and the detection limit (S/N=3) reached 1.29×10-8 mol/L. The method provided high sensitivity, selectivity and reproducibility, and was successfully applied to the determination of trace copper in fruits and vegetables.
Silicon quantum dot has become an attractive nanomaterial due to their excellent biocompatibility and optical performance. However, poor water-solubility of the traditional silicon quantum dot limits its wide application. In this study, we reported the synthesis of water-soluble silicon quantum dots with imidazole groups by using hydrothermal method, in which N-trimethysilylimidazole was used as a precursor of silicon. Compared with sodium borohydride, ascorbic acid, bovine serum protein, cysteine and citric acid, the as-prepared silicon quantum dots offered the strongest fluorescence intensity when sodium citrate was used as the reducing agent and stabilizer for the synthesis. The reaction could complete within 2 h at 220℃. The obtained silicon quantum dots showed good water-solubility with an average particle size of 2.6 nm, and the result of infrared spectroscopic analysis verified the existence of free imidazole groups on the surface. By means of the investigation of the fluorescence quenching behavior of copper ions towards the silicon quantum dots at different temperatures, we found that the degree of fluorescence quenching increased with the increase of temperature. There results proved that the fluorescence decrease belongs to static quenching. Namely, the interaction of Cu2+ with imidazole groups on the surface of silicon quantum dots formed stable complex. In addition, the resonance light scattering analysis also showed that the fluorescence quenching process was accompanied by the agglomeration of particles. Based on the fluorescence quenching behavior of silicon quantum dots, we established a method for the fluorescent detection of Cu2+. When the concentration of Cu2+ was in the range of 0.04-2400 μmol/L, the fluorescence intensity would linearly decrease with the increase of Cu2+ concentration, and the detection limit (S/N=3) reached 1.29×10-8 mol/L. The method provided high sensitivity, selectivity and reproducibility, and was successfully applied to the determination of trace copper in fruits and vegetables.
2016, 44(3): 377-384
doi: 10.11895/j.issn.0253-3820.150694
Abstract:
ZnO nanoparticles (ZnO NPs) were obtained by a direct precipitation method. With the as-prepared ZnO NPs as seeds, Au/ZnO heterostructure was synthesized by seed-mediated growth method without any surfactant, and the diameters of ZnO NPs and Au NPs were about 50 nm and 10 nm, respectively. Then ionic liquids (ILs), trihexyltetradecylphosphonium bis (trifluoromethylsulfonyl) imide ([P(C6)3C14][Tf2N]), and functionalized graphene (GN) were prepared under room temperature. The ILs as bridges could connect Au/ZnO heterostructure to form a new kind of graphene nanocomposite, Au/ZnO/GN. Then the penicillinase and hematein were immobilized on Au/ZnO/GN. And the biosensors based on penicillinase-hematein-Au/ZnO/GN (PH-AZG) were used for detecting penicillin G. In PBS buffer solution (pH 7.0), PH-AZG exhibited a detection range from 2.5×10-14 to 3.3×10-6 mol/L with a detection limit of 1.5×10-14 mol/L (S/N≥ 3). Five PH-AZG electrodes were prepared with the same conditions, and the RSDs for their current response were less than 3.2%. Furthermore, the standard curves were linear in the range of 5×10-14-5×10-7 mol/L for milk. The average recoveries were 99.7%-101.4% with RSDs of 2.3%-3.5% (n=5). The method is sensitive and repeatable, and can be applied to the field of residue analysis about penicillins G with low concentration levels.
ZnO nanoparticles (ZnO NPs) were obtained by a direct precipitation method. With the as-prepared ZnO NPs as seeds, Au/ZnO heterostructure was synthesized by seed-mediated growth method without any surfactant, and the diameters of ZnO NPs and Au NPs were about 50 nm and 10 nm, respectively. Then ionic liquids (ILs), trihexyltetradecylphosphonium bis (trifluoromethylsulfonyl) imide ([P(C6)3C14][Tf2N]), and functionalized graphene (GN) were prepared under room temperature. The ILs as bridges could connect Au/ZnO heterostructure to form a new kind of graphene nanocomposite, Au/ZnO/GN. Then the penicillinase and hematein were immobilized on Au/ZnO/GN. And the biosensors based on penicillinase-hematein-Au/ZnO/GN (PH-AZG) were used for detecting penicillin G. In PBS buffer solution (pH 7.0), PH-AZG exhibited a detection range from 2.5×10-14 to 3.3×10-6 mol/L with a detection limit of 1.5×10-14 mol/L (S/N≥ 3). Five PH-AZG electrodes were prepared with the same conditions, and the RSDs for their current response were less than 3.2%. Furthermore, the standard curves were linear in the range of 5×10-14-5×10-7 mol/L for milk. The average recoveries were 99.7%-101.4% with RSDs of 2.3%-3.5% (n=5). The method is sensitive and repeatable, and can be applied to the field of residue analysis about penicillins G with low concentration levels.
2016, 44(3): 385-390
doi: 10.11895/j.issn.0253-3820.150761
Abstract:
Based on the intermolecular interaction, a molecularly imprinted polymer electrochemical sensor with specific identification of cavity on gold electrode surface was proposed with o-aminophenol as functional monomers and morin as template molecule. The performance and effect of MIP were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Factors affecting the properties of sensor, such as polymeric membrane ratio, scanning cycles, elution time and adsorption time were investigated. Substances which had a similar structure to morin was used to compared the selective response. The result showed that the sensor had a good selectivity to morin. Under the optimized experiment conditions, the current response of the imprinted sensor was linear to the concentration of morin in the range of 0.05-1.7 μmol/L with linear equation as follows: I(μA)= 1.0800lgc(mol/L)+ 9.3599(R=0.9934), and the detection limit of 0.1 μmol/L. The sensor was used to determine the content of morin in black tea samples, and the recoveries of standard addition were between 104.0% and 108.0%.
Based on the intermolecular interaction, a molecularly imprinted polymer electrochemical sensor with specific identification of cavity on gold electrode surface was proposed with o-aminophenol as functional monomers and morin as template molecule. The performance and effect of MIP were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Factors affecting the properties of sensor, such as polymeric membrane ratio, scanning cycles, elution time and adsorption time were investigated. Substances which had a similar structure to morin was used to compared the selective response. The result showed that the sensor had a good selectivity to morin. Under the optimized experiment conditions, the current response of the imprinted sensor was linear to the concentration of morin in the range of 0.05-1.7 μmol/L with linear equation as follows: I(μA)= 1.0800lgc(mol/L)+ 9.3599(R=0.9934), and the detection limit of 0.1 μmol/L. The sensor was used to determine the content of morin in black tea samples, and the recoveries of standard addition were between 104.0% and 108.0%.
2016, 44(3): 391-395
doi: 10.11895/j.issn.0253-3820.150773
Abstract:
A novel electrochemical DNA biosensor was fabricated based on the large area of gold particles on the aligned carbon nanotubes for the detection of promyelocytic leukaemia/retinoic acid receptor α (PML/RARα) fusion gene in acute promyelocytic leukemia. Firstly, the thiol-modified single-stranded DNA (ssDNA, probe 1) was immobilized on the gold particles sputtered on the aligned carbon nanotubes electrode by self-assembly technique. Then, amino-modified ssDNA and carboxyl-modified CdTe quantum dots (QDs) were combined to get CdTe-modified DNA probe through an amidization reaction. After hybridization with target DNA, a sandwich-type assay structure was formed. Finally, the CdTe quantum dots captured on the electrode surface were detected by differential pulse anodic stripping voltammetry. The change of peak current of Cd2+ on the electrode was found to be linear with the logarithm of target DNA concentration in the range of 1.0×10-12 mol/L to 1.0×10-8 mol/L. The Linear equation was ipa (μA)=1.626+0.132lgC (mol/L) (the correlation coefficient R was 0.996) and the detection limit was 4.0×10-13 mol/L (3σ). The fabricated DNA biosensor exhibited excellent reproducibility and stability.
A novel electrochemical DNA biosensor was fabricated based on the large area of gold particles on the aligned carbon nanotubes for the detection of promyelocytic leukaemia/retinoic acid receptor α (PML/RARα) fusion gene in acute promyelocytic leukemia. Firstly, the thiol-modified single-stranded DNA (ssDNA, probe 1) was immobilized on the gold particles sputtered on the aligned carbon nanotubes electrode by self-assembly technique. Then, amino-modified ssDNA and carboxyl-modified CdTe quantum dots (QDs) were combined to get CdTe-modified DNA probe through an amidization reaction. After hybridization with target DNA, a sandwich-type assay structure was formed. Finally, the CdTe quantum dots captured on the electrode surface were detected by differential pulse anodic stripping voltammetry. The change of peak current of Cd2+ on the electrode was found to be linear with the logarithm of target DNA concentration in the range of 1.0×10-12 mol/L to 1.0×10-8 mol/L. The Linear equation was ipa (μA)=1.626+0.132lgC (mol/L) (the correlation coefficient R was 0.996) and the detection limit was 4.0×10-13 mol/L (3σ). The fabricated DNA biosensor exhibited excellent reproducibility and stability.
2016, 44(3): 396-402
doi: 10.11895/j.issn.0253-3820.150811
Abstract:
An on-line solid phase extraction coupled with capillary HPLC method was established for the simultaneous determination of fifteen kinds of biologic amines in cheese. The biogenic amines were concentrated on the solid phase extraction column, and transferred by the six-way valve to analytical column for separation and detection. Separation conditions on capillary HPLC, composition of on-line SPE mobile phase, pH of the sample solution and switching time of six-way switching valve were investigated to get better separation conditions of 15 biogenic amines. Optimum on-line SPE conditions including 5% of the acetonitrile-water as mobile phase for SPE column, pH=11 of the sample solution and 3 min of valve switching time were employed in the analytical method. The linear range of standard curve for fifteen biogenic amines was 0.25-50.0 mg/L; LOD were within the range of 0.05-0.25 mg/L. At spiked levels of 1, 20, 40 mg/kg, the recoveries of fifteen biogenic amines on four kinds of cheese ranged from 79.6% to 118.7% except methylamine, ethylamine, 3-methylbutanamine and 5-hydroxytryptamine; with RSDs from 0.3% to 14.9% except 3-methylbutanamine and 5-hydroxy-tryptamine. The method is accurate and reliable, and can be used to detect biogenic amines in cheese.
An on-line solid phase extraction coupled with capillary HPLC method was established for the simultaneous determination of fifteen kinds of biologic amines in cheese. The biogenic amines were concentrated on the solid phase extraction column, and transferred by the six-way valve to analytical column for separation and detection. Separation conditions on capillary HPLC, composition of on-line SPE mobile phase, pH of the sample solution and switching time of six-way switching valve were investigated to get better separation conditions of 15 biogenic amines. Optimum on-line SPE conditions including 5% of the acetonitrile-water as mobile phase for SPE column, pH=11 of the sample solution and 3 min of valve switching time were employed in the analytical method. The linear range of standard curve for fifteen biogenic amines was 0.25-50.0 mg/L; LOD were within the range of 0.05-0.25 mg/L. At spiked levels of 1, 20, 40 mg/kg, the recoveries of fifteen biogenic amines on four kinds of cheese ranged from 79.6% to 118.7% except methylamine, ethylamine, 3-methylbutanamine and 5-hydroxytryptamine; with RSDs from 0.3% to 14.9% except 3-methylbutanamine and 5-hydroxy-tryptamine. The method is accurate and reliable, and can be used to detect biogenic amines in cheese.
2016, 44(3): 403-408
doi: 10.11895/j.issn.0253-3820.150751
Abstract:
By using the high resolution mass spectrometer TripleTOF 5600, three kinds of standard proteins including bovine serum albumin (BSA), ovalbumin (OVA) and lysozyme C(LYZC) were analyzed, and the correlationship between the ion intensity of mass spectrometry and the relative content of protein sample was investigated. The protein samples were digested by trypsion and diluted to 1-1024 fmol in 7 μL. The ion counts per second (cps) were used to stand for the amounts of proteins and peptides. Then the correlation between sum of ion intensity (cps) of all the peptides, number of peptides detected and the amount of proteins was investigated. By comparing the change of values of the same sample in three parallel experiments, a linear relationship between these indexes and the amount of proteins within 1-1024 fmol was found when the cps was more than 1000. Usually, the maximal ion intensity was no more than 1.5 times of the minimum value for same peptide in triplicate experiments, which suggested that the 3 times or more change of ion intensity was the minimum threshold to determine the differences of proteins amounts in different samples. This study provides a relative quantitative analysis method using qualitative data of high resolution and high scan speed mass spectrometry, which can quickly and easily provide reference for biological and medical research.
By using the high resolution mass spectrometer TripleTOF 5600, three kinds of standard proteins including bovine serum albumin (BSA), ovalbumin (OVA) and lysozyme C(LYZC) were analyzed, and the correlationship between the ion intensity of mass spectrometry and the relative content of protein sample was investigated. The protein samples were digested by trypsion and diluted to 1-1024 fmol in 7 μL. The ion counts per second (cps) were used to stand for the amounts of proteins and peptides. Then the correlation between sum of ion intensity (cps) of all the peptides, number of peptides detected and the amount of proteins was investigated. By comparing the change of values of the same sample in three parallel experiments, a linear relationship between these indexes and the amount of proteins within 1-1024 fmol was found when the cps was more than 1000. Usually, the maximal ion intensity was no more than 1.5 times of the minimum value for same peptide in triplicate experiments, which suggested that the 3 times or more change of ion intensity was the minimum threshold to determine the differences of proteins amounts in different samples. This study provides a relative quantitative analysis method using qualitative data of high resolution and high scan speed mass spectrometry, which can quickly and easily provide reference for biological and medical research.
2016, 44(3): 409-415
doi: 10.11895/j.issn.0253-3820.150769
Abstract:
An automated on-line solid phase extraction-liquid chromatography-tandem mass spectrometry (on-line SPE-LC-MS/MS) method for the simultaneous quantification of six endogenous phytohormones including abscisic acid (ABA), indole-3-acetic acid (IAA), salicylic acid (SA), jasmonic acid (JA), indole-3-propionic acid (IPA) and indole-3-butyric acid (IBA) in rice tissues was described. Plant samples were extracted with methanol and on-line SPE procedure was performed with C18 SPE cartridges. Analytes were eluted to C18 analytical column with mobile phase and further analyzed by LC-MS/MS. The performance of the method was fully validated. Linearity showed good correlation (R2≥0.99). Limits of detections (S/N=3) were in the range of 0.1-0.8 μg／kg. Recoveries varied between 71.2% and 126%. The method was rapid and sensitive to determine multiple phytohormones in rice young panicles and the results were cross-validated with the off-line SPE-LC-MS/MS phytohormone analytical method. Finally, the method was applied to monitor the changes of ABA, IAA, SA and JA in wounded rice leaves. The trends were in accord with plant physiological processes.
An automated on-line solid phase extraction-liquid chromatography-tandem mass spectrometry (on-line SPE-LC-MS/MS) method for the simultaneous quantification of six endogenous phytohormones including abscisic acid (ABA), indole-3-acetic acid (IAA), salicylic acid (SA), jasmonic acid (JA), indole-3-propionic acid (IPA) and indole-3-butyric acid (IBA) in rice tissues was described. Plant samples were extracted with methanol and on-line SPE procedure was performed with C18 SPE cartridges. Analytes were eluted to C18 analytical column with mobile phase and further analyzed by LC-MS/MS. The performance of the method was fully validated. Linearity showed good correlation (R2≥0.99). Limits of detections (S/N=3) were in the range of 0.1-0.8 μg／kg. Recoveries varied between 71.2% and 126%. The method was rapid and sensitive to determine multiple phytohormones in rice young panicles and the results were cross-validated with the off-line SPE-LC-MS/MS phytohormone analytical method. Finally, the method was applied to monitor the changes of ABA, IAA, SA and JA in wounded rice leaves. The trends were in accord with plant physiological processes.
2016, 44(3): 416-422
doi: 10.11895/j.issn.0253-3820.150772
Abstract:
A gas chromalography field ionization time-of-flight mass spectrometric (GC-FI TOF MS) technology was used to characterize the carbon number distribution of paraffins with different levels of isomerization in petroleum middle fractions. Firstly, with GC-FI TOF MS, the paraffins with different levels of isomerization were identified. Secondly, the relative response factors of normal paraffins and iso-paraffins were determined and their quantitative analysis methods were established. Finally, the accuracy and precision of the method were examined. The results indicated that paraffins with the same carbon number could be divided into poly-substituted iso-paraffins, mono-substituted iso-paraffins and normal paraffins by GC-FI TOF MS. The quantitation of paraffins with different levels of isomerization could be obtained. The accuracy and precision were acceptable. The sample pre-separation was not required which greatly shortened the analysis time. The analysis provides the information for the carbon number distribution of iso-paraffins with different levels of isomerization.
A gas chromalography field ionization time-of-flight mass spectrometric (GC-FI TOF MS) technology was used to characterize the carbon number distribution of paraffins with different levels of isomerization in petroleum middle fractions. Firstly, with GC-FI TOF MS, the paraffins with different levels of isomerization were identified. Secondly, the relative response factors of normal paraffins and iso-paraffins were determined and their quantitative analysis methods were established. Finally, the accuracy and precision of the method were examined. The results indicated that paraffins with the same carbon number could be divided into poly-substituted iso-paraffins, mono-substituted iso-paraffins and normal paraffins by GC-FI TOF MS. The quantitation of paraffins with different levels of isomerization could be obtained. The accuracy and precision were acceptable. The sample pre-separation was not required which greatly shortened the analysis time. The analysis provides the information for the carbon number distribution of iso-paraffins with different levels of isomerization.
2016, 44(3): 423-429
doi: 10.11895/j.issn.0253-3820.150726
Abstract:
A method of high performance liquid chromatography-quadrurpole/electrostatic field orbitrap high resolution mass spectrometry (HPLC-Q/Qrbitrap MS) was developed to determine 42 chemical drugs illegally added in herbal medicines and dietary supplements. The samples were pretreated based on the ultrasoni-cassisted extraction by the solvent of methanol-water (6:4, V/V), and centrifuged under 12000 r/min. Subsequently, the solution was filtered by a polytetrafluoroethylene (PTFE) membrane with pore size of 0.22 μm. The analytes were separated on a Phenomenex C18 (100 mm×4.6 mm, 2.6 μm) column through gradient elution with acetonitrile and 0.1% formic acid aqueous solution. The mass spectrometer was operated under Full MS/dd-MS2 experiment using positive and negative mode, respectively. Under the optimal conditions, 42 chemical drugs were well separated. Good linearity was obtained in their respective linear ranges with correlation coefficients higher than 0.99. The average recoveries at three spiked levels (20, 50 and 100 ng/g) were in the range of 69.3%-105.2% and the relative standard deviations (RSDs) lower than 8.9%. Based on the above method, 31 kinds of herbal medicines and dietary supplements were analyzed, in which metformin was found in three samples while sildenafil and hydroxyhomosildenafil were found in one sample, respectively. The proposed method is simple, time saving, high accuracy and sensitive. The method is suitable for confirmation and quantification of 42 chemical drugs in herbal medicines and dietary supplements. The research provides an effective method to control the quality and illegal addition for herbal medical and dietary supplements.
A method of high performance liquid chromatography-quadrurpole/electrostatic field orbitrap high resolution mass spectrometry (HPLC-Q/Qrbitrap MS) was developed to determine 42 chemical drugs illegally added in herbal medicines and dietary supplements. The samples were pretreated based on the ultrasoni-cassisted extraction by the solvent of methanol-water (6:4, V/V), and centrifuged under 12000 r/min. Subsequently, the solution was filtered by a polytetrafluoroethylene (PTFE) membrane with pore size of 0.22 μm. The analytes were separated on a Phenomenex C18 (100 mm×4.6 mm, 2.6 μm) column through gradient elution with acetonitrile and 0.1% formic acid aqueous solution. The mass spectrometer was operated under Full MS/dd-MS2 experiment using positive and negative mode, respectively. Under the optimal conditions, 42 chemical drugs were well separated. Good linearity was obtained in their respective linear ranges with correlation coefficients higher than 0.99. The average recoveries at three spiked levels (20, 50 and 100 ng/g) were in the range of 69.3%-105.2% and the relative standard deviations (RSDs) lower than 8.9%. Based on the above method, 31 kinds of herbal medicines and dietary supplements were analyzed, in which metformin was found in three samples while sildenafil and hydroxyhomosildenafil were found in one sample, respectively. The proposed method is simple, time saving, high accuracy and sensitive. The method is suitable for confirmation and quantification of 42 chemical drugs in herbal medicines and dietary supplements. The research provides an effective method to control the quality and illegal addition for herbal medical and dietary supplements.
2016, 44(3): 430-436
doi: 10.11895/j.issn.0253-3820.150739
Abstract:
A method for multiple solvent extraction coupled with gas chromatography-tandem mass spectrometry (GC-MS/MS) was established for the simultaneous determination of 16 polycyclic aromatic hydrocarbons (PAHs) in hot melt adhesive. The extraction conditions, purification conditions, chromatogphic conditions and tandem MS conditions of analysis were critically examined. The results were also compared with those obtained by gas chromatography-mass spectrometry (GC-MS). The sample was extracted by ultrasonic extraction with n-hexane as solvent at 60℃. Then, the extract was purified by centrifugation after freezing treatment, twice extraction with dimethyl sulfoxide, twice re-extraction with n-hexane in turn. The purified extract was determined by gas chromatography-tandem mass spectrometry under multiple reaction monitoring (MRM) mode. The linear correlation coefficients were above 0.9969, the limits of detection (LOD) ranged from 1.0 μg/kg to 10 μg/kg, the relative standard deviations (RSDs) were below 6.3%, and the recoveries ranged from 80.4% to 117.6% at three spiked levels. The matrix effects of tandem MS were studied, but there was no significance. Compared with GC-MS methods, the established method outperformed the GC-MS methods in LOD, which ranged from 23 μg/kg to 94 μg/kg for GC-MS, and could greatly enhance the accuracy of the qualitative and quantitative analysis of PAHs. The results indicated that the method was sensitive, accurate and reproducible, and suitable for the simultaneous determination of 16 PAHs in hot melt adhesive.
A method for multiple solvent extraction coupled with gas chromatography-tandem mass spectrometry (GC-MS/MS) was established for the simultaneous determination of 16 polycyclic aromatic hydrocarbons (PAHs) in hot melt adhesive. The extraction conditions, purification conditions, chromatogphic conditions and tandem MS conditions of analysis were critically examined. The results were also compared with those obtained by gas chromatography-mass spectrometry (GC-MS). The sample was extracted by ultrasonic extraction with n-hexane as solvent at 60℃. Then, the extract was purified by centrifugation after freezing treatment, twice extraction with dimethyl sulfoxide, twice re-extraction with n-hexane in turn. The purified extract was determined by gas chromatography-tandem mass spectrometry under multiple reaction monitoring (MRM) mode. The linear correlation coefficients were above 0.9969, the limits of detection (LOD) ranged from 1.0 μg/kg to 10 μg/kg, the relative standard deviations (RSDs) were below 6.3%, and the recoveries ranged from 80.4% to 117.6% at three spiked levels. The matrix effects of tandem MS were studied, but there was no significance. Compared with GC-MS methods, the established method outperformed the GC-MS methods in LOD, which ranged from 23 μg/kg to 94 μg/kg for GC-MS, and could greatly enhance the accuracy of the qualitative and quantitative analysis of PAHs. The results indicated that the method was sensitive, accurate and reproducible, and suitable for the simultaneous determination of 16 PAHs in hot melt adhesive.
2016, 44(3): 437-443
doi: 10.11895/j.issn.0253-3820.150765
Abstract:
A derivative spectral estimator (DSE) based on singular perturbation technique was designed and a quantitative analysis method based on derivative spectra information space, termed derivative spectra fusion interval partial least squares (DSF-iPLS) modeling was proposed. DSF-iPLS mainly focused on obtaining final fusion model by making full use of derivative spectra information. The glucose spectra dataset with concentrate ranging from 0.04% to 5% and the beer spectra dataset with the original extract concentration ranging from 4.23 to18.76°P (Plato) were used to evaluate the effectiveness of the proposed quantitative analysis method. The experiment results indicated that DSF-iPLS model for two infrared spectra datasets provided the minimum root mean square error of prediction (RMSEP) and the values were 0.121 and 0.087, respectively. Compared with other single model, DSF-iPLS model based derivative spectra could provide more excellent predictive performance.
A derivative spectral estimator (DSE) based on singular perturbation technique was designed and a quantitative analysis method based on derivative spectra information space, termed derivative spectra fusion interval partial least squares (DSF-iPLS) modeling was proposed. DSF-iPLS mainly focused on obtaining final fusion model by making full use of derivative spectra information. The glucose spectra dataset with concentrate ranging from 0.04% to 5% and the beer spectra dataset with the original extract concentration ranging from 4.23 to18.76°P (Plato) were used to evaluate the effectiveness of the proposed quantitative analysis method. The experiment results indicated that DSF-iPLS model for two infrared spectra datasets provided the minimum root mean square error of prediction (RMSEP) and the values were 0.121 and 0.087, respectively. Compared with other single model, DSF-iPLS model based derivative spectra could provide more excellent predictive performance.
2016, 44(3): 444-450
doi: 10.11895/j.issn.0253-3820.150831
Abstract:
A method was established for the analysis of red Freesia flower volatiles by indirect headspace solid phase microextraction (HS-SPME). The gas collecting tube was used to enrich flower volatiles, and adsorbing material was resolved in the extraction solution. Then, the adsorbing material was analyzed by HS-SPME. The experimental conditions for the quantification of major flower volatiles (linalool, terpineol, ionone and dihydrogen-ionone) were optimized. Florisil was used as adsorbent, with water-methanol solution (9:1, V/V) and 0.6 mol/L hydrochloric acid as the extraction solution. The thermal desorption temperature was 70℃ and the extraction time was 25 min. The results showed that the concentration range of linear relationship for linalool and terpineol (R2≥0.981) was 1-100 μg/mL, with detection limits of 0.05 and 0.10 μg, respectively, and 0.5-50 μg/mL for dihydro ionone and ionone (R2≥0.988) with a detection limit of 0.02 μg.
A method was established for the analysis of red Freesia flower volatiles by indirect headspace solid phase microextraction (HS-SPME). The gas collecting tube was used to enrich flower volatiles, and adsorbing material was resolved in the extraction solution. Then, the adsorbing material was analyzed by HS-SPME. The experimental conditions for the quantification of major flower volatiles (linalool, terpineol, ionone and dihydrogen-ionone) were optimized. Florisil was used as adsorbent, with water-methanol solution (9:1, V/V) and 0.6 mol/L hydrochloric acid as the extraction solution. The thermal desorption temperature was 70℃ and the extraction time was 25 min. The results showed that the concentration range of linear relationship for linalool and terpineol (R2≥0.981) was 1-100 μg/mL, with detection limits of 0.05 and 0.10 μg, respectively, and 0.5-50 μg/mL for dihydro ionone and ionone (R2≥0.988) with a detection limit of 0.02 μg.
2016, 44(3): 451-455
doi: 10.11895/j.issn.0253-3820.150872
Abstract:
In this study, the rapid resolution liquid chromatography quadrupole time-of-flight mass spectrometry (RRLC-QTOF/MS) was used to profile the metabolites of urine samples from Childhood Pneumonia (CP) patients and healthy controls and find the potential biomarkers which can support evidence to early diagnose and cure the disease. Choose 10 CP patients (age 47.72±2.35 months) and 10 healthy controls (age 46.65±1.97 months). The urine samples were analyzed by RRLC-QTOF/MS and then the resulting data matrices were analyzed by principal components analysis (PCA) to find the potential biomarkers. Urine samples of CP patients were successfully distinguished from those of healthy controls. A total of two significantly changed metabolites have been found and identified as potential biomarkers. It is suggested that the disorder of purine metabolism and amino acid metabolism may play an important role in the mechanism of CP.
In this study, the rapid resolution liquid chromatography quadrupole time-of-flight mass spectrometry (RRLC-QTOF/MS) was used to profile the metabolites of urine samples from Childhood Pneumonia (CP) patients and healthy controls and find the potential biomarkers which can support evidence to early diagnose and cure the disease. Choose 10 CP patients (age 47.72±2.35 months) and 10 healthy controls (age 46.65±1.97 months). The urine samples were analyzed by RRLC-QTOF/MS and then the resulting data matrices were analyzed by principal components analysis (PCA) to find the potential biomarkers. Urine samples of CP patients were successfully distinguished from those of healthy controls. A total of two significantly changed metabolites have been found and identified as potential biomarkers. It is suggested that the disorder of purine metabolism and amino acid metabolism may play an important role in the mechanism of CP.
2016, 44(3): 456-461
doi: 10.11895/j.issn.0253-3820.150729
Abstract:
Laser tweezers Raman spectroscopy (LTRS) was used to study the inhibitory effect of indol on staphyloxanthin biosynthesis in Staphylococcus aureus cells and the dynamic changes of this pigment content inside bacterial cells during batch cultivation. The Raman spectra of Staphylococcus aureus cells cultivated for different time and exposed to various doses of indol were acquired. The intensity of 1523 cm-1 band was used for the quantification of staphyloxanthin, in the meantime, the pigment was measured by UV spectrometry. The experimental result showed that an excellent linear relationship existed between the intensities of Raman peak at 1523 cm-1 of bacterial cells and the pigment contents estimated by UV spectrometry, with a correlation coefficient of 0.9772. The spectral data at population level as well as single cell level revealed that indol could inhibit the production of pigment in dose-dependent manner, and the pigment content in bacterial cells incubated with indol decreased by 70%. Under the batch growth condition, the pigment amount in Staphylococcus aureus cells reached the maximum value during the middle exponential growth phase (12 h) and the heterogeneity of pigment content in bacterial cells within certain populations at various time points was relatively small, with RSDs of 39.2% to 61.1%. This investigation indicates that LTRS can be served as a reliable method for the analysis of staphyloxanthin content at single cell level.
Laser tweezers Raman spectroscopy (LTRS) was used to study the inhibitory effect of indol on staphyloxanthin biosynthesis in Staphylococcus aureus cells and the dynamic changes of this pigment content inside bacterial cells during batch cultivation. The Raman spectra of Staphylococcus aureus cells cultivated for different time and exposed to various doses of indol were acquired. The intensity of 1523 cm-1 band was used for the quantification of staphyloxanthin, in the meantime, the pigment was measured by UV spectrometry. The experimental result showed that an excellent linear relationship existed between the intensities of Raman peak at 1523 cm-1 of bacterial cells and the pigment contents estimated by UV spectrometry, with a correlation coefficient of 0.9772. The spectral data at population level as well as single cell level revealed that indol could inhibit the production of pigment in dose-dependent manner, and the pigment content in bacterial cells incubated with indol decreased by 70%. Under the batch growth condition, the pigment amount in Staphylococcus aureus cells reached the maximum value during the middle exponential growth phase (12 h) and the heterogeneity of pigment content in bacterial cells within certain populations at various time points was relatively small, with RSDs of 39.2% to 61.1%. This investigation indicates that LTRS can be served as a reliable method for the analysis of staphyloxanthin content at single cell level.
2016, 44(3): 462-467
doi: 10.11895/j.issn.0253-3820.150764
Abstract:
A method was developed for the quantification of cyclohexylamine in human urine samples by ultra performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) with pre-column derivatization. After the refrigerated centrifugation of urine samples, cyclohexylamine in supernatant was derived with dansyl chloride and then its derivant was purified with solid phase extraction (SPE). The target compounds were separated on a Waters ACQUITY CSHTM C18 column (50 mm×2.1 mm, 1.7 μm) with the gradient elution of methanol and water (containing 0.002 mol/L ammonium acetate) and were determined in electrospray positive ionization (ESI+) and multiple reaction monitoring (MRM) modes. The linear range was 2.5-200 μg/L for cyclohexylamine with the correlation coefficient more than 0.999. The recovery ranged from 98.7% to 102.3%, with the relative standard deviations (RSDs) of 3.1%-5.2%. The limit of detection (LOD) and the limit of quantitation (LOQ) were 1 μg/L and 3 μg/L. The results indicated that the method was accurate and reliable, and suitable for the detection of cyclohexylamine in urine samples. The urine samples of 200 primary school students were analyzed by this method and the positive rate of cyclohexylamine was 34.5%.
A method was developed for the quantification of cyclohexylamine in human urine samples by ultra performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) with pre-column derivatization. After the refrigerated centrifugation of urine samples, cyclohexylamine in supernatant was derived with dansyl chloride and then its derivant was purified with solid phase extraction (SPE). The target compounds were separated on a Waters ACQUITY CSHTM C18 column (50 mm×2.1 mm, 1.7 μm) with the gradient elution of methanol and water (containing 0.002 mol/L ammonium acetate) and were determined in electrospray positive ionization (ESI+) and multiple reaction monitoring (MRM) modes. The linear range was 2.5-200 μg/L for cyclohexylamine with the correlation coefficient more than 0.999. The recovery ranged from 98.7% to 102.3%, with the relative standard deviations (RSDs) of 3.1%-5.2%. The limit of detection (LOD) and the limit of quantitation (LOQ) were 1 μg/L and 3 μg/L. The results indicated that the method was accurate and reliable, and suitable for the detection of cyclohexylamine in urine samples. The urine samples of 200 primary school students were analyzed by this method and the positive rate of cyclohexylamine was 34.5%.
2016, 44(3): 468-473
doi: 10.11895/j.issn.0253-3820.150750
Abstract:
Volume concentration determination for atmospheric krypton and xenon is very important for krypton-85 and radioactive xenon isotopes monitoring. An injection setup integrated adjustable quantity sample injection and quantitative dilution function was designed. The effects of EI source parameters on the sensitivity of MS detector were studied. The optimized values were as following: ionization energy of 70 eV, emission current of 40 mA, cathode voltage of 27 mV, focus voltage of 85 mV and lens compensation of 20 V, respectively. A GC-MS method for the determination of krypton and xenon in atmosphere without of sample pretreatment was developed. The minimal detected concentrations for krypton and xenon were 3.3×10-8(V/V) and 2.6×10-9(V/V). Moreover, the krypton and xenon concentrations in the ground level air around our laboratory were measured with the results of 1.1×10-6 (V/V) and 9.3×10-8 (V/V). The related combined standard uncertainties for krypton and xenon results were 2.38% and 3.15%, respectively.
Volume concentration determination for atmospheric krypton and xenon is very important for krypton-85 and radioactive xenon isotopes monitoring. An injection setup integrated adjustable quantity sample injection and quantitative dilution function was designed. The effects of EI source parameters on the sensitivity of MS detector were studied. The optimized values were as following: ionization energy of 70 eV, emission current of 40 mA, cathode voltage of 27 mV, focus voltage of 85 mV and lens compensation of 20 V, respectively. A GC-MS method for the determination of krypton and xenon in atmosphere without of sample pretreatment was developed. The minimal detected concentrations for krypton and xenon were 3.3×10-8(V/V) and 2.6×10-9(V/V). Moreover, the krypton and xenon concentrations in the ground level air around our laboratory were measured with the results of 1.1×10-6 (V/V) and 9.3×10-8 (V/V). The related combined standard uncertainties for krypton and xenon results were 2.38% and 3.15%, respectively.
2016, 44(3): 474-481
doi: 10.11895/j.issn.0253-3820.150923
Abstract:
Nanofibers have been considered as a potential kind of sorbent for solid phase extraction, accordingly nanofiber-based solid phase extraction (Nanofibers based solid phase extraction, NFs-SPE) becomes a popular research point of sample pretreatment technique. This article reviewed in and abroad research status of practical application in food, environmental and biological sample preparation based on nanofibers mat, and proposed that there was a dual "structure"-"activity" relationship between target adsorption efficiency and the two structures (nanometer morphological structure and molecular structure) of nanofibers, which would be the key breakthrough to explore adsorption mechanism.
Nanofibers have been considered as a potential kind of sorbent for solid phase extraction, accordingly nanofiber-based solid phase extraction (Nanofibers based solid phase extraction, NFs-SPE) becomes a popular research point of sample pretreatment technique. This article reviewed in and abroad research status of practical application in food, environmental and biological sample preparation based on nanofibers mat, and proposed that there was a dual "structure"-"activity" relationship between target adsorption efficiency and the two structures (nanometer morphological structure and molecular structure) of nanofibers, which would be the key breakthrough to explore adsorption mechanism.
Optimization of Performance of Toroidal Ion Trap with Triangular Electrode by Theoretical Simulation
2016, 44(3): 482-488
doi: 10.11895/j.issn.0253-3820.150900
Abstract:
The toroidal ion trap is an ideal candidate for miniaturized ion trap because it has much higher ion trapping capacity than a standard quadrupole ion trap of equal trapping dimensions. A novel toroidal ion trap mass analyzer with triangular electrode which contained a filament end cap, a detector endcap, an inner ring and an outer ring was reported. After designing and optimizing the electrodes by theoretical simulations, we found that the asymmetric triangle electrodes could reduce the affection from toroidal shape and improve the ion ejection rate and the mass resolution of the ion trap. The best design of the toroidal ion trap with a mass resolution of 1486 at m/z 609 was obtained.
The toroidal ion trap is an ideal candidate for miniaturized ion trap because it has much higher ion trapping capacity than a standard quadrupole ion trap of equal trapping dimensions. A novel toroidal ion trap mass analyzer with triangular electrode which contained a filament end cap, a detector endcap, an inner ring and an outer ring was reported. After designing and optimizing the electrodes by theoretical simulations, we found that the asymmetric triangle electrodes could reduce the affection from toroidal shape and improve the ion ejection rate and the mass resolution of the ion trap. The best design of the toroidal ion trap with a mass resolution of 1486 at m/z 609 was obtained.
