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2017 Volume 45 Issue 7
2017, 45(7): 937-943
doi: 10.11895/j.issn.0253-3820.170248
Abstract:
Early diagnosis and intervention is an important way to delay the progress of Alzheimer's disease (AD). Compared with cerebrospinal fluid, blood sampling is not invasive and easy to be obtained in clinic practice. In this study, the serum samples of 9 controls, 10 AD and 12 mild cognitive dysfunction (MCI) patients were analyzed and compared through one by one analysis to screen potential markers for AD diagnosis. The experimental results showed that VGFYESDVMGR of α-2-macroglobulin peptide was closely related to the late stage of AD disease, and the large amount degradation of apolipoprotein C-Ⅲ, histone H1.2 and histone H1.4 was significantly related to early stages of AD progression. The characteristics of serum peptidome were different for the early and late AD, and these four proteins may be used as potential biomarkers of AD disease. In addition, the obvious ladder sequence characteristic was observed for apolipoprotein C-Ⅲ and histone H1, which could partly explain why the peptides distribution in different samples was somewhat contingent. On the contrary, the distribution at protein level was more stable. Finally, it was confirmed that the peptides of proteins such as fibrinogen α-chain, thymosin β-4 and patchy proteins were the dominant peptides in all serum samples. Overall, this study showed that the method of using serum peptidomics to diagnose AD was possible. The results may provide evidence and references for the large-scale clinical validation of AD.
Early diagnosis and intervention is an important way to delay the progress of Alzheimer's disease (AD). Compared with cerebrospinal fluid, blood sampling is not invasive and easy to be obtained in clinic practice. In this study, the serum samples of 9 controls, 10 AD and 12 mild cognitive dysfunction (MCI) patients were analyzed and compared through one by one analysis to screen potential markers for AD diagnosis. The experimental results showed that VGFYESDVMGR of α-2-macroglobulin peptide was closely related to the late stage of AD disease, and the large amount degradation of apolipoprotein C-Ⅲ, histone H1.2 and histone H1.4 was significantly related to early stages of AD progression. The characteristics of serum peptidome were different for the early and late AD, and these four proteins may be used as potential biomarkers of AD disease. In addition, the obvious ladder sequence characteristic was observed for apolipoprotein C-Ⅲ and histone H1, which could partly explain why the peptides distribution in different samples was somewhat contingent. On the contrary, the distribution at protein level was more stable. Finally, it was confirmed that the peptides of proteins such as fibrinogen α-chain, thymosin β-4 and patchy proteins were the dominant peptides in all serum samples. Overall, this study showed that the method of using serum peptidomics to diagnose AD was possible. The results may provide evidence and references for the large-scale clinical validation of AD.
2017, 45(7): 944-950
doi: 10.11895/j.issn.0253-3820.170014
Abstract:
In this work, we used dual-polarization interferometry to explore the binding events between adenosine triphosphate (ATP) and ATP-binding aptamer (ABA) at solid-liquid interface. The single-stranded ABA was immobilized onto the chip surface. After the addition of ATP, the real-time and label-free technique for detailed investigation of their interactions were reflected on the changes of the mass, thickness, and density through DPI. By analysis of the binding curves from changes in mass, the association rate constant (ka, 4.66×103 L/(mol·s), dissociation rate constant (kd, 1.70 × 10-2 s-1), dissociation constant (KA, 2.7 × 105 L/mol), and association constant (KD, 3.7 × 10-6 mol/L) were precisely determined. Moreover, good linear correlations between ATP concentrations and three parameters (mass, thickness, density) resolved by the response to ATP binding were obtained. The detection limits (LOD, 3σ) were 0.22 μmol/L for mass calibration, 0.14 μmol/L for thickness calibration, and 0.32 μmol/L for density calibration. We expect that this DPI-based aptasensor can be utilized to study the interactions of functional ABA with ATP, and also can be used for the detection of ATP with high sensitivity.
In this work, we used dual-polarization interferometry to explore the binding events between adenosine triphosphate (ATP) and ATP-binding aptamer (ABA) at solid-liquid interface. The single-stranded ABA was immobilized onto the chip surface. After the addition of ATP, the real-time and label-free technique for detailed investigation of their interactions were reflected on the changes of the mass, thickness, and density through DPI. By analysis of the binding curves from changes in mass, the association rate constant (ka, 4.66×103 L/(mol·s), dissociation rate constant (kd, 1.70 × 10-2 s-1), dissociation constant (KA, 2.7 × 105 L/mol), and association constant (KD, 3.7 × 10-6 mol/L) were precisely determined. Moreover, good linear correlations between ATP concentrations and three parameters (mass, thickness, density) resolved by the response to ATP binding were obtained. The detection limits (LOD, 3σ) were 0.22 μmol/L for mass calibration, 0.14 μmol/L for thickness calibration, and 0.32 μmol/L for density calibration. We expect that this DPI-based aptasensor can be utilized to study the interactions of functional ABA with ATP, and also can be used for the detection of ATP with high sensitivity.
2017, 45(7): 951-957
doi: 10.11895/j.issn.0253-3820.170104
Abstract:
In the present study, the effect of serum (fetal bovine serum, FBS) on cellular uptake behaviors of DNA tetrahedron (TDNs) was investigated. Fluorescence-labeled TDNs were synthesized by self-assembly and purified with HPLC to achieve TDNs product with purity of 95%. By means of flow cytometry and confocal microscopy, the kinetics of TDNs endocytosis in HeLa cells in the presence or absence of FBS was compared. The results showed that TDNs remained intact in complete medium and cell lysate for more than 12 hours. FBS increased the amount of internalized TDNs in HeLa cells, whereas it did not change the route of caveolin-dependent endocytosis. Herein, our study provided a new insight into the effects of biomolecules on the interaction between cells and DNA nanostructures, which helped the future development of DNA-based intracellular nanocarriers.
In the present study, the effect of serum (fetal bovine serum, FBS) on cellular uptake behaviors of DNA tetrahedron (TDNs) was investigated. Fluorescence-labeled TDNs were synthesized by self-assembly and purified with HPLC to achieve TDNs product with purity of 95%. By means of flow cytometry and confocal microscopy, the kinetics of TDNs endocytosis in HeLa cells in the presence or absence of FBS was compared. The results showed that TDNs remained intact in complete medium and cell lysate for more than 12 hours. FBS increased the amount of internalized TDNs in HeLa cells, whereas it did not change the route of caveolin-dependent endocytosis. Herein, our study provided a new insight into the effects of biomolecules on the interaction between cells and DNA nanostructures, which helped the future development of DNA-based intracellular nanocarriers.
2017, 45(7): 958-964
doi: 10.11895/j.issn.0253-3820.160923
Abstract:
While the near infrared spectroscopy (NIRS) is used to measure the inhomogeneous samples with diffuse reflection mode, the accuracy and robustness of the calibration model is not quite good for the variation of spectrum scattering and absorption coefficient in those samples. Therefore, an establishment strategy of hybrid model based on homogeneous sample and calibration transfer method was proposed to solve the problem of detection inhomogeneous samples by NIRS. This work was focused on the tobacco leaf samples aspect. Three common calibration transfer methods, including Shenk's patented algorithm (Shenk's), piecewise direct standardization (PDS) and calibration transfer based on canonical correlation analysis (CTCCA), were used to construct two hybrid models of tobacco powder mixed with cut tobacco and tobacco powder mixed with tobacco flake samples to predict nicotine content in the samples of cut tobacco and tobacco flake. Experimental results showed that the hybrid model of adding some cut tobacco and tobacco flake samples to the powder model would get preferred prediction ability. Root mean square errors of cut tobacco and tobacco flake samples were reduced by 1.39% and 2.73%, respectively. This showed that the hybrid model was help for the improvement of the predicted results and the robustness of model. Moreover, CTCCA got the optimal performance between these three calibration transfer methods. Therefore, the scheme of building a hybrid model by NIRS homogeneous model and calibration transfer method to determinate the heterogeneous samples is feasible, which can accelerate the development of on-line near infrared spectroscopy technology and will provide reference for the share of near infrared spectral model.
While the near infrared spectroscopy (NIRS) is used to measure the inhomogeneous samples with diffuse reflection mode, the accuracy and robustness of the calibration model is not quite good for the variation of spectrum scattering and absorption coefficient in those samples. Therefore, an establishment strategy of hybrid model based on homogeneous sample and calibration transfer method was proposed to solve the problem of detection inhomogeneous samples by NIRS. This work was focused on the tobacco leaf samples aspect. Three common calibration transfer methods, including Shenk's patented algorithm (Shenk's), piecewise direct standardization (PDS) and calibration transfer based on canonical correlation analysis (CTCCA), were used to construct two hybrid models of tobacco powder mixed with cut tobacco and tobacco powder mixed with tobacco flake samples to predict nicotine content in the samples of cut tobacco and tobacco flake. Experimental results showed that the hybrid model of adding some cut tobacco and tobacco flake samples to the powder model would get preferred prediction ability. Root mean square errors of cut tobacco and tobacco flake samples were reduced by 1.39% and 2.73%, respectively. This showed that the hybrid model was help for the improvement of the predicted results and the robustness of model. Moreover, CTCCA got the optimal performance between these three calibration transfer methods. Therefore, the scheme of building a hybrid model by NIRS homogeneous model and calibration transfer method to determinate the heterogeneous samples is feasible, which can accelerate the development of on-line near infrared spectroscopy technology and will provide reference for the share of near infrared spectral model.
2017, 45(7): 965-972
doi: 10.11895/j.issn.0253-3820.170081
Abstract:
Quantitative calibration strategy as an essential issue in laser ablation ICP-MS plays an important role for the guarantee of analytical accuracy. In this study, uncertainties of reference values in current available glass certified reference materials (NIST, MPI-DING and USGS) as well as the matrix effect among them were systematically evaluated. The results illustrated that NIST610 was better than other reference materials from aspect of reference value uncertainty. The matrix effect among NIST, MPI-DING and USGS reference materials was insignificant under our experimental conditions. A quantification strategy based on two reference materials (NIST610 and StHs6/80-G) and normalization to 100% (w/w) was proposed to avoid the insufficiency of single reference material strategy, which suffered the very low content and large uncertainty for some elements. The comparision of ML3B-G results obtained from three quantification strategies (single reference material NIST610, single reference material StHs6/80-G and two refterence materials) illustrated that the proposed strategy improved the analytical accuracy. Three reference materials (BCR-2G, CGSG-2 and KL-2G) were quantified with the proposed strategy, and almost all data matched well with reference value, meanwhile the data reported here could supplement the reference value database.
Quantitative calibration strategy as an essential issue in laser ablation ICP-MS plays an important role for the guarantee of analytical accuracy. In this study, uncertainties of reference values in current available glass certified reference materials (NIST, MPI-DING and USGS) as well as the matrix effect among them were systematically evaluated. The results illustrated that NIST610 was better than other reference materials from aspect of reference value uncertainty. The matrix effect among NIST, MPI-DING and USGS reference materials was insignificant under our experimental conditions. A quantification strategy based on two reference materials (NIST610 and StHs6/80-G) and normalization to 100% (w/w) was proposed to avoid the insufficiency of single reference material strategy, which suffered the very low content and large uncertainty for some elements. The comparision of ML3B-G results obtained from three quantification strategies (single reference material NIST610, single reference material StHs6/80-G and two refterence materials) illustrated that the proposed strategy improved the analytical accuracy. Three reference materials (BCR-2G, CGSG-2 and KL-2G) were quantified with the proposed strategy, and almost all data matched well with reference value, meanwhile the data reported here could supplement the reference value database.
2017, 45(7): 973-979
doi: 10.11895/j.issn.0253-3820.170150
Abstract:
Trace impurities of Al, Ca, Co, Fe, K, Mg, Mn, Na, Ni in silicon nitride powder were determined by slurry introduction into a solution-cathode glow discharge-atomic emission spectrometer (SCGD-AES). The effect of particle size on the stability of suspension was investigated. A 6-port valve was selected to link sampling system and SCGD-AES, by which the suspension could be introduced into the SCGD-AES to get instantaneous spectrum signal. The calibration curves for quantitative analysis could be established using aqueous standards and the pH of suspension was not required to be adjusted accurately. The applied voltage, solution flow rate, and integral time of PMT were set to 1080 V, 1.2 mL/min and 800 ms, respectively. In this work, slurry sampling was combined with SCGD-AES by a 6 port 2-pos valve. Powder Si3N4 was tested by this way and the limits of detection for all nine elements were 0.2-53.0 mg/kg. The RSDs were 1.1%-5.0%. The detection result of trace impurities in standard reference material ERM-ED101 agreed with that obtained from inductively coupled plasma atomic emission spectrometry. This method was proved to be accurate, reliable and valuable.
Trace impurities of Al, Ca, Co, Fe, K, Mg, Mn, Na, Ni in silicon nitride powder were determined by slurry introduction into a solution-cathode glow discharge-atomic emission spectrometer (SCGD-AES). The effect of particle size on the stability of suspension was investigated. A 6-port valve was selected to link sampling system and SCGD-AES, by which the suspension could be introduced into the SCGD-AES to get instantaneous spectrum signal. The calibration curves for quantitative analysis could be established using aqueous standards and the pH of suspension was not required to be adjusted accurately. The applied voltage, solution flow rate, and integral time of PMT were set to 1080 V, 1.2 mL/min and 800 ms, respectively. In this work, slurry sampling was combined with SCGD-AES by a 6 port 2-pos valve. Powder Si3N4 was tested by this way and the limits of detection for all nine elements were 0.2-53.0 mg/kg. The RSDs were 1.1%-5.0%. The detection result of trace impurities in standard reference material ERM-ED101 agreed with that obtained from inductively coupled plasma atomic emission spectrometry. This method was proved to be accurate, reliable and valuable.
2017, 45(7): 980-986
doi: 10.11895/j.issn.0253-3820.170012
Abstract:
Solid internal pressure is one of the important parameters in traffic bridge and defense field. However, the existing testing equipments have the defects of serious electromagnetic interference, poor reliability, and poor accuracy. To overcome the above problems, a fiber bragg grating (FBG) high pressure solid pressure sensor which used thin plates as elastic bearing diaphragm and applied the deflection under pressure to pull the pressure sensitive grating to realize pressure sensing axial displacement was designed. By calculating on the structure according to the measurement range and finite element simulation, its feasibility was confirmed. In the laboratory with constant temperature, the pressure calibration experiment was carried out, and the temperature compensation was performed by the temperature compensation grating in the same temperature field to correct the temperature drift of strain grating. Experimental results showed that the newly devised FBG pressure sensor could sense the pressure as high as 50 MPa, with a linearity of 99.2%.
Solid internal pressure is one of the important parameters in traffic bridge and defense field. However, the existing testing equipments have the defects of serious electromagnetic interference, poor reliability, and poor accuracy. To overcome the above problems, a fiber bragg grating (FBG) high pressure solid pressure sensor which used thin plates as elastic bearing diaphragm and applied the deflection under pressure to pull the pressure sensitive grating to realize pressure sensing axial displacement was designed. By calculating on the structure according to the measurement range and finite element simulation, its feasibility was confirmed. In the laboratory with constant temperature, the pressure calibration experiment was carried out, and the temperature compensation was performed by the temperature compensation grating in the same temperature field to correct the temperature drift of strain grating. Experimental results showed that the newly devised FBG pressure sensor could sense the pressure as high as 50 MPa, with a linearity of 99.2%.
2017, 45(7): 987-995
doi: 10.11895/j.issn.0253-3820.170180
Abstract:
A method was developed for determination of 12 kinds of phosphate compounds in water and sediment by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) coupled with solid phase extraction (SPE) and ultrasonic extraction. The water samples were concentrated by HLB solid-phase extraction (SPE) column and eluted twice with ethyl acetate, ultrasonic solvent extraction for sediment samples and then repeated the operation of water samples after diluted with deionized water. The sample were separated on a ZORBAX Eclipse Plus C18 (150 mm × 2.1 mm, 3.5 μm) column by a gradient elution with 0.2% formic acid aqueous solution and methanol as the mobile phase. Ion mode analysis was monitored by high performance liquid chromatography mass spectrometer (MRM). The target compounds were quantified by external standard method. At the spiked levels (0.05, 0.1 and 0.5 μg/L), the average recoveries of 12 kinds of OPEs in water samples ranged from 66.4% to 115%, except for TMP (28.5%-47.8%) and TEHP (22.4%-73.8%). The relative standard deviation RSD (n=3) was 0.5%-9.09%, and the method quantification (MOQ) was 0.001-0.05 μg/L, However at the spiked levels of 5, 10 and 50 μg/kg, the average recoveries of 12 kinds of OPEs in sediment samples ranged from 65.4% to 120.0%, except for TMP (35.7%-44.9%) and TCEP (31.2%-48.9%). The relative standard deviation RSD (n=3) was 0.01%-9.54%, and the MOQ for sediment was 0.02-2.0 μg/kg dw. Based on the above methods, the detection and analysis of the targets in the water and sediments samples of Taihu Lake were carried out. The results showed that the concentrations of ΣOPEs were 0.1-1.7 μg/L and 8.1-420 μg/(kg dw), respectively.
A method was developed for determination of 12 kinds of phosphate compounds in water and sediment by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) coupled with solid phase extraction (SPE) and ultrasonic extraction. The water samples were concentrated by HLB solid-phase extraction (SPE) column and eluted twice with ethyl acetate, ultrasonic solvent extraction for sediment samples and then repeated the operation of water samples after diluted with deionized water. The sample were separated on a ZORBAX Eclipse Plus C18 (150 mm × 2.1 mm, 3.5 μm) column by a gradient elution with 0.2% formic acid aqueous solution and methanol as the mobile phase. Ion mode analysis was monitored by high performance liquid chromatography mass spectrometer (MRM). The target compounds were quantified by external standard method. At the spiked levels (0.05, 0.1 and 0.5 μg/L), the average recoveries of 12 kinds of OPEs in water samples ranged from 66.4% to 115%, except for TMP (28.5%-47.8%) and TEHP (22.4%-73.8%). The relative standard deviation RSD (n=3) was 0.5%-9.09%, and the method quantification (MOQ) was 0.001-0.05 μg/L, However at the spiked levels of 5, 10 and 50 μg/kg, the average recoveries of 12 kinds of OPEs in sediment samples ranged from 65.4% to 120.0%, except for TMP (35.7%-44.9%) and TCEP (31.2%-48.9%). The relative standard deviation RSD (n=3) was 0.01%-9.54%, and the MOQ for sediment was 0.02-2.0 μg/kg dw. Based on the above methods, the detection and analysis of the targets in the water and sediments samples of Taihu Lake were carried out. The results showed that the concentrations of ΣOPEs were 0.1-1.7 μg/L and 8.1-420 μg/(kg dw), respectively.
2017, 45(7): 996-1004
doi: 10.11895/j.issn.0253-3820.160853
Abstract:
A ball milling method which is green with simple-manipulation and low-cost was used to prepare graphene as precursor for graphene quantum dots (GQDs) synthesis. Subsequently, GQDs with good dispersibility, uniform size distribution, average diameter of (4.80 ± 0.20) nm and 1-3 layers were prepared by one-step hydrothermal method. The morphology, structure and optical properties of the GQDs were characterized by high-resolution transmission electron microscopy (HRTEM), atomic force microscope (AFM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), UV-Vis absorption and fluorescence spectroscopy. Furthermore, the GQDs were used in label-free and specific detection of ferric ion (Fe3+) with broad linear ranges of 2.0×10-6-7.0×10-4 mol/L and low detection limit of 1.8 × 10-6 mol/L (S/N=3). The possible mechanism was also discussed and the application of GQDs for Fe3+ detection in tap water was demonstrated. Finally, based on their low cytotoxicity and excellent biocompatibility, the as-prepared GQDs were successfully applied to efficient cell imaging. This work provides a new way for preparation of carbon-based nanomaterials and build a foundation for deepening applications of GQDs in bio-/chem- analysis, bioimaging, etc.
A ball milling method which is green with simple-manipulation and low-cost was used to prepare graphene as precursor for graphene quantum dots (GQDs) synthesis. Subsequently, GQDs with good dispersibility, uniform size distribution, average diameter of (4.80 ± 0.20) nm and 1-3 layers were prepared by one-step hydrothermal method. The morphology, structure and optical properties of the GQDs were characterized by high-resolution transmission electron microscopy (HRTEM), atomic force microscope (AFM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), UV-Vis absorption and fluorescence spectroscopy. Furthermore, the GQDs were used in label-free and specific detection of ferric ion (Fe3+) with broad linear ranges of 2.0×10-6-7.0×10-4 mol/L and low detection limit of 1.8 × 10-6 mol/L (S/N=3). The possible mechanism was also discussed and the application of GQDs for Fe3+ detection in tap water was demonstrated. Finally, based on their low cytotoxicity and excellent biocompatibility, the as-prepared GQDs were successfully applied to efficient cell imaging. This work provides a new way for preparation of carbon-based nanomaterials and build a foundation for deepening applications of GQDs in bio-/chem- analysis, bioimaging, etc.
2017, 45(7): 1005-1011
doi: 10.11895/j.issn.0253-3820.160872
Abstract:
Huolinguole lignite was sequentially extracted with carbon disulfide, ethyl acetate, methanol and acetone. All of the extracts were analyzed using a time-of-flight mass spectrometry (TOF-MS) equipped with an atmospheric pressure photoionization (APPI) ion source. Toluene or 1,4-difluorobenzene was chosen as dopant for APPI. The results indicated that both dopants could well ionize compounds which could not be ionized by APPI without dopant. Toluene induced higher ionization efficiency than 1,4-difluorobenzene. Some compounds in the extracts were identified as dimers, which might be formed via molecular association. Heteroatoms were identified in all of the associated molecules. Molecular weight distributions under three APPI ionization modes were similar. Compounds with molecular weight from 200 to 500 Da occupied 60% of all the products and around 10% of the products had molecular weight over 500 Da.
Huolinguole lignite was sequentially extracted with carbon disulfide, ethyl acetate, methanol and acetone. All of the extracts were analyzed using a time-of-flight mass spectrometry (TOF-MS) equipped with an atmospheric pressure photoionization (APPI) ion source. Toluene or 1,4-difluorobenzene was chosen as dopant for APPI. The results indicated that both dopants could well ionize compounds which could not be ionized by APPI without dopant. Toluene induced higher ionization efficiency than 1,4-difluorobenzene. Some compounds in the extracts were identified as dimers, which might be formed via molecular association. Heteroatoms were identified in all of the associated molecules. Molecular weight distributions under three APPI ionization modes were similar. Compounds with molecular weight from 200 to 500 Da occupied 60% of all the products and around 10% of the products had molecular weight over 500 Da.
2017, 45(7): 1012-1018
doi: 10.11895/j.issn.0253-3820.170110
Abstract:
Sulfonamides (SAs), such as sulfaguanidine (SGD), sulfadiazine (SDZ), sulfathiazole (STZ) and sulfamethazine (SMZ), can drastically inhibit the chemiluminescence (CL) intensities generated in both Ag(Ⅲ)-Luminol and Ni(Ⅳ)-Luminol systems. Based on these observations, a novel method of high performance liquid chromatography (HPLC) coupled with CL detection was established. Both the Ag(Ⅲ)-Luminol and Ni(Ⅳ)-Luminol CL systems were employed as detectors, and the performances of the two detecting systems were compared. After separated by HPLC, four SAs reacted with Ag(Ⅲ)-Luminol and Ni(Ⅳ)-Luminol CL system, respectively. Chromatographic conditions were as follows: reversed-phase C18 column (250 mm × 4.6 mm,5 μm), gradient elution, and 0.1% (V/V) formic acid-methanol as mobile phase with flow rate of 1 mL/min. CL conditions were as follows: [Ag(Ⅲ)]=1.4×10-4 mol/L (in 0.12 mol/L NaOH); [Ni(Ⅳ)]=1.5×10-5 mol/L (in 0.12 mol/L NaOH); [Luminol]=1.2×10-7 mol/L; and flow rate=1.0 mL/min. Under the optimal conditions, the detection limits of Ag(Ⅲ)-Luminol CL system were 0.15, 0.96, 1.10, 1.50 μg/mL for SGD, SDZ, STZ, and SMZ, respectively, and the recovery were 81.0%-101.5%. Comparatively, the detection limits of Ni(Ⅳ)-Luminol CL system were 1.5, 17.2, 16.8 μg/mL for SGD, SDZ and STZ, and the recoveries was 83.9%-110.8%. The result showed that the Ag(Ⅲ)-Luminol CL system had a much better performance. The method was applied to the determination of the residues of the above four SAs in milk with satisfactory results.
Sulfonamides (SAs), such as sulfaguanidine (SGD), sulfadiazine (SDZ), sulfathiazole (STZ) and sulfamethazine (SMZ), can drastically inhibit the chemiluminescence (CL) intensities generated in both Ag(Ⅲ)-Luminol and Ni(Ⅳ)-Luminol systems. Based on these observations, a novel method of high performance liquid chromatography (HPLC) coupled with CL detection was established. Both the Ag(Ⅲ)-Luminol and Ni(Ⅳ)-Luminol CL systems were employed as detectors, and the performances of the two detecting systems were compared. After separated by HPLC, four SAs reacted with Ag(Ⅲ)-Luminol and Ni(Ⅳ)-Luminol CL system, respectively. Chromatographic conditions were as follows: reversed-phase C18 column (250 mm × 4.6 mm,5 μm), gradient elution, and 0.1% (V/V) formic acid-methanol as mobile phase with flow rate of 1 mL/min. CL conditions were as follows: [Ag(Ⅲ)]=1.4×10-4 mol/L (in 0.12 mol/L NaOH); [Ni(Ⅳ)]=1.5×10-5 mol/L (in 0.12 mol/L NaOH); [Luminol]=1.2×10-7 mol/L; and flow rate=1.0 mL/min. Under the optimal conditions, the detection limits of Ag(Ⅲ)-Luminol CL system were 0.15, 0.96, 1.10, 1.50 μg/mL for SGD, SDZ, STZ, and SMZ, respectively, and the recovery were 81.0%-101.5%. Comparatively, the detection limits of Ni(Ⅳ)-Luminol CL system were 1.5, 17.2, 16.8 μg/mL for SGD, SDZ and STZ, and the recoveries was 83.9%-110.8%. The result showed that the Ag(Ⅲ)-Luminol CL system had a much better performance. The method was applied to the determination of the residues of the above four SAs in milk with satisfactory results.
2017, 45(7): 1019-1024
doi: 10.11895/j.issn.0253-3820.170145
Abstract:
An efficient method for the analysis of cefotaxime and its metabolite desacetylcefotaxime residues in eggs was developed based on high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The samples were homogenized and extracted with acetonitrile/water (9:1, V/V) solution. The fat was removed by hexane, and the other impurities were removed with C18 sorbent. The separation of cefotaxime and desacetylcefotaxime was performed on an Agilent Eclipse Plus C18 column (100 mm × 2.1 mm, 3.5 μm) using a mobile phase of 0.2% formic acid(A)-acetonitrile(B) by gradient elution. The analytes were detected by MS/MS in positive electrospray ionization mode (ESI+) and multiple reaction monitoring (MRM), quantitated by matrix-matched extemal standard method. Results showed that the calibration curves had a good linearity in the range of 1.0-143 μg/L (cefotaxime) and 1.0-120 μg/L (desacetylcefotaxime), respectively, with correlation coefficient R2>0.999. Limits of detection (LOD, S/N=3) for cefotaxime and desacetylcefotaxime were 0.07 and 0.14 μg/kg, and limits of quantitation (LOQ, S/N=10) for cefotaxime and desacetylcefotaxime were 0.23 and 0.99 μg/kg, respectively. At three spiked concentration levels, the recoveries of cefotaxime and desacetylcefotaxime ranged from 83.1% to 103.0% and 88.2% to 101.0%, respectively, both with RSDs (n=6) less than 6.2%. The results demonstrated that the method was simple, quick, sensitive and reliable, and suitable for determination of cefotaxime and desacetylcefotaxime residues in eggs.
An efficient method for the analysis of cefotaxime and its metabolite desacetylcefotaxime residues in eggs was developed based on high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The samples were homogenized and extracted with acetonitrile/water (9:1, V/V) solution. The fat was removed by hexane, and the other impurities were removed with C18 sorbent. The separation of cefotaxime and desacetylcefotaxime was performed on an Agilent Eclipse Plus C18 column (100 mm × 2.1 mm, 3.5 μm) using a mobile phase of 0.2% formic acid(A)-acetonitrile(B) by gradient elution. The analytes were detected by MS/MS in positive electrospray ionization mode (ESI+) and multiple reaction monitoring (MRM), quantitated by matrix-matched extemal standard method. Results showed that the calibration curves had a good linearity in the range of 1.0-143 μg/L (cefotaxime) and 1.0-120 μg/L (desacetylcefotaxime), respectively, with correlation coefficient R2>0.999. Limits of detection (LOD, S/N=3) for cefotaxime and desacetylcefotaxime were 0.07 and 0.14 μg/kg, and limits of quantitation (LOQ, S/N=10) for cefotaxime and desacetylcefotaxime were 0.23 and 0.99 μg/kg, respectively. At three spiked concentration levels, the recoveries of cefotaxime and desacetylcefotaxime ranged from 83.1% to 103.0% and 88.2% to 101.0%, respectively, both with RSDs (n=6) less than 6.2%. The results demonstrated that the method was simple, quick, sensitive and reliable, and suitable for determination of cefotaxime and desacetylcefotaxime residues in eggs.
2017, 45(7): 1025-1030
doi: 10.11895/j.issn.0253-3820.160877
Abstract:
Paeonol has inhibitory effect on a variety of tumor cells, whereas cadherin is a kind of glycoprotein that is associated with the occurrence and development of different tumor. In this study, the interactions of paeonol and E-cadherin have been investigated by fluorescence spectrometry and atomic force microscopy (AFM). Fluorescence spectrometry results revealed that the addition of paeonol significantly quenched the fluorescence of E-cadherin. Based on the results of the quenching constant, it was inferred that the interaction of paeonol and E-cadherin was a static quenching process. The thermodynamic parameters ΔH and ΔS were calculated to be -4.3×105 J/mol and -1.3×103 J/(mol·K), respectively, which proved the involvement of weak interactive forces such as hydrogen bond van der Waals force. AFM results revealed that cadherin molecules were assembled into the long-chain structure. The addition of paeonol could significantly disrupt these assembling structures into short chains, which could be ascribed to the damage of the interdigitation model from the adjacent cadherin molecules. All these results reveal that cadherin is an important target of paeonol to modulate its activity.
Paeonol has inhibitory effect on a variety of tumor cells, whereas cadherin is a kind of glycoprotein that is associated with the occurrence and development of different tumor. In this study, the interactions of paeonol and E-cadherin have been investigated by fluorescence spectrometry and atomic force microscopy (AFM). Fluorescence spectrometry results revealed that the addition of paeonol significantly quenched the fluorescence of E-cadherin. Based on the results of the quenching constant, it was inferred that the interaction of paeonol and E-cadherin was a static quenching process. The thermodynamic parameters ΔH and ΔS were calculated to be -4.3×105 J/mol and -1.3×103 J/(mol·K), respectively, which proved the involvement of weak interactive forces such as hydrogen bond van der Waals force. AFM results revealed that cadherin molecules were assembled into the long-chain structure. The addition of paeonol could significantly disrupt these assembling structures into short chains, which could be ascribed to the damage of the interdigitation model from the adjacent cadherin molecules. All these results reveal that cadherin is an important target of paeonol to modulate its activity.
2017, 45(7): 1031-1037
doi: 10.11895/j.issn.0253-3820.170063
Abstract:
Molecularly imprinted polymer (MIP) was synthesized by precipitation polymerization using ribavirin as the template molecule and methacrylic acid as the functional monomer. The sensitive film of ribavirin electrode was constructed by molecularly imprinted polymer doped with graphene oxide as the ionophore, poly(vinylchloride) (PVC) as matrix and dioctyl sebacate for plasticizer. The results showed that the best performance of the electrode was obtained when the sensitive film compositions were 100.8 mg of MIP, 14.7 mg of GO, 450.8 mg of PVC and 901.6 mg of dioctyl sebacate, and the inner filling solution composition was 0.1 mol/L NaCl + 0.05 mol/L NaAc-0.05 mol/L HAc + 1.0×10-5 mol/L ribavirin solution. The electrode showed a near-Nernstian slope of 45.565 mV/decade for ribavirin over the range of 1.0×106-1.0×10-4 mol/L and a detection limit of 1.0×10-7 mol/L. The electrode could be used in the pH range of 3 to 5 with response time of less than 3 min. The developed electrode exhibited high selectivity for ribavirin and was successfully applied to the determination of ribavirin in feed and injection with recoveries of 90%-110% and RSD of 3.0%-7.9%.
Molecularly imprinted polymer (MIP) was synthesized by precipitation polymerization using ribavirin as the template molecule and methacrylic acid as the functional monomer. The sensitive film of ribavirin electrode was constructed by molecularly imprinted polymer doped with graphene oxide as the ionophore, poly(vinylchloride) (PVC) as matrix and dioctyl sebacate for plasticizer. The results showed that the best performance of the electrode was obtained when the sensitive film compositions were 100.8 mg of MIP, 14.7 mg of GO, 450.8 mg of PVC and 901.6 mg of dioctyl sebacate, and the inner filling solution composition was 0.1 mol/L NaCl + 0.05 mol/L NaAc-0.05 mol/L HAc + 1.0×10-5 mol/L ribavirin solution. The electrode showed a near-Nernstian slope of 45.565 mV/decade for ribavirin over the range of 1.0×106-1.0×10-4 mol/L and a detection limit of 1.0×10-7 mol/L. The electrode could be used in the pH range of 3 to 5 with response time of less than 3 min. The developed electrode exhibited high selectivity for ribavirin and was successfully applied to the determination of ribavirin in feed and injection with recoveries of 90%-110% and RSD of 3.0%-7.9%.
2017, 45(7): 1038-1044
doi: 10.11895/j.issn.0253-3820.170085
Abstract:
Three kinds of PEGylated gold nanoparticles (PEG-Au NPs) with different surface charges are prepared by assembly of thiolated polyethylene glycol (HS-PEG) with different terminal groups including methoxy, amino or carboxyl on gold nanoparticle surface through sulfur-gold covalent bond, respectively. The experimental results of cell co-culturing and tail intravenous injection in mouse indicate that the biological behaviors of PEG-Au NPs are affected significantly by their surface charges. The cellular internalization amounts of PEG-Au NPs are following the order, positive charge > neutral charge > negative charge. The PEG-Au NPs are gradually transferred to liver and spleen from main organs through the circulation of blood after tail intravenous injection in mouse. The negatively charged PEG-Au NPs have the slowest hepatic clearance rate while the positively charged PEG-Au NPs can cause the strongest response of immune system in mice.
Three kinds of PEGylated gold nanoparticles (PEG-Au NPs) with different surface charges are prepared by assembly of thiolated polyethylene glycol (HS-PEG) with different terminal groups including methoxy, amino or carboxyl on gold nanoparticle surface through sulfur-gold covalent bond, respectively. The experimental results of cell co-culturing and tail intravenous injection in mouse indicate that the biological behaviors of PEG-Au NPs are affected significantly by their surface charges. The cellular internalization amounts of PEG-Au NPs are following the order, positive charge > neutral charge > negative charge. The PEG-Au NPs are gradually transferred to liver and spleen from main organs through the circulation of blood after tail intravenous injection in mouse. The negatively charged PEG-Au NPs have the slowest hepatic clearance rate while the positively charged PEG-Au NPs can cause the strongest response of immune system in mice.
2017, 45(7): 1045-1051
doi: 10.11895/j.issn.0253-3820.160843
Abstract:
Fish oil is an important nutrient component in rainbow trout bone, and the optimization of extraction by enzymatic hydrolytic method is of great significance. This study selected the alkaline protease as the hydrolytic enzyme, and optimized the process conditions of enzymatic hydrolysis of rainbow trout fish using single factor analysis method. Effects of several factors on the extraction of fish oil were studied, including the ratio of material to liquid, pH, enzymatic hydrolysis time, enzymatic hydrolysis temperature and amount of enzyme. Fatty acids were identified by gas chromatography-mass spectrometry (GC-MS). Results showed that the optimum extraction parameters of enzymatic hydrolysis were as follows: 2000 U/g alkaline protease, ratio of material to liquid of 1:1 (w/w), pH 7.5, and extraction at 55℃ for 3h. It was found that the main composition of rainbow trout bone oil was unsaturated fatty acid with the content of 80.4% (w/w). The relative content of monounsaturated fatty acid and polyunsaturated fatty acid was about 76.9% (w/w) and 23.1% (w/w), respectively. The total content of EPA and DHA was 3.4% (w/w). This study optimized the extraction method of rainbow trout fish oil, analyzed and identified the main volatile compounds, and identified the main substances contributing to fish oil flavor. The method thus was of significance for the analysis and identification of fish oil products.
Fish oil is an important nutrient component in rainbow trout bone, and the optimization of extraction by enzymatic hydrolytic method is of great significance. This study selected the alkaline protease as the hydrolytic enzyme, and optimized the process conditions of enzymatic hydrolysis of rainbow trout fish using single factor analysis method. Effects of several factors on the extraction of fish oil were studied, including the ratio of material to liquid, pH, enzymatic hydrolysis time, enzymatic hydrolysis temperature and amount of enzyme. Fatty acids were identified by gas chromatography-mass spectrometry (GC-MS). Results showed that the optimum extraction parameters of enzymatic hydrolysis were as follows: 2000 U/g alkaline protease, ratio of material to liquid of 1:1 (w/w), pH 7.5, and extraction at 55℃ for 3h. It was found that the main composition of rainbow trout bone oil was unsaturated fatty acid with the content of 80.4% (w/w). The relative content of monounsaturated fatty acid and polyunsaturated fatty acid was about 76.9% (w/w) and 23.1% (w/w), respectively. The total content of EPA and DHA was 3.4% (w/w). This study optimized the extraction method of rainbow trout fish oil, analyzed and identified the main volatile compounds, and identified the main substances contributing to fish oil flavor. The method thus was of significance for the analysis and identification of fish oil products.
2017, 45(7): 1052-1058
doi: 10.11895/j.issn.0253-3820.170164
Abstract:
An analytical method of ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC/PDA-QDa) for the qualitative and quantitative analysis of Δ9-tetrahydrocannabinol (Δ9-THC), cannabidiol (CBD), and cannabinol (CBN) in confiscated cannabis was developed. The seized cannabis was extracted in methanol by sonication. The binary mobile phase consisted of methanol (containing 0.1% formic acid) and water. After centrifugation, the supernatant was separated on Waters UPLC BEH C18 column (50 mm×2.1 mm, 1.7 μm) with isocratic elution at a flow rate of 0.2 mL/min. The three cannabinoids were analyzed by photodiode array (PDA) detector at 220 nm and confirmed by mass spectrometer QDa. The correlation coefficient of standard curve for the three cannabinoids in linearity range was not less than 0.999, as well as the recoveries were 82%-102% with the relative standard deviations (RSD) of 0.36%-4.12% at three spiked levels. The method is specific, easy, quick and suitable for confirmation of the cannabinoids in seized cannabis. Cannabis plants in different areas were classified by their chemical phenotype as drug-type or fiber-type plants, taking into account the phenotypic index Δ9-THC, (Δ9-THC+CBN)/CBD, or the Δ9-THC/CBD and the (Δ9-THC+CBN)/CBD ratios. The analysis of the original composition of plant material is necessary for the detection and the quality control of cannabis plants.
An analytical method of ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC/PDA-QDa) for the qualitative and quantitative analysis of Δ9-tetrahydrocannabinol (Δ9-THC), cannabidiol (CBD), and cannabinol (CBN) in confiscated cannabis was developed. The seized cannabis was extracted in methanol by sonication. The binary mobile phase consisted of methanol (containing 0.1% formic acid) and water. After centrifugation, the supernatant was separated on Waters UPLC BEH C18 column (50 mm×2.1 mm, 1.7 μm) with isocratic elution at a flow rate of 0.2 mL/min. The three cannabinoids were analyzed by photodiode array (PDA) detector at 220 nm and confirmed by mass spectrometer QDa. The correlation coefficient of standard curve for the three cannabinoids in linearity range was not less than 0.999, as well as the recoveries were 82%-102% with the relative standard deviations (RSD) of 0.36%-4.12% at three spiked levels. The method is specific, easy, quick and suitable for confirmation of the cannabinoids in seized cannabis. Cannabis plants in different areas were classified by their chemical phenotype as drug-type or fiber-type plants, taking into account the phenotypic index Δ9-THC, (Δ9-THC+CBN)/CBD, or the Δ9-THC/CBD and the (Δ9-THC+CBN)/CBD ratios. The analysis of the original composition of plant material is necessary for the detection and the quality control of cannabis plants.
2017, 45(7): 1059-1065
doi: 10.11895/j.issn.0253-3820.170115
Abstract:
The method of quantitative nuclear magnetic resonance spectroscopy (qNMR) for determination of epigoitrin in Radix Isatidis was established based on solid phase extraction (SPE). The twice ultrasonic extraction method using pure water was used for fully extracting epigoitrin in sample, and then the extraction was enriched and concentrated by poly-Sery MCX SPE cartridge. The effect of sample pretreatment and qNMR experimental conditions was investigated. The qNMR experiment conditions were selected using DMSO as solvent, calibrated 2,3,5-triiodobenzoate as internal standard, and P1(pulse width)=14.1 μs, d1(pulse delay time)=5 s, NS(number of scan)=256. The 1H-NMR peaks of δ 5.365-5.399 (H-7b, d, 1H) of epigoitrin were chosen as the quantitative peaks. Method validation was performed including precision (intra-day precision RSD was 0.5%, and the inter-day precision was 0.8%), linearity (correlation coefficient r>0.9991), LOD (0.05 mg/g, standard curve method) and LOQ (0.19 mg/g, S/N≥150). The recoveries of the SPE-qNMR were 97.4%-101.7%. The result showed that the method was stable, accurate and reliable. With this method the epigoitrin in a real Radix Isatidis was determined to be ＜0.19-1.26 mg/g. SPE combining with qNMR could extend the application field of qNMR, especially in the detection of low-content component in complex samples.
The method of quantitative nuclear magnetic resonance spectroscopy (qNMR) for determination of epigoitrin in Radix Isatidis was established based on solid phase extraction (SPE). The twice ultrasonic extraction method using pure water was used for fully extracting epigoitrin in sample, and then the extraction was enriched and concentrated by poly-Sery MCX SPE cartridge. The effect of sample pretreatment and qNMR experimental conditions was investigated. The qNMR experiment conditions were selected using DMSO as solvent, calibrated 2,3,5-triiodobenzoate as internal standard, and P1(pulse width)=14.1 μs, d1(pulse delay time)=5 s, NS(number of scan)=256. The 1H-NMR peaks of δ 5.365-5.399 (H-7b, d, 1H) of epigoitrin were chosen as the quantitative peaks. Method validation was performed including precision (intra-day precision RSD was 0.5%, and the inter-day precision was 0.8%), linearity (correlation coefficient r>0.9991), LOD (0.05 mg/g, standard curve method) and LOQ (0.19 mg/g, S/N≥150). The recoveries of the SPE-qNMR were 97.4%-101.7%. The result showed that the method was stable, accurate and reliable. With this method the epigoitrin in a real Radix Isatidis was determined to be ＜0.19-1.26 mg/g. SPE combining with qNMR could extend the application field of qNMR, especially in the detection of low-content component in complex samples.
2017, 45(7): 1066-1077
doi: 10.11895/j.issn.0253-3820.170113
Abstract:
Stable isotope coded derivatization (ICD) is an isotope labeling technique for specific functional groups of the target analytes through chemical derivatization. ICD combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) enables systematically analyzing the biomolecules with the same labeling reaction characteristic. ICD technique can effectively solve the limited sensitivity in complex bio-matrices analysis and unavailability of isotope internal standards in quantitative analysis. In recent years, ICD technique has been widely used in metabolomics research field. Based on this background, the ICD technique and the design of ICD reagents are briefly described in this review. The recent advances in ICD reagents for carboxyl, amino, carbonyl, thiol and hydroxyl groups and their applications in the analysis of small molecule metabolites in bio-matrices with LC-MS/MS are reviewed.
Stable isotope coded derivatization (ICD) is an isotope labeling technique for specific functional groups of the target analytes through chemical derivatization. ICD combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) enables systematically analyzing the biomolecules with the same labeling reaction characteristic. ICD technique can effectively solve the limited sensitivity in complex bio-matrices analysis and unavailability of isotope internal standards in quantitative analysis. In recent years, ICD technique has been widely used in metabolomics research field. Based on this background, the ICD technique and the design of ICD reagents are briefly described in this review. The recent advances in ICD reagents for carboxyl, amino, carbonyl, thiol and hydroxyl groups and their applications in the analysis of small molecule metabolites in bio-matrices with LC-MS/MS are reviewed.
2017, 45(7): 1078-1087
doi: 10.11895/j.issn.0253-3820.170157
Abstract:
Nanocarrier systems have been widely used for improving solubility, stability and therapeutic activity of drugs due to their high drug-loading efficiency, good target specificity and long circulation time. To achieve precisely controlled loading and tumor-selective release of drugs, extensive research efforts have been focused on developing nanocarriers with low toxicity, excellent biocomapatibility and biodegradability. As a type of nano-biomaterials with various functions and applications, self-assembled DNA nanostructures explored new ways to develop drug carriers in smart drug delivery based on their well-defined structures, good biocompatibility and stability, high cell membrane permeability and controlled drug releasing property. In this review, we summarized the developing course and the recent advances of DNA nanostructures for drug delivery, including the application of both static and dynamic DNA nanostructures. The application of dynamic DNA nanostructures for controlled drug release showed great potential in smart drug delivery.
Nanocarrier systems have been widely used for improving solubility, stability and therapeutic activity of drugs due to their high drug-loading efficiency, good target specificity and long circulation time. To achieve precisely controlled loading and tumor-selective release of drugs, extensive research efforts have been focused on developing nanocarriers with low toxicity, excellent biocomapatibility and biodegradability. As a type of nano-biomaterials with various functions and applications, self-assembled DNA nanostructures explored new ways to develop drug carriers in smart drug delivery based on their well-defined structures, good biocompatibility and stability, high cell membrane permeability and controlled drug releasing property. In this review, we summarized the developing course and the recent advances of DNA nanostructures for drug delivery, including the application of both static and dynamic DNA nanostructures. The application of dynamic DNA nanostructures for controlled drug release showed great potential in smart drug delivery.
2017, 45(7): 1088-1095
doi: 10.11895/j.issn.0253-3820.170116
Abstract:
Subthalamic nucleus (STN) deep brain stimulation (DBS) has become an important surgical treatment of Parkinson disease, but its exact mechanism is still unclear. In this study, a 16-channel implantable microelectrode array (MEA) was prepared by micro-electromechanical system (MEMS) technique and later modified with platinum black/reduced Graphene Oxide/Nafion (Pt/RGO/Nafion) nanocomposites. Extracellular dopamine (DA) content and spike of dorsal striatum neurons were synchronously recorded before and after STN stimulation. The results showed that the dopamine content began to increase within 20 s after electrical stimulation and dropped to normal level after about 50 s, with the highest rising concentration of 1.72 μmol/L. At the same time, there was an increased spike activity of interneurons in the dopamine ascending phase, and the spike firing rate of medium spiny projection neurons (MSNs) was high when the concentration of DA was higher than the normal level. The MEA sensor can simultaneously record dopamine flux and physiological signals in situ, thus providing an ideal tool for neural information detection.
Subthalamic nucleus (STN) deep brain stimulation (DBS) has become an important surgical treatment of Parkinson disease, but its exact mechanism is still unclear. In this study, a 16-channel implantable microelectrode array (MEA) was prepared by micro-electromechanical system (MEMS) technique and later modified with platinum black/reduced Graphene Oxide/Nafion (Pt/RGO/Nafion) nanocomposites. Extracellular dopamine (DA) content and spike of dorsal striatum neurons were synchronously recorded before and after STN stimulation. The results showed that the dopamine content began to increase within 20 s after electrical stimulation and dropped to normal level after about 50 s, with the highest rising concentration of 1.72 μmol/L. At the same time, there was an increased spike activity of interneurons in the dopamine ascending phase, and the spike firing rate of medium spiny projection neurons (MSNs) was high when the concentration of DA was higher than the normal level. The MEA sensor can simultaneously record dopamine flux and physiological signals in situ, thus providing an ideal tool for neural information detection.
2017, 45(7): 1096-1101
doi: 10.11895/j.issn.0253-3820.170136
Abstract:
An electrospray/ultraviolet lamp dual-source ion trap mass spectrometer was developed for the rapid detection of gas and liquid samples. The instrument used the discontinuous atmospheric pressure sampling technique that both the electrospray ions and gaseous analytes were sampled and transferred using a pinch valve device. The two ionization sources were generally suitable for different kinds of analytes and provided complementary applications. Electrospray was used for the ionization of polar compounds in solution, while the UV ionization source was mainly applied for the analysis of gaseous organic compounds. A variety of samples such as anisole, toluene, 2,4-dimethylaniline, arginine, reserpine and aspartame were employed to test the performance in different working mode of the instrument. The results showed that the two sources were feasible for ionization of different types of samples, and different types of molecular ions could be generated when 2,4-dimethylaniline was analyzed. The two ionization sources could be used alternately or simultaneously without interference, and the working mode was also switched to fit the application requirements. The dual-source configuration was an effective way to extend the applications for miniature mass spectrometers. It did not significantly increase the size of the instrument, but provided more versatile analysis to meet the need for the measurement of different types of samples.
An electrospray/ultraviolet lamp dual-source ion trap mass spectrometer was developed for the rapid detection of gas and liquid samples. The instrument used the discontinuous atmospheric pressure sampling technique that both the electrospray ions and gaseous analytes were sampled and transferred using a pinch valve device. The two ionization sources were generally suitable for different kinds of analytes and provided complementary applications. Electrospray was used for the ionization of polar compounds in solution, while the UV ionization source was mainly applied for the analysis of gaseous organic compounds. A variety of samples such as anisole, toluene, 2,4-dimethylaniline, arginine, reserpine and aspartame were employed to test the performance in different working mode of the instrument. The results showed that the two sources were feasible for ionization of different types of samples, and different types of molecular ions could be generated when 2,4-dimethylaniline was analyzed. The two ionization sources could be used alternately or simultaneously without interference, and the working mode was also switched to fit the application requirements. The dual-source configuration was an effective way to extend the applications for miniature mass spectrometers. It did not significantly increase the size of the instrument, but provided more versatile analysis to meet the need for the measurement of different types of samples.
