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2019 Volume 47 Issue 6
2019, 47(6): 795-804
doi: 10.19756/j.issn.0253-3820.181745
Abstract:
Microdroplets have been widely used in biology, chemistry, material science, and engineering, and the microdroplet generation methods are becoming more efficient and controllable. The development of the generation of microdroplets experienced traditional methods, microfluidic chip-based methods, and recently proposed off-chip methods. In this paper, we first briefly summarized the typical traditional methods and the microfluidic chip-based methods for microdroplet generation, and then emphatically introduced the principles, devices, and applications of the recently developed microdroplet generation methods. The advantages and disadvantages of these methods were discussed and the future development of microdroplet generation technology was also prospected.
Microdroplets have been widely used in biology, chemistry, material science, and engineering, and the microdroplet generation methods are becoming more efficient and controllable. The development of the generation of microdroplets experienced traditional methods, microfluidic chip-based methods, and recently proposed off-chip methods. In this paper, we first briefly summarized the typical traditional methods and the microfluidic chip-based methods for microdroplet generation, and then emphatically introduced the principles, devices, and applications of the recently developed microdroplet generation methods. The advantages and disadvantages of these methods were discussed and the future development of microdroplet generation technology was also prospected.
2019, 47(6): 805-813
doi: 10.19756/j.issn.0253-3820.181742
Abstract:
Micellar electrokinetic chromatography (MEKC) is a hybrid of chromatography and electrophoresis. The separation mechanism is based on the interaction of analytes and pseudo-stationary phase and also the differential mobility in the electric field. Such property of MEKC can be made good use for separations of proteins and peptides, which have high dimensionality. In the past years, either in the form of single dimensional or multi-dimensional separations, MEKC demonstrated its excellent usability in biomolecule separations. Recently, as the development in CE-MS was revisited, there were also new developments in MEKC-MS hyphenation techniques, which further pointed to the usefulness of MEKC in analysis of proteins and peptides. In this article, the recent advances of MEKC applied in separation and analysis of proteins were reviewed and the prospect of this technique was anticipated.
Micellar electrokinetic chromatography (MEKC) is a hybrid of chromatography and electrophoresis. The separation mechanism is based on the interaction of analytes and pseudo-stationary phase and also the differential mobility in the electric field. Such property of MEKC can be made good use for separations of proteins and peptides, which have high dimensionality. In the past years, either in the form of single dimensional or multi-dimensional separations, MEKC demonstrated its excellent usability in biomolecule separations. Recently, as the development in CE-MS was revisited, there were also new developments in MEKC-MS hyphenation techniques, which further pointed to the usefulness of MEKC in analysis of proteins and peptides. In this article, the recent advances of MEKC applied in separation and analysis of proteins were reviewed and the prospect of this technique was anticipated.
2019, 47(6): 814-822
doi: 10.19756/j.issn.0253-3820.191089
Abstract:
Being priority control environmental pollutants, the determination of polycyclic aromatic hydrocarbons (PAHs) is of great significance. In this work, a novel silica monolith was prepared by grafting graphene oxide (GO) onto the surface of silica monolith through amidation reaction. The morphology and structure of the monolith were characterized by scanning electron microscopy, elemental analysis and Raman spectroscopy. Using this monolith as a solid phase microextraction (SPME) medium, the extraction performances for typical PAHs were extensively investigated. The enrichment factors of the monolith for Pyrene (Pyr), Benzo[a] pyrene (BaP) and dibenzo[a, h] anthracene (DahA) were 78.5, 98.2 and 102.4, respectively. The excellent enrichment property of the monolith for PAHs was attributed to the π-π stacking and hydrophobic interactions between GO and PAHs. Therefore, a facile and sensitive detection method for PAHs was developed coupled with high performance liquid chromatography-ultraviolet (HPLC-UV). The linear range was 0.1-150 μg/L for nine PAHs (R2 ≥ 0.9947), with limits of detection (LOD) and limits of quantification (LOQ) of 0.02-0.11 μg/L (S/N=3) and 0.07-0.36 μg/L (S/N=10), respectively. The spiked recoveries of PAHs in cigarette smoke, coke waste water and local atmospheric particles were between 81.5% and 107.8%, with the relative standard deviations (RSDs) from 1.0% to 6.5% (n=3). Furthermore, the developed method was accurate, sensitive, simple and reliable, and had great potential applicability in determination of real samples.
Being priority control environmental pollutants, the determination of polycyclic aromatic hydrocarbons (PAHs) is of great significance. In this work, a novel silica monolith was prepared by grafting graphene oxide (GO) onto the surface of silica monolith through amidation reaction. The morphology and structure of the monolith were characterized by scanning electron microscopy, elemental analysis and Raman spectroscopy. Using this monolith as a solid phase microextraction (SPME) medium, the extraction performances for typical PAHs were extensively investigated. The enrichment factors of the monolith for Pyrene (Pyr), Benzo[a] pyrene (BaP) and dibenzo[a, h] anthracene (DahA) were 78.5, 98.2 and 102.4, respectively. The excellent enrichment property of the monolith for PAHs was attributed to the π-π stacking and hydrophobic interactions between GO and PAHs. Therefore, a facile and sensitive detection method for PAHs was developed coupled with high performance liquid chromatography-ultraviolet (HPLC-UV). The linear range was 0.1-150 μg/L for nine PAHs (R2 ≥ 0.9947), with limits of detection (LOD) and limits of quantification (LOQ) of 0.02-0.11 μg/L (S/N=3) and 0.07-0.36 μg/L (S/N=10), respectively. The spiked recoveries of PAHs in cigarette smoke, coke waste water and local atmospheric particles were between 81.5% and 107.8%, with the relative standard deviations (RSDs) from 1.0% to 6.5% (n=3). Furthermore, the developed method was accurate, sensitive, simple and reliable, and had great potential applicability in determination of real samples.
2019, 47(6): 823-831,889
doi: 10.19756/j.issn.0253-3820.191050
Abstract:
Lanthanide up-conversion nanoparticles have attracted considerable interest as potential drug carriers and imaging agents in tumor tissues. However, it has poor water solubility, which limited its applications in medical researches. In this study by taking advantages of good biocompatibility and multifunctional host-guest properties of β-cyclodextrin (β-CD), the oleic acid ligand on the surface of β-2%Er,20%Yb:NaYF4(β-Er,Yb:NaYF4) could be inserted into the hydrophobic cavity of β-CD, improving the water solubility of β-Er,Yb:NaYF4 by one-step ultrasonic method.Doxorubicin (DOX) was loaded into the gap between oleic acid molecule and β-CD (β-Er,Yb:NaYF4@β-CD-DOX) by hydrophilic action and it was used in the study of anti-hepatoma in vitro. At 980 nm near-infrared light, 540 nm fluorescence and photoacoustic signals were generated to achieve the purpose of double mode imaging. X ray diffraction (XRD), transmission electron microscope (TEM) and infrared spectroscopy (IR) were used to analyze the structure of β-Er,Yb:NaYF4@β-CD of the nano-drug carrier. Endocytosis assay was used to detect the drug delivery and in vitro imaging function. MTT assay was used to detect the inhibitory effect of β-Er,Yb:NaYF4@β-CD-DOX on the proliferation of HepG2 hepatocytes. The imaging effect of in situ injection of β-Er,Yb:NaYF4@β-CD-DOX into mouse tumor irradiated with 980 nm near-infrared light. The results showed that the drug carrier of β-Er,Yb:NaYF4@β-CD was successfully synthesized, as a drug vector with pH-sensitive release effect, which significantly enhanced the toxicity of hepatoma cells and induced apoptosis of tumor cells in vitro. Furthermore, it has excellent up-conversion and photoacoustic imaging function in vivo and in vitro. β-Er,Yb:NaYF4@β-CD-DOX is expected to be a novel drug transfer imaging carrier and can be used in the treatment of hepatocellular carcinoma.
Lanthanide up-conversion nanoparticles have attracted considerable interest as potential drug carriers and imaging agents in tumor tissues. However, it has poor water solubility, which limited its applications in medical researches. In this study by taking advantages of good biocompatibility and multifunctional host-guest properties of β-cyclodextrin (β-CD), the oleic acid ligand on the surface of β-2%Er,20%Yb:NaYF4(β-Er,Yb:NaYF4) could be inserted into the hydrophobic cavity of β-CD, improving the water solubility of β-Er,Yb:NaYF4 by one-step ultrasonic method.Doxorubicin (DOX) was loaded into the gap between oleic acid molecule and β-CD (β-Er,Yb:NaYF4@β-CD-DOX) by hydrophilic action and it was used in the study of anti-hepatoma in vitro. At 980 nm near-infrared light, 540 nm fluorescence and photoacoustic signals were generated to achieve the purpose of double mode imaging. X ray diffraction (XRD), transmission electron microscope (TEM) and infrared spectroscopy (IR) were used to analyze the structure of β-Er,Yb:NaYF4@β-CD of the nano-drug carrier. Endocytosis assay was used to detect the drug delivery and in vitro imaging function. MTT assay was used to detect the inhibitory effect of β-Er,Yb:NaYF4@β-CD-DOX on the proliferation of HepG2 hepatocytes. The imaging effect of in situ injection of β-Er,Yb:NaYF4@β-CD-DOX into mouse tumor irradiated with 980 nm near-infrared light. The results showed that the drug carrier of β-Er,Yb:NaYF4@β-CD was successfully synthesized, as a drug vector with pH-sensitive release effect, which significantly enhanced the toxicity of hepatoma cells and induced apoptosis of tumor cells in vitro. Furthermore, it has excellent up-conversion and photoacoustic imaging function in vivo and in vitro. β-Er,Yb:NaYF4@β-CD-DOX is expected to be a novel drug transfer imaging carrier and can be used in the treatment of hepatocellular carcinoma.
2019, 47(6): 832-837
doi: 10.19756/j.issn.0253-3820.191005
Abstract:
A micro-fabricated semi-packed gas chromatography (μGC) column embedded micro-elliptical pillars was fabricated based on micro-electro-mechanical system (MEMS) technique. The mesoporous silica film (MS) with 2 nm pore size and large specific surface area was coated on the inner surface of the μGC column as stationary phase. Under the same injection volume and the temperature-programmed conditions, the baseline separation of alkanes (C5-C10) was realized by the μGC column used MS as stationary phase, and the resolution of pentane and solvent (impurity) could be as large as 3.6. Compared with the GC column used polydimethylsiloxane (PDMS) as stationary phase, the number of theoretical plates of octane had a 46% increase, which could be up to 14458 plates. Meanwhile, the peak area of nonane increased by 349.8%.
A micro-fabricated semi-packed gas chromatography (μGC) column embedded micro-elliptical pillars was fabricated based on micro-electro-mechanical system (MEMS) technique. The mesoporous silica film (MS) with 2 nm pore size and large specific surface area was coated on the inner surface of the μGC column as stationary phase. Under the same injection volume and the temperature-programmed conditions, the baseline separation of alkanes (C5-C10) was realized by the μGC column used MS as stationary phase, and the resolution of pentane and solvent (impurity) could be as large as 3.6. Compared with the GC column used polydimethylsiloxane (PDMS) as stationary phase, the number of theoretical plates of octane had a 46% increase, which could be up to 14458 plates. Meanwhile, the peak area of nonane increased by 349.8%.
2019, 47(6): 838-845
doi: 10.19756/j.issn.0253-3820.191125
Abstract:
In this work, a novel 3D printed mould-removal method was proposed to fabricate the microchannels with unconventional cross-sections. By modifying the orifice shape of extrusion nozzle with picosecond laser cutting technology, the ABS microchannel moulds with arbitrary cross-sections could be facilely printed by using an ordinary desktop FDM printer. After conducting the PDMS casting and ABS dissolving, the all-PDMS microfluidic chips could be easily produced without complex bonding process. To verify effectiveness of the proposed method, the microchannels with square, semielliptical and triangular sections were designed and successfully fabricated. It was also found that the size of the microchannel section could be flexibly adjusted by just controlling the ABS extrusion amount during the channel mould printing. At last, to explore the effects of channel section on the particle inertial focusing behaviours, the particle lateral migrations in the semielliptical and triangular microchannels were systematically investigated. The results showed that, with the increase of flow rate, the particles flowing in the microchannels moved gradually and laterally to the regions near the centers of each channel edge, and finally forming three stable equilibrium positions for both semielliptical and triangular microchannels.
In this work, a novel 3D printed mould-removal method was proposed to fabricate the microchannels with unconventional cross-sections. By modifying the orifice shape of extrusion nozzle with picosecond laser cutting technology, the ABS microchannel moulds with arbitrary cross-sections could be facilely printed by using an ordinary desktop FDM printer. After conducting the PDMS casting and ABS dissolving, the all-PDMS microfluidic chips could be easily produced without complex bonding process. To verify effectiveness of the proposed method, the microchannels with square, semielliptical and triangular sections were designed and successfully fabricated. It was also found that the size of the microchannel section could be flexibly adjusted by just controlling the ABS extrusion amount during the channel mould printing. At last, to explore the effects of channel section on the particle inertial focusing behaviours, the particle lateral migrations in the semielliptical and triangular microchannels were systematically investigated. The results showed that, with the increase of flow rate, the particles flowing in the microchannels moved gradually and laterally to the regions near the centers of each channel edge, and finally forming three stable equilibrium positions for both semielliptical and triangular microchannels.
2019, 47(6): 846-854
doi: 10.19756/j.issn.0253-3820.191084
Abstract:
Molecular simulation can provide valuable theoretical guidance for rapid selection of functional monomers in imprinted adsorbents. The recognition systems were constructed, which consisted of targeted pollutant carbamazepine (CBZ) as template molecule and 14 functional monomers respectively. The low-energy conformations of template-monomer interaction system were searched by simulated quenching method. This method overcame the shortcoming of the existing searching method by which the conformations were prone to fall into local potential wells. Molecular simulation indicated that the binding capacity of itaconic acid (IA) as monomer to CBZ was the strongest. Adsorption experiments showed that IA-prepared imprinted adsorbent (IA-MIP) performed better than the adsorbent prepared by traditional monomer methylacrylic acid. The adsorption capacity of IA-MIP could reach 9.28 mg/g in aqueous solution. IA-MIP also showed high selectivity to carbamazepine in filtration effluent. After 10 reuses, the adsorption capacity decreased by only 1.3%. The ultraviolet spectra of the imprinted system were calculated theoretically and measured. The experimental results confirmed that a new interaction system was formed between IA and CBZ. Molecular simulation could predict the ultraviolet spectra of IA and CBZ in aqueous solution very well. However, the prediction of the ultraviolet spectra of the interaction system was not ideal, which suggested that there existed a variety of interaction conformations during the specific adsorption process. Energy calculation and hydrogen bond analysis demonstrated that van der Waals and electrostatic force played a major role in the recognition process. Infrared analysis confirmed the existence of hydrogen bond in the system, and the recognition site was located between the carboxylic group of IA and carbamazepine amide, which was consistent with the results of molecular simulation.
Molecular simulation can provide valuable theoretical guidance for rapid selection of functional monomers in imprinted adsorbents. The recognition systems were constructed, which consisted of targeted pollutant carbamazepine (CBZ) as template molecule and 14 functional monomers respectively. The low-energy conformations of template-monomer interaction system were searched by simulated quenching method. This method overcame the shortcoming of the existing searching method by which the conformations were prone to fall into local potential wells. Molecular simulation indicated that the binding capacity of itaconic acid (IA) as monomer to CBZ was the strongest. Adsorption experiments showed that IA-prepared imprinted adsorbent (IA-MIP) performed better than the adsorbent prepared by traditional monomer methylacrylic acid. The adsorption capacity of IA-MIP could reach 9.28 mg/g in aqueous solution. IA-MIP also showed high selectivity to carbamazepine in filtration effluent. After 10 reuses, the adsorption capacity decreased by only 1.3%. The ultraviolet spectra of the imprinted system were calculated theoretically and measured. The experimental results confirmed that a new interaction system was formed between IA and CBZ. Molecular simulation could predict the ultraviolet spectra of IA and CBZ in aqueous solution very well. However, the prediction of the ultraviolet spectra of the interaction system was not ideal, which suggested that there existed a variety of interaction conformations during the specific adsorption process. Energy calculation and hydrogen bond analysis demonstrated that van der Waals and electrostatic force played a major role in the recognition process. Infrared analysis confirmed the existence of hydrogen bond in the system, and the recognition site was located between the carboxylic group of IA and carbamazepine amide, which was consistent with the results of molecular simulation.
2019, 47(6): 855-861
doi: 10.19756/j.issn.0253-3820.191149
Abstract:
A DNA microarray-based fluorescence assay was developed for profiling BRAFV600 mutations through formation of three single-stranded DNA (ssDNA) sequences hybridization systems on microarray. In this assay, the target ssDNAs were recognized by correspondent capturing oligonucleotide probes on microarray, followed by hybridization with a Cy5 modified ssDNA for fluorescence detection. Under the optimal experimental conditions, the DNA microarray-based fluorescence assay achieved a limit of detection (S/N) at sub-nanomolar level for the target ssDNA with BRAFV600E mutation, and could easily differentiate as low as 0.1% BRAFV600E mutation sequence in the mixture of target ssDNAs. The profile results of BRAFV600E mutation level in 15 clinical thyroid tissue samples demonstrated that the DNA microarray-based fluorescence assay had good practicability.
A DNA microarray-based fluorescence assay was developed for profiling BRAFV600 mutations through formation of three single-stranded DNA (ssDNA) sequences hybridization systems on microarray. In this assay, the target ssDNAs were recognized by correspondent capturing oligonucleotide probes on microarray, followed by hybridization with a Cy5 modified ssDNA for fluorescence detection. Under the optimal experimental conditions, the DNA microarray-based fluorescence assay achieved a limit of detection (S/N) at sub-nanomolar level for the target ssDNA with BRAFV600E mutation, and could easily differentiate as low as 0.1% BRAFV600E mutation sequence in the mixture of target ssDNAs. The profile results of BRAFV600E mutation level in 15 clinical thyroid tissue samples demonstrated that the DNA microarray-based fluorescence assay had good practicability.
2019, 47(6): 862-868
doi: 10.19756/j.issn.0253-3820.181795
Abstract:
The microcapsules of chitosan/sodium alginate/porous starch-tea tree essential oil (CS/SA/PS-TTEO) were successfully prepared by polyelectrolyte complex coacervation method with PS as the core material carrier to adsorb TTEO, SA-CS as the wall material, and glutaraldehyde (GA) as crosslinker. The preparation conditions were optimized as follows. The optimum ratio of PS to TTEO was 0.88:1, the concentration of SA was 3.0%, the concentration of CS was 3.0%, the concentration of GA was 2.0%, and the reaction temperature was 30℃. The formation, properties and release behaviors of CS/SA/PS-TTEO microcapsules were analyzed by scanning electron microscope (TEM), thermogravimetry (TGA), Fourier transform infrared spectroscopy (FT-IR), stability test and release rate experiments. The results showed that in the open system, cumulative release rate of CS/SA/PS-TTEO microcapsules for 14 days was 15.77%, and the lowest release rate for a single day was 0.20%. In the closed system, the cumulative release rate of 14 days was 7.37%, and the release rate tended to be stable in about 10 days, with the lowest release rate of 0.04% in a single day, which proved that CS/SA/PS-TTEO microcapsules had the ability of slow release. CS/SA/PS-TTEO microcapsule was stable at -18℃ to 50℃ in the commonly used cosmetic solvent, and this property was beneficial to improve the stability of the storage and transport of cosmetics containing TTEO.
The microcapsules of chitosan/sodium alginate/porous starch-tea tree essential oil (CS/SA/PS-TTEO) were successfully prepared by polyelectrolyte complex coacervation method with PS as the core material carrier to adsorb TTEO, SA-CS as the wall material, and glutaraldehyde (GA) as crosslinker. The preparation conditions were optimized as follows. The optimum ratio of PS to TTEO was 0.88:1, the concentration of SA was 3.0%, the concentration of CS was 3.0%, the concentration of GA was 2.0%, and the reaction temperature was 30℃. The formation, properties and release behaviors of CS/SA/PS-TTEO microcapsules were analyzed by scanning electron microscope (TEM), thermogravimetry (TGA), Fourier transform infrared spectroscopy (FT-IR), stability test and release rate experiments. The results showed that in the open system, cumulative release rate of CS/SA/PS-TTEO microcapsules for 14 days was 15.77%, and the lowest release rate for a single day was 0.20%. In the closed system, the cumulative release rate of 14 days was 7.37%, and the release rate tended to be stable in about 10 days, with the lowest release rate of 0.04% in a single day, which proved that CS/SA/PS-TTEO microcapsules had the ability of slow release. CS/SA/PS-TTEO microcapsule was stable at -18℃ to 50℃ in the commonly used cosmetic solvent, and this property was beneficial to improve the stability of the storage and transport of cosmetics containing TTEO.
2019, 47(6): 869-875
doi: 10.19756/j.issn.0253-3820.191014
Abstract:
Based on the specific combination between aptamer and its target analyte, a disposable aptasensor was built for the sensitive detection of okadaic acid (OA) (a main constituent of diarrhetic shellfish poisoning) in shellfish. The aptamer was employed as the probe and screen-printed gold electrodes (SPGE) as the support. Electrochemical impedance spectroscopy (EIS) was performed to test the change of electron transfer resistances (Ret) of SPGE before and after binding with OA and OA in shellfish samples could be thus quantified. In order to improve the sensitivity of the method, Fe3O4@Au was introduced into the fabrication of SPGE since it could enhance the gold working electrode's surface areas. Compared with antibody, the use of aptamer was cheaper, and SPGE avoided the polish step which was needed of traditional electrodes. The change of Ret was linearly correlated with the natural logarithm of concentration of OA from 1 μg/kg to 800 μg/kg. The limit of detection was 1 μg/kg. Recoveries in diarrhetic shellfish at different spiked levels were in the range of 92.0%-118.6%, and relative standard deviations (RSDs) were less than 12%. The proposed disposable aptasensor was efficient and sensitive with good repeatability, and was suitable for screening and quantification of shellfish samples.
Based on the specific combination between aptamer and its target analyte, a disposable aptasensor was built for the sensitive detection of okadaic acid (OA) (a main constituent of diarrhetic shellfish poisoning) in shellfish. The aptamer was employed as the probe and screen-printed gold electrodes (SPGE) as the support. Electrochemical impedance spectroscopy (EIS) was performed to test the change of electron transfer resistances (Ret) of SPGE before and after binding with OA and OA in shellfish samples could be thus quantified. In order to improve the sensitivity of the method, Fe3O4@Au was introduced into the fabrication of SPGE since it could enhance the gold working electrode's surface areas. Compared with antibody, the use of aptamer was cheaper, and SPGE avoided the polish step which was needed of traditional electrodes. The change of Ret was linearly correlated with the natural logarithm of concentration of OA from 1 μg/kg to 800 μg/kg. The limit of detection was 1 μg/kg. Recoveries in diarrhetic shellfish at different spiked levels were in the range of 92.0%-118.6%, and relative standard deviations (RSDs) were less than 12%. The proposed disposable aptasensor was efficient and sensitive with good repeatability, and was suitable for screening and quantification of shellfish samples.
2019, 47(6): 876-882
doi: 10.19756/j.issn.0253-3820.191069
Abstract:
The monitoring of urinary monohydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) can be used for the risk assessment of human exposure to polycyclic aromatic hydrocarbons (PAHs). In this work, we developed and optimized a new pretreatment method based on solid-phase supported liquid-liquid extraction (SLE). After pretreatment, the analytes were then determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Urine samples were extracted with a mixed solution of dichloromethane and n-hexane (3:7, V/V) by a SLE clean-up using a diatomaceous earth mini-cartridge. The results indicated that the developed pretreated procedure had good recoveries and also significantly reduced the interference of biological matrix. At three concentration levels (10, 50 and 100 μg/L), the recoveries of ten OH-PAHs ranged from 88.5% to 120.9%, and the repeatability ranged from 1.6% to 8.1%. The limits of detection ranged from 0.06 μg/L to 0.3 μg/L and the limits of quantitation were between 0.2 μg/L and 1.0 μg/L. This method was finally successfully applied to the determination of OH-PAHs in urines collected from primary school students in Guangdong. The results showed that 2-OHN was the dominant compound, with the highest concentration of 4.83 μg/L.
The monitoring of urinary monohydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) can be used for the risk assessment of human exposure to polycyclic aromatic hydrocarbons (PAHs). In this work, we developed and optimized a new pretreatment method based on solid-phase supported liquid-liquid extraction (SLE). After pretreatment, the analytes were then determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Urine samples were extracted with a mixed solution of dichloromethane and n-hexane (3:7, V/V) by a SLE clean-up using a diatomaceous earth mini-cartridge. The results indicated that the developed pretreated procedure had good recoveries and also significantly reduced the interference of biological matrix. At three concentration levels (10, 50 and 100 μg/L), the recoveries of ten OH-PAHs ranged from 88.5% to 120.9%, and the repeatability ranged from 1.6% to 8.1%. The limits of detection ranged from 0.06 μg/L to 0.3 μg/L and the limits of quantitation were between 0.2 μg/L and 1.0 μg/L. This method was finally successfully applied to the determination of OH-PAHs in urines collected from primary school students in Guangdong. The results showed that 2-OHN was the dominant compound, with the highest concentration of 4.83 μg/L.
2019, 47(6): 883-889
doi: 10.19756/j.issn.0253-3820.181718
Abstract:
A novel sensing material with high sensitivity and specificity was developed for the detection of methomyl by combining photonic crystal technique with molecularly imprinting technique which was named molecularly imprinted photonic crystal (MIPC). MIPC was prepared by thermal polymerization with SiO2 microspheres array as pore-forming templates, methomyl as imprinting molecule, methacrylic acid and acrylamide as monomers and ethylene dimethacrylate as cross-linker, followed by chemical removal of SiO2 microspheres and imprinting molecules. The morphology of the polymer films was characterized by scanning electron microscopy (SEM). The results showed that a three-dimensional interconnected macroporous array with a typical face-centered cubic structure was formed in the film. The response of the MIPC to methomyl solution was studied by measuring the change of the position of the reflection peak. The results showed that the MIPC film had good specificity to methomyl. When the concentration of methomyl solution changed from 0 to 0.02 g/L, the reflection peak shifted from 533 nm to 589 nm, the apparent color changed from green to orange-red, and the response time was only 13 min. There is no significant peak shift when measuring the analog of methomyl. The response of the MIPC to methomyl in biological samples was tested. When the MIPC was immersed in the matrix solution of cabbage samples with 0.002, 0.02 and 0.2 mg/L of methomyl, the offsets of MIPC reflection peak were 28, 34 and 42 nm, respectively. The results show that the sensor still maintains high selectivity and high sensitivity in the presence of complex matrix interference.
A novel sensing material with high sensitivity and specificity was developed for the detection of methomyl by combining photonic crystal technique with molecularly imprinting technique which was named molecularly imprinted photonic crystal (MIPC). MIPC was prepared by thermal polymerization with SiO2 microspheres array as pore-forming templates, methomyl as imprinting molecule, methacrylic acid and acrylamide as monomers and ethylene dimethacrylate as cross-linker, followed by chemical removal of SiO2 microspheres and imprinting molecules. The morphology of the polymer films was characterized by scanning electron microscopy (SEM). The results showed that a three-dimensional interconnected macroporous array with a typical face-centered cubic structure was formed in the film. The response of the MIPC to methomyl solution was studied by measuring the change of the position of the reflection peak. The results showed that the MIPC film had good specificity to methomyl. When the concentration of methomyl solution changed from 0 to 0.02 g/L, the reflection peak shifted from 533 nm to 589 nm, the apparent color changed from green to orange-red, and the response time was only 13 min. There is no significant peak shift when measuring the analog of methomyl. The response of the MIPC to methomyl in biological samples was tested. When the MIPC was immersed in the matrix solution of cabbage samples with 0.002, 0.02 and 0.2 mg/L of methomyl, the offsets of MIPC reflection peak were 28, 34 and 42 nm, respectively. The results show that the sensor still maintains high selectivity and high sensitivity in the presence of complex matrix interference.
2019, 47(6): 890-898
doi: 10.19756/j.issn.0253-3820.181670
Abstract:
To investigate the characteristics and source apportionment of volatile organic compounds (VOCs) during the BRICS Conference in Xiamen and evaluate the effects of source control and mitigation policies, a online monitoring instrument (AC-GCMS 1000) was used to monitor VOCs, from August 28, 2017 to September 13 in the institute of Xiamen City, Chinese Academy of Sciences. The results showed that the concentrations of total volatile organic compounds (TVOCs) were (19.09±9.65)×10-9(V/V), (9.39±3.35)×10-9(V/V), (14.88±9.68)×10-9(V/V) before, during and after the conference, respectively. During the BRICS Conference, TVOCs decreased by 51% and 37% compared with that of before and after the conference. Specifically, the oxygen volatile organic compounds (OVOCs), aromatics and alkenes, were decreased by 90%, 53% and 38% respectively. The ozone formation potential (OFP) was the highest before the conference (162.06 μg/m3), followed by that after (121.45 μg/m3) and during (77.14 μg/m3) conference. The same pattern was identified for the secondary organic aerosols potential (SOAP), which was calculated as 2.14, 1.65 and 1.93 mg/m3, respectively. Overall, both OFP and SOAP were decreased by 52% and 23%, respectively. Aromatics and Alkenes were the key contributors of OFP. Aromatics played a leading role in the formation of SOA. Five emission sources of VOCs were identified by PMF model, including vehicle exhaust, biogenic VOCs, solvent utilization, gasoline evaporation and the background VOCs. The solvent utilization source was the largest contributor of VOCs during the Xiamen BRICS Conference (32%), which was decreased by 76% compared with that before the conference. The results of this study show that the mitigation of solvent utilization and vehicle exhaust can significantly reduce the concentrations of major VOCs species, and have a great effect on the subsequent control of O3 and SOA production. This work suggests an effective direction to control VOCs emission in Xiamen and other areas.
To investigate the characteristics and source apportionment of volatile organic compounds (VOCs) during the BRICS Conference in Xiamen and evaluate the effects of source control and mitigation policies, a online monitoring instrument (AC-GCMS 1000) was used to monitor VOCs, from August 28, 2017 to September 13 in the institute of Xiamen City, Chinese Academy of Sciences. The results showed that the concentrations of total volatile organic compounds (TVOCs) were (19.09±9.65)×10-9(V/V), (9.39±3.35)×10-9(V/V), (14.88±9.68)×10-9(V/V) before, during and after the conference, respectively. During the BRICS Conference, TVOCs decreased by 51% and 37% compared with that of before and after the conference. Specifically, the oxygen volatile organic compounds (OVOCs), aromatics and alkenes, were decreased by 90%, 53% and 38% respectively. The ozone formation potential (OFP) was the highest before the conference (162.06 μg/m3), followed by that after (121.45 μg/m3) and during (77.14 μg/m3) conference. The same pattern was identified for the secondary organic aerosols potential (SOAP), which was calculated as 2.14, 1.65 and 1.93 mg/m3, respectively. Overall, both OFP and SOAP were decreased by 52% and 23%, respectively. Aromatics and Alkenes were the key contributors of OFP. Aromatics played a leading role in the formation of SOA. Five emission sources of VOCs were identified by PMF model, including vehicle exhaust, biogenic VOCs, solvent utilization, gasoline evaporation and the background VOCs. The solvent utilization source was the largest contributor of VOCs during the Xiamen BRICS Conference (32%), which was decreased by 76% compared with that before the conference. The results of this study show that the mitigation of solvent utilization and vehicle exhaust can significantly reduce the concentrations of major VOCs species, and have a great effect on the subsequent control of O3 and SOA production. This work suggests an effective direction to control VOCs emission in Xiamen and other areas.
2019, 47(6): 899-906
doi: 10.19756/j.issn.0253-3820.181635
Abstract:
An Hg2+-triggered exonuclease Ⅲ-assisted dual-cycle isothermal signal amplification was developed for label-free and ultrasensitive detection of Hg2+ using two designed hairpin probes. In the presence of Hg2+, the Hg2+ discrimination probe could hybridize with the free 3'-terminus of hairpin probe 1 by T-Hg2+-T coordination and a blunt 3'-terminus is formed. In this case, Exo Ⅲ could preferentially bind to the blunt 3'-terminus and catalyze the stepwise hydrolysis of mononucleotides in the 3'-to-5' direction. The released Hg2+ and Hg2+discrimination probe were recycled in a new round of reaction cycle (cycle 1). Undegraded sequence of hairpin probe 1 comprises G-quadruplex-forming sequence and I-region that was completely complementary to the free 3'-terminus of hairpin probe 2 (Ⅰ* region) to form another blunt 3'-terminus. The new blunt 3'-terminus could trigger Exo Ⅲ-assisted cleavage again, and the I-region was released and recycled in a new round of reaction cycle (cycle 2). Cycles 1 and 2 were spontaneous cycle processes. After multiple cycles, a large number of single-stranded G-quadruplex-forming sequences could be generated. The released G-quadruplex-forming sequences could bind hemin to form stable G-quadruplex-hemin DNAzymes, which could efficiently catalyze ABTS-H2O2 system to produce the colored product. Under the optimal experimental conditions, the linear range for detection of Hg2+ was 0.3 pmol/L-50 pmol/L with a detection limit of 0.25 pmol/L, and the regression equation was ΔA420 nm=0.117+0.004CHg2+(pmol/L). This Hg2+ sensing system had excellent selectivity for Hg2+ against otherpossible competing ions. The fabricated sensor was applied to detection of Hg2+ in environmental water samples, and the recoveries were 96.0%-106.0%, respectively. This method was simple with good selectivity, high sensitivity and strong anti-interference ability, and was suitable for the sensitive detection of Hg2+ in environmental water samples.
An Hg2+-triggered exonuclease Ⅲ-assisted dual-cycle isothermal signal amplification was developed for label-free and ultrasensitive detection of Hg2+ using two designed hairpin probes. In the presence of Hg2+, the Hg2+ discrimination probe could hybridize with the free 3'-terminus of hairpin probe 1 by T-Hg2+-T coordination and a blunt 3'-terminus is formed. In this case, Exo Ⅲ could preferentially bind to the blunt 3'-terminus and catalyze the stepwise hydrolysis of mononucleotides in the 3'-to-5' direction. The released Hg2+ and Hg2+discrimination probe were recycled in a new round of reaction cycle (cycle 1). Undegraded sequence of hairpin probe 1 comprises G-quadruplex-forming sequence and I-region that was completely complementary to the free 3'-terminus of hairpin probe 2 (Ⅰ* region) to form another blunt 3'-terminus. The new blunt 3'-terminus could trigger Exo Ⅲ-assisted cleavage again, and the I-region was released and recycled in a new round of reaction cycle (cycle 2). Cycles 1 and 2 were spontaneous cycle processes. After multiple cycles, a large number of single-stranded G-quadruplex-forming sequences could be generated. The released G-quadruplex-forming sequences could bind hemin to form stable G-quadruplex-hemin DNAzymes, which could efficiently catalyze ABTS-H2O2 system to produce the colored product. Under the optimal experimental conditions, the linear range for detection of Hg2+ was 0.3 pmol/L-50 pmol/L with a detection limit of 0.25 pmol/L, and the regression equation was ΔA420 nm=0.117+0.004CHg2+(pmol/L). This Hg2+ sensing system had excellent selectivity for Hg2+ against otherpossible competing ions. The fabricated sensor was applied to detection of Hg2+ in environmental water samples, and the recoveries were 96.0%-106.0%, respectively. This method was simple with good selectivity, high sensitivity and strong anti-interference ability, and was suitable for the sensitive detection of Hg2+ in environmental water samples.
2019, 47(6): 907-915
doi: 10.19756/j.issn.0253-3820.181776
Abstract:
Several conditions of the two-step chemical reduction method for simultaneous determination of both the stable nitrogen and oxygen isotope compositions in atmospheric nitrate (NO3-) particles, such as the pH, reaction time, type of cadmium powder and concentration of NaCl were optimized. The nitrite in the samples was reduced to nitrous oxide (N2O) through the improved method and the produced N2O was measured for their isotope compositions (δ15N and δ18O) by coupling an autosampler and a pre-concentration device with the MAT253 isotope ratio mass spectrometer. The standard curves of nitrogen (R2=0.9999) and oxygen (R2=0.9996) isotope ratios of N2O and NO3- were established by measuring the international standards with known isotope ratios, and the nitrogen and oxygen isotope ratios of nitrates of the sample could be therefore converted. The principle of this method was clear, and only required very small amounts of samples (i.e., 0.8 μg N). The standard deviations of δ15N and δ18O measurements from the present method were 0.08‰ and 0.24‰, respectively. This research method was not only suitable for atmospheric aerosol samples, but also for the other environmental samples such as rainwater and snow samples with low concentrations. This study provided a novel method for better understand emission sources and transformation pathways of atmospheric nitrate.
Several conditions of the two-step chemical reduction method for simultaneous determination of both the stable nitrogen and oxygen isotope compositions in atmospheric nitrate (NO3-) particles, such as the pH, reaction time, type of cadmium powder and concentration of NaCl were optimized. The nitrite in the samples was reduced to nitrous oxide (N2O) through the improved method and the produced N2O was measured for their isotope compositions (δ15N and δ18O) by coupling an autosampler and a pre-concentration device with the MAT253 isotope ratio mass spectrometer. The standard curves of nitrogen (R2=0.9999) and oxygen (R2=0.9996) isotope ratios of N2O and NO3- were established by measuring the international standards with known isotope ratios, and the nitrogen and oxygen isotope ratios of nitrates of the sample could be therefore converted. The principle of this method was clear, and only required very small amounts of samples (i.e., 0.8 μg N). The standard deviations of δ15N and δ18O measurements from the present method were 0.08‰ and 0.24‰, respectively. This research method was not only suitable for atmospheric aerosol samples, but also for the other environmental samples such as rainwater and snow samples with low concentrations. This study provided a novel method for better understand emission sources and transformation pathways of atmospheric nitrate.
2019, 47(6): 916-924
doi: 10.19756/j.issn.0253-3820.181584
Abstract:
The secondary electrospray ionization mass spectrometry (SESI-MS) has great potential in acquiring breathomics by in vivo, real-time and direct breath analysis. However, as an ambient source, the ionization efficiency of exhaled volatile organic compounds (VOCs) can be disturbed by the occurrence of indoor VOCs (background matrix) in SESI source. Therefore, we explored the effects of pure gases in the SESI source on the ionization efficiency of typical exhaled endogenous compounds, i.e., acetone and indole, as well as typical background matrix, i.e., phthalic anhydride (PA) and dibutyl phthalate (DP), by using a homemade SESI source coupled with an ultrahigh resolution mass spectrometer (UHRMS). The pure gases in this study included nitrogen (N2, purity 99.999%), carbon dioxide (CO2, purity 99.99%) and Zero air (VOCs free, 21% O2 and 79% N2 by volume). The results showed that the presence of all three pure gases could significantly increase the signal intensity and signal-to-noise ratio of exhaled acetone and indole. In contrast, the intensities of matrix interferences PA and DA decrease, because the concentrations of these compounds were diluted by the pure gases. Among three pure gases, the effect of N2 was most significant. In summary, the results of this study provided helpful information for SESI source design and parameter setting, which was an important prerequisite for the development of qualitative and quantitative methods for the detection of exhaled VOCs by using SESI-MS.
The secondary electrospray ionization mass spectrometry (SESI-MS) has great potential in acquiring breathomics by in vivo, real-time and direct breath analysis. However, as an ambient source, the ionization efficiency of exhaled volatile organic compounds (VOCs) can be disturbed by the occurrence of indoor VOCs (background matrix) in SESI source. Therefore, we explored the effects of pure gases in the SESI source on the ionization efficiency of typical exhaled endogenous compounds, i.e., acetone and indole, as well as typical background matrix, i.e., phthalic anhydride (PA) and dibutyl phthalate (DP), by using a homemade SESI source coupled with an ultrahigh resolution mass spectrometer (UHRMS). The pure gases in this study included nitrogen (N2, purity 99.999%), carbon dioxide (CO2, purity 99.99%) and Zero air (VOCs free, 21% O2 and 79% N2 by volume). The results showed that the presence of all three pure gases could significantly increase the signal intensity and signal-to-noise ratio of exhaled acetone and indole. In contrast, the intensities of matrix interferences PA and DA decrease, because the concentrations of these compounds were diluted by the pure gases. Among three pure gases, the effect of N2 was most significant. In summary, the results of this study provided helpful information for SESI source design and parameter setting, which was an important prerequisite for the development of qualitative and quantitative methods for the detection of exhaled VOCs by using SESI-MS.
2019, 47(6): 925-932
doi: 10.19756/j.issn.0253-3820.181804
Abstract:
Gangliosides are glycosphingolipid compounds containing sialic acid, which are natural components of vertebrate cell membranes. As a clinical drug, gangliosides are widely used in the treatment of hypoxic ischemic encephalopathy, central nervous system injury, neurodegenerative diseases and peripheral neuropathy. The structural identification of gangliosides helps to understand the composition of the drug and improve the quality of the drug. In this work, an electrospray ionization quadrupole time-of-flight mass spectrometry (ESI-Q-TOF-MS) method for analysis of ganglioside structure was established. The optimization of the mass spectrometry parameters were established based on testing of two gangliosides controls. The mass spectrometry conditions were established (positive mode, capillary voltage of 3500 V, fragmentor voltage of 200 V, and collision energy of 40 eV) to obtain the fragment structure of the sugar chain. The fragmentation structure of ceramide was obtained with collision energy of 80 eV. The method was applied to the structural analysis of 9 gangliosides prepared in the laboratory. The samples were categorized and classified by comparison with molecular weights of the reference substances. Detailed structure analysis was performed based on the characteristic fragments in the secondary mass spectra of the samples. The results of this study indicated that the method could be applied to the mass spectrometric identification of various gangliosides, laying a foundation for more complex ganglioside mass spectrometry analysis.
Gangliosides are glycosphingolipid compounds containing sialic acid, which are natural components of vertebrate cell membranes. As a clinical drug, gangliosides are widely used in the treatment of hypoxic ischemic encephalopathy, central nervous system injury, neurodegenerative diseases and peripheral neuropathy. The structural identification of gangliosides helps to understand the composition of the drug and improve the quality of the drug. In this work, an electrospray ionization quadrupole time-of-flight mass spectrometry (ESI-Q-TOF-MS) method for analysis of ganglioside structure was established. The optimization of the mass spectrometry parameters were established based on testing of two gangliosides controls. The mass spectrometry conditions were established (positive mode, capillary voltage of 3500 V, fragmentor voltage of 200 V, and collision energy of 40 eV) to obtain the fragment structure of the sugar chain. The fragmentation structure of ceramide was obtained with collision energy of 80 eV. The method was applied to the structural analysis of 9 gangliosides prepared in the laboratory. The samples were categorized and classified by comparison with molecular weights of the reference substances. Detailed structure analysis was performed based on the characteristic fragments in the secondary mass spectra of the samples. The results of this study indicated that the method could be applied to the mass spectrometric identification of various gangliosides, laying a foundation for more complex ganglioside mass spectrometry analysis.
2019, 47(6): 933-940
doi: 10.19756/j.issn.0253-3820.191059
Abstract:
A novel simultaneous detection method for isomers by spectrometry feature acquisition-separation parameter optimization-isomer analysis was proposed and verified. Dependent on self-made UV-FAIMS instrument, we investigated the separation of o-, m-, p-xylene by high-field asymmetric waveform ion mobility spectrometry (FAIMS). By analyzing the spectrometry feature of xylene isomers, the characteristic peaks of o-, m-and p-xylene were extracted; by analyzing the relationship between dispersion voltage and characteristic peak position, the best separation voltage range was determined to be 550-800 V, and by further analyzing of superimposing spectrometry, the best separation voltage was found to be 700 V under the carrier gas flow rate to be 400 L/h. Under this experimental condition, the peak positions of o-, m-, p-xylene characteristic ions were 4.36, 14.96 and 11.16 V, which kept a great spacing and maintained a fairly good one-to-one correspondence to xylene mixture detection spectrometry (Peak positions:4.33, 14.71 and 11.25 V) with errors of only 0.03, 0.25 and 0.09 V. The experiment realized the simultaneous separation and detection of the xylene mixture, and the result verified the correctness of the isomer detection method. Under the premise of retaining the characteristic peak, the detection limit of m-xylene was 0.047 mg/m3, which was less than the indoor air detection amount of 0.20 mg/m3 specified in the national standard GB/T 18883-2002, and the linear range was 0.24-2.4 mg/m3. This study provided technical support for the detection of xylene isomers, and provided a methodological basis for the rapid and high-precision detection of isomers by UV-FAIMS.
A novel simultaneous detection method for isomers by spectrometry feature acquisition-separation parameter optimization-isomer analysis was proposed and verified. Dependent on self-made UV-FAIMS instrument, we investigated the separation of o-, m-, p-xylene by high-field asymmetric waveform ion mobility spectrometry (FAIMS). By analyzing the spectrometry feature of xylene isomers, the characteristic peaks of o-, m-and p-xylene were extracted; by analyzing the relationship between dispersion voltage and characteristic peak position, the best separation voltage range was determined to be 550-800 V, and by further analyzing of superimposing spectrometry, the best separation voltage was found to be 700 V under the carrier gas flow rate to be 400 L/h. Under this experimental condition, the peak positions of o-, m-, p-xylene characteristic ions were 4.36, 14.96 and 11.16 V, which kept a great spacing and maintained a fairly good one-to-one correspondence to xylene mixture detection spectrometry (Peak positions:4.33, 14.71 and 11.25 V) with errors of only 0.03, 0.25 and 0.09 V. The experiment realized the simultaneous separation and detection of the xylene mixture, and the result verified the correctness of the isomer detection method. Under the premise of retaining the characteristic peak, the detection limit of m-xylene was 0.047 mg/m3, which was less than the indoor air detection amount of 0.20 mg/m3 specified in the national standard GB/T 18883-2002, and the linear range was 0.24-2.4 mg/m3. This study provided technical support for the detection of xylene isomers, and provided a methodological basis for the rapid and high-precision detection of isomers by UV-FAIMS.
2019, 47(6): 941-949
doi: 10.19756/j.issn.0253-3820.191124
Abstract:
The sugar content and total acidity of red globe grape directly affect the taste and quality of fresh food taste and its by-products. Vitamin C is a necessary nutrient for human beings, and it has become the main index to evaluate the quality of red globe grape. The traditional detection method of red globe grape internal quality is destructive sampling, which is cumbersome and time consuming, and has many drawbacks. In this work, based on near-infrared spectroscopy, the rapid nondestructive detection of red globe grape Vc, sugar content and total acidity was performed. The spectral data of red globe grape samples were collected, and the competitive adaptive reweighed algorithm, stability competitive adaptive reweighed sampling algorithm and successive projection algorithm were respectively applied to extract an effective characteristic band. Then the content of Vc and sugar and the total acidity were measured comparatively, and a corresponding partial least squares regression model was established. SPA was combined to extract a secondary characteristic band on the extraction of an effective characteristic band, and a corresponding PLSR model was established. The results showed that the correlation coefficient between the correction set and the prediction set of the PLSR model established by the secondary characteristic band was higher than that established by the primary characteristic band extraction, and the root mean square error of the model was reduced. The correlation coefficients of correction set and prediction set of the optimal PLSR model for red globe grape Vc, sugar content and total acidity based on the optimal band points extracted from the secondary characteristic band were 0.983, 0.982 and 0.976, respectively, and the correlation coefficients of prediction set were 0.975, 0.980 and 0.975, respectively. This stable model built with fewer bands predicts Vc, sugar content and total acidity, and greatly reduces run time. This model provided a technical support for subsequent portable detector and online dynamic detection research.
The sugar content and total acidity of red globe grape directly affect the taste and quality of fresh food taste and its by-products. Vitamin C is a necessary nutrient for human beings, and it has become the main index to evaluate the quality of red globe grape. The traditional detection method of red globe grape internal quality is destructive sampling, which is cumbersome and time consuming, and has many drawbacks. In this work, based on near-infrared spectroscopy, the rapid nondestructive detection of red globe grape Vc, sugar content and total acidity was performed. The spectral data of red globe grape samples were collected, and the competitive adaptive reweighed algorithm, stability competitive adaptive reweighed sampling algorithm and successive projection algorithm were respectively applied to extract an effective characteristic band. Then the content of Vc and sugar and the total acidity were measured comparatively, and a corresponding partial least squares regression model was established. SPA was combined to extract a secondary characteristic band on the extraction of an effective characteristic band, and a corresponding PLSR model was established. The results showed that the correlation coefficient between the correction set and the prediction set of the PLSR model established by the secondary characteristic band was higher than that established by the primary characteristic band extraction, and the root mean square error of the model was reduced. The correlation coefficients of correction set and prediction set of the optimal PLSR model for red globe grape Vc, sugar content and total acidity based on the optimal band points extracted from the secondary characteristic band were 0.983, 0.982 and 0.976, respectively, and the correlation coefficients of prediction set were 0.975, 0.980 and 0.975, respectively. This stable model built with fewer bands predicts Vc, sugar content and total acidity, and greatly reduces run time. This model provided a technical support for subsequent portable detector and online dynamic detection research.
2019, 47(6): 950-956
doi: 10.19756/j.issn.0253-3820.191043
Abstract:
Fluorescence and absorption spectra of magnoflorine (MAG) were studied. The effects of environmental factors such as pH on fluorescence and absorbance were investigated, and the relationship between spectral properties and molecular structure was revealed. Three fluorescent peaks appeared in the three-dimensional (3D) fluorescence spectra of the aqueous solution of MAG, with excitation wavelengths (λex) of 230, 275 and 315 nm, and the same emission wavelength (λem) of 420 nm. As the pH of the solution increased, the fluorescence peak in the excitation spectrum red-shifted and an equal fluorescence point appeared, and the absorption peak in the absorption spectrum also red-shifted and an isosbestic point formed, indicating that proton ionization occurred in one hydroxyl group in the MAG molecule. The proton ionization constant (pKa=4.77) of MAG was determined by a pH-absorption method. Using L-tryptophan as a reference, the fluorescence quantum yield of the aqueous solution of MAG was determined to be Y=0.19. The characteristic fluorescence peaks of MAG appeared in the 3D fluorescence spectra of various Chinese herbal medicines. Using methanol-water mixed solvent containing 60% methanol, the extract of Sinomenium acutum (Qingfengteng) was prepared and diluted with water, then 3D fluorescence spectra were obtained. It was observed that the fluorescence peak at λex/λem=315 nm/420 nm in the spectrum of the Qingfengteng neutral aqueous solution was not affected by the coexisting components. Based on this, a method for the determination of MAG in Qingfengteng was established. In the range of 0.04-1.25 μg/mL, the regression equation for fluorescence intensity (IF) and MAG concentration (c) was IF=6146.8c + 24.4, (R=0.999, n=11), with a detection limit of 0.52 ng/mL. The content of MAG in the Qingfengteng reference material was determined to be 0.63% by the method, and the recoveries were 101.2%-102.7%. The content of MAG (0.61%) in the same sample was also determined by LC-MS/MS method, which was consistent with the fluorescence method.
Fluorescence and absorption spectra of magnoflorine (MAG) were studied. The effects of environmental factors such as pH on fluorescence and absorbance were investigated, and the relationship between spectral properties and molecular structure was revealed. Three fluorescent peaks appeared in the three-dimensional (3D) fluorescence spectra of the aqueous solution of MAG, with excitation wavelengths (λex) of 230, 275 and 315 nm, and the same emission wavelength (λem) of 420 nm. As the pH of the solution increased, the fluorescence peak in the excitation spectrum red-shifted and an equal fluorescence point appeared, and the absorption peak in the absorption spectrum also red-shifted and an isosbestic point formed, indicating that proton ionization occurred in one hydroxyl group in the MAG molecule. The proton ionization constant (pKa=4.77) of MAG was determined by a pH-absorption method. Using L-tryptophan as a reference, the fluorescence quantum yield of the aqueous solution of MAG was determined to be Y=0.19. The characteristic fluorescence peaks of MAG appeared in the 3D fluorescence spectra of various Chinese herbal medicines. Using methanol-water mixed solvent containing 60% methanol, the extract of Sinomenium acutum (Qingfengteng) was prepared and diluted with water, then 3D fluorescence spectra were obtained. It was observed that the fluorescence peak at λex/λem=315 nm/420 nm in the spectrum of the Qingfengteng neutral aqueous solution was not affected by the coexisting components. Based on this, a method for the determination of MAG in Qingfengteng was established. In the range of 0.04-1.25 μg/mL, the regression equation for fluorescence intensity (IF) and MAG concentration (c) was IF=6146.8c + 24.4, (R=0.999, n=11), with a detection limit of 0.52 ng/mL. The content of MAG in the Qingfengteng reference material was determined to be 0.63% by the method, and the recoveries were 101.2%-102.7%. The content of MAG (0.61%) in the same sample was also determined by LC-MS/MS method, which was consistent with the fluorescence method.
2019, 47(6): 957-963
doi: 10.19756/j.issn.0253-3820.191010
Abstract:
On the basis of the neurochemistry analysis, the effects of ginseng, American ginseng, red ginseng and red American ginseng on 24 neurochemicals in rat plasma were investigated by UPLC-QQQ-MS. Combined with chemometrics multivariate statistical analysis, the data were processed by principal component analysis (PCA) and partial least squares discriminant pattern recognition analysis (PLS-DA). By means of the discriminant coefficient and score contribution of recognition model, potential warm and cool properties markers were screened out and the properties difference of ginseng, American ginseng and their processed ones were evaluated. The result showed that 14 kinds of neurochemicals were discovered to be the warm property markers and 10 were cool property markers of ginseng. Among those markers, Glu and Phe presented the most significant effect on warm property, and Gly and 5-HT showed most correlation with cool property. The scores of warm property markers were positive and the corresponding score of red ginseng group was greater than that of ginseng group, demonstrated that the property of red ginseng was warmer than ginseng. For the American ginseng and red American ginseng groups, the scores of cool property markers were positive and cool property of red American ginseng was less than American ginseng. The influence of processing on the property of American ginseng was demonstrated for the first time. The changes of neurochemicals could reflect the influence of warm and cool property on organisms and neurochemistry analysis method could be applied to evaluate the property effect of traditional Chinese medicine. This research provides a methodology reference for the study of the material basis and pharmacological mechanism of the Chinese medicine property difference.
On the basis of the neurochemistry analysis, the effects of ginseng, American ginseng, red ginseng and red American ginseng on 24 neurochemicals in rat plasma were investigated by UPLC-QQQ-MS. Combined with chemometrics multivariate statistical analysis, the data were processed by principal component analysis (PCA) and partial least squares discriminant pattern recognition analysis (PLS-DA). By means of the discriminant coefficient and score contribution of recognition model, potential warm and cool properties markers were screened out and the properties difference of ginseng, American ginseng and their processed ones were evaluated. The result showed that 14 kinds of neurochemicals were discovered to be the warm property markers and 10 were cool property markers of ginseng. Among those markers, Glu and Phe presented the most significant effect on warm property, and Gly and 5-HT showed most correlation with cool property. The scores of warm property markers were positive and the corresponding score of red ginseng group was greater than that of ginseng group, demonstrated that the property of red ginseng was warmer than ginseng. For the American ginseng and red American ginseng groups, the scores of cool property markers were positive and cool property of red American ginseng was less than American ginseng. The influence of processing on the property of American ginseng was demonstrated for the first time. The changes of neurochemicals could reflect the influence of warm and cool property on organisms and neurochemistry analysis method could be applied to evaluate the property effect of traditional Chinese medicine. This research provides a methodology reference for the study of the material basis and pharmacological mechanism of the Chinese medicine property difference.
