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2018 Volume 46 Issue 12
2018, 46(12): 1851-1862
doi: 10.11895/j.issn.0253-3820.181515
Abstract:
Circulating tumor cells (CTCs) are rare tumor cells shed from primary and metastatic tumor sites into the circulation and have great clinical significance for the early diagnosis and prognosis of cancer patients, as well as have potential value in personalized cancer therapy and drug development. However, CTCs are often rare in blood sample. Therefore, the development of enrichment techniques is turning out to be the bottleneck of its clinical application. Additionally, the distribution of CTCs subtypes and the molecular identification and functional analysis of viable CTCs are more helpful for clinical diagnosis and personalized cancer therapy, and higher requirements for CTCs enrichment technique are put forward. In this paper, the progress in enrichment of CTCs and its subtype capture and post-capture nondestructive release in recent years were reviewed, and the future trends of CTCs enrichment technologies including the challenge and opportunity were discussed.
Circulating tumor cells (CTCs) are rare tumor cells shed from primary and metastatic tumor sites into the circulation and have great clinical significance for the early diagnosis and prognosis of cancer patients, as well as have potential value in personalized cancer therapy and drug development. However, CTCs are often rare in blood sample. Therefore, the development of enrichment techniques is turning out to be the bottleneck of its clinical application. Additionally, the distribution of CTCs subtypes and the molecular identification and functional analysis of viable CTCs are more helpful for clinical diagnosis and personalized cancer therapy, and higher requirements for CTCs enrichment technique are put forward. In this paper, the progress in enrichment of CTCs and its subtype capture and post-capture nondestructive release in recent years were reviewed, and the future trends of CTCs enrichment technologies including the challenge and opportunity were discussed.
2018, 46(12): 1863-1871
doi: 10.11895/j.issn.0253-3820.181552
Abstract:
Microfluidics has been widely used in the life science, analytical chemistry, environmental science and some other fields in recent years. Traditional microfluidics systems usually refer to a highly integrated system with multiple components, aims at handle the fluid in the micro scale. The design and fabrication of integrated microfluidics usually require highly sophisticated instruments and professionals. With the experience inherited from intergrated circuit(IC) and micro electro mechanical system(MEMS) technology, the modular microfluidic system was experienced a rapid development in the recent years, modular microfluidics is a combination of series of individual modules to realize complicated liquid handling functions. Compared with conventional microfluidic approach, the advantage of modular microfluidics includes the potential for significantly reduce the fabrication cost with massive production, the modular microfluidics is also easy to use, and the user could easily combine the modules for their customized microfluidic system. The concept of modular microfluidics also indicate a way for the future standardization of microfluidic system and provide a promising approach for the industrial massive production in the future. However, the study of modular microfluidics is still in an early stage, lots of studies have been conducted with varies materials, fabrication methods and interface technologies. In study is trying to provide a comprehensive review for the latest research on the modular microfluidics and applications in biological and medical fields, the future research trends for modular microfluidics is also provided in this study.
Microfluidics has been widely used in the life science, analytical chemistry, environmental science and some other fields in recent years. Traditional microfluidics systems usually refer to a highly integrated system with multiple components, aims at handle the fluid in the micro scale. The design and fabrication of integrated microfluidics usually require highly sophisticated instruments and professionals. With the experience inherited from intergrated circuit(IC) and micro electro mechanical system(MEMS) technology, the modular microfluidic system was experienced a rapid development in the recent years, modular microfluidics is a combination of series of individual modules to realize complicated liquid handling functions. Compared with conventional microfluidic approach, the advantage of modular microfluidics includes the potential for significantly reduce the fabrication cost with massive production, the modular microfluidics is also easy to use, and the user could easily combine the modules for their customized microfluidic system. The concept of modular microfluidics also indicate a way for the future standardization of microfluidic system and provide a promising approach for the industrial massive production in the future. However, the study of modular microfluidics is still in an early stage, lots of studies have been conducted with varies materials, fabrication methods and interface technologies. In study is trying to provide a comprehensive review for the latest research on the modular microfluidics and applications in biological and medical fields, the future research trends for modular microfluidics is also provided in this study.
2018, 46(12): 1872-1877
doi: 10.11895/j.issn.0253-3820.181298
Abstract:
The polygonal electrode linear ion trap (PeLIT) can produce quadrupolar electric field plus some higher order field, which balances the relationship between mass resolution and electrode manufactruing difficulties. The electrodes of PeLIT are relatively simple, but have a good mass resolving power. This study analyzed the structures and performances of PeLIT through theoretical simulation and experimental study. Simulations showed that the polygonal electrode linear ion traps with different structures had different mass analysis performances, and the negative decapole field reduced its performances significantly. The experimental results showed that the mass resolution of reserpine ions (m/z 609) was more than 2500 using a polygonal electrode ion trap. At the same time, mass selective excitation and tandem mass spectrometry experiments were also performed.
The polygonal electrode linear ion trap (PeLIT) can produce quadrupolar electric field plus some higher order field, which balances the relationship between mass resolution and electrode manufactruing difficulties. The electrodes of PeLIT are relatively simple, but have a good mass resolving power. This study analyzed the structures and performances of PeLIT through theoretical simulation and experimental study. Simulations showed that the polygonal electrode linear ion traps with different structures had different mass analysis performances, and the negative decapole field reduced its performances significantly. The experimental results showed that the mass resolution of reserpine ions (m/z 609) was more than 2500 using a polygonal electrode ion trap. At the same time, mass selective excitation and tandem mass spectrometry experiments were also performed.
2018, 46(12): 1878-1885
doi: 10.11895/j.issn.0253-3820.181475
Abstract:
An ultraviolet (UV) digital micromirror spectrometer using a digital micromirror device (DMD) as a spatial light modulator, a grating as a spectroscope and a photomultiplier tube (PMT) as a detector, was specially designed for dispersive hydride generation atomic fluorescence spectrometry (HG-AFS). To improve detection ability of the spectrometer for weak fluorescence signals at 180-320 nm, a high UV transmittance DMD was used and the signal acquisition system was improved, the control parameters of DMD and PMT negative high voltage were optimized. The feasibility of the spectrometer was demonstrated with analyzing standard sample of As, Sb, Bi and Hg, the atomic emission and fluorescence spectra were obtained. The scattering interference caused by the light source was discussed. The results showed that the UV digital micromirror spectrometer had a preliminary ability for the excitation fluorescence analysis by HG-AFS. The UV digital micromirror spectrometer contained no moving parts, was simply structured, and speedy spectral analysis (0.848 s per spectrum scan).
An ultraviolet (UV) digital micromirror spectrometer using a digital micromirror device (DMD) as a spatial light modulator, a grating as a spectroscope and a photomultiplier tube (PMT) as a detector, was specially designed for dispersive hydride generation atomic fluorescence spectrometry (HG-AFS). To improve detection ability of the spectrometer for weak fluorescence signals at 180-320 nm, a high UV transmittance DMD was used and the signal acquisition system was improved, the control parameters of DMD and PMT negative high voltage were optimized. The feasibility of the spectrometer was demonstrated with analyzing standard sample of As, Sb, Bi and Hg, the atomic emission and fluorescence spectra were obtained. The scattering interference caused by the light source was discussed. The results showed that the UV digital micromirror spectrometer had a preliminary ability for the excitation fluorescence analysis by HG-AFS. The UV digital micromirror spectrometer contained no moving parts, was simply structured, and speedy spectral analysis (0.848 s per spectrum scan).
2018, 46(12): 1886-1894
doi: 10.11895/j.issn.0253-3820.181262
Abstract:
A novel wireless sensing device was designed by adopting remote controlling procedure through wireless electronic transmitting/receiving modules for acquiring potential data based on 3-mercaptopropanesulfonic acid (MPS) modified gold electrode, which could be applied to remote ultrasensitive monitoring of Hg2+. The surface properties of MPS membrane electrodes with Hg2+ combined and uncombined were characterized by means of SEM, XPS, electrochemical impedance spectroscopy and cyclic voltammetry, indicating that the MPS containing the terminal of sulfonic group exhibited good recognition interaction toward Hg2+ through electrostatic adsorption, which was due to the formation of double electric layer resulting in change of membrane potential. In Tris-HCl buffer solution (pH=6.0), the MPS membrane electrode had good linear relationship between potential response and Hg2+ concentration in the range of 1.0×10-8-1.0×10-3 mol/L with a slope of 59.08 mV/(-pC) (25℃), and the detection limit was calculated to be 8.31 nmol/L. In addition, the MPS-based wireless sensor displayed fast response time, i.e. 8 s, with good stability, reproducibility and selectivity. This method was successfully used for the determination of Hg2+ in real water samples with recovery of 93.7%-101.9%, showing important application prospects in real-time monitoring of environmental water.
A novel wireless sensing device was designed by adopting remote controlling procedure through wireless electronic transmitting/receiving modules for acquiring potential data based on 3-mercaptopropanesulfonic acid (MPS) modified gold electrode, which could be applied to remote ultrasensitive monitoring of Hg2+. The surface properties of MPS membrane electrodes with Hg2+ combined and uncombined were characterized by means of SEM, XPS, electrochemical impedance spectroscopy and cyclic voltammetry, indicating that the MPS containing the terminal of sulfonic group exhibited good recognition interaction toward Hg2+ through electrostatic adsorption, which was due to the formation of double electric layer resulting in change of membrane potential. In Tris-HCl buffer solution (pH=6.0), the MPS membrane electrode had good linear relationship between potential response and Hg2+ concentration in the range of 1.0×10-8-1.0×10-3 mol/L with a slope of 59.08 mV/(-pC) (25℃), and the detection limit was calculated to be 8.31 nmol/L. In addition, the MPS-based wireless sensor displayed fast response time, i.e. 8 s, with good stability, reproducibility and selectivity. This method was successfully used for the determination of Hg2+ in real water samples with recovery of 93.7%-101.9%, showing important application prospects in real-time monitoring of environmental water.
2018, 46(12): 1895-1903
doi: 10.11895/j.issn.0253-3820.181407
Abstract:
Peptide nucleic acid (PNA) is a kind of nucleic acid analog which consists of purines, pyrimidines bases, and a neutrally charged peptide backbone. PNA has the potential to be a very useful biological probe for proteins analysis since it has more in vivo biological stability as compared to DNA-or RNA-based aptamers. Usually, the addition of amino acids or peptide to PNA backbone is used to improve its water-solubility and cell-permeability, but these modifications may affect the interaction between PNA and proteins. In this research, we designed two types of amino acid modified PNAs:(Lys)2-PNA and (Glu)2-PNA which kept the same base sequence with 15-mer thrombin aptamer and had two basic lysine and two acidic glutamic acid units on N-terminal of the peptide backbone, respectively. To rapidly assess the binding affinity and specificity of modified PNA and proteins, the online CE reaction method was developed to analyze interactions of (Lys)2-PNA/(Glu)2-PNA and three proteins including thrombin (THB), single-stranded DNA-binding protein (SSB) and human serum albumin (HSA). Meanwhile, the interactions of (Lys)2-PNA/(Glu)2-PNA and thrombin were compared with that of the corresponding complementary base sequence (Lys)2-cPNA/(Glu)2-cPNA and thrombin. The online CE reaction results showed that the interaction of (Lys)2-PNA and (Glu)2-PNA with three proteins was in the order of THB > SSB > HSA. However, (Lys)2-PNA and (Lys)2-cPNA showed similar binding affinity with thrombin; while the binding affinity of (Glu)2-PNA with thrombin was stronger than that of (Glu)2-cPNA with thrombin. Moreover, the binding constant Kb of (Glu)2-PNA and three proteins was determined by affinity capillary electrophoresis (ACE). The Kb was calculated as 8.39×106 L/mol for thrombin and 5.91×105 L/mol for SSB, while the binding affinity of (Glu)2-PNA with HSA was too weak to be calculated. The quantitative results of ACE showed agreement with the online CE reaction results, verifying the reliability of online CE reaction method. Besides, the online CE reaction eliminated the requirement of incubation and thus it was faster in detection, simpler in operation with low testing cost. The presented method was particularly suitable for the interaction studies of expensive modified PNAs and proteins, and would assist the design of PNA probe that binds to proteins.
Peptide nucleic acid (PNA) is a kind of nucleic acid analog which consists of purines, pyrimidines bases, and a neutrally charged peptide backbone. PNA has the potential to be a very useful biological probe for proteins analysis since it has more in vivo biological stability as compared to DNA-or RNA-based aptamers. Usually, the addition of amino acids or peptide to PNA backbone is used to improve its water-solubility and cell-permeability, but these modifications may affect the interaction between PNA and proteins. In this research, we designed two types of amino acid modified PNAs:(Lys)2-PNA and (Glu)2-PNA which kept the same base sequence with 15-mer thrombin aptamer and had two basic lysine and two acidic glutamic acid units on N-terminal of the peptide backbone, respectively. To rapidly assess the binding affinity and specificity of modified PNA and proteins, the online CE reaction method was developed to analyze interactions of (Lys)2-PNA/(Glu)2-PNA and three proteins including thrombin (THB), single-stranded DNA-binding protein (SSB) and human serum albumin (HSA). Meanwhile, the interactions of (Lys)2-PNA/(Glu)2-PNA and thrombin were compared with that of the corresponding complementary base sequence (Lys)2-cPNA/(Glu)2-cPNA and thrombin. The online CE reaction results showed that the interaction of (Lys)2-PNA and (Glu)2-PNA with three proteins was in the order of THB > SSB > HSA. However, (Lys)2-PNA and (Lys)2-cPNA showed similar binding affinity with thrombin; while the binding affinity of (Glu)2-PNA with thrombin was stronger than that of (Glu)2-cPNA with thrombin. Moreover, the binding constant Kb of (Glu)2-PNA and three proteins was determined by affinity capillary electrophoresis (ACE). The Kb was calculated as 8.39×106 L/mol for thrombin and 5.91×105 L/mol for SSB, while the binding affinity of (Glu)2-PNA with HSA was too weak to be calculated. The quantitative results of ACE showed agreement with the online CE reaction results, verifying the reliability of online CE reaction method. Besides, the online CE reaction eliminated the requirement of incubation and thus it was faster in detection, simpler in operation with low testing cost. The presented method was particularly suitable for the interaction studies of expensive modified PNAs and proteins, and would assist the design of PNA probe that binds to proteins.
2018, 46(12): 1904-1912
doi: 10.11895/j.issn.0253-3820.181570
Abstract:
The lectin microarray-based resonance light scattering (RLS) assay has been developed to evaluate the interactions of Staphylococcus aureus (S. aureus) with three broad-spectrum antibiotics (amoxicillin, vancomycin and streptomycin). S. aureus was firstly captured by immobilized lectins on the substrate surface, and then labeled with Griffonia simplicifolia Ⅱ (GSⅡ) modified 38.5 nm gold nanoparticles (GNP@GSⅡ) for generating RLS signal. The investigation of the binding affinity of S. aureus with 16 lectins in the presence of antibiotics showed that amoxicillin and vancomycin could significantly reduce the expression level of glycans on S. aureus membrane, while streptomycin could increase the expression level of glycans on S. aureus membrane. The experimental result may suggest the different action mechanisms of antibiotics with S. aureus. Furthermore, the minimum inhibitory concentration (MIC) values and bactericidal efficiency of antibiotics could also be determined by the drug induced change of RLS intensity of GSⅡ subarray and lectin binding patterns of S. aureus, respectively.
The lectin microarray-based resonance light scattering (RLS) assay has been developed to evaluate the interactions of Staphylococcus aureus (S. aureus) with three broad-spectrum antibiotics (amoxicillin, vancomycin and streptomycin). S. aureus was firstly captured by immobilized lectins on the substrate surface, and then labeled with Griffonia simplicifolia Ⅱ (GSⅡ) modified 38.5 nm gold nanoparticles (GNP@GSⅡ) for generating RLS signal. The investigation of the binding affinity of S. aureus with 16 lectins in the presence of antibiotics showed that amoxicillin and vancomycin could significantly reduce the expression level of glycans on S. aureus membrane, while streptomycin could increase the expression level of glycans on S. aureus membrane. The experimental result may suggest the different action mechanisms of antibiotics with S. aureus. Furthermore, the minimum inhibitory concentration (MIC) values and bactericidal efficiency of antibiotics could also be determined by the drug induced change of RLS intensity of GSⅡ subarray and lectin binding patterns of S. aureus, respectively.
2018, 46(12): 1913-1922
doi: 10.11895/j.issn.0253-3820.181481
Abstract:
Titanium dioxide (TiO2) nanowires array prepared on the fluorine-doped tin oxide (FTO) substrate by the hydrothermal synthesis method was combined with internal extractive electrospray ionization mass spectrometry (iEESI-MS), allowing selective enrichment and direct analysis of the phospholipids from soybean. The experimental parameters including ratio of trifluoroacetic acid (TFA) in methanol, adsorption time, composition, and flow rate of eluent were investigated. The results showed that the optimal signal of phospholipids was obtained under the optimized conditions such as the extraction solution of 2% (V/V) TFA in methanol, adsorption time of 60 s, eluent of 1.5% (V/V) ammonia in methanol and flow rate of 7 μL/min. A total of 18 kinds of phospholipids were detected from the grinding soybean solution. Based on these components, the soybeans from Heilongjiang, Jiangsu, Sichuan, Shandong and Henan were preliminarily separated by principal component analysis (PCA). The limits of detection (S/N ≥ 3) were 0.01 μg/L and the relative standard deviations (RSDs, n=3) were 1.6%-6.5%, showing high sensitivity in the quantitative analysis of phospholipids from soybean. Besides, accurate and rapid screening of the quality of commercial soybean oil was also achieved. This method was featured by less sample consumption, rapid analysis and simple operation, and could be used for direct and rapid detection of phospholipids in soybean.
Titanium dioxide (TiO2) nanowires array prepared on the fluorine-doped tin oxide (FTO) substrate by the hydrothermal synthesis method was combined with internal extractive electrospray ionization mass spectrometry (iEESI-MS), allowing selective enrichment and direct analysis of the phospholipids from soybean. The experimental parameters including ratio of trifluoroacetic acid (TFA) in methanol, adsorption time, composition, and flow rate of eluent were investigated. The results showed that the optimal signal of phospholipids was obtained under the optimized conditions such as the extraction solution of 2% (V/V) TFA in methanol, adsorption time of 60 s, eluent of 1.5% (V/V) ammonia in methanol and flow rate of 7 μL/min. A total of 18 kinds of phospholipids were detected from the grinding soybean solution. Based on these components, the soybeans from Heilongjiang, Jiangsu, Sichuan, Shandong and Henan were preliminarily separated by principal component analysis (PCA). The limits of detection (S/N ≥ 3) were 0.01 μg/L and the relative standard deviations (RSDs, n=3) were 1.6%-6.5%, showing high sensitivity in the quantitative analysis of phospholipids from soybean. Besides, accurate and rapid screening of the quality of commercial soybean oil was also achieved. This method was featured by less sample consumption, rapid analysis and simple operation, and could be used for direct and rapid detection of phospholipids in soybean.
2018, 46(12): 1923-1930
doi: 10.11895/j.issn.0253-3820.181144
Abstract:
Ionic liquid matrix 2,5-dihydroxybenzoic acid/N,N-dimethylaniline (DHB/DMA) and ultrasonic spray deposition method were selected for matrix-assisted laser desorption ionization-mass spectrometry (MALDI-MS) analysis and MALDI-MS imaging of small molecule components on the surface of mulberry leaf and in leaf vein, including protocatechuic acid, chlorogenic acid, monosaccharide and disaccharide, astragalin, rutin, isoquercetin, cyanidin-3-O-glucoside, quercetin-3-O-6"-O-acetyl-β-D-glucopyranoside and kaempferol-3-O-rutinoside. The ultrasonic spray method was performed to deposit the ionic liquid matrix on sample slice with less diffusion of the analytes and improved reproducibility and sensitivity compared with spotting method and airbrush deposition method. The experimental conditions were optimized according to their effects on signal-to-noise ratio, and as a result, laser energy of 70%, ultrasonic spray 12 times, and 7.5 mmol/L additive KBr were selected. The distributions of different components on the surface of mulberry leaf or in leaf vein slice were analyzed by MALDI-MS imaging. The result suggested that the ionic liquid matrix and ultrasonic spray deposition matrix method could be well applied in MALDI-MS imaging of small molecular components in traditional Chinese medicine or plant.
Ionic liquid matrix 2,5-dihydroxybenzoic acid/N,N-dimethylaniline (DHB/DMA) and ultrasonic spray deposition method were selected for matrix-assisted laser desorption ionization-mass spectrometry (MALDI-MS) analysis and MALDI-MS imaging of small molecule components on the surface of mulberry leaf and in leaf vein, including protocatechuic acid, chlorogenic acid, monosaccharide and disaccharide, astragalin, rutin, isoquercetin, cyanidin-3-O-glucoside, quercetin-3-O-6"-O-acetyl-β-D-glucopyranoside and kaempferol-3-O-rutinoside. The ultrasonic spray method was performed to deposit the ionic liquid matrix on sample slice with less diffusion of the analytes and improved reproducibility and sensitivity compared with spotting method and airbrush deposition method. The experimental conditions were optimized according to their effects on signal-to-noise ratio, and as a result, laser energy of 70%, ultrasonic spray 12 times, and 7.5 mmol/L additive KBr were selected. The distributions of different components on the surface of mulberry leaf or in leaf vein slice were analyzed by MALDI-MS imaging. The result suggested that the ionic liquid matrix and ultrasonic spray deposition matrix method could be well applied in MALDI-MS imaging of small molecular components in traditional Chinese medicine or plant.
2018, 46(12): 1931-1936
doi: 10.11895/j.issn.0253-3820.181284
Abstract:
Molybdenum disulfide/porous graphene (MoS2/pGN) composite was synthesized by a simple hydrothermal method. The pGN was not easy to aggregate and could provide large surface for MoS2 growing. Therefore, the stacking of MoS2 nanosheets was effectively restrained and showed few-layer nanosheet structure, showing outstanding electrochemical feature. In addition, the pGN could shorten the diffusion pathways and facilitate the electron transfer of target analyte. Hence, the composite modified electrode presented sensitive response to luteolin. The linear determination range was 0.01-5.0 μmol/L and the detection limit was 6.0 nmol/L (S/N=3). The sensor could be applied to the detection of luteolin in oral solution and peanut hulls, with recoveries of 91.8%-102.4% and relative standard deviations (RSDs) of below 5.6%.
Molybdenum disulfide/porous graphene (MoS2/pGN) composite was synthesized by a simple hydrothermal method. The pGN was not easy to aggregate and could provide large surface for MoS2 growing. Therefore, the stacking of MoS2 nanosheets was effectively restrained and showed few-layer nanosheet structure, showing outstanding electrochemical feature. In addition, the pGN could shorten the diffusion pathways and facilitate the electron transfer of target analyte. Hence, the composite modified electrode presented sensitive response to luteolin. The linear determination range was 0.01-5.0 μmol/L and the detection limit was 6.0 nmol/L (S/N=3). The sensor could be applied to the detection of luteolin in oral solution and peanut hulls, with recoveries of 91.8%-102.4% and relative standard deviations (RSDs) of below 5.6%.
2018, 46(12): 1937-1944
doi: 10.11895/j.issn.0253-3820.181461
Abstract:
A new Schiff base fluorescent probe, pyridine-2-carboxylic acid (2,5-dihydroxy-benzylidene)-hydrazide (L), based on 2,5-dihydroxybenzylaldehyde and picolinohydrazide was developed. L and Al3+ could form a complex with a stoichiometric ratio of 1:1 in DMSO-H2O (9:1, V/V, pH=6.25) solution. Simultaneously, a significant color change from colorless to light yellow and significant enhancement of fluorescence emission at 530 nm could be observed easily, which showed a high selectivity to Al3+. Moreover, a good linear relationship between fluorescence intensity and Al3+ concentration in the range of 1-10 μmol/L was obtained. The detection limit for Al3+ was 0.727 μmol/L (RSD=1.1%), showing a high sensitivity to the selective identification detection of Al3+. By combining ESI-mass and 1H NMR spectra, the formation of the complex and the binding mode of L and Al3+ were determined. Finally, by expanding the probe into the biological sample, the probe was proved to have low toxicity to liver cancer cell (line BEL-7402) by standard MTT assay. Confocal fluorescence and bright-field images of liver cancer cells (line BEL-7402) showed that the probe L could be used to detect the exogenous Al3+ in the living cell.
A new Schiff base fluorescent probe, pyridine-2-carboxylic acid (2,5-dihydroxy-benzylidene)-hydrazide (L), based on 2,5-dihydroxybenzylaldehyde and picolinohydrazide was developed. L and Al3+ could form a complex with a stoichiometric ratio of 1:1 in DMSO-H2O (9:1, V/V, pH=6.25) solution. Simultaneously, a significant color change from colorless to light yellow and significant enhancement of fluorescence emission at 530 nm could be observed easily, which showed a high selectivity to Al3+. Moreover, a good linear relationship between fluorescence intensity and Al3+ concentration in the range of 1-10 μmol/L was obtained. The detection limit for Al3+ was 0.727 μmol/L (RSD=1.1%), showing a high sensitivity to the selective identification detection of Al3+. By combining ESI-mass and 1H NMR spectra, the formation of the complex and the binding mode of L and Al3+ were determined. Finally, by expanding the probe into the biological sample, the probe was proved to have low toxicity to liver cancer cell (line BEL-7402) by standard MTT assay. Confocal fluorescence and bright-field images of liver cancer cells (line BEL-7402) showed that the probe L could be used to detect the exogenous Al3+ in the living cell.
2018, 46(12): 1945-1952
doi: 10.11895/j.issn.0253-3820.181582
Abstract:
Copper is an essential element for life and constitutes copper proteins, and attends life activities in human body. However, an excess of copper is poisonous, and can cause hepatitis, gastroenteritis and pneumonia. copper enters into biosphere from ores by weathering and erosion and exists in water in the form of a divalent copper ion. Therefore, it is necessary to detect copper ions in an ultrasensitive and quantitative way. Herein, a dual-functional DNAzymatic visual biosensor was developed, optimized and validated to detect divalent copper ions sensitively and selectively in tap water. In the method, dual DNAzymes with different functions were designed within one biosensor. One DNAzyme was Cu2+-dependent cleaving DNAzyme, which could be cleaved by Cu2+ for signal recognition. The other one was G-quadruplex DNAzyme, which was induced by terminal deoxynucleotidyl transferase (TdT) for "one-to-multiplex" signal amplification and output. In the middle of two steps, the exponential amplification reaction (EXPAR) was applied to amplify the recognitive signal exponentially. Under optimized conditions, Cu2+ could be selectively observed with the naked eyes with the detection limit (LOD) of 10 pmol/L and with the microplate reader with LOD of 7.6 pmol/L in about 2 h. Furthermore, Cu2+ in the concentration range of 10 pmol/L-200 pmol/L in tap water samples could be discriminated by naked eyes. The platform provides an ultrasensitive and colorimetric detective tool for the analysis of trace Cu2+in tap water with high specificity, and will have broad application prospect in many fields.
Copper is an essential element for life and constitutes copper proteins, and attends life activities in human body. However, an excess of copper is poisonous, and can cause hepatitis, gastroenteritis and pneumonia. copper enters into biosphere from ores by weathering and erosion and exists in water in the form of a divalent copper ion. Therefore, it is necessary to detect copper ions in an ultrasensitive and quantitative way. Herein, a dual-functional DNAzymatic visual biosensor was developed, optimized and validated to detect divalent copper ions sensitively and selectively in tap water. In the method, dual DNAzymes with different functions were designed within one biosensor. One DNAzyme was Cu2+-dependent cleaving DNAzyme, which could be cleaved by Cu2+ for signal recognition. The other one was G-quadruplex DNAzyme, which was induced by terminal deoxynucleotidyl transferase (TdT) for "one-to-multiplex" signal amplification and output. In the middle of two steps, the exponential amplification reaction (EXPAR) was applied to amplify the recognitive signal exponentially. Under optimized conditions, Cu2+ could be selectively observed with the naked eyes with the detection limit (LOD) of 10 pmol/L and with the microplate reader with LOD of 7.6 pmol/L in about 2 h. Furthermore, Cu2+ in the concentration range of 10 pmol/L-200 pmol/L in tap water samples could be discriminated by naked eyes. The platform provides an ultrasensitive and colorimetric detective tool for the analysis of trace Cu2+in tap water with high specificity, and will have broad application prospect in many fields.
Preparation and Characterization of PEGylated Thiophilic Nanoparticles for Rapid Antibody Separation
2018, 46(12): 1953-1960
doi: 10.11895/j.issn.0253-3820.181530
Abstract:
New core-shell structure based magnetic nanoparticles for immunoglobulin separation were prepared, in which thiophilic property of sulfone groups and protein resistance of poly(ethylene glycol) (PEG) moieties were displayed. The step-wise surface reactions on the nanoparticles were characterized by 1H nuclear magnetic resonance (NMR) and surface Zeta potential measurement. With human immunoglobulin G (human IgG) and bovine serum albumin (BSA) as model proteins, the effects of PEG chain length, conjugation group, solution pH and salt concentration on IgG selectivity were investigated using static adsorption experiments. The experiment results showed that mPEG2000-NH2 modified magnetic nanoparticles had an adsorption capacity of 132.8 mg/g and selectivity of 32.5 towards IgG under the condition of pH 7.45 and 0.15 mol/L NaCl. In complex biochemical solutions, the PEG modified magnetic nanoparticles could separate IgG from fetal calf serum and Omalizumab from cell culture supernatant with purities of 96% and 99%, respectively. Moreover, the binding affinities of the core-shell structure towards IgG from four species (human, bovine, rabbit and goat) were quantified by bio-layer interferometer. The results showed that the selectivity of this structure towards IgG varied from traditional Protein A method, suggesting its potentials in rapid separation and purification of IgG with low affinity towards Protein A.
New core-shell structure based magnetic nanoparticles for immunoglobulin separation were prepared, in which thiophilic property of sulfone groups and protein resistance of poly(ethylene glycol) (PEG) moieties were displayed. The step-wise surface reactions on the nanoparticles were characterized by 1H nuclear magnetic resonance (NMR) and surface Zeta potential measurement. With human immunoglobulin G (human IgG) and bovine serum albumin (BSA) as model proteins, the effects of PEG chain length, conjugation group, solution pH and salt concentration on IgG selectivity were investigated using static adsorption experiments. The experiment results showed that mPEG2000-NH2 modified magnetic nanoparticles had an adsorption capacity of 132.8 mg/g and selectivity of 32.5 towards IgG under the condition of pH 7.45 and 0.15 mol/L NaCl. In complex biochemical solutions, the PEG modified magnetic nanoparticles could separate IgG from fetal calf serum and Omalizumab from cell culture supernatant with purities of 96% and 99%, respectively. Moreover, the binding affinities of the core-shell structure towards IgG from four species (human, bovine, rabbit and goat) were quantified by bio-layer interferometer. The results showed that the selectivity of this structure towards IgG varied from traditional Protein A method, suggesting its potentials in rapid separation and purification of IgG with low affinity towards Protein A.
2018, 46(12): 1961-1967
doi: 10.11895/j.issn.0253-3820.181459
Abstract:
A method for rapidly preparing titanium dioxide nanotube array/titanium (TiO2NTAs/Ti) as a pH electrode by using anodization method in a mixed solution containing NH4F and ethylene glycol and water was established. The electrodes were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The possible pH response mechanisms were discussed by the hydrophilicity, specific surface area, and surface chemisorbed oxygen (OH) of the electrodes. Under the optimized conditions including electrolysis voltage of 30 V, a mixed solution containing NH4F (0.5%, w/w) and ethylene glycol and water (9:1, V/V) as electrolyte and anodization time of 10 min, the prepared TiO2NTAs/Ti electrode in Beretan-Robson (B-R) buffer solution (pH=3-11) exhibited an excellent pH response with a sensitivity of (-55.17±0.28) mV/pH and a correlation coefficient (R2) of above 0.9966. The results of the ion interference experiments showed that the effect of common ion on the electrode was negligible. The electrode had good stability and was successfully applied to the determination of pH value of vitamin drink and seawater.
A method for rapidly preparing titanium dioxide nanotube array/titanium (TiO2NTAs/Ti) as a pH electrode by using anodization method in a mixed solution containing NH4F and ethylene glycol and water was established. The electrodes were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The possible pH response mechanisms were discussed by the hydrophilicity, specific surface area, and surface chemisorbed oxygen (OH) of the electrodes. Under the optimized conditions including electrolysis voltage of 30 V, a mixed solution containing NH4F (0.5%, w/w) and ethylene glycol and water (9:1, V/V) as electrolyte and anodization time of 10 min, the prepared TiO2NTAs/Ti electrode in Beretan-Robson (B-R) buffer solution (pH=3-11) exhibited an excellent pH response with a sensitivity of (-55.17±0.28) mV/pH and a correlation coefficient (R2) of above 0.9966. The results of the ion interference experiments showed that the effect of common ion on the electrode was negligible. The electrode had good stability and was successfully applied to the determination of pH value of vitamin drink and seawater.
2018, 46(12): 1968-1974
doi: 10.11895/j.issn.0253-3820.181593
Abstract:
Palladium/graphene nanocomposites (Pd/GN) were synthesized through a rapid, microwave irradiation, "one pot" method with epigallocatechin gallate (EGCG) as a reducing agent. The loading amount and size of Pd nanoparticles in Pd/Graphene nanocomposites could be controlled by the irradiation time and the ratio of the graphite oxide (GO) and H2PdCl4. Results showed that Pd nanoparticles were well dispersed on the surface of graphene in Pd/GN nanocomposite. When the additive amount of graphene oxide (GO) was 0.25 mL and the microwave irradiation time was 1 min, the size of Pd nanoparticles was about 10 nm. The electro-catalytic activity of the as-prepared Pd/GN towards the oxidation of methanol was studied by cyclic voltammetry (CV) and chronoamperometry (CA) methods. The electrochemical active area (ECSA) value of Pd/GN nanocomposite catalysts was about 60.5 m2/g, which was 1.97 times higher than that of the commercial Pd/C catalyst (30.7 m2/g). The peak current density on the Pd/GN catalyst for methanol oxidation was much larger than that of Pd/C catalyst in the alkaline conditions. When the loading amount of the Pd/GN catalyst was about 15.5 μg/cm2, the value of the oxidation peak current density reached 7.95 mA/cm2. All the experimental results indicated that the Pd/GN catalyst significantly enhanced catalytic activity and stability than the commercial Pd/C catalyst.
Palladium/graphene nanocomposites (Pd/GN) were synthesized through a rapid, microwave irradiation, "one pot" method with epigallocatechin gallate (EGCG) as a reducing agent. The loading amount and size of Pd nanoparticles in Pd/Graphene nanocomposites could be controlled by the irradiation time and the ratio of the graphite oxide (GO) and H2PdCl4. Results showed that Pd nanoparticles were well dispersed on the surface of graphene in Pd/GN nanocomposite. When the additive amount of graphene oxide (GO) was 0.25 mL and the microwave irradiation time was 1 min, the size of Pd nanoparticles was about 10 nm. The electro-catalytic activity of the as-prepared Pd/GN towards the oxidation of methanol was studied by cyclic voltammetry (CV) and chronoamperometry (CA) methods. The electrochemical active area (ECSA) value of Pd/GN nanocomposite catalysts was about 60.5 m2/g, which was 1.97 times higher than that of the commercial Pd/C catalyst (30.7 m2/g). The peak current density on the Pd/GN catalyst for methanol oxidation was much larger than that of Pd/C catalyst in the alkaline conditions. When the loading amount of the Pd/GN catalyst was about 15.5 μg/cm2, the value of the oxidation peak current density reached 7.95 mA/cm2. All the experimental results indicated that the Pd/GN catalyst significantly enhanced catalytic activity and stability than the commercial Pd/C catalyst.
2018, 46(12): 1975-1981
doi: 10.11895/j.issn.0253-3820.181587
Abstract:
A novel solid phase microextraction (SPME) sampler consisted of gold-immobilized wood-based toothpick was developed for the rapid detection of mercury in environmental water samples via direct analysis in thermal desorption-atomic absorption spectrometry (TD-AAS). Several parameters affecting headspace extraction efficiency of mercury such as gold ions concentration, loading time, extraction time, shaking rate and salt effect, were investigated. The results showed short field analytical time (less than 20 min), good linearity (R2 ≥ 0.998) in the range of 0.25-10 ng/mL with the detection limit of 0.03 ng/mL (S/N=3). Furthermore, the relative standard deviations (RSDs) for the sampler-to-sampler reproducibility of eight as-prepared SPME samplers were 2.1% at the spiking level of 1.0 ng/mL. The detection result was in agreement with the certified value of water reference material. The method was applied to analysis of four water samples including tap water, lake water, sea water and waste water with satisfactory spiked recoveries of 89.6%-92.9%, 90.2%-95.3% and 93.8%-106.2% at 1.0 ng/mL, 5.0 ng/mL and 10.0 ng/mL spiking level, respectively, demonstrating the practicality of the proposed method for the determination of mercury in environmental water samples. Characterized by low cost, ease of fabrication and excellent sampler-to-sampler reproducibility, the homemade wood-based SPME sampler in combination with portable TD-AAS is suitable for the on-site screening and risk identification of aqueous mercury contamination.
A novel solid phase microextraction (SPME) sampler consisted of gold-immobilized wood-based toothpick was developed for the rapid detection of mercury in environmental water samples via direct analysis in thermal desorption-atomic absorption spectrometry (TD-AAS). Several parameters affecting headspace extraction efficiency of mercury such as gold ions concentration, loading time, extraction time, shaking rate and salt effect, were investigated. The results showed short field analytical time (less than 20 min), good linearity (R2 ≥ 0.998) in the range of 0.25-10 ng/mL with the detection limit of 0.03 ng/mL (S/N=3). Furthermore, the relative standard deviations (RSDs) for the sampler-to-sampler reproducibility of eight as-prepared SPME samplers were 2.1% at the spiking level of 1.0 ng/mL. The detection result was in agreement with the certified value of water reference material. The method was applied to analysis of four water samples including tap water, lake water, sea water and waste water with satisfactory spiked recoveries of 89.6%-92.9%, 90.2%-95.3% and 93.8%-106.2% at 1.0 ng/mL, 5.0 ng/mL and 10.0 ng/mL spiking level, respectively, demonstrating the practicality of the proposed method for the determination of mercury in environmental water samples. Characterized by low cost, ease of fabrication and excellent sampler-to-sampler reproducibility, the homemade wood-based SPME sampler in combination with portable TD-AAS is suitable for the on-site screening and risk identification of aqueous mercury contamination.
2018, 46(12): 1982-1989
doi: 10.11895/j.issn.0253-3820.181505
Abstract:
Zirconia (ZrO2) nanofibers with a diameter of (194±30) nm were successfully fabricated by electrospinning zirconium salt-containing nanofibers followed by calcination. Scanning electron microscopy, transmission electron microscopy and X-ray diffraction characterization results revealed that the fibers were mainly composed of monoclinic nano-crystallite of ZrO2. The ZrO2 nanofiber-modified glassy carbon electrode (GCE) was prepared by drop-coating the mixture of ZrO2 nanofibre, Super P and polyvinylidenefluoride (PVDF), were successfully applied to the detection of methyl parathion (MP). Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to study the electrochemical behavior of MP on the modified electrode surface. Under the optimal conditions, the DPV peak current of the electrode showed a linear relationship with MP concentration in the range of 0.1-1.2 mg/L with a detection limit of 0.06 μg/L (S/N=3). The sensor had good stability, reproducibility and anti-interference property. The real water samples were analyzed, with MP recovery of 96.7%-102.4% and relative standard deviation of less than 5%. This electrode could be used as a highly sensitive sensor for MP measurement.
Zirconia (ZrO2) nanofibers with a diameter of (194±30) nm were successfully fabricated by electrospinning zirconium salt-containing nanofibers followed by calcination. Scanning electron microscopy, transmission electron microscopy and X-ray diffraction characterization results revealed that the fibers were mainly composed of monoclinic nano-crystallite of ZrO2. The ZrO2 nanofiber-modified glassy carbon electrode (GCE) was prepared by drop-coating the mixture of ZrO2 nanofibre, Super P and polyvinylidenefluoride (PVDF), were successfully applied to the detection of methyl parathion (MP). Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to study the electrochemical behavior of MP on the modified electrode surface. Under the optimal conditions, the DPV peak current of the electrode showed a linear relationship with MP concentration in the range of 0.1-1.2 mg/L with a detection limit of 0.06 μg/L (S/N=3). The sensor had good stability, reproducibility and anti-interference property. The real water samples were analyzed, with MP recovery of 96.7%-102.4% and relative standard deviation of less than 5%. This electrode could be used as a highly sensitive sensor for MP measurement.
2018, 46(12): 1990-1996
doi: 10.11895/j.issn.0253-3820.181416
Abstract:
In this work, melamine/o-phthalaldehyde covalent organic framework was used as a novel trapping media in solid-phase extraction of sulfonamides at ultra-trace levels in real water samples. Six sulfonamides, including sulfadiazine (SDZ), sulfathiazole (ST), sulfapyridine (SPD), sulfamethyldiazine (SM1), sulfamethazine (SM2), sulfamethoxazole (SMX), were absorbed on the SPE cartridge. Important factors affecting extraction effect were optimized by single factor optimization method, and the optimized relevant parameters were as follows:eluent and its volume, 8 mL MA; sample flow rate, 3 mL/min; sample pH, pH=4 and sample volume, 200 mL. Sulfonamide antibiotics were detected and quantified by liquid chromatography-tandem mass spectrometry. Low limits of detection (0.05-0.36 ng/L), wide linearity range (0.25-1000 ng/L), good repeatability and high recovery (82.5%-104.8%) for sulfonamides were obtained under the optimized conditions. The optimized method was used in the analysis of sulfonamides in real environmental water samples (drinking water, tap water and pool water) successfully. The novel COFs as a solid phase trapping material was a good choice for the rapid and effective analysis of sulfonamides at ultra trace levels in environmental water samples.
In this work, melamine/o-phthalaldehyde covalent organic framework was used as a novel trapping media in solid-phase extraction of sulfonamides at ultra-trace levels in real water samples. Six sulfonamides, including sulfadiazine (SDZ), sulfathiazole (ST), sulfapyridine (SPD), sulfamethyldiazine (SM1), sulfamethazine (SM2), sulfamethoxazole (SMX), were absorbed on the SPE cartridge. Important factors affecting extraction effect were optimized by single factor optimization method, and the optimized relevant parameters were as follows:eluent and its volume, 8 mL MA; sample flow rate, 3 mL/min; sample pH, pH=4 and sample volume, 200 mL. Sulfonamide antibiotics were detected and quantified by liquid chromatography-tandem mass spectrometry. Low limits of detection (0.05-0.36 ng/L), wide linearity range (0.25-1000 ng/L), good repeatability and high recovery (82.5%-104.8%) for sulfonamides were obtained under the optimized conditions. The optimized method was used in the analysis of sulfonamides in real environmental water samples (drinking water, tap water and pool water) successfully. The novel COFs as a solid phase trapping material was a good choice for the rapid and effective analysis of sulfonamides at ultra trace levels in environmental water samples.
2018, 46(12): 1997-2003
doi: 10.11895/j.issn.0253-3820.181602
Abstract:
A novel method for fabrication of gold nanocluster by using bacitracin as a reducing agent and stabilizer in aqueous solution was developed. The fluorescence of bacitracin-templated gold nanoclusters (AuNCs@Bacitracin) could be quenched in the presence of Fe3+. The property of fluorescence quenched by Fe3+ could be applied to preparation of a "turn-on" probe for detection of adenosine triphosphate (ATP). Under the optimized conditions, AuNCs were prepared by the reaction of bacitracin and HAuCl4 with the molar ratio of 1:1 at pH=1 for 2 h. 98% of original intensity of AuNC fluorescence was quenched in the presence of 5 mmol/L Fe3+. Besides, the value of lg(F/F0) was linearly related with the concentration of ATP (R2=0.9902) in the range of 10 μmol/L-8 mmol/L. The fabricated probe was then applied to detection of the level of ATP in artificial serum with recovery of 103.0%-105.0% and RSD<1.0%, which suggested that the method was accurate and reliable.
A novel method for fabrication of gold nanocluster by using bacitracin as a reducing agent and stabilizer in aqueous solution was developed. The fluorescence of bacitracin-templated gold nanoclusters (AuNCs@Bacitracin) could be quenched in the presence of Fe3+. The property of fluorescence quenched by Fe3+ could be applied to preparation of a "turn-on" probe for detection of adenosine triphosphate (ATP). Under the optimized conditions, AuNCs were prepared by the reaction of bacitracin and HAuCl4 with the molar ratio of 1:1 at pH=1 for 2 h. 98% of original intensity of AuNC fluorescence was quenched in the presence of 5 mmol/L Fe3+. Besides, the value of lg(F/F0) was linearly related with the concentration of ATP (R2=0.9902) in the range of 10 μmol/L-8 mmol/L. The fabricated probe was then applied to detection of the level of ATP in artificial serum with recovery of 103.0%-105.0% and RSD<1.0%, which suggested that the method was accurate and reliable.
2018, 46(12): 2004-2010
doi: 10.11895/j.issn.0253-3820.181309
Abstract:
Short-chain chlorinated paraffins (SCCPs) are a new kind of persistent organic pollutant. Accurate analysis of SCCPs in water is important for good understanding of their pollution level, spatial distribution and environmental behavior in water environment. In this study, a simple, sensitive, and environmentally friendly method for the determination of trace SCCPs in water samples has been established based on headspace solid phase micro-extraction (HS-SPME) and comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC×GC-TOF-MS). The key parameters of HS-SPME were systematically optimized including fiber type, extraction temperature, extraction time, ionic strength, etc. Under the optimum extraction conditions, the calibration curves showed a good linearity (R2 ≥ 0.999) in the concentration range of 0.2-20.0 μg/L. The detection limits of this method were 0.06-0.13 μg/L. The accuracy of the method was evaluated by calculating the recovery at 10 μg/L, resulting in good recovery values between 80.9% and 95.4%. The method precision was also satisfactory, with the RSD values less than 7.1% and 14.0% for intra-day and inter-day tests, respectively. Finally, the proposed method was applied to detection of SCCPs in real water samples of leather processing area in Hebei Province. In conclusion, the main advantages of the proposed method are the small sample volume, solvent-free extraction, automated online operation, and meeting the requirement of quality detection on SCCPs in water as set by most environmental regulations, thus we believe that this method is a good choice for the detection of SCCPs in water samples.
Short-chain chlorinated paraffins (SCCPs) are a new kind of persistent organic pollutant. Accurate analysis of SCCPs in water is important for good understanding of their pollution level, spatial distribution and environmental behavior in water environment. In this study, a simple, sensitive, and environmentally friendly method for the determination of trace SCCPs in water samples has been established based on headspace solid phase micro-extraction (HS-SPME) and comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC×GC-TOF-MS). The key parameters of HS-SPME were systematically optimized including fiber type, extraction temperature, extraction time, ionic strength, etc. Under the optimum extraction conditions, the calibration curves showed a good linearity (R2 ≥ 0.999) in the concentration range of 0.2-20.0 μg/L. The detection limits of this method were 0.06-0.13 μg/L. The accuracy of the method was evaluated by calculating the recovery at 10 μg/L, resulting in good recovery values between 80.9% and 95.4%. The method precision was also satisfactory, with the RSD values less than 7.1% and 14.0% for intra-day and inter-day tests, respectively. Finally, the proposed method was applied to detection of SCCPs in real water samples of leather processing area in Hebei Province. In conclusion, the main advantages of the proposed method are the small sample volume, solvent-free extraction, automated online operation, and meeting the requirement of quality detection on SCCPs in water as set by most environmental regulations, thus we believe that this method is a good choice for the detection of SCCPs in water samples.
2018, 46(12): 2011-2018
doi: 10.11895/j.issn.0253-3820.181199
Abstract:
A simple sensitive and green method was established for the rapid determination of six kinds of triazine herbicides in cereal samples. The method combined the advantages of microwave assisted extraction, water steam extraction and floating solvent extraction. Certain amount of dodecanol was added to the sample in the extraction vessel, and then triazines were extracted by water steam under microwave energy, after that, sodium chloride was added into the extract liquor. After the extract liquor was thoroughly stirred and put into the ice-water bath, the sample scoop was taken out and the dodecanol solid of triazine herbicide was removed and transferred to the centrifuge tube. After thawing, the content was filtered, and then triazine herbicides were tested by liquid chromatography tandem mass spectrometry. In the experiment, the experimental conditions of microwave assisted water steam extraction and solidification of floating organic drop were optimized. Under the optimal experimental conditions such as 800 W of microwave extraction power, 12 mL of extract liquor volume, 140 μL of dodecanol as floating solvent, 2.0 g of NaCl and extract liquior at pH 7, the linearity region for detection of six triazine herbicides was 2-200 ng/g, with correlation coefficient of 0.9979-0.9998. The limits of detection and the recoveries of triazines were 0.28-0.61 ng/g and 82.2%-99.5%, respectively. The relative standard deviations of intra-day and inter-day variations were 2%-7% and 3%-6%, respectively. Compared with the traditional extraction method, the proposed method was more environmentally friendly, rapid in detection and simpler in operation. Besides, the method had many advantages such as low cost, high concentration fold and low organic solvent, and could be used for detection of triazine herbicides in complex solid samples.
A simple sensitive and green method was established for the rapid determination of six kinds of triazine herbicides in cereal samples. The method combined the advantages of microwave assisted extraction, water steam extraction and floating solvent extraction. Certain amount of dodecanol was added to the sample in the extraction vessel, and then triazines were extracted by water steam under microwave energy, after that, sodium chloride was added into the extract liquor. After the extract liquor was thoroughly stirred and put into the ice-water bath, the sample scoop was taken out and the dodecanol solid of triazine herbicide was removed and transferred to the centrifuge tube. After thawing, the content was filtered, and then triazine herbicides were tested by liquid chromatography tandem mass spectrometry. In the experiment, the experimental conditions of microwave assisted water steam extraction and solidification of floating organic drop were optimized. Under the optimal experimental conditions such as 800 W of microwave extraction power, 12 mL of extract liquor volume, 140 μL of dodecanol as floating solvent, 2.0 g of NaCl and extract liquior at pH 7, the linearity region for detection of six triazine herbicides was 2-200 ng/g, with correlation coefficient of 0.9979-0.9998. The limits of detection and the recoveries of triazines were 0.28-0.61 ng/g and 82.2%-99.5%, respectively. The relative standard deviations of intra-day and inter-day variations were 2%-7% and 3%-6%, respectively. Compared with the traditional extraction method, the proposed method was more environmentally friendly, rapid in detection and simpler in operation. Besides, the method had many advantages such as low cost, high concentration fold and low organic solvent, and could be used for detection of triazine herbicides in complex solid samples.
2018, 46(12): 2019-2024
doi: 10.11895/j.issn.0253-3820.181520
Abstract:
A method was developed for determination of 6 kinds of indictor polychlorinated biphenyls in animal feed by chromatography-tandem mass spectrometry (GC-MS/MS). Analytical procedure consisted of accelerate solvent extraction (ASE), lipid removal with 44% acidic silica and clean-up using a column packed with multilayer silica. The analytes were separated on a DB-5MS capillary column, detected with electron ionization (EI) and multiple reaction monitor mode (MRM), and quantified using isotope dilution technique. The result showed that the calibration curves with good correlation coefficients (R2>0.999) were obtained in the concentration range of 0.1-500.0 ng/mL. The average relative response factors of PCBs in calibration solvent were 1.08-1.21, and the limit of quantification were 5.5-9.2 pg/g. The average recoveries of PCBs in animal feed at two spiked concentration levels ranged from 92.8% to 109.7% with relative standard deviations (RSDs) of 1.6%-14.8% (n=5), and the average recoveries of quantitative internal standards were 32.6%-90.2%. Then the proposed method was successfully applied to detect the compound feed samples from the surrounding area of Beijing, and it was found that the 6 kinds of indictor PCBs were detected in all samples (n=10) with the total concentration ranges of 54.7-191.7 pg/g, which were far below the limit standard (10 μg/kg) of Chinese National Standards.
A method was developed for determination of 6 kinds of indictor polychlorinated biphenyls in animal feed by chromatography-tandem mass spectrometry (GC-MS/MS). Analytical procedure consisted of accelerate solvent extraction (ASE), lipid removal with 44% acidic silica and clean-up using a column packed with multilayer silica. The analytes were separated on a DB-5MS capillary column, detected with electron ionization (EI) and multiple reaction monitor mode (MRM), and quantified using isotope dilution technique. The result showed that the calibration curves with good correlation coefficients (R2>0.999) were obtained in the concentration range of 0.1-500.0 ng/mL. The average relative response factors of PCBs in calibration solvent were 1.08-1.21, and the limit of quantification were 5.5-9.2 pg/g. The average recoveries of PCBs in animal feed at two spiked concentration levels ranged from 92.8% to 109.7% with relative standard deviations (RSDs) of 1.6%-14.8% (n=5), and the average recoveries of quantitative internal standards were 32.6%-90.2%. Then the proposed method was successfully applied to detect the compound feed samples from the surrounding area of Beijing, and it was found that the 6 kinds of indictor PCBs were detected in all samples (n=10) with the total concentration ranges of 54.7-191.7 pg/g, which were far below the limit standard (10 μg/kg) of Chinese National Standards.
