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2021 Volume 49 Issue 4
2021, 49(4): 483-495
doi: 10.19756/j.issn.0253-3820.201700
Abstract:
The dissemination of circulating tumor cells (CTCs) in peripheral blood is an important intermediate step for cancer metastasis. CTC can provide complete information of cell biology and thus has become one of the most promising targets of "liquid biopsy". However, due to the extremely rarity, complex environment and strong heterogeneity of CTC in peripheral blood, the development of efficient enrichment and separation methods are the key in the accurate detection of CTC. Current reported CTC enrichment and analysis techniques are mainly based on the physical or biological characteristics of CTC. These methods are commonly combined with the traditional techniques including density gradient centrifugation, superfine membrane filtration and immunomagnetic separation, the novel methods such as microfluidic chip separation and two-dimensional electrophoresis-field separation, and the analysis techniques such as reverse transcription-polymerase chain reaction, flow cytometry, immunocytochemistry, photoacoustic imaging, surface-enhancement Raman scattering and electrochemistry to realize the accurate detection of CTC. In this review, the recent progress on enrichment techniques and detection methods for CTC was summarized, also the challenge and their clinical application status were discussed, which could provide reference for further improvement of the technology of enrichment, accurate counting and molecular phenotype analysis for CTC, as well as the application in scientific research and clinical practice.
The dissemination of circulating tumor cells (CTCs) in peripheral blood is an important intermediate step for cancer metastasis. CTC can provide complete information of cell biology and thus has become one of the most promising targets of "liquid biopsy". However, due to the extremely rarity, complex environment and strong heterogeneity of CTC in peripheral blood, the development of efficient enrichment and separation methods are the key in the accurate detection of CTC. Current reported CTC enrichment and analysis techniques are mainly based on the physical or biological characteristics of CTC. These methods are commonly combined with the traditional techniques including density gradient centrifugation, superfine membrane filtration and immunomagnetic separation, the novel methods such as microfluidic chip separation and two-dimensional electrophoresis-field separation, and the analysis techniques such as reverse transcription-polymerase chain reaction, flow cytometry, immunocytochemistry, photoacoustic imaging, surface-enhancement Raman scattering and electrochemistry to realize the accurate detection of CTC. In this review, the recent progress on enrichment techniques and detection methods for CTC was summarized, also the challenge and their clinical application status were discussed, which could provide reference for further improvement of the technology of enrichment, accurate counting and molecular phenotype analysis for CTC, as well as the application in scientific research and clinical practice.
2021, 49(4): 496-503
doi: 10.19756/j.issn.0253-3820.201705
Abstract:
A chemiluminescence sensor, using ochratoxin A (OTA) aptamer as the activation switch of the split DNAzyme, is established to achieve high-sensitivity detection of OTA in wine. Guanine-rich oligonucleotide can fold into a parallel G-quadruplex in the presence of K+. Hemin as a ligand is able to specifically bind to parallel G-quadruplexes. Hemin-G-quadruplex complexes display peroxidase-like activity, named as DNAzyme. The activity of the DNAzyme can be measured by chemiluminescence via the H2O2 mediated-oxidation with luminol. Guanine-rich oligonucleotide splits into two fragments, and when they are near to each other, they can reform DNAzyme. OTA aptamer as a switch is inserted into the nucleic acid sequence of DNAzyme. In the absence of OTA, the unfolded OTA aptamer inhibits the split DNAzyme effectively self-assemble to form a structure with enzymatic activity. In the presence of OTA, OTA induces the aptamer to form an antiparallel G-quadruplex and draws the tail of the aptamer closer, so that the two fragments of split DNAzyme refold and complexes with hemin. Folding degree of the aptamer will directly affect the activity of DNAzyme. The high-sensitive detection of OTA can be obtained through monitoring the enhancing ratio of chemiluminescence intensity. The linear range of this method is 0.10-2.00 nmol/L, and the limit of detection is 0.10 nmol/L.
A chemiluminescence sensor, using ochratoxin A (OTA) aptamer as the activation switch of the split DNAzyme, is established to achieve high-sensitivity detection of OTA in wine. Guanine-rich oligonucleotide can fold into a parallel G-quadruplex in the presence of K+. Hemin as a ligand is able to specifically bind to parallel G-quadruplexes. Hemin-G-quadruplex complexes display peroxidase-like activity, named as DNAzyme. The activity of the DNAzyme can be measured by chemiluminescence via the H2O2 mediated-oxidation with luminol. Guanine-rich oligonucleotide splits into two fragments, and when they are near to each other, they can reform DNAzyme. OTA aptamer as a switch is inserted into the nucleic acid sequence of DNAzyme. In the absence of OTA, the unfolded OTA aptamer inhibits the split DNAzyme effectively self-assemble to form a structure with enzymatic activity. In the presence of OTA, OTA induces the aptamer to form an antiparallel G-quadruplex and draws the tail of the aptamer closer, so that the two fragments of split DNAzyme refold and complexes with hemin. Folding degree of the aptamer will directly affect the activity of DNAzyme. The high-sensitive detection of OTA can be obtained through monitoring the enhancing ratio of chemiluminescence intensity. The linear range of this method is 0.10-2.00 nmol/L, and the limit of detection is 0.10 nmol/L.
2021, 49(4): 504-511
doi: 10.19756/j.issn.0253-3820.201632
Abstract:
A method for determination of four kinds of illegal additives kojic acid, benzodiazepine acid, 2-mercapto-5-methyl-1,3,4-thiadiazole and thiabendazole in wheat flour and flour treatment agent was developed by using high performance liquid chromatography (HPLC). The sample was first extracted with methanol. Then the analytes were separated on a ZORBAX Eclipse Plus C18 column, separated by gradient elution with methanol and 0.01% H3PO4 aqueous solution, detected by diode array detector, and quantified by external standard method. The chromatographic conditions and pretreatment methods were optimized. Effects of several important factors, including influence of mobile phase composition on separation degree and the improvement of extraction efficiency by different extraction solvents, were investigated to acquire optimum conditions. The results showed that the 4 kinds of illegal additives had good linear relationship in the concentration range of 0.1-2.0 μg/mL (R2 ≥ 0.9998). The limits of detection (LODs, S/N ≥ 3) for the 4 kind of illegal additives were 0.3-0.7 mg/kg, and the recoveries in wheat flour and flour treatment agent were 80.8%-95.9% at 3 spiking levels with the relative standard deviations (RSDs) of 0.5%-4.9% (n=6). This method was simple, accurate, and had good purification effect, which was suitable for the screening and determination of illegal additives in wheat flour and flour treatment agent.
A method for determination of four kinds of illegal additives kojic acid, benzodiazepine acid, 2-mercapto-5-methyl-1,3,4-thiadiazole and thiabendazole in wheat flour and flour treatment agent was developed by using high performance liquid chromatography (HPLC). The sample was first extracted with methanol. Then the analytes were separated on a ZORBAX Eclipse Plus C18 column, separated by gradient elution with methanol and 0.01% H3PO4 aqueous solution, detected by diode array detector, and quantified by external standard method. The chromatographic conditions and pretreatment methods were optimized. Effects of several important factors, including influence of mobile phase composition on separation degree and the improvement of extraction efficiency by different extraction solvents, were investigated to acquire optimum conditions. The results showed that the 4 kinds of illegal additives had good linear relationship in the concentration range of 0.1-2.0 μg/mL (R2 ≥ 0.9998). The limits of detection (LODs, S/N ≥ 3) for the 4 kind of illegal additives were 0.3-0.7 mg/kg, and the recoveries in wheat flour and flour treatment agent were 80.8%-95.9% at 3 spiking levels with the relative standard deviations (RSDs) of 0.5%-4.9% (n=6). This method was simple, accurate, and had good purification effect, which was suitable for the screening and determination of illegal additives in wheat flour and flour treatment agent.
2021, 49(4): 512-519
doi: 10.19756/j.issn.0253-3820.211119
Abstract:
Orbitrap based high performance liquid chromatography-high resolution tandem mass spectrometry (HPLC-HRMS) was used to study the post-translational modification (PTM) of cyclopeptides in commercial flaxseed extract, flaxseed varieties and processing conditions. The oxidation degree and oxidation sites of cyclolinopeptides were used to evaluate the quality of flaxseed oil under different processing conditions. The identification and quantitative methods were established after optimizing analytical conditions. By exact mass and tandem mass spectrometry analysis, 16 and 21 oxidized cyclolinopeptides were identified in raw and cooked flaxseed extracts, respectively. The oxidation degree was presented as the ratio of the peak area of cyclolinopeptides with and without oxidation. The results showed that the high temperature drying process had a significant effect on the oxidation of methionine residues in cyclolinopeptides and the oxidation level of brown flaxseed was more sensitive to temperature and oxygen conditions than golden one.
Orbitrap based high performance liquid chromatography-high resolution tandem mass spectrometry (HPLC-HRMS) was used to study the post-translational modification (PTM) of cyclopeptides in commercial flaxseed extract, flaxseed varieties and processing conditions. The oxidation degree and oxidation sites of cyclolinopeptides were used to evaluate the quality of flaxseed oil under different processing conditions. The identification and quantitative methods were established after optimizing analytical conditions. By exact mass and tandem mass spectrometry analysis, 16 and 21 oxidized cyclolinopeptides were identified in raw and cooked flaxseed extracts, respectively. The oxidation degree was presented as the ratio of the peak area of cyclolinopeptides with and without oxidation. The results showed that the high temperature drying process had a significant effect on the oxidation of methionine residues in cyclolinopeptides and the oxidation level of brown flaxseed was more sensitive to temperature and oxygen conditions than golden one.
2021, 49(4): 520-527
doi: 10.19756/j.issn.0253-3820.211074
Abstract:
Online solid phase extraction-high performance liquid chromatography-inductively coupled plasma mass spectrometry (Online SPE-HPLC-ICP-MS) technique was developed for simultaneous determination of six kinds of polybrominated diphenyl ethers and five kinds of hydroxyl metabolites in serum sample. By automatic injection, 200 μL of serum sample was directly analyzed after protein precipitation and dilution. The targets in samples were automatically enriched on a solid phase extraction column, and then separated and analyzed by liquid chromatography-inductively coupled plasma mass spectrometry with methanol/acetonitrile/water mixed solvent. After optimizing the main parameters such as loading rate, elution time and elution solvent, the Oasis HLB online solid phase extraction column was finally selected. The loading solvent was pure water with a rate of 3.0 mL/min, the elution solvent was the mixture of methanol, acetonitrile and water (54:26:20, V/V), the elution flow rate was 1.0 mL/min, and the liquid chromatography column was ZORBAX Eclipse Plus C18. The limits of quantification (LOQ) of the method were 0.14-0.74 ng/L, the recoveries of matrix addition were from 61.8% to 77.7%, and the relative standard deviations (RSDs) of the results were from 3.7% to 10.1% (n=3). The established method was successfully applied to the analysis of 30 serum samples. Four kinds of polybrominated diphenyl ethers and two kinds of hydroxy polybrominated diphenyl ethers were detected, and their occurrence characteristics were consistent with the previous reports. The results showed that this method could be applied to analysis and detection of large quantities of actual samples, and had a great practical value.
Online solid phase extraction-high performance liquid chromatography-inductively coupled plasma mass spectrometry (Online SPE-HPLC-ICP-MS) technique was developed for simultaneous determination of six kinds of polybrominated diphenyl ethers and five kinds of hydroxyl metabolites in serum sample. By automatic injection, 200 μL of serum sample was directly analyzed after protein precipitation and dilution. The targets in samples were automatically enriched on a solid phase extraction column, and then separated and analyzed by liquid chromatography-inductively coupled plasma mass spectrometry with methanol/acetonitrile/water mixed solvent. After optimizing the main parameters such as loading rate, elution time and elution solvent, the Oasis HLB online solid phase extraction column was finally selected. The loading solvent was pure water with a rate of 3.0 mL/min, the elution solvent was the mixture of methanol, acetonitrile and water (54:26:20, V/V), the elution flow rate was 1.0 mL/min, and the liquid chromatography column was ZORBAX Eclipse Plus C18. The limits of quantification (LOQ) of the method were 0.14-0.74 ng/L, the recoveries of matrix addition were from 61.8% to 77.7%, and the relative standard deviations (RSDs) of the results were from 3.7% to 10.1% (n=3). The established method was successfully applied to the analysis of 30 serum samples. Four kinds of polybrominated diphenyl ethers and two kinds of hydroxy polybrominated diphenyl ethers were detected, and their occurrence characteristics were consistent with the previous reports. The results showed that this method could be applied to analysis and detection of large quantities of actual samples, and had a great practical value.
2021, 49(4): 528-537
doi: 10.19756/j.issn.0253-3820.211007
Abstract:
A method for determination of 16 kinds of perfluoroalkyl substances in fish muscle by multi-plug filtration cleanup (m-PFC) combined with ulrahigh performance liquid chromatography-Q-extractive orbitrap high resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS) was established. The samples were ultrasonically extracted by 1% formic acid-acetonitrile, purified by solid phase extraction using m-PFC column and concentrated to 1 mL under nitrogen. The analytes were separated on an Acquity Waters BEH C18 (50 mm×2.1 mm, 1.7 μm) column, and gradient eluted with 5 mmol/L ammonium acetate and methanol. The MS acquisition mode was Full MS/dd-MS2 in both negative and positive ionization mode, and the internal standard method was used for quantification. Under the best analytical conditions, a total of 16 target compounds were well separated within 13 min, and the accurate mass deviation of each substance was less than 2.83×10-6. A good linearity was obtained in the concentration ranges of 0.10-20.0 μg/L with correlation coefficients of greater than 0.990. The MDLs ranged from 0.015 μg/kg to 0.05 μg/kg. The average recoveries of 16 kinds of PFASs spiked at 0.50, 2.0 and 5.0 μg/kg were 70.7%-110.1% and the relative standard deviations (RSDs) were 0.5%-12.8%. The established method was successfully applied to the rapid detection of 25 wild fish samples. Ten PFASs were detected, in which PFOS were the predominant pollutant. The method was simple, rapid, accurate and sensitive, and suitable for the rapid detection of 16 kinds of PFASs in fish muscle.
A method for determination of 16 kinds of perfluoroalkyl substances in fish muscle by multi-plug filtration cleanup (m-PFC) combined with ulrahigh performance liquid chromatography-Q-extractive orbitrap high resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS) was established. The samples were ultrasonically extracted by 1% formic acid-acetonitrile, purified by solid phase extraction using m-PFC column and concentrated to 1 mL under nitrogen. The analytes were separated on an Acquity Waters BEH C18 (50 mm×2.1 mm, 1.7 μm) column, and gradient eluted with 5 mmol/L ammonium acetate and methanol. The MS acquisition mode was Full MS/dd-MS2 in both negative and positive ionization mode, and the internal standard method was used for quantification. Under the best analytical conditions, a total of 16 target compounds were well separated within 13 min, and the accurate mass deviation of each substance was less than 2.83×10-6. A good linearity was obtained in the concentration ranges of 0.10-20.0 μg/L with correlation coefficients of greater than 0.990. The MDLs ranged from 0.015 μg/kg to 0.05 μg/kg. The average recoveries of 16 kinds of PFASs spiked at 0.50, 2.0 and 5.0 μg/kg were 70.7%-110.1% and the relative standard deviations (RSDs) were 0.5%-12.8%. The established method was successfully applied to the rapid detection of 25 wild fish samples. Ten PFASs were detected, in which PFOS were the predominant pollutant. The method was simple, rapid, accurate and sensitive, and suitable for the rapid detection of 16 kinds of PFASs in fish muscle.
2021, 49(4): 538-545
doi: 10.19756/j.issn.0253-3820.211015
Abstract:
Based on nanoparticle tracking analysis (NTA) techinque, a dispersion and detection method for titanium dioxide nanoparticles was developed. Influencing parameters on dispersion such as reagent type, ultrasonic method, ultrasonic time, ultrasonic temperature, dispersion reagent concentration and pH value were investigated. The dispersion method had good universality for commercial titanium dioxide nanoparticles. NTA was used to measure particle size and particle number concentration, and the dilution reagent concentration and dilution factor during the detection process were optimized. The results of particle number concentration and size using NTA by the established dispersion method was verified using single particle-inductively coupled plasma-mass spectrometry (SP-ICPMS) and dynamic light scattering (DLS) techniques, and the deviations were ±10% and ±5%, respectively. By using the developed dispersion and detection methods, the sample could maintain stable up to over a month, which coud be used for the development of basic research and related detection methods.
Based on nanoparticle tracking analysis (NTA) techinque, a dispersion and detection method for titanium dioxide nanoparticles was developed. Influencing parameters on dispersion such as reagent type, ultrasonic method, ultrasonic time, ultrasonic temperature, dispersion reagent concentration and pH value were investigated. The dispersion method had good universality for commercial titanium dioxide nanoparticles. NTA was used to measure particle size and particle number concentration, and the dilution reagent concentration and dilution factor during the detection process were optimized. The results of particle number concentration and size using NTA by the established dispersion method was verified using single particle-inductively coupled plasma-mass spectrometry (SP-ICPMS) and dynamic light scattering (DLS) techniques, and the deviations were ±10% and ±5%, respectively. By using the developed dispersion and detection methods, the sample could maintain stable up to over a month, which coud be used for the development of basic research and related detection methods.
2021, 49(4): 546-553
doi: 10.19756/j.issn.0253-3820.201650
Abstract:
A high accuracy liquid chromatography-isotopic dilution mass spectrometry method for determination of aflatoxins B1, B2, G1, G2, deoxynivalenol, zearalenone, ochratoxin A and fumonisin B1 in maize was developed. For the first time, a positive sample was used to optimize the extraction solvent. The sample was soaked in acetonitrile-water-formic acid (80:19.9:0.1, V/V) for 12 hours for the first extraction, and then acetonitrile-water-formic acid (20:79.9:0.1, V/V) was used for the second extraction. The results proved that the optimization of extraction conditions for positive samples was more scientific and accurate. The effects of soaking time and sampling volume before sample extraction on extraction efficiency and method precision were also investigated. The results showed that after the sample was soaked for 12 hours, the target substance could be extracted more effectively. Due to the uneven distribution of mycotoxins in the matrix, the amount of sampling directly affected the precision of the method. The minimum sampling volume of this method was 10 g. The matrix effects of 8 mycotoxins in maize were also studied in detail. The results showed that mycotoxins had strong matrix inhibition in maize, and the matrix effects were between 22% and 77%. Moreover, the matrix effects of individual toxins and their corresponding isotope markers were quite different. If a solvent calibration solution was used for the determination, the matrix effect would directly affect the accuracy of the measurement results. Therefore, in the absence of a blank matrix, the correction factor θ could be used to correct the quantitative results to eliminate the influence of matrix effects. The method was simple and fast, and had many advantages such as high accuracy and high sensitivity, and could be applied to the assignment of certified reference material.
A high accuracy liquid chromatography-isotopic dilution mass spectrometry method for determination of aflatoxins B1, B2, G1, G2, deoxynivalenol, zearalenone, ochratoxin A and fumonisin B1 in maize was developed. For the first time, a positive sample was used to optimize the extraction solvent. The sample was soaked in acetonitrile-water-formic acid (80:19.9:0.1, V/V) for 12 hours for the first extraction, and then acetonitrile-water-formic acid (20:79.9:0.1, V/V) was used for the second extraction. The results proved that the optimization of extraction conditions for positive samples was more scientific and accurate. The effects of soaking time and sampling volume before sample extraction on extraction efficiency and method precision were also investigated. The results showed that after the sample was soaked for 12 hours, the target substance could be extracted more effectively. Due to the uneven distribution of mycotoxins in the matrix, the amount of sampling directly affected the precision of the method. The minimum sampling volume of this method was 10 g. The matrix effects of 8 mycotoxins in maize were also studied in detail. The results showed that mycotoxins had strong matrix inhibition in maize, and the matrix effects were between 22% and 77%. Moreover, the matrix effects of individual toxins and their corresponding isotope markers were quite different. If a solvent calibration solution was used for the determination, the matrix effect would directly affect the accuracy of the measurement results. Therefore, in the absence of a blank matrix, the correction factor θ could be used to correct the quantitative results to eliminate the influence of matrix effects. The method was simple and fast, and had many advantages such as high accuracy and high sensitivity, and could be applied to the assignment of certified reference material.
2021, 49(4): 554-562
doi: 10.19756/j.issn.0253-3820.211031
Abstract:
Ractopamine (RAC) is a synthetic β-adrenergic receptor agonist and one of the lean meat powder substances. The purity standard substance is the source of the traceability of the value. In this work, the organic impurities in RAC were analyzed by high performance liquid chromatography quadrupole-time of flight mass spectrometry (HPLC-Q-TOF/MS), including 4 main organic impurities A (m/z 286.1802), B (m/z 316.1907), C (m/z 438.2275) and D (m/z 372.2533). The range of impurity's fragment ion peak mass deviation (m/z) was (-0.6-0.6) mDa and the relative mass deviation was from -3.7×10-6 to 2.1×10-6. Using mass spectrometry data, the fragmentation pathway of ractopamine and the fragment ions of organic impurities was established. It was inferred that impurity A was a byproduct of the dehydration and hydrogenation of ractopamine, and B, C, D and ractopamine had the same molecular skeleton structure. In addition, high-performance liquid chromatography ion trap-time of flight mass spectrometry (HPLC-IT-TOF/MS) was used to compare and verify the mass spectra fragments of organic impurities. The results showed that the two different types of mass spectrometry were consistnet. This study provided a new way of verifying results for the accurate qualitative determination of organic impurities.
Ractopamine (RAC) is a synthetic β-adrenergic receptor agonist and one of the lean meat powder substances. The purity standard substance is the source of the traceability of the value. In this work, the organic impurities in RAC were analyzed by high performance liquid chromatography quadrupole-time of flight mass spectrometry (HPLC-Q-TOF/MS), including 4 main organic impurities A (m/z 286.1802), B (m/z 316.1907), C (m/z 438.2275) and D (m/z 372.2533). The range of impurity's fragment ion peak mass deviation (m/z) was (-0.6-0.6) mDa and the relative mass deviation was from -3.7×10-6 to 2.1×10-6. Using mass spectrometry data, the fragmentation pathway of ractopamine and the fragment ions of organic impurities was established. It was inferred that impurity A was a byproduct of the dehydration and hydrogenation of ractopamine, and B, C, D and ractopamine had the same molecular skeleton structure. In addition, high-performance liquid chromatography ion trap-time of flight mass spectrometry (HPLC-IT-TOF/MS) was used to compare and verify the mass spectra fragments of organic impurities. The results showed that the two different types of mass spectrometry were consistnet. This study provided a new way of verifying results for the accurate qualitative determination of organic impurities.
2021, 49(4): 563-570
doi: 10.19756/j.issn.0253-3820.201620
Abstract:
A new method for rapid detection of isotope distribution and abundance of deuterium-labeled compounds by quadrupole orbitrap high resolution mass spectrometry (Q-Orbitrap HRMS) was devoloped. The calculation methods of instrument mass deviation (IME) and isotope deviation (ID) were established firstly. Then, the applicable conditions of the method were defined, that was, instrument mass deviation was less than the isotope deviation (IME9 (TMQ-D9) as an example, a peristaltic pump was used to inject the analyte working solution (100 μg/kg), and the total ion current diagram (TIC) in 1 min was collected. Mass spectrums were selected every 0.1 min on the TIC, and a total of 10 typical spectra were obtained for analysis. The effects of the allowable deviation (Δ) and the analysis quantity of mass spectrometry on the isotopic distribution and abundance were investigated. The results showed that the measurement results were accurate and reliable when the (Δ) value was less than the ID value of the analyte and the analysis quantity of mass spectrum was more than 10 pieces. The method was applied to the analysis of isotope distribution and abundance of TMQ-D9 and 9 deuterium-labeled β-receptor agonists, and the detection results were compared with the "Mass cluster" classification detection results and the isotope abundance values labeled on standard products. It was found that the established method had higher sensitivity, and could find more unlabeled compounds. Besides, it was more simple and rapid, and suitable for wide application.
A new method for rapid detection of isotope distribution and abundance of deuterium-labeled compounds by quadrupole orbitrap high resolution mass spectrometry (Q-Orbitrap HRMS) was devoloped. The calculation methods of instrument mass deviation (IME) and isotope deviation (ID) were established firstly. Then, the applicable conditions of the method were defined, that was, instrument mass deviation was less than the isotope deviation (IME
2021, 49(4): 571-580
doi: 10.19756/j.issn.0253-3820.211029
Abstract:
An analytical method for simultaneous determination of three organic pollutants, including polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and organic phosphorus flame retardants (OPFRs), in sediments was developed. Accelerated solvent extraction (ASE) was used to extract the targets from sediment samples, and the extracts were purified by solid phase extraction coupled with chromatography column purification. After optimization of the reaction conditions, the recoveries were 104.1%-121.7% for PCBs, 80.7%-101.6% for PBDEs, and 80.7%-132.2% for OPFRs. The developed method effectively eliminated the matrix effects. The method was verified by SRM-1944, showing satisfying accuracy. The method was further applied to detection of 20 surface sediment samples collected from the Yellow River Delta, and 12 compounds including PBDEs and OPFRs were detected with the concentration ranges of 0.01-0.38 ng/g and 1.18-21.99 ng/g. The results showed that the content of organophosphorus flameretardants in this area was higher than that of brominated flame retardants, and the method could be used for the detection of real samples.
An analytical method for simultaneous determination of three organic pollutants, including polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and organic phosphorus flame retardants (OPFRs), in sediments was developed. Accelerated solvent extraction (ASE) was used to extract the targets from sediment samples, and the extracts were purified by solid phase extraction coupled with chromatography column purification. After optimization of the reaction conditions, the recoveries were 104.1%-121.7% for PCBs, 80.7%-101.6% for PBDEs, and 80.7%-132.2% for OPFRs. The developed method effectively eliminated the matrix effects. The method was verified by SRM-1944, showing satisfying accuracy. The method was further applied to detection of 20 surface sediment samples collected from the Yellow River Delta, and 12 compounds including PBDEs and OPFRs were detected with the concentration ranges of 0.01-0.38 ng/g and 1.18-21.99 ng/g. The results showed that the content of organophosphorus flameretardants in this area was higher than that of brominated flame retardants, and the method could be used for the detection of real samples.
2021, 49(4): 581-592
doi: 10.19756/j.issn.0253-3820.201491
Abstract:
As a kind of biocatalyst with high specificity, natural enzymes can be applied in recognition and detection by selective catalysis. However, the high cost and easy inactivation limit their practical applications. Nanozyme is a kind of nanomaterial which can mimic enzyme-like properties via the instinct ability, with many advantages such as low cost, stable performance and wide applications. The biomedical detection based on nanozymes with high sensitivity, excellent specificity and low limit of detection is promising. In this paper, several main types of nanozymes were summarized, followed by the introduction of their research progress in biomedical detection. The outlook of nanozymes in biomedical detection was also proposed at the end of this paper.
As a kind of biocatalyst with high specificity, natural enzymes can be applied in recognition and detection by selective catalysis. However, the high cost and easy inactivation limit their practical applications. Nanozyme is a kind of nanomaterial which can mimic enzyme-like properties via the instinct ability, with many advantages such as low cost, stable performance and wide applications. The biomedical detection based on nanozymes with high sensitivity, excellent specificity and low limit of detection is promising. In this paper, several main types of nanozymes were summarized, followed by the introduction of their research progress in biomedical detection. The outlook of nanozymes in biomedical detection was also proposed at the end of this paper.
2021, 49(4): 593-601
doi: 10.19756/j.issn.0253-3820.201436
Abstract:
Multivariate optical computing (MOC) is a technique that uses optical filters to modulate the light to achieve calculation and obtain qualitative or quantitative results directly by a single-point detector. Therefore, the complicated instrument design and cumbersome data processing are no longer needed for the MOC-based analytical instrument. The key technique for MOC is the design of the filter to achieve the detection that directly reflects the result for different purposes. In recent years, much efforts have been made for designation and optimization of the filters to enhance the performance. MOC-based spectrometer is a perfect combination of chemometrics and instrument design, and thus it is praised as the next-generation spectrometer. In this paper, the history, principle and recent advances of MOC related techniques were summarized with an emphasis on the filter design, filter optics and applications, and the challenges in the design and the optical implementation of the filters were discussed, as well as the integration of the instrument system.
Multivariate optical computing (MOC) is a technique that uses optical filters to modulate the light to achieve calculation and obtain qualitative or quantitative results directly by a single-point detector. Therefore, the complicated instrument design and cumbersome data processing are no longer needed for the MOC-based analytical instrument. The key technique for MOC is the design of the filter to achieve the detection that directly reflects the result for different purposes. In recent years, much efforts have been made for designation and optimization of the filters to enhance the performance. MOC-based spectrometer is a perfect combination of chemometrics and instrument design, and thus it is praised as the next-generation spectrometer. In this paper, the history, principle and recent advances of MOC related techniques were summarized with an emphasis on the filter design, filter optics and applications, and the challenges in the design and the optical implementation of the filters were discussed, as well as the integration of the instrument system.
2021, 49(4): 602-610
doi: 10.19756/j.issn.0253-3820.201694
Abstract:
Herein we proposed an integrated microfluidic chip to perform an aptamer-based affinity electrophoresis assay for the analysis of trace-level protein. The integrated platform included two functional units, a nanoporous membrane for sample preconcentration to improve detection sensitivity and a long gel sieving matrix for effective sample separation. The spatially controlled photopatterning technology was used to create poly(N-isopropylacrylamide) (PNIPAAm) nanoporous membrane microstructure inside the glass microchip, and methylcellulose (MC) gel solution was perfused adjacent to the membrane in the separation channel enabled zero dead volume. A model aptamer targeting thrombin was demonstrated to evaluate the performance of integrated microchip, and a simple double-T microchip was designed as a reference without the preconcentration unit. A confocal laser-induced fluorescence detection system (LIF) was utilized to quantitate the target protein thrombin. After 30 s of preconcentration and 120 s of separation, the integrated microfluidic chip showed significant signal enhancement and good separation resolution of thrombin complex with a detection range of 1-40 nmol/L and a detection limit of 1 nmol/L (S/N=3), which was over 100-fold lower than a simple double-T microchip (the detection limit was 100 nmol/L, S/N=3). The integrated platform presented in this work is anticipated to improve sensitivity of other affinity electrophoresis-based analytes.
Herein we proposed an integrated microfluidic chip to perform an aptamer-based affinity electrophoresis assay for the analysis of trace-level protein. The integrated platform included two functional units, a nanoporous membrane for sample preconcentration to improve detection sensitivity and a long gel sieving matrix for effective sample separation. The spatially controlled photopatterning technology was used to create poly(N-isopropylacrylamide) (PNIPAAm) nanoporous membrane microstructure inside the glass microchip, and methylcellulose (MC) gel solution was perfused adjacent to the membrane in the separation channel enabled zero dead volume. A model aptamer targeting thrombin was demonstrated to evaluate the performance of integrated microchip, and a simple double-T microchip was designed as a reference without the preconcentration unit. A confocal laser-induced fluorescence detection system (LIF) was utilized to quantitate the target protein thrombin. After 30 s of preconcentration and 120 s of separation, the integrated microfluidic chip showed significant signal enhancement and good separation resolution of thrombin complex with a detection range of 1-40 nmol/L and a detection limit of 1 nmol/L (S/N=3), which was over 100-fold lower than a simple double-T microchip (the detection limit was 100 nmol/L, S/N=3). The integrated platform presented in this work is anticipated to improve sensitivity of other affinity electrophoresis-based analytes.
2021, 49(4): 611-617
doi: 10.19756/j.issn.0253-3820.201696
Abstract:
The self-assembly of amyloid peptides in crowded environment has attracted tremendous attention due to its close relation to human neurological diseases. The experiments investigated the aggregation and diffusion behavior of Aβ16-22 in the water nanofilm adsorbed on the surface of mica substrate under a closed environment. The result showed that the peptide molecules could diffuse and aggregate in water layer and formed peptide nanosheets with different heights under various conditions, and the nanosheet formation was remarkably affected by the incubation temperature and peptide concentration. The elastic modulus of Aβ16-22 nanosheets was further evaluated by PeakForce-QNM, and it was found that the elastic modulus were estimated to be about (5.0±0.4) GPa, notably stiffer than that of amyloid fibrils ((3.1±0.2) GPa) formed in bulk solution. NanoIR analysis indicated that the secondary structure of nanosheets adsorbed on mica surface was mainly related to α-helix conformations, unlike the β-sheet structure of amyloid fibrils. We attributed the discrepancy of compression elasticity to the difference of peptide second structure of these two species.
The self-assembly of amyloid peptides in crowded environment has attracted tremendous attention due to its close relation to human neurological diseases. The experiments investigated the aggregation and diffusion behavior of Aβ16-22 in the water nanofilm adsorbed on the surface of mica substrate under a closed environment. The result showed that the peptide molecules could diffuse and aggregate in water layer and formed peptide nanosheets with different heights under various conditions, and the nanosheet formation was remarkably affected by the incubation temperature and peptide concentration. The elastic modulus of Aβ16-22 nanosheets was further evaluated by PeakForce-QNM, and it was found that the elastic modulus were estimated to be about (5.0±0.4) GPa, notably stiffer than that of amyloid fibrils ((3.1±0.2) GPa) formed in bulk solution. NanoIR analysis indicated that the secondary structure of nanosheets adsorbed on mica surface was mainly related to α-helix conformations, unlike the β-sheet structure of amyloid fibrils. We attributed the discrepancy of compression elasticity to the difference of peptide second structure of these two species.
2021, 49(4): 618-627
doi: 10.19756/j.issn.0253-3820.211002
Abstract:
A novel approach was developed for simultaneous determination of 20(S)-ginsenoside Rg3 (G-Rg3) and its main metabolite 20(S)-ginsenoside Rh2 (G-Rh2) in rats plasma by UHPLC-QQQ MS to compare the pharmacokinetic behavior of normal and UVB-induced depression model after oral administration of G-Rg3. In this method, an Ascentis® Express C18 chromatographic column (5 mm×3.0 mm, 2.7 μm) was used for qualitative and quantitative analysis of G-Rg3 and G-Rh2 under gradient elution with 0.1% formic acid in water-acetonitrile as the mobile phase. Simultaneously, the flow rate was 0.3 mL/min and the injection volume of sample solution was 5 μL. The MS analysis was operated in multiple-reaction monitoring (MRM) mode using electrospray ionization (ESI) under negative ion mode. With 20(S)-ginsenoside Rb1 (G-Rb1) as internal standard, G-Rg3 and G-Rh2 were quantitatively analyzed. The ions for quantification were m/z 783.5/621.4, 621.4/459 and 1107.6/954.5, respectively. The results showed that the intra-day and inter-day precisions, recovery, matrix effect and stability could meet the pharmacokinetic analysis requirement, and the whole analysis procedure could be completed in 10 minutes. Both G-Rg3 and G-Rh2 had a good linear relationship in the concentration ranges of 2.0-2500 ng/mL and 2.0-2500 ng/mL (R2>0.9907). The results indicated that the metabolic process of G-Rg3 conformed to a two-compartment pharmacokinetic model after single oral administration in the normal and model groups. The t1/2α were (0.35±0.116) and (1.954±0.609) h, the t1/2β were (66.103±6.425) and (52.496±33.639) h, the AUC(0-t) were (346.75±14.108) and (551.374±117.557) mg·L/h, and the AUC(0-t) were (497.66±39.673) and (694.523±213.077) mg·L/h. There were significant differences in pharmacokinetic parameters between the two groups (p<0.01), which was concluded that the internal environment of depression model rats might have been changed by UVB radiation, might also affecting the absorption and metabolism of G-Rg3. This method was simple, rapid, selective and sensitive, and could be used for the pharmacokinetic analysis of Rg3 and Rh2. More important, it was suitable for pharmacokinetic study of G-Rg3 in vivo.
A novel approach was developed for simultaneous determination of 20(S)-ginsenoside Rg3 (G-Rg3) and its main metabolite 20(S)-ginsenoside Rh2 (G-Rh2) in rats plasma by UHPLC-QQQ MS to compare the pharmacokinetic behavior of normal and UVB-induced depression model after oral administration of G-Rg3. In this method, an Ascentis® Express C18 chromatographic column (5 mm×3.0 mm, 2.7 μm) was used for qualitative and quantitative analysis of G-Rg3 and G-Rh2 under gradient elution with 0.1% formic acid in water-acetonitrile as the mobile phase. Simultaneously, the flow rate was 0.3 mL/min and the injection volume of sample solution was 5 μL. The MS analysis was operated in multiple-reaction monitoring (MRM) mode using electrospray ionization (ESI) under negative ion mode. With 20(S)-ginsenoside Rb1 (G-Rb1) as internal standard, G-Rg3 and G-Rh2 were quantitatively analyzed. The ions for quantification were m/z 783.5/621.4, 621.4/459 and 1107.6/954.5, respectively. The results showed that the intra-day and inter-day precisions, recovery, matrix effect and stability could meet the pharmacokinetic analysis requirement, and the whole analysis procedure could be completed in 10 minutes. Both G-Rg3 and G-Rh2 had a good linear relationship in the concentration ranges of 2.0-2500 ng/mL and 2.0-2500 ng/mL (R2>0.9907). The results indicated that the metabolic process of G-Rg3 conformed to a two-compartment pharmacokinetic model after single oral administration in the normal and model groups. The t1/2α were (0.35±0.116) and (1.954±0.609) h, the t1/2β were (66.103±6.425) and (52.496±33.639) h, the AUC(0-t) were (346.75±14.108) and (551.374±117.557) mg·L/h, and the AUC(0-t) were (497.66±39.673) and (694.523±213.077) mg·L/h. There were significant differences in pharmacokinetic parameters between the two groups (p<0.01), which was concluded that the internal environment of depression model rats might have been changed by UVB radiation, might also affecting the absorption and metabolism of G-Rg3. This method was simple, rapid, selective and sensitive, and could be used for the pharmacokinetic analysis of Rg3 and Rh2. More important, it was suitable for pharmacokinetic study of G-Rg3 in vivo.
2021, 49(4): 628-635
doi: 10.19756/j.issn.0253-3820.201603
Abstract:
The magnetic molecularly imprinted nanoparticles were prepared by surface molecular imprinting technology with Fe3O4 magnetic nanoparticles as matrix material, ursolic acid as template molecule and 3-aminopropyl triethoxysilane as functional monomer. The prepared magnetic molecularly imprinted nanoparticles were used for rapid separation of ursolic acid with high selectivity. These resulting nanocomposites were well characterized by transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The adsorption performance of the magnetic molecularly imprinted nanoparticles was investigated by adsorption kinetics and adsorptionisotherm experiments. Experimental results showed that the maximum adsorption capacity of the magnetic molecularly imprinted microspheres for ursolic acid was 58.17 mg/g, and the imprinting factor was 3.65. Moreover, the prepared magnetic molecularly imprinted nanospheres showed good stability and repeatability, and could be used for the adsorption of ursolic acid with recoveries of 96.5%-97.8% and RSD of 2.2%-3.1% (n=5). The proposed ursolic acid magnetic molecularly imprinted microspheres were demonstrated to be simple, environment friendly, and high sensitive in rapid separation and extraction of ursolic acid.
The magnetic molecularly imprinted nanoparticles were prepared by surface molecular imprinting technology with Fe3O4 magnetic nanoparticles as matrix material, ursolic acid as template molecule and 3-aminopropyl triethoxysilane as functional monomer. The prepared magnetic molecularly imprinted nanoparticles were used for rapid separation of ursolic acid with high selectivity. These resulting nanocomposites were well characterized by transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The adsorption performance of the magnetic molecularly imprinted nanoparticles was investigated by adsorption kinetics and adsorptionisotherm experiments. Experimental results showed that the maximum adsorption capacity of the magnetic molecularly imprinted microspheres for ursolic acid was 58.17 mg/g, and the imprinting factor was 3.65. Moreover, the prepared magnetic molecularly imprinted nanospheres showed good stability and repeatability, and could be used for the adsorption of ursolic acid with recoveries of 96.5%-97.8% and RSD of 2.2%-3.1% (n=5). The proposed ursolic acid magnetic molecularly imprinted microspheres were demonstrated to be simple, environment friendly, and high sensitive in rapid separation and extraction of ursolic acid.
2021, 49(4): 636-641
doi: 10.19756/j.issn.0253-3820.201467
Abstract:
Derivative synchronous fluorescence spectrometry with double scans method was established to simultaneously determine the dissolved 1-methylphenanthrene (1-MP) and its metabolites such as 1-hydroxy-2-naphthoic acid (1H2NA) and salicylic acid (SA). With this method, the linear ranges for determination of 1-MP, 1H2NA and SA were 0.02-1.30 μmol/L, 0.02-7.60 μmol/L and 0.01-5.20 μmol/L, the detection limits (LODs) of 1-MP, 1H2NA and SA were 0.11, 0.33 and 2.90 nmol/L, the relative standard deviations (RSD) were less than 2%, and the recoveries were 97.4%-108.6%. This method was suitable for the simultaneous determination of 1-MP, 1H2NA and SA in the dissolved 1-MP microbial degradation process under the laboratory simulation condition, showing practical application potential in investigation of 1-MP degradation process and mechanism in situ.
Derivative synchronous fluorescence spectrometry with double scans method was established to simultaneously determine the dissolved 1-methylphenanthrene (1-MP) and its metabolites such as 1-hydroxy-2-naphthoic acid (1H2NA) and salicylic acid (SA). With this method, the linear ranges for determination of 1-MP, 1H2NA and SA were 0.02-1.30 μmol/L, 0.02-7.60 μmol/L and 0.01-5.20 μmol/L, the detection limits (LODs) of 1-MP, 1H2NA and SA were 0.11, 0.33 and 2.90 nmol/L, the relative standard deviations (RSD) were less than 2%, and the recoveries were 97.4%-108.6%. This method was suitable for the simultaneous determination of 1-MP, 1H2NA and SA in the dissolved 1-MP microbial degradation process under the laboratory simulation condition, showing practical application potential in investigation of 1-MP degradation process and mechanism in situ.
2021, 49(4): 642-651
doi: 10.19756/j.issn.0253-3820.201735
Abstract:
Rhodamine B (RhB) dyes usually have no selectivity in fluorescence detection of Fe3+, which limits their application in analytical detection. In this study, a composite material (RhB@PCN-777) with RhB encapsulated in a zirconium-based organic framework (PCN-777) channel was synthesized and applied to the specific detection of Fe3+ in water. Compared with free RhB, RhB@PCN-777 exhibited drastically improved fluorescence stability and high selectivity for the determination of Fe3+. RhB@PCN-777 composite featured a yellow emission at 586 nm when dispersed in aqueous solution, which could detect Fe3+ in water with high sensitivity and selectivity, with a detection limit as low as 0.16 μmol/L. Moreover, RhB@PCN-777 was successfully used to detect Fe3+ in real water samples with recoveries ranging from 94.2% to 103.9%, indicating that the fluorescent probe had high reliability in actual environmental aqueous samples.
Rhodamine B (RhB) dyes usually have no selectivity in fluorescence detection of Fe3+, which limits their application in analytical detection. In this study, a composite material (RhB@PCN-777) with RhB encapsulated in a zirconium-based organic framework (PCN-777) channel was synthesized and applied to the specific detection of Fe3+ in water. Compared with free RhB, RhB@PCN-777 exhibited drastically improved fluorescence stability and high selectivity for the determination of Fe3+. RhB@PCN-777 composite featured a yellow emission at 586 nm when dispersed in aqueous solution, which could detect Fe3+ in water with high sensitivity and selectivity, with a detection limit as low as 0.16 μmol/L. Moreover, RhB@PCN-777 was successfully used to detect Fe3+ in real water samples with recoveries ranging from 94.2% to 103.9%, indicating that the fluorescent probe had high reliability in actual environmental aqueous samples.
