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2018 Volume 46 Issue 8
2018, 46(8): 1161-1170
doi: 10.11895/j.issn.0253-3820.171153
Abstract:
Fast and accurate detection of complex samples in either medical diagnosis or food safety analysis is of great significance for the safeguarding of human health. The magnetic relaxation switches(MRS) technology based on superparamagnetic nanoparticles (SMP) is the combination of nano-biotechnology,nuclear magnetic resonance, chemistry and immunoassay. MRS assay has the characteristics of high sensitivity and specificity, as well as nondestructive and time-saving, and can be used in turbid complex samples. In this paper, with brief discussion about the detection theory of superparamagnetic nanosensor, the target type, structural characteristics, limit of detection, state of magnetic nanoparticles and the change of T2 value of MRS were reviewed. The research progresses of magnetic relaxation switch sensor in medical diagnosis of different biomarkers and the analysis of food hazard factor were also summarized. Accordingly, the future research targets from three aspects, e.g., preparation and modification of magnetic nanoparticles, the improvement of detection sensitivity and construction of high flux magnetic relaxation switch sensor, have been put forward.
Fast and accurate detection of complex samples in either medical diagnosis or food safety analysis is of great significance for the safeguarding of human health. The magnetic relaxation switches(MRS) technology based on superparamagnetic nanoparticles (SMP) is the combination of nano-biotechnology,nuclear magnetic resonance, chemistry and immunoassay. MRS assay has the characteristics of high sensitivity and specificity, as well as nondestructive and time-saving, and can be used in turbid complex samples. In this paper, with brief discussion about the detection theory of superparamagnetic nanosensor, the target type, structural characteristics, limit of detection, state of magnetic nanoparticles and the change of T2 value of MRS were reviewed. The research progresses of magnetic relaxation switch sensor in medical diagnosis of different biomarkers and the analysis of food hazard factor were also summarized. Accordingly, the future research targets from three aspects, e.g., preparation and modification of magnetic nanoparticles, the improvement of detection sensitivity and construction of high flux magnetic relaxation switch sensor, have been put forward.
2018, 46(8): 1171-1177
doi: 10.11895/j.issn.0253-3820.171488
Abstract:
A new quartz crystal microbalance with dissipation monitoring (QCMD) was developed based on quadrature modulation method. Combined with insert software and hardware circuit, the instrument made automatch and precise calculation of quartz resonate frequency possible within wider range. In the meantime, capacitance compensation circuit was introduced to compensate static capacitance, and thus eliminating the differences under higher viscoelastic loads. Through several tests of viscoelastic loads environment, constantly lower mass loads adding and electrochemical combination, the functionality and performance were proved and verified. The test results showed that, the QCMD instrument had wider frequency of quartz crystal and auto compensation to static capacitance. The accuracy of frequency calculation reached 0.1 Hz, and the instrument could calculate dissipation factors spontaneously and constantly. The homemade QCMD system could be used in combination with multiple electrochemistry methods, exhibiting advantages of lower consumables costs and rich functions.
A new quartz crystal microbalance with dissipation monitoring (QCMD) was developed based on quadrature modulation method. Combined with insert software and hardware circuit, the instrument made automatch and precise calculation of quartz resonate frequency possible within wider range. In the meantime, capacitance compensation circuit was introduced to compensate static capacitance, and thus eliminating the differences under higher viscoelastic loads. Through several tests of viscoelastic loads environment, constantly lower mass loads adding and electrochemical combination, the functionality and performance were proved and verified. The test results showed that, the QCMD instrument had wider frequency of quartz crystal and auto compensation to static capacitance. The accuracy of frequency calculation reached 0.1 Hz, and the instrument could calculate dissipation factors spontaneously and constantly. The homemade QCMD system could be used in combination with multiple electrochemistry methods, exhibiting advantages of lower consumables costs and rich functions.
2018, 46(8): 1178-1185
doi: 10.11895/j.issn.0253-3820.181119
Abstract:
An aptasensor was constructed based on upconversion fluorescence resonance energy transfer (UC-FRET) between sandwich-structure upconversion nanoparticles (SWUCNPs, donor) and polydopamine nanoparticles (PDA NPs, receptor). With the π-π stacking between PDA NPs and carcinoembryonic antigen (CEA) aptamer which was covalently coupled to polyacrytic acid modified SWUCNPs, the fluorescence of SWUCNPs could be quenched up to 95%. After introducing CEA, the aptamer preferentially combined with CEA, which blocked the energy transfer process between SWUCNPs and PDA NPs, and thus the fluorescence of SWUCNPs was recovered. Under the optimized experimental conditions, the fluorescence restoration of SWUCNPs was linearly related to CEA concentration ranging from 1.0 ng/mL to 250.0 ng/mL in both buffer solution and human serum samples. The aptasensor exhibited good selectivity for CEA bearing little interference from other substances. Simple synthesis, good quenching ability, water solubility and label-free property ensure PDA NPs as a kind of alternative energy acceptor of UCNPs, which will extend the applications of UC-FRET biosensing platform.
An aptasensor was constructed based on upconversion fluorescence resonance energy transfer (UC-FRET) between sandwich-structure upconversion nanoparticles (SWUCNPs, donor) and polydopamine nanoparticles (PDA NPs, receptor). With the π-π stacking between PDA NPs and carcinoembryonic antigen (CEA) aptamer which was covalently coupled to polyacrytic acid modified SWUCNPs, the fluorescence of SWUCNPs could be quenched up to 95%. After introducing CEA, the aptamer preferentially combined with CEA, which blocked the energy transfer process between SWUCNPs and PDA NPs, and thus the fluorescence of SWUCNPs was recovered. Under the optimized experimental conditions, the fluorescence restoration of SWUCNPs was linearly related to CEA concentration ranging from 1.0 ng/mL to 250.0 ng/mL in both buffer solution and human serum samples. The aptasensor exhibited good selectivity for CEA bearing little interference from other substances. Simple synthesis, good quenching ability, water solubility and label-free property ensure PDA NPs as a kind of alternative energy acceptor of UCNPs, which will extend the applications of UC-FRET biosensing platform.
2018, 46(8): 1186-1192
doi: 10.11895/j.issn.0253-3820.181296
Abstract:
An analytical method was proposed for determination of antituberculosis drug isoniazid at single-molecule level by protein nanopores equipped with a cyclodextrin adapter. The developed method is rapid, highly sensitive and specific. The influence of channel protein, pH of buffer solution and recording voltage on detection signal was investigated. The results showed that (M113R)7 could provide an enhanced resolution for isoniazid recognition compared with that observed in wild-type protein or (M113N)7. The addition of isoniazid from cis side during relatively high voltage and neutral pH conditions could improve the detection sensitivity. Some common pharmaceutical excipients (glucose, sucrose and starch), metal ions that may coexist in solution and synthetic intermediates of isoniazid, isonicotinic acid (the concentrations of all analytes were above 40 times of isoniazid) were added to evaluate the selectivity of the sensing platform, and it was found that no obvious response could be observed after adding these analytes mentioned above, showing a good selectivity. The linear range and the detection limit of the sensor were 0.5-30 μmol/L and 2 nmol/L. The method was directly applied to the rapid detection of isoniazid, with the recoveries of 92.9%-108.2%.
An analytical method was proposed for determination of antituberculosis drug isoniazid at single-molecule level by protein nanopores equipped with a cyclodextrin adapter. The developed method is rapid, highly sensitive and specific. The influence of channel protein, pH of buffer solution and recording voltage on detection signal was investigated. The results showed that (M113R)7 could provide an enhanced resolution for isoniazid recognition compared with that observed in wild-type protein or (M113N)7. The addition of isoniazid from cis side during relatively high voltage and neutral pH conditions could improve the detection sensitivity. Some common pharmaceutical excipients (glucose, sucrose and starch), metal ions that may coexist in solution and synthetic intermediates of isoniazid, isonicotinic acid (the concentrations of all analytes were above 40 times of isoniazid) were added to evaluate the selectivity of the sensing platform, and it was found that no obvious response could be observed after adding these analytes mentioned above, showing a good selectivity. The linear range and the detection limit of the sensor were 0.5-30 μmol/L and 2 nmol/L. The method was directly applied to the rapid detection of isoniazid, with the recoveries of 92.9%-108.2%.
2018, 46(8): 1193-1200
doi: 10.11895/j.issn.0253-3820.181146
Abstract:
Gold nano-stars with average size of 25 nm were prepared using a one-step method simply through mixing of HAuCl4 solution with HEPES buffer (pH 7.4). UV-Vis spectroscopy measurement result showed that the absorption peak of the nano-stars was 750 nm. The 16-mercaptohexadecanoic acid (C16H32O2S) was conjugated to the gold nano-stars through Au-S bond, and then doxorubicin (DOX) was loaded onto C16H32O2S through hydrophobic interaction. The absorption peak of the nanomaterial was red shifted to 800 nm and a characteristic peak of DOX at 480 nm occurred. Next, bovine serum albumin (BSA) was coated onto the surface of the nanomaterials to increase their stability and biocompatibility. Accordingly, the absorption peak was red shifted to 806 nm with an increase of the particle size measured by DLS, which indicated that BSA was successfully wrapped onto the drug-loaded nano-stars. The as-synthesized nanocomposites were added into the breast cancer cells (MCF-7) to explore the effect of chemo-and photothermal synergistic therapy. The cell viability analysis results showed that pure laser irradiation had no significant effects on cell viability. Nanomaterials without loaded DOX only decreased the cell viability by 15%, which indicated the low cytotoxicity of the drug delivery vector. With the addition of above vector with DOX and laser irradiation, the cell survival rate decreased to 25% compared with the negative control, while the survival rate of the cells was kept 70% after being incubated with the same concentration of free DOX and irradiated with same power density of laser. The above results demonstrated that the as-prepared DOX-loaded nano-stars realized chemo-and photothermal synergistic therapy of breast cancer (MCF-7) with an enhanced therapeutic efficiency.
Gold nano-stars with average size of 25 nm were prepared using a one-step method simply through mixing of HAuCl4 solution with HEPES buffer (pH 7.4). UV-Vis spectroscopy measurement result showed that the absorption peak of the nano-stars was 750 nm. The 16-mercaptohexadecanoic acid (C16H32O2S) was conjugated to the gold nano-stars through Au-S bond, and then doxorubicin (DOX) was loaded onto C16H32O2S through hydrophobic interaction. The absorption peak of the nanomaterial was red shifted to 800 nm and a characteristic peak of DOX at 480 nm occurred. Next, bovine serum albumin (BSA) was coated onto the surface of the nanomaterials to increase their stability and biocompatibility. Accordingly, the absorption peak was red shifted to 806 nm with an increase of the particle size measured by DLS, which indicated that BSA was successfully wrapped onto the drug-loaded nano-stars. The as-synthesized nanocomposites were added into the breast cancer cells (MCF-7) to explore the effect of chemo-and photothermal synergistic therapy. The cell viability analysis results showed that pure laser irradiation had no significant effects on cell viability. Nanomaterials without loaded DOX only decreased the cell viability by 15%, which indicated the low cytotoxicity of the drug delivery vector. With the addition of above vector with DOX and laser irradiation, the cell survival rate decreased to 25% compared with the negative control, while the survival rate of the cells was kept 70% after being incubated with the same concentration of free DOX and irradiated with same power density of laser. The above results demonstrated that the as-prepared DOX-loaded nano-stars realized chemo-and photothermal synergistic therapy of breast cancer (MCF-7) with an enhanced therapeutic efficiency.
2018, 46(8): 1201-1207
doi: 10.11895/j.issn.0253-3820.181081
Abstract:
The spherical nano ZnO and polyaniline (PANI)/ZnO composites were prepared respectively by low-temperature hydrothermal method and in situ polymerization with zinc acetate, sodium hydroxide and ammonium persulfate etc. A new film-type methanol gas sensor was designed by transferring ZnO/PANI nanocomposites onto corning glass substrate with Pt-inter digital electrodes using dip-coating method. The crystalline phase and microstructure of ZnO/PANI nanocomposites were displayed by X-ray diffraction (XRD) and scanning electron microscope (SEM), and the sensitive mechanism and electrochemical characteristic of ZnO/PANI were analyzed by X-ray photoelectron spectroscopy (XPS). These characteristic tests of methanol sensor were carried out on the traits of sensitive performance, temperature, relative humidity, dynamic response, selectivity and stability in gas sensor test system. As a result, the methanol sensor based on PZ50 nanocomposites had a high response (1795.6) and a high relatively humidity level (90%) and its dynamic response time and recover time of methanol sensor were 6.9 and 19.6 s respectively, when the operating temperature was 30℃ and the methanol gas concentration was 25 mg/m3. This kind of sensor showed good anti-disturbance to the gases, including N2O, formaldehyde, ethanol, acetone and 1,3-butadiene. Besides, the response value of methanol sensor was only attenuated about 2.3% after it was continually applied to the methanol detection on automobile for about 12 weeks.
The spherical nano ZnO and polyaniline (PANI)/ZnO composites were prepared respectively by low-temperature hydrothermal method and in situ polymerization with zinc acetate, sodium hydroxide and ammonium persulfate etc. A new film-type methanol gas sensor was designed by transferring ZnO/PANI nanocomposites onto corning glass substrate with Pt-inter digital electrodes using dip-coating method. The crystalline phase and microstructure of ZnO/PANI nanocomposites were displayed by X-ray diffraction (XRD) and scanning electron microscope (SEM), and the sensitive mechanism and electrochemical characteristic of ZnO/PANI were analyzed by X-ray photoelectron spectroscopy (XPS). These characteristic tests of methanol sensor were carried out on the traits of sensitive performance, temperature, relative humidity, dynamic response, selectivity and stability in gas sensor test system. As a result, the methanol sensor based on PZ50 nanocomposites had a high response (1795.6) and a high relatively humidity level (90%) and its dynamic response time and recover time of methanol sensor were 6.9 and 19.6 s respectively, when the operating temperature was 30℃ and the methanol gas concentration was 25 mg/m3. This kind of sensor showed good anti-disturbance to the gases, including N2O, formaldehyde, ethanol, acetone and 1,3-butadiene. Besides, the response value of methanol sensor was only attenuated about 2.3% after it was continually applied to the methanol detection on automobile for about 12 weeks.
2018, 46(8): 1208-1214
doi: 10.11895/j.issn.0253-3820.181167
Abstract:
Non-enzymatic photoelectrochemical (PEC) method for the rapid detection of ethanol in alcoholic beverages was established by using vertical plate-like WO3 arrays (VAP-WO3) grown on the FTO surface. The morphology, elemental composition and lattice characteristics of VAP-WO3 were characterized by SEM, EDX and XRD techniques, respectively. The results of PEC experiments showed that ethanol could significantly enhance the photocurrent of VAP-WO3/FTO electrode. The effects of sodium tungstate amount, bias voltage, and pH values on the PEC properties of VAP-WO3/FTO electrode in the detection of ethanol were investigated. Under optimized conditions, the linear equation for ethanol detection was ΔI=6.773+0.0494CEthanol (μg/mL), and the linear range was from 20.0 μg/mL to 160.0 μg/mL with a detection limit of 7.3 μg/mL. In addition, the VAP-WO3/FTO electrode revealed good reusability and high selectivity in ethanol detection. The method was applied to the determination of ethanol in alcoholic beverages. The measured values were in good agreement with the labeling values of the alcohols, which was also consistent with the results obtained according to the corresponding national standard of China. The spiked recoveries of the sample were 93.9%-107.0%.
Non-enzymatic photoelectrochemical (PEC) method for the rapid detection of ethanol in alcoholic beverages was established by using vertical plate-like WO3 arrays (VAP-WO3) grown on the FTO surface. The morphology, elemental composition and lattice characteristics of VAP-WO3 were characterized by SEM, EDX and XRD techniques, respectively. The results of PEC experiments showed that ethanol could significantly enhance the photocurrent of VAP-WO3/FTO electrode. The effects of sodium tungstate amount, bias voltage, and pH values on the PEC properties of VAP-WO3/FTO electrode in the detection of ethanol were investigated. Under optimized conditions, the linear equation for ethanol detection was ΔI=6.773+0.0494CEthanol (μg/mL), and the linear range was from 20.0 μg/mL to 160.0 μg/mL with a detection limit of 7.3 μg/mL. In addition, the VAP-WO3/FTO electrode revealed good reusability and high selectivity in ethanol detection. The method was applied to the determination of ethanol in alcoholic beverages. The measured values were in good agreement with the labeling values of the alcohols, which was also consistent with the results obtained according to the corresponding national standard of China. The spiked recoveries of the sample were 93.9%-107.0%.
2018, 46(8): 1215-1221
doi: 10.11895/j.issn.0253-3820.171157
Abstract:
Preparation of gold nanoparticles (AuNPs) with good stability is the key to construct metal nanoparticles based colorimetric assay method. Two kinds of AuNPs with glutathione as ligand were prepared using the one-step method and two-step method respectively. The particle size and colloid stability of the as-prepared AuNPs were compared. The two-step method prepared AuNPs was more stable. Then, a non-aggregation colorimetric strategy for detection of ascorbic acid (AA) based on metal nanoparticles was constructed using the AuNPs prepared by two-step method as seeds and catalyst. This strategy combined the target-induced silver deposition reaction and the extraordinarily high molar extinction coefficient of silver nanoparticles, which exhibited high detection sensitivity and good specificity. The presence of AA could reduce Ag+ to Ag0 on the surface of AuNPs, and the resulting color change of the detection solution and the A410 was used for AA detection. The detection limit was as low as 0.75 μmol/L(S/N=3). In brief, a simple, fast and sensitive colorimetric assay method for detection of AA with good specificity and strong anti-interference ability was proposed. This method was applied to AA detection in real complex samples, which showed great prospect in bioanalytical applications.
Preparation of gold nanoparticles (AuNPs) with good stability is the key to construct metal nanoparticles based colorimetric assay method. Two kinds of AuNPs with glutathione as ligand were prepared using the one-step method and two-step method respectively. The particle size and colloid stability of the as-prepared AuNPs were compared. The two-step method prepared AuNPs was more stable. Then, a non-aggregation colorimetric strategy for detection of ascorbic acid (AA) based on metal nanoparticles was constructed using the AuNPs prepared by two-step method as seeds and catalyst. This strategy combined the target-induced silver deposition reaction and the extraordinarily high molar extinction coefficient of silver nanoparticles, which exhibited high detection sensitivity and good specificity. The presence of AA could reduce Ag+ to Ag0 on the surface of AuNPs, and the resulting color change of the detection solution and the A410 was used for AA detection. The detection limit was as low as 0.75 μmol/L(S/N=3). In brief, a simple, fast and sensitive colorimetric assay method for detection of AA with good specificity and strong anti-interference ability was proposed. This method was applied to AA detection in real complex samples, which showed great prospect in bioanalytical applications.
2018, 46(8): 1222-1230
doi: 10.11895/j.issn.0253-3820.171202
Abstract:
Twenty five molecular imprinting prepolymerization systems were performed based on COMPASS force field to optimize the imprinting shell of the fluorescent sensor. The result revealed that the optimum mole ratio of 4-Nitrophenol (4-NP), 3-aminopropyltriethoxysilane (APTES) and tetraethylorthosilicate (TEOS) in this system was 10:20:80, which was the most stable between template and functional monomer cluster. Uniform magnetite nanaocrystals prepared by hydrothermal method were subsequently embedded in the spherical silica using the reverse microemulsion polymerization. The magnetic silica microspheres were modified with amide groups to adsorb the mercaptoacetic acid capped CdTe nanocrystals. Finally, according to the results of molecular dynamics simulation, the imprinting shell was anchored on the multifunctional nanocomposites. Under the optimal conditions, a linear relationship between relative fluorescence intensity and concentration of 4-NP was obtained covering the concentration range from 5 to 150 ng/mL with a limit of detection of 1 ng/ml. The feasibility of the fluorescent sensor was successfully evaluated through the analysis of 4-NP in river water. The recoveries were from 98.7% to 101.2%, and the relative standard deviation ranged from 1.5% to 2.4%.
Twenty five molecular imprinting prepolymerization systems were performed based on COMPASS force field to optimize the imprinting shell of the fluorescent sensor. The result revealed that the optimum mole ratio of 4-Nitrophenol (4-NP), 3-aminopropyltriethoxysilane (APTES) and tetraethylorthosilicate (TEOS) in this system was 10:20:80, which was the most stable between template and functional monomer cluster. Uniform magnetite nanaocrystals prepared by hydrothermal method were subsequently embedded in the spherical silica using the reverse microemulsion polymerization. The magnetic silica microspheres were modified with amide groups to adsorb the mercaptoacetic acid capped CdTe nanocrystals. Finally, according to the results of molecular dynamics simulation, the imprinting shell was anchored on the multifunctional nanocomposites. Under the optimal conditions, a linear relationship between relative fluorescence intensity and concentration of 4-NP was obtained covering the concentration range from 5 to 150 ng/mL with a limit of detection of 1 ng/ml. The feasibility of the fluorescent sensor was successfully evaluated through the analysis of 4-NP in river water. The recoveries were from 98.7% to 101.2%, and the relative standard deviation ranged from 1.5% to 2.4%.
2018, 46(8): 1231-1237
doi: 10.11895/j.issn.0253-3820.181195
Abstract:
A dual-mode "light-on" assay platform based on enhanced fluorescent and colorimetric signals of Fe3+-H2O2-OPD system for detection of dopamine was designed. Fe3+ can catalyze the H2O2-mediated oxidation of colorless and nonfluorescent o-phenylenediamine (OPD), and the resultant of 2,3-diaminophenazine (DAP) exhibits a visible yellow color, emitting a yellow fluorescence. However, the reaction rate is extremely slow. When dopamine is introduced, it involves a Fenton type reaction which generates hydroxyl radical (·OH) continuously, thus increasing the conversion rate of OPD to DAP. Correspondingly, both color and fluorescence of the sensing system are enhanced obviously. On the basis of this fact, a sensor with dual-readout for the detection of dopamine is established via measuring the fluorescent and colorimetric signals of the Fe3+-H2O2-OPD system. The linear ranges are 0.05-20 μ mol/L and 0.10-18 μ mol/L, and the detection limits are calculated to be 15 and 65 nmol/L (S/N=3) for fluorescent and colorimetric detection, respectively. The fluorescent and colorimetric dual-readout method developed in the present work features simplicity, high sensitivity and visualization, and enhances the detection accuracy of dopamine. Moreover, the method has been successfully applied to detection of dopamine in human urine with satisfactory results.
A dual-mode "light-on" assay platform based on enhanced fluorescent and colorimetric signals of Fe3+-H2O2-OPD system for detection of dopamine was designed. Fe3+ can catalyze the H2O2-mediated oxidation of colorless and nonfluorescent o-phenylenediamine (OPD), and the resultant of 2,3-diaminophenazine (DAP) exhibits a visible yellow color, emitting a yellow fluorescence. However, the reaction rate is extremely slow. When dopamine is introduced, it involves a Fenton type reaction which generates hydroxyl radical (·OH) continuously, thus increasing the conversion rate of OPD to DAP. Correspondingly, both color and fluorescence of the sensing system are enhanced obviously. On the basis of this fact, a sensor with dual-readout for the detection of dopamine is established via measuring the fluorescent and colorimetric signals of the Fe3+-H2O2-OPD system. The linear ranges are 0.05-20 μ mol/L and 0.10-18 μ mol/L, and the detection limits are calculated to be 15 and 65 nmol/L (S/N=3) for fluorescent and colorimetric detection, respectively. The fluorescent and colorimetric dual-readout method developed in the present work features simplicity, high sensitivity and visualization, and enhances the detection accuracy of dopamine. Moreover, the method has been successfully applied to detection of dopamine in human urine with satisfactory results.
2018, 46(8): 1238-1244
doi: 10.11895/j.issn.0253-3820.181137
Abstract:
The development of safe and high-performance ionization source as an alternative is highly demanded. In this work, a negative ion mode of microwave induced plasma ionization ion mobility spectrometer (MIPI-IMS) was developed. The components of reactant ions were investigated in negative ion mode. Experiments showed that the reactant ions and the sensitivity in detecting pentaerythritol tetranitrate (PETN) were mainly influenced by the discharge gas flow rate. The comparison between the background of air and the mobility spectrum of PETN were displayed under different discharge gas flow rates. The optimized discharge gas flow rate was 300 mL/min. The reactant ion was mainly NO3-, which was confirmed by mass spectrometry. The signal intensity was higher than 4 nA with gate pulse width of 100 μs under the optimized parameters. Finally, the MIPI-IMS was used in the detection of trace explosives such as nitroglycerine (NG), 1,3,5-trinitrohexahydro-1,3,5-triazine (RDX), pentaerythritol tetranitrate (PETN), 2,4,6-trinitrotoluene (TNT), and 2,4-dinitrotoluene (2,4-DNT). The linear range for MIPI-IMS in detecting NG and PETN were 100 pg-10 ng and 100 pg-5 ng respectively. The limits of detection of NG, 2,4-DNT, TNT, RDX and PETN were 8 pg, 14 pg, 12 pg, 14 pg and 13 pg, respectively.
The development of safe and high-performance ionization source as an alternative is highly demanded. In this work, a negative ion mode of microwave induced plasma ionization ion mobility spectrometer (MIPI-IMS) was developed. The components of reactant ions were investigated in negative ion mode. Experiments showed that the reactant ions and the sensitivity in detecting pentaerythritol tetranitrate (PETN) were mainly influenced by the discharge gas flow rate. The comparison between the background of air and the mobility spectrum of PETN were displayed under different discharge gas flow rates. The optimized discharge gas flow rate was 300 mL/min. The reactant ion was mainly NO3-, which was confirmed by mass spectrometry. The signal intensity was higher than 4 nA with gate pulse width of 100 μs under the optimized parameters. Finally, the MIPI-IMS was used in the detection of trace explosives such as nitroglycerine (NG), 1,3,5-trinitrohexahydro-1,3,5-triazine (RDX), pentaerythritol tetranitrate (PETN), 2,4,6-trinitrotoluene (TNT), and 2,4-dinitrotoluene (2,4-DNT). The linear range for MIPI-IMS in detecting NG and PETN were 100 pg-10 ng and 100 pg-5 ng respectively. The limits of detection of NG, 2,4-DNT, TNT, RDX and PETN were 8 pg, 14 pg, 12 pg, 14 pg and 13 pg, respectively.
2018, 46(8): 1245-1252
doi: 10.11895/j.issn.0253-3820.181053
Abstract:
Analysis of uranium particles is extremely important for nuclear safeguards and nuclear forensics. This work describes the technical advancements for determining uranium isotope ratios and 230Th/234U in single uranium particle without chemical separation procedure by multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS). The proposed method includes:(1) measuring the 238U, 230Th and 232Th in the procedure blank samples; (2) dispersing the particles with ultrasonic concussion; (3) indentifying the uranium particles using SEM-EDX; (4) transferring single particle to PFA bottle by micromanipulator; (5) dissolving the particles in 0.1 mL HNO3 at 7.5 mol/L; (6) Measuring 235U/238U, 234U/235U and 236U/235U by MC-ICP-MS; (7) Determinating 230Th/234U. Results show that the total mass of 238U and 232Th in process blank is less than 8×10-5 ng and 1.5×10-3 ng, respectively. The relative expanded uncertainties for 235U/238U, 234U/235U, 236U/235U and 230Th/234U in CRM124-4, GBW04234 and GBW04238 could be better than 3.6%, 3.5%, 3.8% and 15% (k=2), respectively. The results agree with the certificated values within uncertainty range. In addition, an alternative approach for measuring 235U/238U, 234U/235U, 236U/235U and 230Th/234U in single uranium particle is proposed for nuclear forensics and nuclear safeguard.
Analysis of uranium particles is extremely important for nuclear safeguards and nuclear forensics. This work describes the technical advancements for determining uranium isotope ratios and 230Th/234U in single uranium particle without chemical separation procedure by multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS). The proposed method includes:(1) measuring the 238U, 230Th and 232Th in the procedure blank samples; (2) dispersing the particles with ultrasonic concussion; (3) indentifying the uranium particles using SEM-EDX; (4) transferring single particle to PFA bottle by micromanipulator; (5) dissolving the particles in 0.1 mL HNO3 at 7.5 mol/L; (6) Measuring 235U/238U, 234U/235U and 236U/235U by MC-ICP-MS; (7) Determinating 230Th/234U. Results show that the total mass of 238U and 232Th in process blank is less than 8×10-5 ng and 1.5×10-3 ng, respectively. The relative expanded uncertainties for 235U/238U, 234U/235U, 236U/235U and 230Th/234U in CRM124-4, GBW04234 and GBW04238 could be better than 3.6%, 3.5%, 3.8% and 15% (k=2), respectively. The results agree with the certificated values within uncertainty range. In addition, an alternative approach for measuring 235U/238U, 234U/235U, 236U/235U and 230Th/234U in single uranium particle is proposed for nuclear forensics and nuclear safeguard.
2018, 46(8): 1253-1260
doi: 10.11895/j.issn.0253-3820.181258
Abstract:
An analytical method was established for accurate determination of trace toxic elements in activated clay by inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) with different digestion processes. The activated clay was digested by microwave and closed pressurized acid, respectively. Eight kinds of toxic elements including Cr, Ni, As, Cd, Sn, Sb, Hg and Pb were measured by ICP-MS/MS. In the MS/MS mode, O2 and NH3/He were employed as reaction gases to eliminate the interference during the determination process. The analysis results shown good linearity (R2 ≥ 0.9999), and the limit of detection was 0.35-5.20 ng/g. The accuracy and precision of the analytical method were evaluated by the national standard material stream sediment (GBW07306) that is similar to the matrix composition of activated clay. The results shown that the measured values of microwave digestion and closed pressurized acid digestion were in good agreement with the certified values of the standard reference materials with the relative standard deviation (RSD) less than or equal to 5.2%, which proves that the analysis results are accurate, reliable and high precision. The method is considered to be suitable for high-throughput analysis of trace toxic elements in activated clay by advantages of fast analysis, low limit of detection and interference-free.
An analytical method was established for accurate determination of trace toxic elements in activated clay by inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) with different digestion processes. The activated clay was digested by microwave and closed pressurized acid, respectively. Eight kinds of toxic elements including Cr, Ni, As, Cd, Sn, Sb, Hg and Pb were measured by ICP-MS/MS. In the MS/MS mode, O2 and NH3/He were employed as reaction gases to eliminate the interference during the determination process. The analysis results shown good linearity (R2 ≥ 0.9999), and the limit of detection was 0.35-5.20 ng/g. The accuracy and precision of the analytical method were evaluated by the national standard material stream sediment (GBW07306) that is similar to the matrix composition of activated clay. The results shown that the measured values of microwave digestion and closed pressurized acid digestion were in good agreement with the certified values of the standard reference materials with the relative standard deviation (RSD) less than or equal to 5.2%, which proves that the analysis results are accurate, reliable and high precision. The method is considered to be suitable for high-throughput analysis of trace toxic elements in activated clay by advantages of fast analysis, low limit of detection and interference-free.
2018, 46(8): 1261-1268
doi: 10.11895/j.issn.0253-3820.171529
Abstract:
Based on the inhibition of protein phosphatase 2A (PP2A) by diarrhetic shellfish poisoning (DSP), mainly okadaic acid (OA) and its analogues (dinophysistoxins, DTXs), colorimetric protein phosphatase inhibition assay (PPIA) was built to detect DSP in shellfish in which 4-nitrophenyl phosphate (p-NPP) was used as the substrate. After hydrolyzed by PP2A, the product (4-nitrophenol, p-NP) was measured at 405 nm, then toxins in samples could be quantified according to the standard dose-effect curve developed with a series of toxin standard solutions. In order to overcome the instability of PP2A and preserve the enzymatic activity well, sol-gel, accompanied with hydroxyethyl-cellulose (HEC), was used to encapsulate and immobilize PP2A at the bottom of the microwells. Also, D-glucose was employed as the template or pore-forming agent to improve the sensitivity. The PP2A immobilized sol-gel exhibited a storage stability of 4 months at -18℃. The limit of detection was 50 μg OA eq./kg, the spiked recoveries for OA in shellfish samples were between 68.8% and 119.4%, and the linear range was from 50 to 800 μg/kg. The PPIA with good recovery and reproducibility was simple and convenient. Samples and substrate solutions were added directly when used, demonstrating this proposed method could be used as an efficient analysis tool for rapid screening of DSP and be suited for regular monitoring program to control shellfish toxicity.
Based on the inhibition of protein phosphatase 2A (PP2A) by diarrhetic shellfish poisoning (DSP), mainly okadaic acid (OA) and its analogues (dinophysistoxins, DTXs), colorimetric protein phosphatase inhibition assay (PPIA) was built to detect DSP in shellfish in which 4-nitrophenyl phosphate (p-NPP) was used as the substrate. After hydrolyzed by PP2A, the product (4-nitrophenol, p-NP) was measured at 405 nm, then toxins in samples could be quantified according to the standard dose-effect curve developed with a series of toxin standard solutions. In order to overcome the instability of PP2A and preserve the enzymatic activity well, sol-gel, accompanied with hydroxyethyl-cellulose (HEC), was used to encapsulate and immobilize PP2A at the bottom of the microwells. Also, D-glucose was employed as the template or pore-forming agent to improve the sensitivity. The PP2A immobilized sol-gel exhibited a storage stability of 4 months at -18℃. The limit of detection was 50 μg OA eq./kg, the spiked recoveries for OA in shellfish samples were between 68.8% and 119.4%, and the linear range was from 50 to 800 μg/kg. The PPIA with good recovery and reproducibility was simple and convenient. Samples and substrate solutions were added directly when used, demonstrating this proposed method could be used as an efficient analysis tool for rapid screening of DSP and be suited for regular monitoring program to control shellfish toxicity.
2018, 46(8): 1269-1274
doi: 10.11895/j.issn.0253-3820.181156
Abstract:
A new method is used to prepare poly(vinyl alcohol) (PVA) microspheres. Droplet formation technology can produce a large number of uniform scale and monodisperse PVA droplets on the microfluidic chip quickly and continuously, and the droplet preparation speed can reach 6/sec. The size of the PVA droplets can be controlled by changing the injection flow rate of the two-phase fluid and the width of microfluidic channel. Then the PVA microspheres are formed by physical crosslinking. This method has high preparation efficiency and good monodisperse effect of the obtained microspheres. Moreover, the process does not require the incorporation of chemical crosslinking agents, avoiding interference with the inclusion material, and is well suited for applications such as drug carrier.
A new method is used to prepare poly(vinyl alcohol) (PVA) microspheres. Droplet formation technology can produce a large number of uniform scale and monodisperse PVA droplets on the microfluidic chip quickly and continuously, and the droplet preparation speed can reach 6/sec. The size of the PVA droplets can be controlled by changing the injection flow rate of the two-phase fluid and the width of microfluidic channel. Then the PVA microspheres are formed by physical crosslinking. This method has high preparation efficiency and good monodisperse effect of the obtained microspheres. Moreover, the process does not require the incorporation of chemical crosslinking agents, avoiding interference with the inclusion material, and is well suited for applications such as drug carrier.
2018, 46(8): 1275-1281
doi: 10.11895/j.issn.0253-3820.181057
Abstract:
To address the issues of tylosin residues in food and environment, a good specific polyclonal antibody was prepared by animal immunization based on a new hapten achieved by oxidizing the aldehyde group on the side chain of tylosin to carboxyl. Further, an indirect competitive enzyme-linked immunosorbent assay (icELISA) was established. The main experimental conditions were as follows:the coating antigen and the antibody were respectively diluted by 6000 times and 2000 times, the reaction buffer was PBST (pH 7.4), and the Tween concentration and ionic concentration were 0.1% and 0.01 mol/L, respectively. The dilution ratio of the secondary antibody was 4000 times and the secondary reaction time was 30 min. Under the optimized conditions, the IC50 and the linear range of this method were 1.39 ng/mL and 0.17-11.0 ng/mL, respectively. The detection limit was 0.07 ng/mL, and the cross-reactivity with analogues was less than 0.1%. The recoveries of spiked raw milk and water samples were 78.4%-105.6% with relative standard deviation less than 15%. Besides, the detection results had good correlation with HPLC method (R2=0.97). This method is suitable for rapid and specific screening of tylosin residues in milk and water samples.
To address the issues of tylosin residues in food and environment, a good specific polyclonal antibody was prepared by animal immunization based on a new hapten achieved by oxidizing the aldehyde group on the side chain of tylosin to carboxyl. Further, an indirect competitive enzyme-linked immunosorbent assay (icELISA) was established. The main experimental conditions were as follows:the coating antigen and the antibody were respectively diluted by 6000 times and 2000 times, the reaction buffer was PBST (pH 7.4), and the Tween concentration and ionic concentration were 0.1% and 0.01 mol/L, respectively. The dilution ratio of the secondary antibody was 4000 times and the secondary reaction time was 30 min. Under the optimized conditions, the IC50 and the linear range of this method were 1.39 ng/mL and 0.17-11.0 ng/mL, respectively. The detection limit was 0.07 ng/mL, and the cross-reactivity with analogues was less than 0.1%. The recoveries of spiked raw milk and water samples were 78.4%-105.6% with relative standard deviation less than 15%. Besides, the detection results had good correlation with HPLC method (R2=0.97). This method is suitable for rapid and specific screening of tylosin residues in milk and water samples.
2018, 46(8): 1282-1288
doi: 10.11895/j.issn.0253-3820.171193
Abstract:
A metal organic skeleton ZIF-8 derived nitrogen-containing porous carbon (ZIF-8-NC) was used as the adsorbent for the solid-phase extraction of Cu2+, Pb2+, Cd2+, Cr3+, Ni2+, Co2+ from tea samples prior to flame atomic absorption spectrometric detection. The ZIF-8-NC had a large specific surface area of 1240 m2/g due to the presence of plenty of micropores and mesopores. Its high adsorption capability could be attributed to the surface nitrogen-containing groups which coordinated with metal ions. The effects of important experimental parameters on the extraction efficiency were investigated and optimized. Under the optimal conditions, the limits of detections (LODs) were found to be 0.05-0.07 μg/kg. The correlation coefficients were between 0.9988 and 0.9993. The method recoveries of the analytes in the spiked samples were 76.8%-101.0%, with relative standard deviations ranging from 5.9% to 11.3%. The established method provides a new and environmentally friendly approach for determination of metal ions in complex matrix samples.
A metal organic skeleton ZIF-8 derived nitrogen-containing porous carbon (ZIF-8-NC) was used as the adsorbent for the solid-phase extraction of Cu2+, Pb2+, Cd2+, Cr3+, Ni2+, Co2+ from tea samples prior to flame atomic absorption spectrometric detection. The ZIF-8-NC had a large specific surface area of 1240 m2/g due to the presence of plenty of micropores and mesopores. Its high adsorption capability could be attributed to the surface nitrogen-containing groups which coordinated with metal ions. The effects of important experimental parameters on the extraction efficiency were investigated and optimized. Under the optimal conditions, the limits of detections (LODs) were found to be 0.05-0.07 μg/kg. The correlation coefficients were between 0.9988 and 0.9993. The method recoveries of the analytes in the spiked samples were 76.8%-101.0%, with relative standard deviations ranging from 5.9% to 11.3%. The established method provides a new and environmentally friendly approach for determination of metal ions in complex matrix samples.
2018, 46(8): 1289-1296
doi: 10.11895/j.issn.0253-3820.181052
Abstract:
A cellulose derivative (C-C4) synthesized by "click" reaction and methylation reaction in sequence was mixed with ionic liquid bonded polysilxoane (PIL-C12-NTf2) to prepare a capillary column (C-C4@PIL-C12) for gas chromatography. The prepared column has a column efficiency of 2778 plates/m (for naphthalene k=6.20, 100℃) and exhibits satisfying durability. Abraham's solvation parameter model was used to reveal the interaction characteristics and some representative compounds were employed to investigate the separation selectivity. It was resulted that compared with the two commercially available polar stationary phases of Elite-waxetr and TG-17ms, C-C4@PIL-C12 possessed moderate strength of the hydrogen bond basicity, dipolarity/polarizability and hydrogen bond acidity, and displayed better separation selectivity for the tested analytes, such as aromatic isomers, substituted alkanes, aliphatic acid esters, n-alkanes and phthalic acid esters.
A cellulose derivative (C-C4) synthesized by "click" reaction and methylation reaction in sequence was mixed with ionic liquid bonded polysilxoane (PIL-C12-NTf2) to prepare a capillary column (C-C4@PIL-C12) for gas chromatography. The prepared column has a column efficiency of 2778 plates/m (for naphthalene k=6.20, 100℃) and exhibits satisfying durability. Abraham's solvation parameter model was used to reveal the interaction characteristics and some representative compounds were employed to investigate the separation selectivity. It was resulted that compared with the two commercially available polar stationary phases of Elite-waxetr and TG-17ms, C-C4@PIL-C12 possessed moderate strength of the hydrogen bond basicity, dipolarity/polarizability and hydrogen bond acidity, and displayed better separation selectivity for the tested analytes, such as aromatic isomers, substituted alkanes, aliphatic acid esters, n-alkanes and phthalic acid esters.
2018, 46(8): 1297-1305
doi: 10.11895/j.issn.0253-3820.171530
Abstract:
A method was developed for the determination of fipronil and its metabolites fipronil-desulfinyl, fipronil-sulfone and fipronil-sulfide in eggs, animal muscle, viscera and egg products by ultra liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). On the basis of QuEChERS method, the extraction solvent, extraction times and sorbents were optimized to ensure the extraction efficiency and the purification of extraction. Finally, the samples were extracted with acetonitrile, followed by centrifugation in the presence of anhydrous magnesium sulfate and sodium chloride. The upper solvent was then cleaned-up by PSA and C18, detected with UPLC MS/MS and quantified with external matrix standards. The result indicated that the average spiked recoveries of fipronil, fipronil-desulfinyl, fipronil-sulfone and fipronil-sulfide in vegetative foods samples were 75.7%-104.5% with relative standard deviations (RSDs) of 1.3%-10.4%, the LODs were 0.5-1.6 μg/kg, and the LOQs were 5.0 μg/kg. This method was simple, sensitive and accurate, and could be used for the routine analysis of fipronil and its three metabolites residues in eggs, animal muscle, viscera and egg products.
A method was developed for the determination of fipronil and its metabolites fipronil-desulfinyl, fipronil-sulfone and fipronil-sulfide in eggs, animal muscle, viscera and egg products by ultra liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). On the basis of QuEChERS method, the extraction solvent, extraction times and sorbents were optimized to ensure the extraction efficiency and the purification of extraction. Finally, the samples were extracted with acetonitrile, followed by centrifugation in the presence of anhydrous magnesium sulfate and sodium chloride. The upper solvent was then cleaned-up by PSA and C18, detected with UPLC MS/MS and quantified with external matrix standards. The result indicated that the average spiked recoveries of fipronil, fipronil-desulfinyl, fipronil-sulfone and fipronil-sulfide in vegetative foods samples were 75.7%-104.5% with relative standard deviations (RSDs) of 1.3%-10.4%, the LODs were 0.5-1.6 μg/kg, and the LOQs were 5.0 μg/kg. This method was simple, sensitive and accurate, and could be used for the routine analysis of fipronil and its three metabolites residues in eggs, animal muscle, viscera and egg products.
2018, 46(8): 1306-1313
doi: 10.11895/j.issn.0253-3820.171283
Abstract:
A method for determination of 8 kinds of alkylphenols (APs) and alkylphenol ethoxylates (APEOs) in soil was developed in this work. The samples were extracted by ultrasonic-assisted procedure for three times with dichloromethane-ethyl acetate (4:1, V/V), and purified by silica gel cartridge. Then the eight compounds were separated in 16 min by high performance liquid chromatography (HPLC) with a chromatographic column of Waters PAH C18 column (250 mm×4.6 mm, 5.0 μm). The mobile phase was acetonitrile-water (85:15, V/V) with a flow rate of 0.8 mL/min. Fluorescence detection was used to sensitively measure the targets. The excitation and emission wavelength was 228 nm and 300 nm, respectively. The qualitative and the quantitative detection were carried out based on retention time and external calibration peak area, respectively. The results indicated that linear relationships (R) were higher than 0.999 in the range of 10.0-500 μg/L for 8 kinds of APs and APEOs. The detection limits (MDL) were 1.2-3.0 μg/kg, and the quantification limits were 4.8-12.0 μg/kg. The recoveries of the 8 kinds of targets at high and low spiked levels were in the range of 69.9%-81.8% and 70.3%-84.8%, respectively. The corresponding relative standard deviations (RSD) were 2.2%-6.8% and 5.1%-12.1%, respectively. The method was simple and sensitive with high reproducibility, and could be applied in the detection of 8 kinds of alkylphenols and alkylphenol ethoxylates in soil.
A method for determination of 8 kinds of alkylphenols (APs) and alkylphenol ethoxylates (APEOs) in soil was developed in this work. The samples were extracted by ultrasonic-assisted procedure for three times with dichloromethane-ethyl acetate (4:1, V/V), and purified by silica gel cartridge. Then the eight compounds were separated in 16 min by high performance liquid chromatography (HPLC) with a chromatographic column of Waters PAH C18 column (250 mm×4.6 mm, 5.0 μm). The mobile phase was acetonitrile-water (85:15, V/V) with a flow rate of 0.8 mL/min. Fluorescence detection was used to sensitively measure the targets. The excitation and emission wavelength was 228 nm and 300 nm, respectively. The qualitative and the quantitative detection were carried out based on retention time and external calibration peak area, respectively. The results indicated that linear relationships (R) were higher than 0.999 in the range of 10.0-500 μg/L for 8 kinds of APs and APEOs. The detection limits (MDL) were 1.2-3.0 μg/kg, and the quantification limits were 4.8-12.0 μg/kg. The recoveries of the 8 kinds of targets at high and low spiked levels were in the range of 69.9%-81.8% and 70.3%-84.8%, respectively. The corresponding relative standard deviations (RSD) were 2.2%-6.8% and 5.1%-12.1%, respectively. The method was simple and sensitive with high reproducibility, and could be applied in the detection of 8 kinds of alkylphenols and alkylphenol ethoxylates in soil.
2018, 46(8): 1314-1320
doi: 10.11895/j.issn.0253-3820.171513
Abstract:
A rapid method based on a full evaporation headspace gas chromatography-mass spectrometry (FEHS-GC-MS) for determination of 54 fragrance allergens in ABS plastic toys was developed. The samples were extracted by dissolution-precipitation approach. In this way, a complete extraction of fragrances could be obtained from plastic samples. Then 40 μL of supernatant was transferred into a headspace vial. Under the optimized headspace conditions (equilibration temperature=200℃; equilibration time=6 min; pressing pressure=80 kPa), the fragrances and solvent were evaporated to gaseous state quickly and reached dynamic equilibrium within 6 min, then 1 mL of gas in the quantitative loop was introduced to GC-MS. The separations were performed on a DB-35MS column and then quantified by external standard method. As the plastic matrix was deposited at the bottom of the vial, the results showed that the interference caused by different sample matrices was negligible. The proposed method exhibited sufficient sensitivity with LOQ of 0.5-15 mg/kg for all fragrances. The calibration curves showed good linearity in the range of 0.5-750 mg/kg with the correlation coefficients greater than 0.9987. The average recoveries ranged from 81.0% to 135.7%, and the RSD (n=6) varied from 1.7% to 16.8%. Finally, the method was applied to monitor the fragrances in 20 commercial toys. This study provides a good reference for rapidly determining the volatile organic compounds and semi-volatile organic compounds in plastic samples.
A rapid method based on a full evaporation headspace gas chromatography-mass spectrometry (FEHS-GC-MS) for determination of 54 fragrance allergens in ABS plastic toys was developed. The samples were extracted by dissolution-precipitation approach. In this way, a complete extraction of fragrances could be obtained from plastic samples. Then 40 μL of supernatant was transferred into a headspace vial. Under the optimized headspace conditions (equilibration temperature=200℃; equilibration time=6 min; pressing pressure=80 kPa), the fragrances and solvent were evaporated to gaseous state quickly and reached dynamic equilibrium within 6 min, then 1 mL of gas in the quantitative loop was introduced to GC-MS. The separations were performed on a DB-35MS column and then quantified by external standard method. As the plastic matrix was deposited at the bottom of the vial, the results showed that the interference caused by different sample matrices was negligible. The proposed method exhibited sufficient sensitivity with LOQ of 0.5-15 mg/kg for all fragrances. The calibration curves showed good linearity in the range of 0.5-750 mg/kg with the correlation coefficients greater than 0.9987. The average recoveries ranged from 81.0% to 135.7%, and the RSD (n=6) varied from 1.7% to 16.8%. Finally, the method was applied to monitor the fragrances in 20 commercial toys. This study provides a good reference for rapidly determining the volatile organic compounds and semi-volatile organic compounds in plastic samples.
2018, 46(8): 1321-1328
doi: 10.11895/j.issn.0253-3820.181084
Abstract:
A high-affinity polyclonal antibody was prepared by immunizing animals with haptens FFD and FFM. Under the optimal combination of coating antigen and antibody, an indirect competitive enzyme-linked immunosorbent assay (icELISA) for simultaneously detecting florfenicol and thiamphenicol residues in animal meat and urine samples was developed. The icELISA showed an IC50 value of 1.32 ng/mL for florfenicol and 2.13 ng/mL for thiamphenicol, respectively. The linear ranges were from 0.31 to 5.61 ng/mL with a limit of detection of 0.12 ng/mL for florfenicol, and 0.41 to 11.2 ng/mL with a limit of detection of 0.15 ng/mL for thiamphenicol, respectively. The average recoveries of florfenicol and thiamphenicol in spiked samples ranged from 77.2% to 116.0% with a relative standard deviation of less than 15%. Therefore, this proposed icELISA provided a valid detection for florfenicol and thiamphenicol residues in animal meat product and urine samples.
A high-affinity polyclonal antibody was prepared by immunizing animals with haptens FFD and FFM. Under the optimal combination of coating antigen and antibody, an indirect competitive enzyme-linked immunosorbent assay (icELISA) for simultaneously detecting florfenicol and thiamphenicol residues in animal meat and urine samples was developed. The icELISA showed an IC50 value of 1.32 ng/mL for florfenicol and 2.13 ng/mL for thiamphenicol, respectively. The linear ranges were from 0.31 to 5.61 ng/mL with a limit of detection of 0.12 ng/mL for florfenicol, and 0.41 to 11.2 ng/mL with a limit of detection of 0.15 ng/mL for thiamphenicol, respectively. The average recoveries of florfenicol and thiamphenicol in spiked samples ranged from 77.2% to 116.0% with a relative standard deviation of less than 15%. Therefore, this proposed icELISA provided a valid detection for florfenicol and thiamphenicol residues in animal meat product and urine samples.
