CN119223825B - Magnetic nanoparticle mass concentration measurement method based on nuclear magnetic resonance spectrum chemical shift - Google Patents
Magnetic nanoparticle mass concentration measurement method based on nuclear magnetic resonance spectrum chemical shiftInfo
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
- G01N15/06—Investigating concentration of particle suspensions
- G01N15/0656—Investigating concentration of particle suspensions using electric, e.g. electrostatic methods or magnetic methods
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- G—PHYSICS
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N24/00—Investigating or analyzing materials by the use of nuclear magnetic resonance, electron paramagnetic resonance or other spin effects
- G01N24/08—Investigating or analyzing materials by the use of nuclear magnetic resonance, electron paramagnetic resonance or other spin effects by using nuclear magnetic resonance
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Abstract
本发明公开了一种基于核磁共振波谱化学位移的磁纳米粒子质量浓度测量方法，属于磁纳米材料测试技术领域，本发明以磁纳米粒子诱使局部磁场不均匀而导致磁共振波谱产生变化为媒介，建立了磁纳米粒子的质量浓度与磁共振波谱化学位移偏移量之间的关系，由于单个磁纳米粒子的饱和磁化强度固定，所以磁纳米粒子的质量浓度的变化本质上是磁纳米粒子的数量变化，质量浓度与磁共振波谱化学位移偏移量具有线性关系，通过测量磁共振波谱化学位移的偏移可以反映出磁纳米粒子质量浓度的变化，实现对磁纳米粒子质量浓度的测量。
This invention discloses a method for measuring the mass concentration of magnetic nanoparticles based on the chemical shift of nuclear magnetic resonance spectroscopy, belonging to the field of magnetic nanomaterial testing technology. This invention uses the change in the magnetic resonance spectrum caused by the inhomogeneity of the local magnetic field induced by magnetic nanoparticles as a medium to establish the relationship between the mass concentration of magnetic nanoparticles and the chemical shift of the magnetic resonance spectrum. Since the saturation magnetization of a single magnetic nanoparticle is fixed, the change in the mass concentration of magnetic nanoparticles is essentially a change in the number of magnetic nanoparticles. The mass concentration and the chemical shift of the magnetic resonance spectrum have a linear relationship. By measuring the shift of the chemical shift of the magnetic resonance spectrum, the change in the mass concentration of magnetic nanoparticles can be reflected, thus realizing the measurement of the mass concentration of magnetic nanoparticles.
Description
Technical Field
The invention belongs to the technical field of magnetic nano material testing, and particularly relates to a magnetic nano particle mass concentration measuring method based on nuclear magnetic resonance spectrum parameters.
Background
The magnetic nanoparticles MNPs (Magnetic Nanoparticles) can alter the uniformity of the magnetic field, thereby affecting the relaxation rate, reflected in the magnetic resonance spectrum as chemical shifts and changes in half-width. In practical application, MNPs are coated by surfactant and uniformly dispersed in base solution to form stable colloid suspension, and passed through exogenous magnetic fieldAfter being magnetized, MNPs in the solution form a certain cluster structure and change the distribution condition of magnetic fields around the MNPs, so that the local magnetic field is uneven, the phenomenon changes the distribution of the magnetic field around deuterium atoms, and the degree of deviation of chemical displacement of the MNPs is changed. The magnetic nano particles have good linear relation between the mass concentration and the offset of chemical displacement, and the traditional solution mass concentration measurement method has the problems of extremely high cost, large required sample quantity and lower applicability while maintaining high precision. Therefore, under the condition that enough data are established through the magnetic resonance experiment, in order to achieve sufficient utilization of resources, corresponding mass concentration and chemical displacement expression can be established by utilizing the data obtained in the magnetic resonance experiment, and the function of predicting the mass concentration of the sample reagent to be detected through the chemical displacement of the magnetic resonance spectrum is realized.
Disclosure of Invention
In order to solve the technical problems in the prior art, the invention provides a magnetic nanoparticle mass concentration measurement method based on nuclear magnetic resonance spectrum chemical shift, which is characterized in that a mathematical model of the magnetic resonance spectrum chemical shift and the mass concentration is established on the basis of magnetic resonance, and the mass concentration of a sample to be measured is predicted through the corresponding spectrum chemical shift of the sample to be measured by means of the mathematical model.
To achieve the above object, according to a first aspect of the present invention, there is provided a magnetic nanoparticle mass concentration measurement method based on chemical shift of nuclear magnetic resonance spectroscopy, the method comprising the steps of:
S1, measuring a pure deuterium water reagent without adding magnetic nano particles by adopting a nuclear magnetic resonance method at a set temperature T, and recording the numerical value of chemical shift (CHEMCIAL SHIFT) in nuclear magnetic resonance spectrum ;
S2, selecting magnetic nanoparticle reagents with consistent nominal particle sizes, diluting the magnetic nanoparticle reagents into reagents with different mass concentrations according to a proportion, performing nuclear magnetic resonance experiments on the magnetic nanoparticle reagents with different concentrations, and recording the numerical value of chemical shift in the corresponding nuclear magnetic resonance spectrum;
S3, sample points corresponding to the mass concentration and the chemical shift recorded in S2 are in the form of discrete data points, and the linear relation between the nuclear magnetic resonance spectrum chemical shift and the mass concentration of the magnetic nanoparticles under the condition that the particle sizes of the magnetic nanoparticles are uniform is obtained after the discrete data points are linearly fitted, wherein,Slope of linear relation between nuclear magnetic resonance spectrum chemical shift and magnetic nanoparticle mass concentration, C is the mass concentration of magnetic nanoparticle in the test sample;
S4. Passing the inverse function of the model in S3 Obtaining the relational expression of the mass concentration and chemical displacement of the magnetic nano particlesAccording to the relation, the nuclear magnetic resonance spectrum chemical shift corresponding to the magnetic nanoparticle reagent with known concentration to be measuredCan predict the mass concentration of the magnetic nanoparticle reagent to be detected。
Preferably, the fluctuation range of the set temperature T in measurement is limited to 280K-320K.
Preferably, parameters which remain consistent during the test are temperature T, magnetic nanoparticle particle size d, exogenous magnetic field。
Through the above scheme of the invention, the following beneficial effects can be obtained:
according to the invention, the linear regression curve is established by utilizing the corresponding relation between the parameters and the concentration of the magnetic nanoparticles in the magnetic resonance spectrum, the mass concentration of the magnetic nanoparticle sample is predicted according to the curve, and the mass concentration of the magnetic nanoparticles is reflected by the chemical displacement of the magnetic resonance spectrum, so that the measurement precision of the mass concentration is high.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. For a clearer description of the technical solutions of the present invention, the drawings that are used in the embodiments will be briefly described, in which:
FIG. 1 is a flow chart of a method for measuring mass concentration of magnetic nanoparticles based on chemical shift of nuclear magnetic resonance spectroscopy according to an embodiment of the present invention;
FIG. 2 is a graph showing the relationship between the SHP-05 sample and the magnetic resonance chemical shift under different mass concentrations according to the embodiment of the present invention;
FIG. 3 is a graph showing the relationship between the SHP-10 sample and the magnetic resonance chemical shift under different mass concentrations according to the embodiment of the present invention;
FIG. 4 is a graph showing the relationship between the SHP-15 sample and the magnetic resonance chemical shift under different mass concentrations according to the embodiment of the present invention;
FIG. 5 is a graph showing the relationship between the SHP-20 sample and the magnetic resonance chemical shift under different mass concentrations according to the embodiment of the present invention;
FIG. 6 is a graph showing the relationship between the SHP-25 sample and the magnetic resonance chemical shift under different mass concentrations according to the embodiment of the present invention;
FIG. 7 is a graph showing the relationship between the SHP-30 sample and the magnetic resonance chemical shift under different mass concentrations according to the embodiment of the present invention;
FIG. 8 is a graph showing the absolute value of the error between the predicted mass concentration and the actual mass concentration of SHP-05 according to an embodiment of the present invention;
FIG. 9 is a graph showing the absolute value of the error between the predicted mass concentration and the actual mass concentration of SHP-10 according to an embodiment of the present invention;
FIG. 10 is a graph showing the absolute value of the error between the predicted mass concentration and the actual mass concentration of SHP-15 according to an embodiment of the present invention;
FIG. 11 is a graph showing the absolute value of the error between the predicted mass concentration and the actual mass concentration of SHP-20 according to an embodiment of the present invention;
FIG. 12 is a graph showing the absolute value of the error between the predicted mass concentration and the actual mass concentration of SHP-25 according to an embodiment of the present invention;
FIG. 13 is a graph showing the absolute value of the error between the predicted mass concentration and the actual mass concentration of SHP-30 according to an embodiment of the present invention;
Detailed Description
In order to make the objects and technical solutions of the present invention clearer, the present invention will be further described in detail with reference to the accompanying drawings and examples. The specific embodiments described herein are to be considered in an illustrative sense only and are not intended to limit the invention.
The invention has the general idea that the mass concentration of the magnetic nano particles in a sample is calculated by utilizing the relationship between the chemical displacement of the magnetic nano particles in a magnetic resonance spectrum and the mass concentration of the magnetic nano particles and by utilizing the linear relationship between the chemical displacement and the mass concentration. In nuclear magnetic resonance, magnetic nanoparticles are magnetized under the action of an exogenous magnetic field to generate an induced magnetic field, and the induced magnetic field affects local magnetic fields around the magnetic nanoparticles, so that the local magnetic fields are uneven. The change of the mass concentration of the magnetic nano particles can lead the induction magnetization intensity of the magnetic nano particles in a magnetic field to change, the induction magnetic field can influence the distribution of the magnetic field around the magnetic nano particles, and the transverse relaxation time of water protons is further changedChemical shift during mass concentration changeHas linear relation with mass concentration through chemical displacementAnd the mathematical model of the mass concentration can realize the mass concentration calculation of the sample to be tested.
As shown in fig. 1, the invention provides a magnetic nanoparticle mass concentration measurement method based on nuclear magnetic resonance spectrum chemical shift, which comprises the following steps:
Step S1, measuring a pure deuterium water reagent without adding magnetic nano particles by adopting a nuclear magnetic resonance method at a set temperature T, and recording the numerical value of chemical shift (CHEMCIAL SHIFT) in nuclear magnetic resonance spectrum ;
In order to obtain the chemical shift of pure deuterium water when no magnetic nanoparticle is added, carrying out magnetic resonance experiment on the pure deuterium water reagent by Spinsolve nuclear magnetic resonance spectrometer to obtain the chemical shift in magnetic resonance spectrumThis value is the fixed intercept of the linear expression of the mass concentration and chemical shift involved in the subsequent step.
S2, selecting magnetic nanoparticle reagents with consistent nominal particle sizes, diluting the magnetic nanoparticle reagents into reagents with different mass concentrations according to a proportion, performing nuclear magnetic resonance experiments on the magnetic nanoparticle reagents with different concentrations, and recording the numerical value of chemical shift in the corresponding nuclear magnetic resonance spectrum;
And (3) diluting the magnetic nanoparticles with consistent nominal particle sizes in proportion to obtain magnetic nanoparticle reagents with different mass concentrations, taking the mass concentrations of the magnetic nanoparticles in the reagents as independent variables, performing magnetic resonance test, and recording the chemical shift of the magnetic resonance spectrum of the magnetic nanoparticles for the purpose of establishing the linear relationship between the mass concentrations and the chemical shifts of the magnetic nanoparticles.
S3, sample points corresponding to the mass concentration and the chemical shift recorded in S2 are in the form of discrete data points, and the linear relation between the nuclear magnetic resonance spectrum chemical shift and the mass concentration of the magnetic nanoparticles under the condition that the particle sizes of the magnetic nanoparticles are uniform is obtained after the discrete data points are linearly fitted, wherein,Slope of linear relation between nuclear magnetic resonance spectrum chemical shift and magnetic nanoparticle mass concentration, C is the mass concentration of magnetic nanoparticle in the test sample;
And testing a plurality of groups of reagents with different mass concentrations by a magnetic resonance method to obtain a plurality of discrete sample points with mass concentrations and chemical displacements, and obtaining the linear relation between the mass concentrations of the magnetic nanoparticles and the chemical displacements by fitting the sample points.
Step S4. Passing the inverse function of the model in S3Obtaining the relational expression of the mass concentration and chemical displacement of the magnetic nano particlesAccording to the relation, the nuclear magnetic resonance spectrum chemical shift corresponding to the magnetic nanoparticle reagent with known concentration to be measuredCan predict the mass concentration of the magnetic nanoparticle reagent to be detected;
For the sample with the mass concentration to be measured, after knowing the chemical shift of the magnetic resonance spectrum corresponding to the magnetic nano particles in the reagent, the sample is prepared byThe mass concentration can be calculatedThe measured deviation value is obtained by comparing the mass concentration of the sample with the mass concentration of the known sample, so that the measurement accuracy is measured.
Examples
1. And obtaining the magnetic resonance chemical shift without adding the magnetic nanoparticle reagent.
Magnetic resonance experiment is carried out on the pure deuterium water reagent, and the chemical shift of the nuclear magnetic resonance spectrum is recorded as。
2. And obtaining the magnetic nanoparticle reagent with uniform particle size and different mass concentrations.
SHP series magnetic nanoparticle reagents SHP-05, SHP-10, SHP-15, SHP-20, SHP-25 and SHP-30 (Ocean NanoTech company) with nominal core particle diameters of 5nm, 10nm, 15nm, 20nm, 25nm and 30nm are selected, and the magnetic nanoparticles are all magnetic cores made of Fe 3O4, and a single-layer oleic acid and a single-layer amphiphilic polymer are coated on the surfaces of the magnetic cores, so that the magnetic cores have good water solubility and monodispersity;
And respectively selecting alternative magnetic nanoparticle reagents with mass concentrations of 0.01mg/mL, 0.025mg/mL, 0.05mg/mL, 0.1mg/mL and 0.25mg/mL in sequence, performing a magnetic resonance experiment on the magnetic nanoparticle reagents by using a Spinsolve nuclear magnetic resonance spectrometer, and recording nuclear magnetic resonance spectrum chemical shift values of the magnetic nanoparticle reagents, wherein the linear relations of the magnetic nanoparticle reagents SHP-05, SHP-10, SHP-15, SHP-20, SHP-25 and SHP-30 under different mass concentrations are shown in figures 2, 3, 4, 5, 6 and 7.
3. Obtaining the linear relation between chemical displacement and mass concentration corresponding to different particle sizes.
Fitting the chemical shift values obtained by the samples with different mass concentrations to obtain the sample with the form ofChemical shift and mass concentration linear curves corresponding to different particle diameters of particles, which are respectively:
Wherein, the In the expression of (2), wherein,The slope of the linear relationship between the chemical shift of nuclear magnetic resonance spectrum and the mass concentration of the magnetic nano particles is given, C is the mass concentration of the magnetic nano particles in the test sample,Is the correlation coefficient of the linear regression type,Is the experimental condition of each fitting type data acquisition, as in the formula (1)Expressed asIn the linear relation of (a),The value of the product was-12.3275,Is a corresponding linear relationship under the condition of 4.73 ppm,The correlation coefficient of the corresponding linear regression expression in expression (1) is referred to as 0.99988,The method is shown to be a fitting formula of magnetic resonance chemical displacement obtained by measuring SHP-05 aqueous solution samples at different mass concentrations by using a nuclear magnetic resonance apparatus with a main magnetic field of 1.41T.
4. And obtaining a mass concentration measurement function.
The relation obtained by step 3Its inverse functionCan be expressed as a relationship between magnetic nanoparticle mass concentration and chemical shiftFor the sample to be tested, its chemical shift is carried outThe mass concentration of the sample can be calculated by bringing the sample into the above way。
5. Calculated mass concentrationIs obtained for the deviation of (2).
By using the aboveCalculating to obtain the mass concentration of the sampleAnd is measured to obtainComparing the mass concentration of the sample with the mass concentration of the known sample to obtain mass concentration measurement deviationAs shown in fig. 8, 9, 10, 11, 12, and 13.
From practical experimental data, the chemical shift and the mass concentration of the magnetic nano reagent have good linear relation.
It will be readily appreciated by those skilled in the art that the foregoing description is merely a preferred embodiment of the invention and is not intended to limit the invention, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (4)
1. The magnetic nanoparticle mass concentration measurement method based on nuclear magnetic resonance spectrum chemical shift is characterized by comprising the following steps of:
S1, measuring a pure deuterium water reagent without adding magnetic nano particles by adopting a nuclear magnetic resonance method at a set temperature T, and recording the numerical value of chemical shift (CHEMCIAL SHIFT) in nuclear magnetic resonance spectrum ;
S2, selecting magnetic nanoparticle reagents with consistent nominal particle sizes, diluting the magnetic nanoparticle reagents into reagents with different mass concentrations according to a proportion, performing nuclear magnetic resonance experiments on the magnetic nanoparticle reagents with different concentrations, and recording the numerical value of chemical shift in the corresponding nuclear magnetic resonance spectrum;
S3, sample points corresponding to the mass concentration and the chemical shift recorded in S2 are in the form of discrete data points, and the linear relation between the nuclear magnetic resonance spectrum chemical shift and the mass concentration of the magnetic nanoparticles under the condition that the particle sizes of the magnetic nanoparticles are uniform is obtained after the discrete data points are linearly fitted, wherein,Slope of linear relation between nuclear magnetic resonance spectrum chemical shift and magnetic nanoparticle mass concentration, C is the mass concentration of magnetic nanoparticle in the test sample;
S4. Passing the inverse function of the model in S3 Obtaining the relational expression of the mass concentration and chemical displacement of the magnetic nano particlesAccording to the relation, the nuclear magnetic resonance spectrum chemical shift corresponding to the magnetic nanoparticle reagent with known concentration to be measuredCan predict the mass concentration of the magnetic nanoparticle reagent to be detected。
2. The method for measuring the mass concentration of the magnetic nanoparticles based on chemical shift of nuclear magnetic resonance spectroscopy according to claim 1, wherein in S1, the fluctuation range of the temperature T set during measurement is limited to 280K to 320K.
3. The method for measuring the mass concentration of the magnetic nanoparticles based on chemical shift of nuclear magnetic resonance spectrum according to claim 1, wherein parameters which keep consistent in the measurement process are temperature T, particle size d of the magnetic nanoparticles and an exogenous magnetic field。
4. The method for measuring the mass concentration of the magnetic nanoparticles based on chemical shift of nuclear magnetic resonance spectroscopy according to claim 3, wherein in actual experimental data, the temperature T, the particle diameter d of the magnetic nanoparticles and an external magnetic fieldThe relationship between chemical shift and mass concentration of magnetic nanoparticles is linear under the condition of keeping consistency.
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| CN104115006A (en) * | 2011-12-12 | 2014-10-22 | 纳诺努德股份公司 | A method for determining catalyst powder in oil |
| CN108663391A (en) * | 2018-08-10 | 2018-10-16 | 华中科技大学 | A kind of magnetic nanometer Pressure, Concentration, Temperature method based on paramagnetic shift |
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| CN104122284A (en) * | 2014-07-09 | 2014-10-29 | 张祥林 | Low field NMR (nuclear magnetic resonance)-based magnetic bead concentration detection method and application thereof |
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| CN108663391A (en) * | 2018-08-10 | 2018-10-16 | 华中科技大学 | A kind of magnetic nanometer Pressure, Concentration, Temperature method based on paramagnetic shift |
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