Method for detecting trace water in organic solvent

Abstract

The invention belongs to the technical field of fluorescence detection, and particularly relates to a method for detecting trace water in an organic solvent. In the invention, the sodium erbium tetrafluoride serving as the probe can emit light under the irradiation of exciting light, and the detection of trace water in an organic solvent can be realized through the change of the intensity ratio of two specific light-emitting peaks along with the water content by utilizing the difference of the multi-phonon relaxation probability influence degrees of water molecules on the light-emitting energy levels of all excited states of erbium ions. The trace water detection nanoprobe adopted by the invention is non-toxic, stable in photochemical property, strong in anti-interference capability, easy to store, high in detection sensitivity and simple to operate, and is expected to be used in the fields of industrial production, drug synthesis, food processing, environmental monitoring and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of fluorescence detection, and particularly relates to a method for detecting trace water in an organic solvent. Background Art

[0002] Moisture determination technology plays a very important role in the fields of chemical industry, environmental monitoring, food and drug safety, scientific research, etc. Among them, quantitative detection of trace moisture has become one of the research hotspots in the field of modern analysis. At present, the standard method for moisture detection in various countries is the Karl Fischer method. Although it has been optimized and improved many times, the Karl Fischer method still faces many problems in practical applications. For example, this method requires the use of toxic reagents such as pyridine, methanol, and sulfur dioxide. It has strict requirements on the ventilation system of the experimental site and the professional protection of the operators. The operation steps are complicated and time-consuming, and professionally trained technicians are required to operate. Therefore, it is urgent to develop new green detection technologies to achieve safer, more efficient and accurate moisture determination.

[0003] Fluorescence water detection has the advantages of simple operation, fast response, real-time and contactless detection. Inorganic rare earth fluorescent nanomaterials have a series of advantages such as narrow emission band, large (anti) Stokes shift, high photochemical stability, long luminescence lifetime, near-infrared excitation, low toxicity, etc., and have attracted more and more attention in the field of water detection. However, the existing inorganic rare earth fluorescent water detection nanoprobes all rely on the intensity change of a single emission peak, which is easily interfered by factors such as probe concentration and excitation source power fluctuation, resulting in poor detection accuracy and anti-interference.

[0004] Therefore, there is an urgent need to develop a safe, non-toxic, stable, anti-interference and highly sensitive trace water detection method. Summary of the invention

[0005] The purpose of the present invention is to provide a method for detecting trace water in an organic solvent.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a method for detecting trace water in an organic solvent, comprising the following steps:

[0008] The sample to be tested and the probe are mixed, and the obtained solution to be tested is subjected to fluorescence detection to obtain the fluorescence intensity ratio of the solution to be tested; the probe comprises sodium erbium tetrafluoride;

[0009] The excitation wavelength of the fluorescence detection is 808 nm, and the fluorescence intensity ratio is I 1530nm / I 1060nm ; where I 1530nm is the fluorescence intensity at an emission wavelength of 1530 nm, I 1060nmis the fluorescence intensity at an emission wavelength of 1060 nm;

[0010] Obtaining the water content in the organic solvent to be tested according to the fluorescence intensity ratio of the test liquid and a predetermined standard curve;

[0011] The predetermined standard curve uses the logarithm of water content as an independent variable and the fluorescence intensity ratio as a dependent variable;

[0012] The organic solvent in the sample to be tested includes N,N-dimethylformamide, dimethyl sulfoxide or acetonitrile.

[0013] Preferably, the probe is replaced by rare earth ion doped sodium erbium tetrafluoride or wrapped sodium erbium tetrafluoride;

[0014] The wrapped sodium erbium tetrafluoride comprises sodium erbium tetrafluoride and a shell layer wrapping the sodium erbium tetrafluoride.

[0015] Preferably, the rare earth ions include one or more of ytterbium ions, cerium ions and neodymium ions;

[0016] The molar content of the rare earth ions in the rare earth ion-doped sodium erbium tetrafluoride is 0-50%, and is not 0.

[0017] Preferably, the material of the shell layer includes one or more of sodium yttrium tetrafluoride, sodium gadolinium tetrafluoride and sodium lutetium tetrafluoride; the thickness of the shell layer is 0 to 5 nm, and is not 0.

[0018] Preferably, the mass concentration of the probe in the test solution is 0.001-0.020 g / mL.

[0019] Preferably, the preparation method of sodium erbium tetrafluoride comprises the following steps:

[0020] Mixing an erbium precursor, oleic acid and 1-octadecene, and dissolving them under a protective atmosphere to obtain a first precursor solution;

[0021] dissolving sodium hydroxide and ammonium fluoride in methanol to obtain a second precursor solution;

[0022] The first precursor solution and the second precursor solution are mixed and reacted to obtain sodium erbium tetrafluoride.

[0023] Preferably, the erbium precursor includes erbium chloride, erbium nitrate or erbium acetate.

[0024] Preferably, the volume ratio of oleic acid to 1-octadecene is 2:19 to 19:2;

[0025] The molar concentration of the erbium precursor in the first precursor solution is 0.024 to 0.07 mol / L;

[0026] The molar mass ratio of the sodium hydroxide to ammonium fluoride is 1:2 to 1:5; and the concentration of the sodium hydroxide in the second precursor solution is 0.01 to 0.04 g / mL.

[0027] Preferably, the volume ratio of the first precursor solution to the second precursor solution is 4:1 to 2:1.

[0028] Preferably, the reaction temperature is 290-320° C., and the insulation time is 1-3 hours.

[0029] The present invention provides a method for detecting trace water in an organic solvent, comprising the following steps: mixing a sample to be tested and a probe, performing fluorescence detection on the obtained liquid to be tested, and obtaining a fluorescence intensity ratio of the liquid to be tested; the probe comprises sodium erbium tetrafluoride; the excitation wavelength of the fluorescence detection is 808 nm, and the fluorescence intensity ratio = I 1530nm / I 1060nm ; where I 1530nm is the fluorescence intensity at an emission wavelength of 1530 nm, I 1060nm is the fluorescence intensity at an emission wavelength of 1060 nm; according to the fluorescence intensity ratio of the test liquid and a predetermined standard curve, the water content in the test organic solvent is obtained; the predetermined standard curve takes the logarithm of the water content as the independent variable and the fluorescence intensity ratio as the dependent variable; the organic solvent in the test sample includes N,N-dimethylformamide, dimethyl sulfoxide or acetonitrile.

[0030] In the present invention, sodium erbium tetrafluoride as a probe can emit light under the irradiation of excitation light, and the efficient energy migration between erbium ions makes it more susceptible to the high-frequency vibration of water molecules in the outside world, thereby improving the detection sensitivity of water; utilizing the difference in the degree of influence of water molecules on the multi-phonon relaxation probability of each excited state luminescence energy level of erbium ions, through the change of the intensity ratio of two specific luminescence peaks with water content, trace water detection in organic solvents can be achieved. The trace water detection nanoprobe used in the present invention is non-toxic, stable in photochemical properties, strong in anti-interference ability, easy to store, high in detection sensitivity and simple to operate, and is expected to be used in industrial production, drug synthesis, food processing, environmental monitoring and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The X-ray diffraction spectrum of rare earth ytterbium ion-doped sodium erbium tetrafluoride prepared in Example 3;

[0032] Figure 2 This is a transmission electron microscope photograph of rare earth ytterbium ion-doped sodium erbium tetrafluoride prepared in Example 3;

[0033] Figure 3 This is a graph showing the relationship between the luminescence of the rare earth ytterbium ion-doped sodium erbium tetrafluoroethylene probe under 808 nm excitation and the change in water content in N,N-dimethylformamide in Example 8;

[0034] Figure 4 This is a standard curve of the luminescence peak intensity ratio of the rare earth ytterbium ion-doped sodium erbium tetrafluoroethylene probe in Example 8 and the water content in N,N-dimethylformamide. DETAILED DESCRIPTION

[0035] The present invention provides a method for detecting trace water in an organic solvent, comprising the following steps:

[0036] The sample to be tested and the probe are mixed, and the obtained solution to be tested is subjected to fluorescence detection to obtain the fluorescence intensity ratio of the solution to be tested; the probe comprises sodium erbium tetrafluoride;

[0037] The excitation wavelength of the fluorescence detection is 808 nm, and the fluorescence intensity ratio is I 1530nm / I 1060nm ; where I 1530nm is the fluorescence intensity at an emission wavelength of 1530 nm, I 1060nm is the fluorescence intensity at an emission wavelength of 1060 nm;

[0038] Obtaining the water content in the organic solvent to be tested according to the fluorescence intensity ratio of the test liquid and a predetermined standard curve;

[0039] The predetermined standard curve uses the logarithm of water content as an independent variable and the fluorescence intensity ratio as a dependent variable;

[0040] The organic solvent in the sample to be tested includes N,N-dimethylformamide, dimethyl sulfoxide or acetonitrile.

[0041] In the present invention, the preparation method of sodium erbium tetrafluoride preferably comprises the following steps:

[0042] Mixing an erbium precursor, oleic acid and 1-octadecene, and dissolving them under a protective atmosphere to obtain a first precursor solution;

[0043] dissolving sodium hydroxide and ammonium fluoride in methanol to obtain a second precursor solution;

[0044] The first precursor solution and the second precursor solution are mixed and reacted to obtain sodium erbium tetrafluoride;

[0045] The invention mixes an erbium precursor, oleic acid and 1-octadecene, and dissolves them under a protective atmosphere to obtain a first precursor solution.

[0046] In the present invention, the erbium precursor preferably includes erbium chloride, erbium nitrate or erbium acetate, and more preferably ErCl 3. In the present invention, the volume ratio of oleic acid to 1-octadecene is preferably 2:19 to 19:2; the concentration of the erbium precursor in the first precursor solution is preferably 0.024 to 0.07 mol / L. In the present invention, the protective atmosphere is preferably nitrogen. In the present invention, the dissolution temperature is preferably 160°C, the dissolution is preferably carried out under stirring, and the stirring time is preferably 30 minutes.

[0047] The present invention dissolves sodium hydroxide and ammonium fluoride in methanol to obtain a second precursor solution.

[0048] In the present invention, the molar mass ratio of the sodium hydroxide to ammonium fluoride is preferably 1:2 to 1:5; and the concentration of the sodium hydroxide in the second precursor solution is preferably 0.01 to 0.04 g / mL.

[0049] After obtaining the first precursor solution and the second precursor solution, the present invention mixes the first precursor solution and the second precursor solution to react and obtain sodium erbium tetrafluoride.

[0050] In the present invention, the volume ratio of the first precursor solution to the second precursor solution is preferably 4:1 to 2:1. In the present invention, the reaction temperature is 290 to 320°C, and the insulation time is 1 to 3 hours. In the present invention, before the reaction, it is also preferred to increase the temperature to remove methanol in the system, and the temperature of the increase is preferably 85°C.

[0051] After the reaction, the present invention also preferably includes post-treatment of the obtained system, and the post-treatment preferably includes: cooling the system to room temperature, mixing with acetone for precipitation and centrifugation, and dispersing the obtained precipitate in cyclohexane; then adding ethanol for precipitation and centrifugation, and dispersing the obtained precipitate in cyclohexane for storage. In the present invention, the sodium tetrafluoroerbium is preferably present in the form of a sodium tetrafluoroerbium cyclohexane dispersion (referred to as a probe dispersion).

[0052] In the present invention, the probe is preferably replaced by rare earth ion doped sodium erbium tetrafluoride or wrapped sodium erbium tetrafluoride; the wrapped sodium erbium tetrafluoride includes sodium erbium tetrafluoride and a shell layer wrapping the sodium erbium tetrafluoride. In the present invention, the rare earth ions preferably include one or more of ytterbium ions, cerium ions and neodymium ions; the molar content of the rare earth ions in the rare earth ion doped sodium erbium tetrafluoride is preferably 0 to 50%, and is not 0. In the present invention, the material of the shell layer preferably includes one or more of sodium yttrium tetrafluoride, sodium gadolinium tetrafluoride and sodium lutetium tetrafluoride; the thickness of the shell layer is preferably 0 to 5nm, and is not 0.

[0053] In the present invention, rare earth ion doped sodium erbium tetrafluoride is used as a probe, and the energy transfer or cross relaxation between the doped ions and the erbium ions can regulate the luminescence of the erbium ions and the interaction between the erbium ions and the water molecules, thereby further improving the detection performance.

[0054] In the present invention, when the probe is rare earth ion-doped sodium erbium tetrafluoride, the preparation method of the rare earth ion-doped sodium erbium tetrafluoride is preferably referred to the preparation method of sodium erbium tetrafluoride, except that a rare earth precursor is added to the first precursor solution, and the rare earth precursor preferably includes a chloride containing a rare earth metal, a nitrate containing a rare earth metal, or an acetate containing a rare earth metal, and more preferably a chloride containing a rare earth; the chloride containing a rare earth preferably includes YbCl 3 In the present invention, the molar ratio of the rare earth precursor to the erbium precursor is preferably 1:99 to 1:1. In the present invention, the rare earth ion-doped sodium erbium tetrafluoride is preferably in the form of a rare earth ion-doped sodium erbium tetrafluoride cyclohexane dispersion (referred to as probe dispersion).

[0055] In the present invention, since the probe is in the form of a probe dispersion, when used, the solvent of the probe dispersion needs to be replaced with an organic solvent of the same type as the organic solvent in the sample to be tested. In the present invention, the replacement method preferably includes replacement method one and replacement method two.

[0056] In the present invention, the replacement method 1 preferably includes:

[0057] NOBF 4 Dissolve in organic solvent to obtain NOBF 4 Solution;

[0058] The NOBF 4 The solution and the probe dispersion are mixed by ultrasound to obtain a mixed system;

[0059] The lower layer liquid of the mixed system is mixed with isopropanol, centrifuged, and then washed with an organic solvent to obtain an organic solvent containing the probe.

[0060] In the present invention, the NOBF 4 The concentration of the solution is preferably 0.01 to 0.20 M; the NOBF 4 The volume ratio of the solution to the probe dispersion is preferably 1: 1. In the present invention, the ultrasonic time is preferably 10 to 30 minutes, more preferably 15 to 20 minutes.

[0061] In the present invention, the second replacement method preferably includes:

[0062] The diluted hydrochloric acid and the probe dispersion are stirred and mixed to obtain a mixed system;

[0063] The lower layer liquid of the mixed system is mixed with isopropanol, centrifuged, and then washed with an organic solvent to obtain an organic solvent containing the probe.

[0064] In the present invention, the concentration of the dilute hydrochloric acid is preferably 0.01 to 1 M, and the volume ratio of the dilute hydrochloric acid to the probe dispersion is preferably 1: 1. In the present invention, the stirring and mixing time is preferably 10 min to 24 h.

[0065] In the present invention, the mass concentration of the probe in the test solution is preferably 0.001 to 0.020 g / mL.

[0066] The present invention has no special limitation on the process of fluorescence detection, and those skilled in the art may adopt the method known to those skilled in the art. In the present invention, during the process of fluorescence detection, the peak values ​​of the emission wavelength are preferably 1060 nm and 1530 nm.

[0067] In the present invention, the method for drawing the standard curve preferably includes: preparing a series of mixed systems with different water contents, the mixed system including an organic solvent, a probe and water; the probe including sodium erbium tetrafluoride; performing fluorescence detection on the series of mixed systems respectively to obtain a fluorescence intensity ratio; drawing a standard curve with the logarithm of the water content as an independent variable and the intensity ratio as a dependent variable. In the present invention, the conditions for the fluorescence detection are consistent with the conditions defined in the above technical solution, and will not be repeated here.

[0068] In the present invention, the replacement method described in the above technical solution is preferably used to replace the organic solvent containing the probe to prepare the mixed system, specifically: adding organic solvents with different water contents to the organic solvent containing the probe to obtain the series of mixed systems with different water contents. In the present invention, the mass concentration of the probe in the mixed system is preferably 0.001 to 0.020 g / mL.

[0069] Unless otherwise specified, the materials and equipment used in the present invention are all commercially available products in the art.

[0070] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0071] Example 1

[0072] 0.2752 g ErCl 3Add 6 mL of oleic acid and 15 mL of 1-octadecene to the anhydrous powder and stir under nitrogen to isolate the air; heat the mixture to 160 °C and stir for 30 min to allow ErCl 3 dissolving to obtain a first precursor solution;

[0073] Dissolve 0.1003 g of sodium hydroxide and 0.1483 g of ammonium fluoride in 5 mL of methanol to obtain a second precursor solution;

[0074] The first precursor solution and the second precursor solution obtained above were mixed, first heated to 85°C to remove methanol, and then heated to 310°C for reaction for 1.5h; after cooling to room temperature, 18mL of acetone was added for precipitation and then centrifuged, the precipitate was dispersed in 8mL of cyclohexane, 16mL of ethanol was added for precipitation and then centrifuged again, and the obtained NaErF 4 The nanoparticles were dispersed in 16 mL of cyclohexane for storage, thereby obtaining a probe dispersion.

[0075] Example 2

[0076] According to the method of Example 1, ytterbium ion-doped NaErF 4 ;

[0077] The difference is that 0.2752g of ErCl 3 Anhydrous powder was replaced with 0.2617 g ErCl 3 Anhydrous powder and 0.0141g YbCl 3 Anhydrous powder;

[0078] Preparation of NaErF 4 : 5% Yb nanoparticles, where 5% represents the molar content of ytterbium ions in the probe.

[0079] Example 3

[0080] According to the method of Example 1, ytterbium ion-doped NaErF 4 ;

[0081] The difference is that 0.2752g of ErCl 3 Anhydrous powder was replaced with 0.2477 g ErCl 3 Anhydrous powder and 0.0280g YbCl 3 Anhydrous powder;

[0082] Preparation of NaErF 4 : 10% Yb nanoparticles, where 10% represents the molar content of ytterbium ions in the probe.

[0083] Figure 1 The X-ray diffraction spectrum of rare earth ytterbium ion-doped sodium erbium tetrafluoride prepared in Example 3; Figure 2This is a transmission electron microscope photo of rare earth ytterbium ion-doped sodium erbium tetrafluoride prepared in Example 3; Figure 1 and Figure 2 It can be seen that the prepared rare earth ytterbium ion-doped sodium erbium tetrafluoride has a pure hexagonal phase structure with uniform size of about 20nm.

[0084] Example 4

[0085] According to the method of Example 1, ytterbium ion-doped NaErF 4 ;

[0086] The difference is that 0.2752g of ErCl 3 Anhydrous powder was replaced with 0.2201 g ErCl 3 Anhydrous powder and 0.0561g YbCl 3 Anhydrous powder;

[0087] Preparation of NaErF 4 : 20% Yb nanoparticles, where 20% represents the molar content of ytterbium ions in the probe.

[0088] Example 5

[0089] According to the method of Example 1, ytterbium ion-doped NaErF 4 ;

[0090] The difference is that 0.2752g of ErCl 3 Anhydrous powder was replaced with 0.1931 g ErCl 3 Anhydrous powder and 0.0841g YbCl 3 Anhydrous powder;

[0091] Preparation of NaErF 4 : 30% Yb nanoparticles, where 30% represents the molar content of ytterbium ions in the probe.

[0092] Example 6

[0093] 0.0087 g of NOBF 4 The powder was dissolved in 12 mL of N,N-dimethylformamide, added to 12 mL of the probe dispersion obtained in Example 1 and ultrasonicated for 15 min. The lower layer of liquid was mixed with isopropanol, centrifuged and then washed with anhydrous N,N-dimethylformamide to obtain NaErF 4 The nanoprobes were dispersed in 6 mL of anhydrous N,N-dimethylformamide to obtain a DMF dispersion containing the probes.

[0094] Take 1mL of the above dispersion and add it to a series of cuvettes containing N,N-dimethylformamide with different water contents. During the preparation process, the sample volume in each cuvette is kept at 2mL, and the water content is 0%, 0.05%, 0.1%, 0.2%, 0.5%, 1% (v / v), respectively. The mass concentration of the probe in each sample is 0.0037g / mL. The fluorescence spectra of the above samples are measured by fluorescence spectrometer with 808nm as the excitation wavelength.

[0095] The luminescence peaks at 1060nm and 1530nm were integrated respectively, with the logarithm of water content as the horizontal axis, and the fluorescence intensity ratio I 1530nm / I 1060nm As the vertical axis, draw the standard curve: I 1530nm / I 1060nm =-8.3247*Lg[H 2 O]+13.528.

[0096] The detection limit of water content in N,N-dimethylformamide solvent obtained by the above standard curve is 0.0229% (v / v), and the linear detection range is 0-1%;

[0097] 1 mL of simulated N,N-dimethylformamide (with a water content of 0.5%) and 1 mL of the DMF dispersion containing the probe obtained above were mixed and placed in a cuvette to obtain a test solution;

[0098] The fluorescence spectrum of the test liquid was measured by fluorescence spectrometer with 808 nm as the excitation wavelength, and the luminescence peaks at 1060 nm and 1530 nm were integrated to obtain the fluorescence intensity ratio I of the test liquid. 1530nm / I 1060nm ;

[0099] According to the fluorescence intensity ratio I 1530nm / I 1060nm According to the standard curve, the water content in the simulated N,N-dimethylformamide was obtained to be 0.526%.

[0100] Example 7

[0101] A standard curve was drawn in the manner of Example 6, and the water content in the simulated N,N-dimethylformamide to be tested was tested;

[0102] The difference is that the NaErF obtained in Example 2 4 : 5% Yb nanoparticles were used as probes to draw the standard curve: I 1530nm / I 1060nm =-10.212*Lg[H 2 O]+14.560.NaErF 4: The detection limit of 5% Yb nanoparticles as a ratiometric water detection probe in N,N-dimethylformamide solvent is 0.0137% (v / v), and the linear detection range is 0-1%;

[0103] 1 mL of simulated N,N-dimethylformamide (with a water content of 0.5%) and 1 mL of the DMF dispersion containing the probe obtained above were mixed and placed in a cuvette to obtain a test solution;

[0104] The fluorescence spectrum of the test liquid was measured by fluorescence spectrometer with 808 nm as the excitation wavelength, and the luminescence peaks at 1060 nm and 1530 nm were integrated to obtain the fluorescence intensity ratio I of the test liquid. 1530nm / I 1060nm ;

[0105] According to the fluorescence intensity ratio I 1530nm / I 1060nm According to the standard curve, the water content in the simulated N,N-dimethylformamide was obtained to be 0.494%.

[0106] Example 8

[0107] A standard curve was drawn in the manner of Example 6, and the water content in the simulated N,N-dimethylformamide to be tested was tested;

[0108] The difference is that the NaErF obtained in Example 3 4 : 10% Yb nanoparticles were used as probes, and the standard curve was drawn: I 1530nm / I 1060nm =-13.420*Lg[H 2 O]+22.521.NaErF 4 :The detection limit of 10% Yb nanoparticles as a ratiometric water detection probe in N,N-dimethylformamide solvent is 0.0088% (v / v), and the linear detection range is 0-1%;

[0109] 1 mL of simulated N,N-dimethylformamide (with a water content of 0.5%) and 1 mL of the DMF dispersion containing the probe obtained above were mixed and placed in a cuvette to obtain a test solution;

[0110] The fluorescence spectrum of the test liquid was measured by fluorescence spectrometer with 808 nm as the excitation wavelength, and the luminescence peaks at 1060 nm and 1530 nm were integrated to obtain the fluorescence intensity ratio I of the test liquid. 1530nm / I 1060nm ;

[0111] According to the fluorescence intensity ratio I 1530nm / I 1060nmAccording to the standard curve, the water content in the simulated N,N-dimethylformamide was obtained to be 0.488%.

[0112] Figure 3 This is a graph showing the relationship between the luminescence of the rare earth ytterbium ion-doped sodium erbium tetrafluoroethylene probe under 808 nm excitation and the change in water content in N,N-dimethylformamide in Example 8; Figure 4 This is a standard curve of the luminescence peak intensity ratio of the rare earth ytterbium ion-doped sodium erbium tetrafluoroethylene probe in Example 8 and the water content in N,N-dimethylformamide.

[0113] Example 9

[0114] 12 mL of 1M dilute hydrochloric acid was mixed with 12 mL of the probe dispersion (NaErF 4 : 10% Yb) and stirred vigorously for 10 min. The lower layer of liquid was taken and mixed with isopropanol and centrifuged, then washed with anhydrous N,N-dimethylformamide and dispersed in 6 mL of anhydrous N,N-dimethylformamide to obtain a DMF dispersion containing the probe;

[0115] Take 1mL of the above dispersion and add it to a series of cuvettes containing N,N-dimethylformamide with different water contents. During the preparation process, the volume of the solution in each cuvette is kept at 2mL, and the water content is 0%, 0.05%, 0.1%, 0.2%, 0.5%, and 1% v / v, respectively. The mass concentration of the probe in each sample is 0.0037g / mL. With 808nm as the excitation wavelength, measure the fluorescence spectra of the above samples by fluorescence spectrometer;

[0116] The luminescence peaks at 1060nm and 1530nm were integrated respectively, with the logarithm of water content as the horizontal axis, and the fluorescence intensity ratio I 1530nm / I 1060nm As the vertical axis, draw the standard curve: I 1530nm / I 1060nm =-12.164*Lg[H 2 O]+20.326.NaErF 4 :The detection limit of 10% Yb nanoparticles as a ratiometric water detection probe in N,N-dimethylformamide solvent is 0.0116% (v / v), and the linear detection range is 0-1%;

[0117] 1 mL of simulated N,N-dimethylformamide (with a water content of 0.5%) and 1 mL of the DMF dispersion containing the probe obtained above were mixed and placed in a cuvette to obtain a test solution;

[0118] The fluorescence spectrum of the test liquid was measured by fluorescence spectrometer with 808 nm as the excitation wavelength, and the luminescence peaks at 1060 nm and 1530 nm were integrated to obtain the fluorescence intensity ratio I of the test liquid.1530nm / I 1060nm ;

[0119] According to the fluorescence intensity ratio I 1530nm / I 1060nm According to the standard curve, the water content in the simulated N,N-dimethylformamide was obtained to be 0.515%.

[0120] Example 10

[0121] A standard curve was drawn in the manner of Example 6, and the water content in the simulated N,N-dimethylformamide to be tested was tested;

[0122] The difference is that the NaErF obtained in Example 4 4 : 20% Yb nanoparticles were used as probes, and the standard curve was drawn: I 1530nm / I 1060nm =-10.640*Lg[H 2 O]+25.030.NaErF 4 : The detection limit of 20% Yb nanoparticles as a ratiometric water detection probe in N,N-dimethylformamide solvent is 0.0149% (v / v), and the linear detection range is 0-1%;

[0123] 1 mL of simulated N,N-dimethylformamide (with a water content of 0.5%) and 1 mL of the DMF dispersion containing the probe obtained above were mixed and placed in a cuvette to obtain a test solution;

[0124] The fluorescence spectrum of the test liquid was measured by fluorescence spectrometer with 808 nm as the excitation wavelength, and the luminescence peaks at 1060 nm and 1530 nm were integrated to obtain the fluorescence intensity ratio I of the test liquid. 1530nm / I 1060nm ;

[0125] According to the fluorescence intensity ratio I 1530nm / I 1060nm According to the standard curve, the water content in the simulated N,N-dimethylformamide was obtained to be 0.486%.

[0126] Embodiment 11

[0127] A standard curve was drawn according to the method of implementation 6, and the water content in the simulated N,N-dimethylformamide to be tested was tested;

[0128] The difference is that the NaErF obtained in Example 5 4 : 30% Yb nanoparticles as probe, the obtained standard curve is plotted: I 1530nm / I 1060nm =-7.833*Lg[H2 O]+12.369.NaErF 4 : The detection limit of 30% Yb nanoparticles as a ratiometric water detection probe in N,N-dimethylformamide solvent is 0.0242% (v / v), and the linear detection range is 0-1%;

[0129] 1 mL of simulated N,N-dimethylformamide (with a water content of 0.5%) and 1 mL of the DMF dispersion containing the probe obtained above were mixed and placed in a cuvette to obtain a test solution;

[0130] The fluorescence spectrum of the test liquid was measured by fluorescence spectrometer with 808 nm as the excitation wavelength, and the luminescence peaks at 1060 nm and 1530 nm were integrated to obtain the fluorescence intensity ratio I of the test liquid. 1530nm / I 1060nm ;

[0131] According to the fluorescence intensity ratio I 1530nm / I 1060nm According to the standard curve, the water content in the simulated N,N-dimethylformamide was obtained to be 0.482%.

[0132] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for detecting trace water in an organic solvent, characterized in that: The following steps are involved: The sample to be tested and the probe are mixed, and the obtained solution to be tested is subjected to fluorescence detection to obtain the fluorescence intensity ratio of the solution to be tested; the probe comprises sodium erbium tetrafluoride; The excitation wavelength of the fluorescence detection is 808 nm, and the fluorescence intensity ratio is I 1530nm / I 1060nm ; where I 1530nm is the fluorescence intensity at an emission wavelength of 1530 nm, I 1060nm is the fluorescence intensity at an emission wavelength of 1060 nm; Obtaining the water content in the organic solvent to be tested according to the fluorescence intensity ratio of the test liquid and a predetermined standard curve; The predetermined standard curve takes the logarithm of water content as an independent variable and the fluorescence intensity ratio as a dependent variable; The organic solvent in the sample to be tested includes N,N-dimethylformamide, dimethyl sulfoxide or acetonitrile.

2. The detection method according to claim 1, characterized in that: The probe is replaced by rare earth ion doped sodium erbium tetrafluoride or wrapped sodium erbium tetrafluoride; The wrapped sodium erbium tetrafluoride comprises sodium erbium tetrafluoride and a shell layer wrapping the sodium erbium tetrafluoride.

3. The detection method according to claim 2, characterized in that: The rare earth ions include one or more of ytterbium ions, cerium ions and neodymium ions; The molar content of the rare earth ions in the rare earth ion-doped sodium erbium tetrafluoride is 0-50%, and is not 0.

4. The detection method according to claim 2, characterized in that: The material of the shell layer includes one or more of sodium yttrium tetrafluoride, sodium gadolinium tetrafluoride and sodium lutetium tetrafluoride; the thickness of the shell layer is 0 to 5 nm and is not 0.

5. The detection method according to claim 1, characterized in that: The mass concentration of the probe in the test solution is 0.001-0.020 g / mL.

6. The detection method according to claim 1, characterized in that: The preparation method of sodium erbium tetrafluoride comprises the following steps: Mixing an erbium precursor, oleic acid and 1-octadecene, and dissolving them under a protective atmosphere to obtain a first precursor solution; dissolving sodium hydroxide and ammonium fluoride in methanol to obtain a second precursor solution; The first precursor solution and the second precursor solution are mixed and reacted to obtain sodium erbium tetrafluoride.

7. The detection method according to claim 6, characterized in that: The erbium precursor includes erbium chloride, erbium nitrate or erbium acetate.

8. The detection method according to claim 6, characterized in that: The volume ratio of oleic acid to 1-octadecene is 2:19 to 19:2; The molar concentration of the erbium precursor in the first precursor solution is 0.024 to 0.07 mol / L; The molar mass ratio of the sodium hydroxide to ammonium fluoride is 1:2 to 1:5; and the concentration of the sodium hydroxide in the second precursor solution is 0.01 to 0.04 g / mL.

9. The detection method according to claim 8, characterized in that: The volume ratio of the first precursor solution to the second precursor solution is 4:1 to 2:

1.

10. The detection method according to claim 6 or 8, characterized in that: The reaction temperature is 290-320° C., and the insulation time is 1-3 hours.

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