A method for replacing deoxynucleotide triphosphate amine salts with sodium salts

Abstract

The application relates to the field of organic membrane separation, and specifically discloses a method for replacing deoxyribonucleotide triphosphate amine salt with sodium salt by adopting nanofiltration roll type membrane. The method specifically comprises the following steps: a concentration step, concentrating deoxyribonucleotide triphosphate amine salt fraction after high-pressure liquid phase purification; a replacement step, adding 1.5mol / L-6mol / L sodium (potassium) carbonate or sodium (potassium) hydrogen carbonate 0.5V-2V salt solution to the deoxyribonucleotide triphosphate amine salt solution for low-temperature replacement; and a desalination step, introducing carbon dioxide into the system in the above step, and washing with water until sodium ions cannot be detected in the filtered liquid, so as to obtain a deoxyribonucleotide triphosphate sodium salt solution. The preparation method can replace the organic amine salt with sodium salt, and 100% replacement of the organic amine salt can be realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of organic membrane separation, more particularly, it relates to a method for replacing amine salt of deoxynucleotide triphosphate with sodium salt. BACKGROUND

[0002] The nanofiltration membrane separation technology plays an important role in the separation of liquid mixtures. The process of membrane treatment can be summarized as follows: under the driving of pressure, the solution system is separated on the surface of the organic membrane. The solvent (generally water or alcohol aqueous solution) and other small molecule solutes pass through the organic membrane with asymmetric microporous structure, and the macromolecular solutes or particles are retained on the surface of the membrane. The separation process does not change phase and does not occur chemical reaction. The asymmetric structure of the membrane and the high-speed flow of the liquid in the equipment make it difficult for the retained substances to block the membrane pores, so that the membrane can be used for a long time.

[0003] The commercially available deoxynucleotide triphosphate monomer is mostly lyophilized sodium salt or sodium salt aqueous solution. The last step is separated and purified by anion exchange resin. The disadvantages are poor separation effect, high cost of filler, and the equivalent sodium ions of the final product cannot be accurately controlled. High-purity products are mostly separated by reverse-phase ion-pair liquid chromatography. In the process of preparing high-purity deoxynucleotide triphosphate monomer by liquid chromatography, the mobile phase modifier mostly contains organic amine salt, such as triethylamine (TFA), diisopropylamine (DIPA), tripropylamine (TPA), diisopropyl ethylamine (DIEA), n-hexylamine (HA) and the like, resulting in the final product of the process being organic amine salt. However, the solubility of the organic amine salt of deoxynucleotide triphosphate monomer is lower than that of sodium salt, and it is difficult to prepare a high-concentration aqueous solution of the final product. The salt content of the lyophilized product is also higher than that of sodium salt. The reconstitution of the lyophilized product also has the problem of difficult dissolution and clarification.

[0004] Therefore, how to efficiently, quickly and low-cost prepare sodium salt of deoxynucleotide triphosphate monomer is an important problem to be solved at present. SUMMARY

[0005] The dNTP or deoxynucleotide triphosphate of the present application represents any one of dGTP, dATP, dCTP, dTTP and dUTP.

[0006] The target volume described in the present application refers to the volume of the final product with a concentration of 100±5mM. The detection wavelength and molar absorption coefficient of dGTP, dATP, dCTP, dTTP and dUTP are shown in Table 1. The concentration of the target compound in the to-be-processed fraction = absorbance x dilution factor ÷ molar absorption coefficient ÷ optical path unit: molar absorption coefficient mM -1 cm) is taken as an example. At a detection wavelength of 267nm, the molar absorption coefficient of dTTP is 9.6mM -1·cm, assuming the volume of the initial processing fraction is 10 L, take a sample of 100 uL, after dilution 200 times, the absorbance of UV 1 cm test is 0.610, the molar concentration of the solution in the processing fraction is calculated as 0.610*200 / 9.6=13 mM, and the volume of the target concentration of 100 mM is 10 L*13 mM / 100 mM=1.3 L.

[0007] Table 1

[0008]

[0009] The kind, purity detection method and conversion method of dGTP, dATP, dCTP and dUTP ammonium salt in the present application are the same as those of dTTP, so the present application is only explained by taking dTTP as an example.

[0010] The permeation rate described in the present application is the amount of the target compound permeating into the waste liquid inside the nanofiltration membrane divided by the total amount of the target compound.

[0011] The rejection rate in the present application is (total content of target compound - content of target compound in waste liquid) ÷ total content of target compound.

[0012] To solve the above technical problems, the present application provides a method for replacing deoxynucleotide triphosphate ammonium salt with sodium salt, and the flow chart of the method is shown in Figure 1 .

[0013] The method for replacing deoxynucleotide triphosphate ammonium salt with sodium salt provided in the present application adopts the following technical scheme: the method is a nanofiltration roll-type membrane salt replacement method, which specifically includes the steps of fraction concentration, replacement and desalination;

[0014] S1, the concentration step: concentrating the deoxynucleotide triphosphate ammonium salt fraction after high-pressure liquid phase purification;

[0015] S2, the replacement: adding 2 mol / L-6 mol / L alkali metal salt solution to the deoxynucleotide triphosphate ammonium salt solution for low-temperature replacement;

[0016] S3, desalination: washing with water until no sodium ions can be detected in the filtrate, obtaining a deoxynucleotide triphosphate sodium salt solution.

[0017] By adopting the above technical scheme, the existing technology generally adopts the method of separating and purifying sodium deoxyribonucleotide triphosphate by using anion exchange resin, but this method has poor separation effect, high feeding cost, low purity, and the sodium ion equivalent cannot be accurately controlled. The application separates the organic phase in the deoxyribonucleotide triphosphate amine salt solution by a roll-type nanofiltration membrane separation system, improves the purity of the deoxyribonucleotide triphosphate amine salt solution, then adds a high-concentration monovalent or divalent alkali metal salt solution, such as sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium nitrate, potassium nitrate, sodium chloride, potassium chloride solution, uses high-concentration sodium ions to replace low-concentration amine ions, and then washes with water to remove excess sodium ions in the system.

[0018] By adopting the above technical scheme, the deoxyribonucleotide triphosphate monomer organic amine salt is replaced by deoxyribonucleotide triphosphate sodium salt or deoxyribonucleotide triphosphate potassium salt, which solves the problems of low solubility of deoxyribonucleotide triphosphate amine salt and difficulty in preparing high-concentration end product aqueous solution, and solves the problem that the high salt content of deoxyribonucleotide triphosphate amine salt lyophilizate leads to unqualified dissolution clarity after reconstitution. The solution of the product obtained after replacement has a clarity that is higher than that of a solution of the same concentration of amine salt. Figure 2 .

[0019] When the replacement step uses a carbonate salt, carbon dioxide needs to be introduced into the system before water washing to convert the carbonate salt into a bicarbonate salt, so that the carbonate ions that cannot pass through the membrane are converted into bicarbonate ions that can pass through the membrane, so that the sodium salt replacement, removal of excess acid ions and concentration are all carried out in the nanofiltration membrane.

[0020] In the replacement reaction, the alkali metal salt is preferably a carbonate salt or a bicarbonate salt, the carbonate salt is sodium carbonate or potassium carbonate, and the concentration of the carbonate salt solution is preferably 2-4 mol / L; the bicarbonate salt is sodium bicarbonate or potassium bicarbonate, and the concentration of the bicarbonate salt is preferably 4-6 mol / L, and the volume is preferably 0.5-2 times the target volume, and more preferably a 3M carbonate salt solution is used, and the volume is equal to the target volume.

[0021] The above technical scheme, the initial concentration of deoxyribonucleotide triphosphate amine salt is obtained by the following method: initial concentration = absorbance x dilution factor ÷ molar absorption coefficient (unit: molar absorption coefficient mM -1 ·cm); the absolute content of the deoxyribonucleotide triphosphate amine salt to be treated is equal to the initial concentration multiplied by the volume of the solution to be treated. The amount of substance of the alkali metal ions in the alkali metal salt is greater than or equal to 60 times the absolute content of the deoxyribonucleotide triphosphate amine salt.

[0022] In the above technical solution, because the amount of substance required for bicarbonate is too much compared with carbonate, the dissolution amount of the salt in a certain volume may be limited, so carbonate is preferred, and the concentration of carbonate is preferably 3M, and finally a high-purity aqueous solution of deoxyribonucleotide triphosphate sodium salt or potassium salt is obtained, which is high in purity and free of any organic amine salt residue.

[0023] Preferably, in the displacement step, the flow rate of the deoxyribonucleotide triphosphate amine salt solution is in the range of 15L / min to 20L / min, and the pressure in the membrane is in the range of 1.5MPa to 2.0MPa.

[0024] By using the above technical solution, as the flow rate and pressure increase, the displacement reaction of the deoxyribonucleotide triphosphate amine salt solution and sodium carbonate is accelerated, and the displacement efficiency is improved. However, if the flow rate is too fast and the pressure is too high, the permeation rate increases, and the retention rate or yield decreases. Therefore, in the case of ensuring the stability of the displacement reaction, the flow rate is in the range of 15L / min to 20L / min, and the equipment operating pressure is in the range of 1.5MPa to 2.0MPa, which is the most suitable.

[0025] Preferably, the concentration, displacement and desalination steps are carried out at -10℃ to 5℃.

[0026] By using the above technical solution, since the deoxyribonucleotide triphosphate monomer is unstable at high temperature, it is most suitable to set the system temperature in the range of -10℃ to 5℃.

[0027] Preferably, the concentration, displacement and desalination steps are carried out in a nanofiltration instrument circulating tank.

[0028] By using the above technical solution, the concentration, displacement and desalination steps can be completed in the nanofiltration instrument circulating tank, and the production efficiency is higher.

[0029] Preferably, in the desalination step, CO2 is introduced to a pH value of 7.0-7.5.

[0030] By using the above technical solution, on the one hand, the solubility of carbonate is better, and on the other hand, carbon dioxide is introduced into the nanofiltration instrument circulating tank, so that carbonate ions are converted into bicarbonate ions to permeate the nanofiltration membrane. When the amount of alkali metal ions is too small, an aqueous bicarbonate solution can also be added to completely convert the amine salt into an alkali metal salt.

[0031] By using the above technical solution, the sodium ion online detection system is used to detect the concentration of sodium ions in the desalination step to determine whether the amine salt is completely prepared into a sodium salt. If the equivalent of sodium ions is too small, it means that the displacement is not complete, a small amount of aqueous sodium bicarbonate solution is added, carbon dioxide is introduced to adjust the pH value, and the purity of the prepared deoxyribonucleotide triphosphate sodium salt is improved.

[0032] When the deoxy nucleoside triphosphate amine salt fraction contains acetonitrile or tetrahydrofuran, water is added to dilute the acetonitrile or tetrahydrofuran to a concentration of less than 5%.

[0033] By adopting the technical scheme, the influence of acetonitrile or tetrahydrofuran on the retention rate of the nanofiltration membrane can be reduced by reducing the concentration of acetonitrile or tetrahydrofuran, and the loss of deoxy nucleoside triphosphate amine salt can be prevented.

[0034] Preferably, the types of organic amines that can be replaced by the replacement method include but are not limited to: triethylamine (TFA), diisopropylamine (DIPA), tripropylamine (TPA), diisopropyl ethylamine (DIEA), n-hexylamine (HA).

[0035] By adopting the steps of concentration and salt replacement, the amine salt of the above various components can be converted into an alkali metal salt.

[0036] In summary, the present application has the following beneficial technical effects:

[0037] 1. The present application adopts a nanofiltration membrane treatment method to replace 100% of the deoxy nucleoside triphosphate amine salt into an alkali metal salt. The nuclear magnetic resonance spectrum shows that there is no residual organic amine, so the salt replacement effect is good. And replacing 100% of the deoxy nucleoside triphosphate amine salt into an alkali metal salt can improve the solubility of deoxy nucleoside triphosphate.

[0038] 2. The replacement method of the present application can replace triethylamine, diisopropylamine, tripropylamine, diisopropyl ethylamine, and n-hexylamine.

[0039] 3. The replacement method of the present application produces only salt solution as the three wastes, which has little pollution and is conducive to green environmental protection, energy saving and emission reduction.

[0040] Figure description

[0041] Figure 1 The flowchart of the present application.

[0042] Figure 2 The clarity comparison of the product solution of the present application with the solution of the same concentration of amine salt; the left is the deoxy nucleoside triphosphate sodium salt solution prepared by the method of the present application; and the left is the solution of the same concentration of amine salt.

[0043] Figure 3 The nuclear magnetic resonance spectrum of the deoxy nucleoside triphosphate amine salt with a purity of 99.5% (HPLC purity) prepared by the present application.

[0044] Figure 4 The nuclear magnetic resonance spectrum of dTTP sodium salt after replacement.

[0045] Figure 5 The high performance liquid chromatogram of dNTP after the method. DETAILED DESCRIPTION

[0046] The liquid phase conditions for detecting the purity of deoxynucleotide triphosphate amine salt in the present application are as follows:

[0047] Table 2

[0048]

[0049] Sodium carbonate in the following examples of the present application also represents potassium carbonate, and thus the carbonate salt of the present application refers to any one of sodium carbonate or potassium carbonate.

[0050] Sodium bicarbonate in the following examples of the present application also represents potassium bicarbonate, and thus the bicarbonate salt of the present application refers to any one of sodium bicarbonate or potassium bicarbonate.

[0051] Sodium chloride in the present application has the same effect as sodium nitrate, potassium nitrate, potassium chloride and other monovalent metal salts, and thus only sodium chloride is taken as an example.

[0052] The present application will be further described in detail in combination with specific contents.

[0053] The deoxynucleotide triphosphate amine salt used in the present application contains one or more of triethylamine, diisopropylamine, tripropylamine, diisopropyl ethylamine, n-hexylamine, and in the following examples and comparative examples, n-hexylamine is specifically used;

[0054] In the concentration step, the mobile phase A used in high-pressure liquid purification adopts tetraethylammonium bromide, and the mobile phase B can adopt one of methanol, ethanol, tetrahydrofuran and acetonitrile.

[0055] <Material source>

[0056] The raw materials used in the present application are all commercially available products, and specifically are:

[0057] Deoxynucleotide triphosphate, purchased from Shanghai Sikeui Biological Technology Co., Ltd.

[0058] N-hexylamine, purchased from Shanghai Maikelin Biochemical Technology Co., Ltd.

[0059] Sodium carbonate, purchased from Jiaxing Changli Chemical Co., Ltd.

[0060] Sodium bicarbonate, purchased from Jiangsu Cailei Biological Technology Co., Ltd.

[0061] Methanol, purchased from Jinan Chuangshi Chemical Co., Ltd.

[0062] Tetraethylammonium bromide, purchased from Shanghai Denovo Chemical Co., Ltd.

[0063] Acetonitrile, purchased from Anhui Jiuxing Chemical Technology Co., Ltd.

[0064] <Example>

[0065] Example 1

[0066] A method for replacing deoxynucleotide triphosphate amine salt with sodium salt, comprising the following steps:

[0067] S1 concentration step: 99.5% HPLC purity deoxynucleotide triphosphate amine salt obtained after high pressure liquid chromatography preparation separation, its composition is shown in Table 1 Figure 3 ( Separation system is mobile phase A phase tetraethyl ammonium bromide and B phase methanol), the molar concentration of deoxynucleotide triphosphate amine salt is determined by UV absorbance coefficient or HPLC external standard method, the target volume of 100 ± 5 mmol / L concentration is converted, and then the deoxynucleotide triphosphate amine salt is added to the nanofiltration instrument circulating tank for concentration to the target volume; if the separation system uses B phase acetonitrile or tetrahydrofuran, water needs to be added for dilution before concentration until the proportion of acetonitrile or tetrahydrofuran is less than 5%, and then the concentration treatment is carried out to the target volume.

[0068] S2 replacement step: adding a salt solution of sodium carbonate with a concentration of 1.5 mol / L to the above deoxynucleotide triphosphate amine salt solution, and the reaction time is 10-15 minutes;

[0069] S3 desalination: introducing carbon dioxide into the system of the above step to adjust the pH value to 7.0-7.5, converting the carbonate that cannot pass through the membrane into bicarbonate that can pass through the membrane, reducing the salt content of the system, and then performing multiple water washing and filtration until no sodium ion can be detected in the filtered liquid;

[0070] Using a sodium ion online detection system, the final sodium ion concentration in the system is controlled, if the sodium ion equivalent is too little, a small amount of sodium bicarbonate aqueous solution can be added, after the introduction of carbon dioxide to pH 7.0-7.5, the introduction of carbon dioxide is stopped, if the sodium ion equivalent is too much, tertiary water is added for dilution, and finally the deoxynucleotide triphosphate sodium salt aqueous solution with a concentration of 100-200 mmol / L is prepared by concentration.

[0071] The above concentration, replacement and desalination steps are carried out in the nanofiltration instrument circulating tank, the flow rate is 15 L / min, the equipment operating pressure is 1.5 MPa, and the equipment temperature is -10℃.

[0072] Example 2

[0073] A method for replacing deoxynucleotide triphosphate amine salt with sodium salt, which is different from example 1 in that the replacement reaction time is 30 minutes, and the remaining steps are the same as example 1.

[0074] Example 3

[0075] A method for replacing deoxynucleotide triphosphate amine salt with sodium salt, which differs from Example 1 in that the molar concentration of the added sodium carbonate salt solution is 3 mol / L, and the remaining steps are the same as those of Example 1.

[0076] Example 4

[0077] A method for replacing deoxynucleotide triphosphate amine salt with sodium salt, which differs from Example 1 in that the molar concentration of the added sodium carbonate salt solution is 4 mol / L, and the remaining steps are the same as those of Example 1.

[0078] Example 5

[0079] A method for replacing deoxynucleotide triphosphate amine salt with sodium salt, which differs from Example 1 in that 1.5 mol / L of sodium bicarbonate is added in the replacement step, and the remaining steps are the same as those of Example 1.

[0080] Example 6

[0081] A method for replacing deoxynucleotide triphosphate amine salt with sodium salt, which differs from Example 5 in that the replacement reaction time is 30 minutes, and the remaining steps are the same as those of Example 5.

[0082] Example 7

[0083] A method for replacing deoxynucleotide triphosphate amine salt with sodium salt, which differs from Example 1 in that 4 mol / L of sodium bicarbonate is added in the replacement step, and the remaining steps are the same as those of Example 1.

[0084] Example 8

[0085] A method for replacing deoxynucleotide triphosphate amine salt with sodium salt, which differs from Example 7 in that the replacement reaction time is 30 minutes, and the remaining steps are the same as those of Example 7.

[0086] Example 9

[0087] A method for replacing deoxynucleotide triphosphate amine salt with sodium salt, which differs from Example 1 in that 6 mol / L of sodium bicarbonate is added in the replacement step, and the remaining steps are the same as those of Example 1.

[0088] The experimental results of Examples 1-9 are shown in Table 3:

[0089] Table 3

[0090] Salt type 1V salt concentration Salt replacement time Whether n-hexylamine remains Example 1 Sodium carbonate 1.5M 10 min Remains Example 2 Sodium carbonate 1.5M 30 min Remains Example 3 Sodium carbonate 3M 10 min No remains Example 4 Sodium carbonate 4M 10 min No remains Example 5 Sodium bicarbonate 1.5M 10 min Remains Example 6 Sodium bicarbonate 1.5M 30 min Remains Example 7 Sodium bicarbonate 4M 10 min Remains Example 8 Sodium bicarbonate 4M 30 min Remains Example 9 Sodium bicarbonate 6M 10 min No remains

[0091] The nuclear magnetic resonance spectrum of the deoxynucleotide triphosphate amine salt with a purity of 99.5% (HPLC purity) used in Examples 1-9 is shown in Figure 3The spectrum shows that the amine salt of dTTP is n-hexylamine salt. In the spectrum, the four peaks from left to right are: the first triplet peak, two hydrogens at 2.69 ppm, is the hydrogen spectrum of the two hydrogens beside -NH2; the second is two hydrogens at 1.52 ppm; the third peak is six hydrogens at 1.28 to 1.29 ppm; and the fourth peak (the first peak on the right) is three hydrogens at 0.88 ppm.

[0092] The nuclear magnetic resonance spectrum of the dTTP sodium salt obtained after the replacement in Example 3-4 and Example 9 is shown in Figure 4 The spectrum shows that the n-hexylamine salt has disappeared.

[0093] In the experiment of Example 1-9, it is found that when the concentration of sodium carbonate is 1.5 mol / L and the volume of the added sodium carbonate is 1 target volume, the amine salt cannot be completely replaced by the alkali metal salt. The complete replacement can be achieved by adding sodium bicarbonate during the replacement process. This indicates that the amount of alkali metal ions should be greater than or equal to 60 times the amount of dTTP amine salt or the concentration of alkali metal ions should be greater than or equal to 30 times the concentration of the amine salt in order to complete the replacement. When the alkali metal salt is sodium bicarbonate or potassium bicarbonate, the volume used is 1 target volume and the concentration used should reach 6 M to achieve complete replacement, which again proves the relationship between the amount of alkali metal ions and the amine salt.

[0094] It is also found in the experiment that the pH should be maintained between 7.0 and 7.5 to ensure the conversion of carbonate to bicarbonate and to avoid an acidic system to achieve complete conversion. Similar pressure and flow rate should not be too high. If the flow rate or pressure is too high, the pressure in the membrane will be too high, resulting in a decrease in the retention rate of dTTP amine salt and an excessive loss rate, which may be caused by the increase in the pore size of the membrane due to excessive pressure. On the other hand, if the flow rate or pressure is too low, it will slow down the sample processing speed.

[0095] Similarly, it is found in the experiment that if acetonitrile or tetrahydrofuran is present in the system and the concentration is greater than 5%, the salt retention rate will decrease and the loss rate will be too large, which may be caused by the increase in the pore size of the membrane due to the presence of acetonitrile or tetrahydrofuran.

[0096] Examples 10-13

[0097] Examples 10-13 are different from Example 9 in that sodium nitrate, potassium nitrate, sodium chloride, and potassium chloride are used instead of sodium bicarbonate, and the concentration used is 6 M, and there is no need to adjust the pH with carbon dioxide. The results can all replace the dTTP amine salt with alkali metal salt.

[0098] In summary, alkali metal salts with monovalent or divalent anions, such as sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium nitrate, potassium nitrate, sodium chloride, and potassium chloride, can all achieve the replacement of dTTP amine salt with alkali metal salt.

[0099] Examples 14-17

[0100] Examples 14-17 are different from Example 3 in that dATP, dCTP, dGTP and dUTP are sequentially treated by the method of Example 3 respectively. The high performance liquid chromatogram of dNTP sodium salt after replacement by this method Figure 5 is shown from top to bottom as dGTP, dATP, dCTP, dTTP and dUTP. The results before and after treatment are shown in the following table Figure 5 We can see that the purity of dNTP sodium salt is high after replacement by this method.

[0101] Examples 18-21

[0102] Examples 18-21 are different from Example 3 in that the amine salts are triethylamine (TFA), diisopropylamine (DIPA), tripropylamine (TPA), and diisopropylethylamine (DIEA) respectively. The results before and after treatment are similar to those of n-hexylamine salt, and are not described in detail for brevity.

[0103] Comparative Examples

[0104] Comparative Example 1

[0105] A method for replacing amine salt of deoxynucleotide triphosphate with sodium salt, which is different from Example 3 in that sodium phosphate is used instead of sodium carbonate, and the remaining steps are the same as those of Example 3.

[0106] Comparative Example 2

[0107] A method for replacing amine salt of deoxynucleotide triphosphate with sodium salt, which is different from Example 3 in that monobasic sodium phosphate is used instead of sodium carbonate, and the replacement reaction time is 30 minutes, and the remaining steps are the same as those of Example 3.

[0108] Experiments show that neither phosphate nor monobasic phosphate can completely replace amine salt of deoxynucleotide triphosphate with alkali metal salt, which may be due to the fact that phosphate or monobasic phosphate ions are too large to pass through the nanofiltration membrane.

[0109] In summary, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium nitrate, potassium nitrate, sodium chloride, and potassium chloride can all achieve the replacement of amine salt of deoxynucleotide triphosphate with alkali metal salt. Those skilled in the art can freely choose the type of alkali metal salt according to the convenience of operation or market demand. Therefore, any equivalent changes made in accordance with the principles of this application should be covered within the scope of protection of this application.

Claims

1. A method for replacing deoxynucleoside triphosphate salts with sodium salts, characterized in that: The method is a nanofiltration spiral wound membrane salt replacement method, which specifically includes the steps of fraction concentration, replacement, and desalination. S1 Concentration step: Concentrate the deoxynucleoside triphosphate salt fraction purified by high pressure liquid phase to a concentration of 100mM±5mM; The displacement step S2 involves adding 1.5 mol / L to 6 mol / L of an alkali metal salt with a monovalent or divalent anion to the deoxynucleoside triphosphate solution for low-temperature displacement. The alkali metal salt with a monovalent or divalent anion is selected from sodium carbonate, sodium bicarbonate, sodium nitrate, and sodium chloride. The volume of the added alkali metal salt solution is equal to 0.5 to 2 times the volume of the concentrated fraction in step S1. In the displacement step, the flow rate of the deoxynucleoside triphosphate solution is in the range of 15 L / min to 20 L / min, and the membrane pressure is 1.5 MPa to 2.0 MPa. S3 Desalination Step: Wash with water until sodium ions are undetectable in the filtrate to obtain a sodium deoxynucleoside triphosphate solution; and when the acid anion is a monovalent or divalent alkali metal salt, which is sodium carbonate, the S3 step involves bubbling carbon dioxide into the S2 step system until the pH value is between 7.0 and 7.5, and washing with water until alkali metal ions are undetectable in the filtrate; in the desalination step, if the amount of sodium carbonate added is insufficient to completely convert the amine salt into sodium salt, sodium bicarbonate is added until the displacement is complete; The concentration, displacement, and desalination steps are carried out in the circulation tank of the nanofiltration instrument, and the concentration, displacement, and desalination steps are carried out at -10℃ to 5℃. The amine in the deoxynucleoside triphosphate salt is an organic amine, selected from triethylamine, diisopropylamine, tripropylamine, diisopropylethylamine, and n-hexylamine.

2. The method for replacing deoxynucleoside triphosphate with sodium salt according to claim 1, characterized in that: The concentration of sodium carbonate used in the displacement reaction is 2 mol / L to 4 mol / L, or the concentration of sodium bicarbonate used in the displacement reaction is 4 mol / L to 6 mol / L.

3. The method for replacing deoxynucleoside triphosphate with sodium salt according to claim 1, characterized in that: In the concentration step, when the deoxynucleoside triphosphate salt fraction contains acetonitrile or tetrahydrofuran, water is first added to dilute it until the acetonitrile or tetrahydrofuran content in the concentrated fraction is below 5% before concentration.

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