JPH1062401A - Filler for liquid chromatography - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the separation capacity of a solute substance having a specific size to make the same effective at a time of the use of a solvent relatively high in polarity by using a silica porous material having a center pore diameter within a specific range as a filler. SOLUTION: A silica porous material has a center pore diameter of 1-10nm and 60% or more of the total pore vol. thereof is contained within a range of a center pore diameter of ±40% and the crystallinity thereof is high and the pores thereof are uniform. Therefore, this porous material is advantageous in the separation of large molecules near to a center pore diameter, molecules capable of entering pores and molecules incapable of entering pores. Because of a peculiar pore structure, this porous material is strong in the adsorbing force of org. matter as compared with a silica gel and effective in the separation of a solute at a time of the use of a solvent relatively high in polarity. This porous material can be adapted to liquid column chromatography, high performance liquid chromatography and thin-layer chromatography.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filler for liquid chromatography used for separating a substance to be separated dissolved in a liquid.

[0002]

2. Description of the Related Art Recently, there has been an increasing need for separating functional molecules such as pharmaceuticals, and there has been a demand for the development of a chromatographic packing material for efficiently separating them. Current,
Various fillers for liquid chromatography, such as silica gel, alumina, diatomaceous earth, and zeolite, have been used. When the same solvent is used, there is a difference in the ability to separate solute substances due to differences in the surface characteristics and pore diameter of the filler.

[0003] Silica gel, which has been used as a usual filler, has a pore size that is not so uniform, and the separation performance is insufficient when separating substances close to the pore size. In addition, separation performance was similarly insufficient even for a dissolved substance in a solvent having a relatively high polarity.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has a high resolution for a solute substance of a specific size and is effective when a relatively polar solvent is used. It is intended to provide a filler.

[0005]

The filler for liquid chromatography of the present invention has a central pore diameter in a range of 1 to 10 nm, and a total pore diameter of ± 40% of the central pore diameter. A silica-based porous material containing 60% or more of the volume, and is characterized in that it is used as a filler for liquid chromatography. On the other hand, the silica-based porous body desirably has one or more peaks at a position of a diffraction angle (2θ) corresponding to a d value of 1 nm or more in the X-ray diffraction pattern.

As liquid chromatography, column chromatography, high performance liquid chromatography (HPL)
C) and thin layer chromatography (TLC).

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The filler for liquid chromatography of the present invention is composed of a silica-based porous material. This silica-based porous material has a center pore diameter in the range of 1 to 10 nm, and a total pore volume of 6% within a range of ± 40% of the center pore diameter.
It contains 0% or more, has high crystallinity, and has uniform pores.
Therefore, it is advantageous for separating large molecules close to the central pore diameter into molecules that can enter the pores and molecules that cannot. In addition, because of its unique pore structure, it has a stronger adsorptivity to organic substances than silica gel, and is effective in separating solutes when using a relatively polar solvent.

This pore structure has a pore diameter of 1 to 10 nm.
Because of the uniform and cylindrical deep pores in the range, a solute can be firmly captured even with a highly polar (high elution rate) solvent. Silanol groups on the pore surface act on organic matter. The same applies to silica gel. As a silica-based porous body, for example,
Mesoporous materials synthesized by allowing a surfactant to act on a layered silicate can be used. This mesoporous material has a thickness of 2 to 12 nm.
Has a structure in which silicates that are curved at a constant period are vertically coupled by convex portions, and the gap between the sheets has a diameter of 1 to 10
The cylindrical pores of nm are arranged at regular intervals.

The X-ray diffraction pattern of this mesoporous material is 1
At least one peak including a diffraction peak having the maximum intensity is observed at a position having a d value of nm or more.
In addition, there are two to four diffraction peaks showing a hexagonal structure, and the transmission electron micrograph thereof shows
A honeycomb skeleton is observed. As another porous body, there is a mesoporous molecular sieve (MCM-41) synthesized using a micelle structure of a surfactant as a template.
This MCM also has a structure in which cylindrical pores having a diameter of 1 to 10 nm are regularly arranged and has a honeycomb-shaped cross section, but the structure inside the pore wall is different from that of the previous material. This M
In the X-ray diffraction pattern of CM-41, at least one peak including a diffraction peak having the maximum intensity is observed at a position having a d value of 1 nm or more.

[0010] No clear diffraction peak is observed in the X-ray diffraction pattern of conventional porous silica, for example, silica gel. An X-ray diffraction peak means that a periodic structure having a d value corresponding to the peak angle is present in the material. Therefore, at least d =
0.15 to 12 nm (corresponding to 0.7 <2θ <60 °)
Has no periodic structure. That is, it indicates that it is amorphous. On the other hand, the porous body of the present invention has one or more peaks including the strongest peak at a d value of 1 nm or more, and has a periodic structure.

[0011] Specifically, these peaks have a diameter of 1 to
This reflects a structure in which 10 nm pores are regularly arranged at intervals of 2 nm or more. As a result, the diameter of the pores in the structure is irregular due to the irregular structure of the conventional silica gel, whereas the porous body of the present invention has uniform pores reflecting the regularity of the structure. It will be. The composition of the silica-based porous body may be a pure silica oxide, but silica (aluminum (Al), titanium (Ti), magnesium (Mg), zirconium (Zr), gallium (Ga), beryllium (Be) , Yttrium (Y),
Lanthanum (La), tin (Sn), lead (Pb), vanadium (V), boron (B), or the like may be mixed.

Next, a method for synthesizing a mesoporous material from a layered silicate will be described. The layered silicate, e.g. kanemite _{(NaHSi 2 O 5 · 3H 2} O) is preferred. Other layered silicates include sodium disilicate crystals (Na ₂ Si ₂ O ₅ ) and macatite (Na ₂ Si ₄ O).
₉ · 5H ₂ O), Airaaito _{(Na 2 Si 8 O 17 ·} X
H ₂ O), Makadiaito _{(Na 2 Si 14 O 29 ·} XH 2
O), Kenyanite (Na ₂ Si ₂₀ O ₄₁ .XH ₂ O) and the like are typical, but not limited thereto.

Examples of the surfactant include alkyl trimethyl ammonium, dimethyl dialkyl ammonium, alkyl ammonium, and benzyl methyl ammonium chloride, bromide, and iodide. The layered silicate is dispersed in a solution in which the surfactant is dissolved. The solvent is preferably water, but may be a water-alcohol mixed solvent or another solvent. The concentration of the surfactant aqueous solution is preferably 0.05 to 1 mol. The addition amount of the layered silicate is preferably, for example, 5 to 200 g of kanemite based on 1000 ml of a 0.1 mol aqueous surfactant solution. This dispersion is
Heat at 0-150 ° C. The heating time is preferably 3 hours or more. During the heating, the dispersion may or may not be stirred. Further, the pH of the solution does not need to be particularly adjusted, but after heating at a high pH of 10 or more at first, lowering it to 9 or less, and further heating, a mesoporous body with particularly high crystallinity and heat resistance is obtained. be able to. After heating the dispersion, the solid product is recovered by filtration. By repeatedly washing the solid product with clean water, a mesoporous body having higher heat resistance can be obtained. After drying the solid product, the solid product is calcined at a high temperature of 550 ° C. or higher, or treated with a mixed solution of hydrochloric acid / ethanol, thereby removing the surfactant incorporated in the crystal and forming a mesoporous material. When firing, it is preferable to heat for 1 hour or more in an atmosphere such as air, oxygen, or nitrogen.

In the synthesis method in which a surfactant is allowed to act on the layered silicate, an amorphous silicate such as water glass or powdered sodium silicate is used in place of the layered silicate, and the other synthesis conditions are exactly the same. Is carried out to obtain the filler of the present invention. The pore distribution curve refers to a curve in which a value (dV / dD) obtained by differentiating the pore volume (V) by the pore diameter (D) is plotted against the pore diameter (D). The pore distribution curve is created by, for example, a gas adsorption method described below.
The most commonly used gas in this method is nitrogen.

First, a liquid nitrogen temperature (-196
° C), and the amount of absorption is determined by a quantitative method or a gravimetric method. That is, the pressure of the nitrogen gas introduced into the porous filler is gradually increased, and the adsorption amount of nitrogen gas is plotted with respect to each equilibrium pressure to create an adsorption isotherm. From the created adsorption isotherm, for example,
The above pore size distribution can be obtained by using the calculation methods of the Cranston-Inklay method and the Pollimore-Heal method.

In a range of ± 40% of the pore diameter showing the maximum peak in the pore diameter distribution curve (for example, when the maximum peak in the entire pore distribution curve is 2.7 nm, the pore diameter becomes 1.62 to 1.62 nm). That is, the total volume of a pore (in the range of 3.78 nm) accounts for more than 60% of the total pore volume. Specifically, the integral value of the pore distribution curve in the range of the pore diameter of 1.62 to 3.78 nm accounts for 60% or more of the total integral value of the curve.

The pore diameter range of ± 40% of the pore diameter showing the maximum peak in the pore distribution curve is 60% of the total pore volume.
If the porous body has a pore size of less than 1, the pore diameter is not uniform, which is not preferable for effectively utilizing the pore diameter.

[0018]

The present invention will be specifically described below with reference to examples. Production of mesoporous body 1 (FSM / 8, 10, 12, 14,
16) Powdered sodium silicate (SiO ₂ / N) manufactured by Nippon Chemical Industry Co., Ltd.
a ₂ O = 2.00) was calcined in air at 700 ° C. for 6 hours to crystallize into sodium disilicate (δ-Na ₂ Si ₂ O ₅ ). 50 g of these crystals are dispersed in 500 ml of water,
Stirred for hours. Thereafter, the solid content was recovered by filtration to obtain kanemite crystals.

50 g of kanemite in a dry weight was dispersed in 1000 ml of a 0.1 mol aqueous solution of hexadecyltrimethylammonium chloride (C ₁₆ H ₃₃ N (CH ₃ ) ₃ Cl) and heated at 70 ° C. with stirring for 3 hours. The pH at the beginning of heating was 12.3. Thereafter, while heating and stirring at 70 ° C., 2N hydrochloric acid was added to lower the pH of the dispersion to 8.5. Thereafter, the mixture was heated at 70 ° C. for 3 hours and allowed to cool to room temperature. Once the solid product is filtered, 1000
The mixture was dispersed and stirred in ml of deionized water. After repeating the filtration / dispersion stirring of the ion-exchanged water 5 times,
For 24 hours. This solid content sample is 550 in air.
A mesoporous body was obtained by baking at 6 ° C. for 6 hours.

In the same operation as above, alkyl (C _n H) is used instead of hexadecyltrimethylammonium chloride.
_{2n + 1)} the chain length (n) is four different alkyltrimethylammonium _{(C n H 2n + 1 (} CH 3) 3 chloride) (n = 14) or bromide (n = 8, 10,
Using 12), a total of five types of mesoporous materials were produced. The number (n) of the length of the alkyl chain of the alkyltrimethylammonium used is given, and FSM / 8, FSM /
10, FSM / 12, FSM / 14 and FSM / 16.

Production of mesoporous material 2 (FSM / M05,1)
0,20) In the above method for producing a mesoporous material, except that mesitylene (C ₆ H ₃ (CH ₃ ) ₃ ) was added in addition to 0.1 mol of hexadecyltrimethylammonium chloride. A mesoporous body was synthesized under the same conditions as in Production 1. The addition amount of mesitylene is 0.05, 0.
It was prepared under three conditions of 1 mol and 0.2 mol, and the numbers after the decimal point of these molar amounts were adopted to obtain FSM / M05.
The symbols FSM / M10 and FSM / M20 were given.

Synthesis of mesoporous material 3 50 g of powdered sodium silicate (SiO ₂ / Na ₂ O = 2.00 manufactured by Nippon Chemical Industry Co., Ltd.) or δ-Na ₂ Si obtained by calcining it in air at 700 ° C. for 6 hours 50 g of ₂ O ₅ , 0.
The mixture was dispersed in 1000 ml of a 1 mol aqueous solution of hexadecyltrimethylammonium chloride and heated at 70 ° C. for 3 hours with stirring. Thereafter, the pH of the dispersion was adjusted to 8.5 by dropwise addition of a 2N aqueous hydrochloric acid solution. Then, the mixture was further stirred at 70 ° C. for 3 hours, and then cooled to room temperature. The solid product was filtered, dispersed in 1000 ml of deionized water, stirred for about 5 minutes and filtered again.
This operation of dispersion and filtration was repeated five times. After the product has been dried, it is calcined in air at 550 ° C. for 6 hours to give 2
Different kinds of powder samples were obtained. These samples are in turn FSM /
16P, FSM / 16D.

The FSM / 16P was prepared by reacting a powdered sodium silicate with a linear surfactant, and
M / 16D is named as synthesized via δ-Na ₂ Si ₂ O ₅ . X-ray diffraction of mesoporous body The powder X-ray diffraction pattern of the synthesized mesoporous body was measured. The X-ray diffraction was scanned at 2 degrees (2θ) / min using CuKα as a radiation source using a Rigaku RAD-B apparatus. The slit width is 1 degree-0.3 mm-1 degree. The results are shown in FIGS.

As shown in the X-ray diffraction patterns of FIGS. 1 and 2, several peaks were observed when the diffraction angle (2θ) was 10 degrees or less. Table 1 shows the values obtained by converting the diffraction angles of the peaks into d values. FSM / 12, FSM / 14, FSM /
16, FSM / M05, FSM / 16P, FSM / 16
As for D, the peak having a d value of d = 1 nm or more is 3
４4 were observed. These peaks were indexed into a hexagonal structure.

On the other hand, FSM / 8, FSM / 10, FSM
Regarding / M10, one or two peaks having a d value of d = 1 nm or more were observed. For FSM / M20, no peak having a d value of d = 1 nm or more was observed under these measurement conditions, but the slit width was set to 0.5 ° -0.1 °.
In the case of 5 mm-0.5 degrees, as shown in FIG.
= One peak was observed at a position of 1 nm or more. The results of these X-ray diffraction patterns show that these mesoporous materials have a regular periodic structure.

Pore distribution curve of mesoporous material A pore distribution curve of the mesoporous material was determined from a nitrogen adsorption isotherm. The nitrogen adsorption isotherm was measured as follows. The equipment is equipped with a pressure sensor (MKS, Baratron 127AA, range 100)
0 mmHg) and two control valves (MKS, 248A) are connected so that nitrogen gas can be automatically introduced into a vacuum line and into a sample tube.

About 40 mg of the mesoporous sample was placed in a glass sample tube and connected to a vacuum line. The sample tube was vacuum degassed at 130 ° C. for about 1 hour. Ultimate vacuum is 1
It was 0 ^-4 mmHg. The sample tube is immersed in liquid nitrogen, and a predetermined pressure of nitrogen gas is introduced into the vacuum line. After the pressure stabilizes, open the control valve on the sample tube and record the equilibrium pressure after the pressure has stabilized. Equilibrium pressure is 0-7
The same operation was repeated at 16 to 18 points in the range of 60 mmHg.

The time to equilibrium varies with pressure, but was in the range of 20 to 60 minutes. By plotting the amount of adsorption determined from the equilibrium pressure and the pressure change, the nitrogen adsorption isotherm of each mesoporous material was prepared. Fig. 4 shows the results.
And FIG. From this nitrogen adsorption isotherm, Cranston-I
The pore distribution curve was determined by the nklay method. The results are shown in FIGS. The pore diameter showing the largest peak in the pore distribution curve (referred to as central pore diameter) and the ratio of the total pore volume to the pore volume included in a pore range of ± 40% of the central pore diameter are shown. 1 is shown. These mesoporous materials have a center diameter in the range of 1 to 10 nm and a pore range of ± 40% of the pore diameter showing the maximum peak in the pore distribution curve. included.

[0029]

[Table 1] On the other hand, silica gel (commercially available A: (TL
The nitrogen adsorption isotherm and the pore distribution of the C plate C ₆₀ F ₂₅₄ silica gel) are shown in FIGS. 8 and 9. Table 1 shows the center pore diameter and the ± 40% porosity. The silica gel had a center pore diameter in the range of 1 to 10 nm, but had a ± 40% porosity of less than 60%.

TLC Evaluation (Preparation of TLC Plate) Using a planetary ball mill (manufactured by FRITSCH) for FSM / 16, set the rotation speed range to 5
For 15 minutes. From the results of the X-ray diffraction, it was confirmed that there was no structural destruction due to the pulverization. Crushed F
SM / 16 is passed through a 100 mesh sieve and the particle size is 15
FSM / 16 of 0 μm or less was collected. FSM collected
/ 16 (35 g) and about 1% of the fluorescent indicator F of the adsorbent
₂₅₄ (MERCK) 0.35 g was uniformly dispersed in 110 ± 20 ml of a mixed solution of chloroform / methanol = 2/1. Two glass slides washed by immersion in concentrated hydrochloric acid are superimposed, immersed in the dispersion liquid, pulled up in the vertical direction, the two glass slides are peeled off, and the thin layer is dried upward to obtain TLC. A plate was made.

As a comparative example, a commercially available silica gel T
A commercial product A was obtained using an LC plate C ₆₀ F ₂₅₄ (manufactured by MERCK). In addition, the particle diameter of the filler for chromatography is, specifically, the particle diameter of the filler for column chromatography, in which the solvent flows by gravity by gravity, is 63 to 250.
In the case of a column chromatography filler in which a solvent is flowed by pressurization with air or forced pumping by a pump, the thickness is 40 to 63 μm or less. Also, T
In LC, it is 63 μm or less. However, in this example, the one having a thickness of 150 μm or less was used.

In this embodiment, no special treatment was applied to the pretreatment of the chromatographic filler. By chemically modifying the hydroxyl groups on the silica surface, the state and properties of the surface can be changed, and the separation performance can be improved. (TLC Evaluation) About 1% of a developing solution (chloroform solution) was applied to a position 1 cm from the lower end of the TLC plate using a capillary so that the number of spots was as small as possible, and the plate was sufficiently dried. In addition, a developing solvent of about 5 mm was put in a developing tank (for example, a beaker), a filter paper was attached to a vessel wall, a lid was placed on the developing tank, and the developing tank was left for a while, and the inside of the developing tank was saturated with a solvent vapor. The lower end of the plate was immersed in a developing solvent in a developing tank by about 5 mm to perform the developing. After the development, the moved spot was detected by irradiating ultraviolet rays. From the position of the spot, the _Rf value of the developed product with respect to the developing solvent was determined. The R _f value in FIG.

[0033]

(Equation 1) It can be said that the larger the difference of this R _f value for each sample, the higher the separation ability of the filler. One to three experiments were performed on the same sample, and the average value was obtained.

(Results of TLC Evaluation) As a developed product, benzene-based organic substances such as aniline, N-methylaniline, N, N-dimethylaniline, phenol, dibutyl phthalate, and naphthyl red were used. Chloroform and acetone were used as developing solvents, and their R _f values were determined. The results are shown in FIGS. Although the size of the developed product is not close to the size of the pore diameter, when the developing solution is chloroform, the difference in the R _f value of the commercial product is larger and the separation performance is better than that of FSM / 16. When the developing solvent is acetone having a relatively high polarity, FSM / 1
No. 6 has a larger R _f value difference and better separation performance. Also,
By increasing the uniformity of the thin tank, the separation performance of FSM / 16 is further improved.

[0035]

The filler made of the porous silica material of the present invention has high crystallinity and uniform pores. For this reason, it is advantageous to separate molecules that can be in the pores from large molecules close to the central pore diameter and those that cannot. Also, compared to silica gel, the pore diameter is uniform in the range of 1 to 10 nm,
In addition, since the cylindrical deep pores, a solute (substance to be separated) can be firmly held even with a highly polar solvent. For this reason, it effectively acts on solute separation. As a result, high separation ability can be expected as a packing material for liquid chromatography.

[Brief description of the drawings]

FIG. 1 is an X-ray diffraction pattern of a mesoporous material synthesized in an example.

FIG. 2 is an X-ray diffraction pattern of a mesoporous material synthesized in an example.

FIG. 3 is an X-ray diffraction pattern measured by changing the slit width of the FSM / M20 of the example.

FIG. 4 is a graph of a nitrogen adsorption isotherm of a mesoporous material of an example.

FIG. 5 is a graph of a nitrogen adsorption isotherm of a mesoporous material of an example.

FIG. 6 is a graph showing a pore distribution curve of an example.

FIG. 7 is a graph showing the pore distribution ratio of FSM / 16D and FSM / 16P in Examples.

FIG. 8 is a graph showing a nitrogen adsorption isotherm of silica gel of a commercial product A.

FIG. 9 is a graph showing a pore distribution ratio of silica gel of a commercial product A.

FIG. 10 is a schematic diagram illustrating calculation of an R _f value.

FIG. 11: FS when chloroform is used as a developing solvent
It is a bar graph which shows the _Rf value of M / C16 Example product and the commercial product A of a comparative example.

FIG. 12 shows the results of FSM /
It is a bar graph which shows the _Rf value of C16 Example product and the commercial product A of a comparative example.

Claims (3)

[Claims] 1. A silica-based porous material having a central pore diameter in a range of 1 to 10 nm and containing ± 60% or more of the total pore volume in a range of ± 40% of the central pore diameter. A packing material for liquid chromatography, which is used as a packing material for liquid chromatography. 2. An X-ray diffraction pattern having a d value of 1 nm
A filler for liquid chromatography, which is a silica-based porous material having one or more peaks at positions corresponding to the diffraction angle (2θ) corresponding to the above, and used as a filler for liquid chromatography. 3. The liquid chromatography includes column chromatography, high performance liquid chromatography (HPL).
C), thin-layer chromatography (TLC).
Or the filler for liquid chromatography according to any one of 2.