JPH05346422A - Loading material for separating/analyzing anion - Google Patents

Abstract

PURPOSE:To efficiently separate fluoride ions in solution with high selectivity simultaneously with coexisting anions by employing a loading material, composed of porous basic material dispersed with a specified metal oxide containing water, as a separation column. CONSTITUTION:The loading material for separating/analyzing anions is produced by carrying a metal oxide containing water represented by a formula I, M.nH2O on a porous basic material through hydrolysis of metallic alkoxide represented by formula II, MM(OR)4. In the formula, M represents a metallic element and zirconium or cerium is employed in view point of easy availability. (n) is a positive integer and an integer in the range of 1-6 is preferably employed in view point of easy availability. R represents an alkyl group. A crosslinked porous polymer material is preferably employed as the porous basic material in view point of resistance against mobile phase or solvent in sample solution. When such loading material is employed as a separation column, fluoride ions in sample solution can be separated selectively and efficiently together with coexisting anions.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a packing material for separating and analyzing anions.

[0002]

2. Description of the Related Art Conventionally, liquid chromatography or ion chromatography using a column packed with an anion exchange resin is most often used for separating and analyzing anions in a solution (mainly an aqueous solution). ..

However, the selectivity of the anion exchange resin used in the separation column of an ion chromatography (rank ion exchange) _{^{is, SO 4 2-> HPO 4 2-}} > NO 3 -
_{^{> Br -> NO 2 ->}} Cl -> HCOO -> CH 3 COO ->
Since the order is F ^{− and} the selectivity for fluoride ion is extremely low, the fluoride ion overlaps with the peak (usually called water dip) due to the solvent of the solution to be measured, and accurate measurement is not possible. Have difficulty. Also, when nonionic or cationic substances coexist, these substances elute at the same position as the solvent,
Good separation of fluoride ions becomes difficult. Furthermore, when a large amount of acetate ions having similar selectivity coexist, mutual separation is impossible.

As a solution to the above problem, the nature of the base material of the anion exchange resin is devised, and interaction other than ion exchange action is taken into account to separate the fluoride ion from the water dip and improve the separation. The method is taken. That is, when a totally porous hydrophilic resin is used as the base material, the interaction with the base material resin enhances the retention of the fluoride ions, and the water dip can be separated. However, even if such a filler is used, it is difficult to perform mutual separation when a large amount of acetate ions having similar selectivity coexist.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above problems, and provides a fluoride ion capable of efficiently separating and analyzing anions containing a fluoride ion in a solution. It is an object of the present invention to provide a packing material for separating and analyzing anions which exhibits high selectivity with respect to anion.

[0006]

[Means for Solving the Problems] In order to develop a method for efficiently separating and analyzing anions coexisting with fluoride ions in a sample solution by a chromatographic method, the present inventors have developed various methods. As a result of repeated studies of the above, if a packing material in which hydrous metal oxides are dispersed and supported on a porous substrate is used as a separation column, anions that selectively and efficiently coexist with fluoride ions in the sample solution They have found that they can be separated simultaneously with other species, and have completed the present invention based on this finding.

That is, the present invention provides a hydrous metal oxide represented by the general formula (I) MO ₂ · nH ₂ O (I) (wherein M represents a metal element and n represents a positive integer). , General formula (II) M (OR) ₄ (II) (wherein M represents a metal element and R represents an alkyl group)
The present invention relates to a packing material for separating and analyzing anions, which is carried on the surface of a multi-porous substrate by hydrolysis of a metal alkoxide represented by:

The packing material for separation and analysis of anions in the present invention is obtained by impregnating a porous substrate with a metal alkoxide and then hydrolyzing the metal alkoxide to form a hydrous metal oxide on the surface of the porous substrate. It can be manufactured by supporting. The porous substrate is not particularly limited, for example, porous polystyrene, porous methylolated polystyrene, porous polymethacrylic acid ester, porous polyurethane, porous polyethylene, porous polyvinyl chloride, porous polypropylene, porous Examples include porous polymeric materials such as water-soluble polyvinyl alcohol, porous silica gel, porous alumina, porous carbon, porous inorganic materials such as activated carbon, etc. Considering resistance, crosslinked porous polymer materials such as crosslinked polystyrene, crosslinked methylolated polystyrene, crosslinked polymethacrylic acid ester, and crosslinked polyvinyl alcohol are preferable. Regarding the shape of this porous substrate, the specific surface area is 50 to 800 m ² / g and the average pore size is 5 to 10 from the viewpoints of separability, measurement time, pressure resistance and the like.
Those having a particle size of 0 nm and a particle diameter of 2 to 20 μm are preferably used.

In the present invention, impregnating a porous substrate with a hydrous metal oxide can be carried out by, for example, formula (II) M (OR) ₄ (II) (wherein M represents a metal element and R represents Indicates an alkyl group)
It can be carried out by dissolving the metal alkoxide represented by the following in an organic solvent having a low boiling point, mixing this solution with the dried porous substrate, and then distilling off the solvent.

The metal element of M in the general formulas (I) and (II) is not particularly limited, but zirconium, cerium and the like are preferable from the viewpoint of easy availability. Also,
N in the general formula (I) is 1 to 1 from the viewpoint of availability and the like.
It is preferably an integer of 6.

Examples of the alkyl group represented by R in the general formula (II) include methyl, ethyl, n-propyl and iso-.
Examples thereof include propyl, n-butyl, iso-butyl and tert-butyl groups.

As the low boiling point organic solvent, alcohols corresponding to metal alkoxides, that is, methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, te
Examples include rt-butanol, acetone, benzene, toluene and the like.

Next, the metal alkoxide impregnated in the porous base material is hydrolyzed with an acid or an alkali to form a hydrous metal oxide in the pores and on the surface of the porous base material. Are supported on the porous substrate.

The hydrolysis of the metal alkoxide is carried out at pH 2.
It is preferable to use an acidic aqueous solution of 0 or less or an alkaline aqueous solution of pH 11.0 or more. Further, the higher the temperature is, the faster the hydrolysis is performed. Usually pH 1.0
The metal alkoxide can be hydrolyzed by heating under reflux for 20 to 100 hours in an aqueous solution of sulfuric acid of up to 2.0.

In the filler thus obtained, the polymerized hydrous metal oxide is uniformly decomposed and deposited on the inner surface of the pores of the porous substrate, and the fluoride ion is favorably adsorbed. In addition, since the hydrous metal oxide has extremely low solubility in acids and alkalis, the dissolution of the metal when passing through the mobile phase is negligibly small, and it can be continuously and reproducibly used.

When anions are separated using the packing material for separation and analysis of anions according to the present invention, the pH is usually 2.0 to 9.0 depending on the retention capacity of the packing material for fluoride ions. Mobile phases can be used. If the pH is less than 2.0 or exceeds 9.0, the amount of retained fluoride ions tends to decrease. However, in the case of performing chromatographic separation analysis, it is preferable to elute from the separation column with a good peak shape in a short time, and it is possible to sufficiently use even if the pH exceeds 9.0. Practically, pH
It is preferably used in the range of 2.0 to 11.0.

Even when such an acidic or alkaline aqueous solution is passed, desorption of the bound metal ions is not observed at all, and therefore, in the measurement of anions containing fluoride ions using a chromatographic method, Anions containing fluoride ions can be continuously separated and analyzed with good reproducibility without desorbing metal ions from the packing material.

[0018]

The present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. Example 1 10 g of methylolated polystyrene-based filler tetra-n-butoxyzirconium loaded with hydrous zirconium oxide
Was dissolved in 30 ml of isopropyl alcohol, and 10 g of porous methylolated polystyrene resin (average particle diameter 12 μm) which had been washed and dried in advance was added thereto.
The mixture was placed under reduced pressure at room temperature for 60 minutes, after which the isopropyl alcohol was distilled off under reduced pressure. 50 for the resin obtained
ml of sulfuric acid aqueous solution of pH 2.0 was added and refluxed for 20 hours. After washing with water, the resin not supporting zirconium oxide or having a low supporting amount (utilizing the fact that the specific gravity is lighter than that of the resin supporting zirconium oxide) was removed by decantation and dried. The zirconium content of the filler thus obtained is 1.4 mol / g
Met.

Example 2 The filler obtained in Example 1 was used with an inner diameter of 6 mm and a length of 75 mm.
Packed in a column, attached to an ion chromatograph, and
After washing with H3.0 sulfuric acid aqueous solution, 3 mM sodium carbonate was passed as a mobile phase and used for separation of anions. 10p each for fluoride ion and chloride ion
When 50 μl of the sample solution containing pm was injected into the column for separation, chloride ions and fluoride ions were eluted in this order and good separation was exhibited. FIG. 1 shows the chromatogram of this example.

Example 3 The column used in Example 2 and the column used in ordinary ion chromatography were connected in series, and Example 2 was used.
The anion mixed solution was separated under the same conditions as in. The fluoride ion was eluted after the chloride ion, and the anions including the fluoride ion could be well separated without being affected by the water dip. FIG. 2 shows a chromatogram of this example.

Comparative Example 1 An attempt was made to separate the same sample under the same conditions as in Example 3 except that only the column for ion chromatography used in Example 3 was used. With the column used here, anions can be favorably separated as shown in FIG. However, fluoride ions are eluted by overlapping with the peak (called water dip) due to the solvent in the sample solution, and when the fluoride ion concentration is low or the composition of the solvent and coexisting substances in the sample solution changes. In that case, it is difficult to accurately quantify the fluoride ion.

Measurement conditions in Examples and Comparative Examples Example 2 Mobile phase: 3 mM Na ₂ CO ₃ Flow rate: 1.0 ml / min Sample: F = 10 ppm, Cl = 10 ppm Injection amount: 50 μl Detector: Conductivity detector temperature: 40 ° C. example 3 and Comparative example 1 mobile _{phase: 4mM Na 2 CO 3 / 4mM} NaHCO 3 flow rate: 1.0 ml / min specimen: F = 5ppm, Cl = 10ppm , Br = 10
ppm, NO ₃ = 30 ppm, SO ₄ = 40 ppm Injection amount: 50 μl Detector: Conductivity detector Temperature: 40 ° C.

[0023]

INDUSTRIAL APPLICABILITY The packing material for separating and analyzing anions of the present invention is capable of selectively measuring fluoride ions and separating anions in a sample solution containing a large amount of fluoride ions. it can. Moreover, since the bound hydrous metal oxide is not desorbed, it is possible to continuously separate and analyze anions with good reproducibility.

[Brief description of drawings]

FIG. 1 is a chromatogram measured under the conditions of Example 2 using the column prepared in Example 2.

FIG. 2 is a chromatogram measured under the conditions of Example 3 by connecting the column prepared in Example 2 and an ordinary column for ion chromatography in series.

FIG. 3 is a chromatogram measured under the conditions of Comparative Example 1 using only the ordinary column for ion chromatography used in Example 3.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshishige Suzuki 4-2-1, Gintake, Miyagino-ku, Sendai-shi, Miyagi Inside the Tohoku Institute of Industrial Research, Institute of Industrial Technology (72) Yoshinori Inoue 2-chome, Nakamachi, Musashino-shi, Tokyo 9-32 Yokogawa Electric Co., Ltd. (72) Inventor Osamu Hirai 4-13-1, Higashimachi, Hitachi-shi, Ibaraki Hitachi Chemical Co., Ltd. Ibaraki Research Institute

Claims (3)

[Claims] 1. A hydrated metal oxide represented by the general formula (I): MO ₂ .nH ₂ O (I) (wherein M represents a metal element and n represents a positive integer). (II) M (OR) ₄ (II) (wherein M represents a metal element and R represents an alkyl group)
A packing material for separation and analysis of anions, which is supported on the surface of a porous substrate by hydrolysis of a metal alkoxide represented by: 2. The packing material for separation and analysis of anions according to claim 1, wherein M in the general formula (I) is zirconium or cerium, and n is an integer of 1 to 6. 3. The packing for separating and analyzing anions according to claim 1, wherein the amount of the hydrous metal oxide represented by the general formula (I) supported is 5 to 50% by weight with respect to the porous substrate. Agent.