JPH03249911A - Ceramic filter for removing protein - Google Patents

Abstract

PURPOSE:To reduce the treating pressure and the amt. of residual liq. and to enhance the recovery rate by molding a ceramic filter for removing protein consisting of the sintered molded boy of hydroxyapatite having 50-90% porosity and >=10m<2>/g specific surface. CONSTITUTION:A slurry of the hydroxyapatite having >= about 50m<2>/g specific surface and with its molar ratio of Ca to P controlled to about 1.6-1.8 is spray- dried and granulated, or the apatite powder is wet or dry-granulated. The granulated material is press-molded, the molded body is sintered, and a ceramic filter for removing protein having 50-90% porosity and >=10m<2>/g BET specific surface is obtained. The average grain diameter of the apatite powder to be used is appropriately controlled to about 40-150mum, the forming pressure to about 10-500kg/cm<2> and the sintering temp. to about 500-800 deg.C.

Description

Detailed Description of the Invention "Industrial Application Field" The present invention is aimed at preventing reduction in column life due to abundant proteins when quantifying target components such as biological samples using high performance liquid chromatography (HPLC). This article is about protein removal filters used for pretreatment.

"Prior art" When quantifying a target component in a biological sample using high-performance liquid chromatography, a large amount of substances other than the target component exist, which may interfere with the quantification of the target component or shorten the life of the HPLC column. Problems occur. Therefore, sample pretreatment is performed to remove impurities. For example, in blood and tissue extracts, proteins present in large quantities are adsorbed to the column and shorten the column life, so protein removal procedures are necessary. - Protein removal for boat fishing is done by: - A method of adding an acid such as perchloric acid or trichloroacetic acid or a water-soluble organic solvent such as acetonitrile or methanol to aggregate the protein and centrifuging it. Method using filtration membrane,
■Methods such as adsorption separation using disposable column packing materials are used.

However, methods ① and ② are used when processing a large amount of samples, and are not suitable when processing a large number of samples in small quantities because the operations are complicated. In this case, method (■) is used. However, although the pretreatment is easy for ■, it is difficult to fill it evenly, so the filtration area cannot be increased.
Since there is a large amount of residual processing liquid, a large amount of sample is required.
Recovery rate decreases. Furthermore, if the filtration area is increased, the filler will not be filled uniformly, causing problems such as the sample not flowing uniformly. Therefore, it becomes necessary to increase the filling amount, which eventually causes problems such as excessive pressure. In addition, it requires a column to contain the filler and a supporting filter to prevent the leakage of filler particles, which poses problems such as being uneconomical if it is disposable.

[Specific means for solving the problem] The present inventors
In view of the problems of the prior art, the present invention has been arrived at as a result of intensive studies. That is, the present invention has a porosity of 50 to
This is a ceramic filter for protein removal consisting of a sintered body of hydroxyapatite with a BET specific surface area of 90% and a side area of 10 m.

The filter of the present invention is made by sintering hydroxyapatite, and the specific surface area of the sintered body is lQm/
g or more is preferable. When the specific surface area is smaller than this, the amount of protein adsorbed is not sufficient. There is no particular upper limit to the specific surface area, but it is up to 120 m/g for boat fishing. Further, the porosity is preferably in the range of 50 to 90%. If it is less than this range, it will take time to process the liquid, and if it exceeds this range, the mechanical strength will not be sufficient. Further, the average pore diameter is preferably in the range of 5 to 80 μm; if it is less than this range, high pressure will be required for liquid passage, and if it exceeds this range, contact between solid and liquid will be insufficient and the amount of adsorption will decrease.

Furthermore, the bending strength is preferably 5Kg/cut or more, and 5Kg/cut or more.
If the g/cI is less than 11, there are problems such as destruction during passage of liquid and the need for careful handling.

In order to obtain such a molded article, the hydroxyapatite used preferably has a specific surface area of 50 m/g or more.

Further, the Ca/P molar ratio is preferably in the range of 1.6 to 1.8.

To manufacture the ceramic filter used in the present invention, the apatite slurry liquid is spray-dried and granulated, or
Alternatively, spherical particles obtained by dry or wet granulation of apatite powder may be used, this may be pressure molded, and the molded body may be fired. At this time, it is better to make the particle size of the tight particle as uniform as possible, so that when it is made into a molded product, the pore size and pore distribution will be uniform, the sample liquid will flow uniformly, and the protein adsorption performance will be effectively exhibited. Such spherical particles are excellent in that uniform porous molded bodies can be produced with good reproducibility, but in the present invention,
Apatite of various shapes can be used without necessarily being limited to such spherical particles. For example, a method of adding a foaming agent to an apatite slurry, foaming, drying, and firing, or a method of adding a thermally decomposable substance can also be applied. The particle size of the powder is an average particle size of 20 to 200 μm, preferably 40 to 150 μm.
μm is preferable; if it is smaller than this, it is difficult for the sample liquid to flow, and if it is larger, it is difficult to maintain the strength as a filter, and the liquid flows too fast, making it difficult to fully exhibit adsorption performance.

The molding pressure is preferably 10 to 500 kg/cnl; if it is lower than this, the strength of the filter will be weakened, and if it is higher than this, the spherical shape will be broken, making it impractical. Firing temperature is 400-1200℃
, preferably 500 to 800°C. If it is lower than this, sintering will not progress so much and the filter will not have any strength, and if it is higher than this, the adsorption performance will decrease.

The filter of the present invention can have a larger filtration area than conventional treatment methods, and since it is a uniformly porous material, there is no need to make the filter thicker. Therefore, the processing pressure is low, the amount of residual liquid is small, and the recovery rate is high. Furthermore, since it is a ceramic molded body, it can be used simply by simply setting the ceramic molded body in a filter holder, and it is also highly economical since it does not require a filter or column to prevent particle leakage.

Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 H3poa (6 mol) and Ca (OH) 2
(After reacting at a reaction temperature of 40°C for a reaction time of 5 hours, the resulting slurry liquid was spray-dried to obtain a granulated product with an average particle size of 501 Jm. After compression molding at a pressure of 200 KgZd, sintering was performed. It was fired at a temperature of 600° C. for 0.5 hours to obtain a molded body of 25φ×3 mm.The molded body had a specific surface area of 40 m/g, a porosity of 72.5%, and an average pore diameter of 12 μm. Also, the bending strength is 22
K g/cnt.

An adsorption test was conducted using this molded body. Commercially available bovine serum was diluted 50 times and sample 2W11 was injected. The concentration of this liquid in terms of albumin was 920 μg/if. The albumin concentration of the permeate is IOμg/-, and its 98
．． 9% was removed by adsorption.

Example 2 A granulated product with an average particle size of 70 μm produced in the same manner as in Example 1 was compression molded at a pressure of 1 OOK g/crA, and then fired at a firing temperature of 800°C for 0.5 hours to form a 25φ×3
A molded body of mrn was obtained. The specific surface area of this molded body is 24.
m/g, the porosity is 71.0%, and the average pore diameter is 1.
It was 5 μm. In addition, the bending strength is 18Kg/cffl
Met. An adsorption test was conducted using this molded article in the same manner as in Example 1. As a result, the albumin concentration of the passed-through liquid was 52 μg/rnl, and 94.3% of it was adsorbed and removed.

Example 3 A granulated product with an average particle diameter of 50 μm produced in the same manner as in Example 1 was compression molded at a pressure of 200 Kg/ad, and then fired at a firing temperature of 500° C. for 0.5 hours to obtain a molded product of 25φ x 3 mm. Ta. The specific surface area of this molded body is 55 m/g,
The porosity was 74% and the average pore diameter was 10 μm. Also, the bending strength is 15Kg/an! Met. Using this molded article, an adsorption test was conducted using a snake in the same manner as in Example 1. As a result, the albumin concentration of the passed fluid was 25μg/m! 97.2% of it was removed by adsorption.

[Effect of the invention 1] The apatite filter of the present invention is excellent as a material for protein removal used in the pretreatment of biological samples, and compared to conventional materials filled with powder, the protein removal performance remains the same, but there is less powder leakage. There is no need for a support filter to prevent this, and since it is a molded product, it is easy to handle and has excellent versatility.

Claims (1)

[Claims] A ceramic filter for protein removal consisting of a sintered compact of hydroxyapatite with a porosity of 50 to 90% and a BET specific surface area of 10 m^2/g or more.