# Patent

## Title
Pre-filled columns for flash chromatography with higher separating efficiency

## Abstract

A column for flash chromatography having spherical, or semi-spherical, and porous silica gel having a granule size between 3 and 45 μm and pores between 30 and 300 Å.

## Background
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to pre-filled columns for flash chromatography. These columns, which are filled with spherical and porous silica gel or with semi-spherical and porous silica gel, allow a considerable increase in the quality of the purification of synthetic products by means of flash chromatography.
The technique of flash chromatography can particularly be applied to the fast purification under low and medium pressure of synthetic products in pharmaceutical, cosmetic, agrochemical and biotechnology research.
2. State of the Art of Flash Chromatography
The technique of chromatography was discovered more than 100 years ago by a Russian chemist named TSWETT. This chemist described the separating power of alumina oxide placed in a glass column on which he deposited chlorophyll. He observed the descending migration of color rings along the glass column.
Since his discovery, numerous analytical, preparative, and industrial applications have been developed.
Gas chromatography (GC) and high performance liquid chromatography (HPLC) can be cited as being among the most important applications. Flash chromatography was born from the need to purify synthetic products rapidly and simply in a laboratory context and in quantities comprised between 10 mg to 100 g.
Flash chromatography differs from preparative HPLC in the particle size of the silica gel granules, namely the granules are bigger in flash chromatography, and provide a simpler and more rapid application of flash chromatography.
Pre-filled flash chromatography columns filled with irregular porous silica gel having particle size of 40-60 μm or 20-40 μm, have been on the market for several years. These new chromatography columns brought an enhanced ease of use through immediate application. However, these columns did not bring any advantage in terms of the quality of separation.
SUMMARY OF THE INVENTION
In the invention described herein, the separating properties of flash chromatography columns have been increased significantly, while maintaining the ease of use of the technique combined with a low working counter-pressure.


DETAILED DESCRIPTION OF THE INVENTION
According to one aspect of the invention, there are provided columns for flash chromatography with spherical and porous silica gel having particle size between 3 and 45 μm and pores between 30 and 300 Å. According to another aspect of the invention, there are provided columns for flash chromatography with semi-spherical and porous silica gel having particle size between 3 and 45 μm and pores between 30 and 300 Å.
A pre-filled column for flash chromatography is manufactured by filling a tube or a syringe or any other suitable body, on which a frit (filter) is attached to prevent the silica gel from leaving.
A quantity of spherical and porous silica gel or of semi-spherical and porous silica gel is poured.
A second frit is then placed with force on top of the bed that has been created.
In order to have good homogeneity in the filling of the tube, syringe or other suitable body and to eliminate preferential paths that are detrimental to the technique, the column is made to vibrate while, at the same time, the upper frit is pushed by means of an appropriate object so as to achieve a homogenous compression on the entire surface of the frit.
A homogenous packing can also be obtained though use of liquids or gasses.
After the dead volume has been reabsorbed, the flash chromatography column is ready for use.
It is possible to improve the quality of the compression by passing a solvent through the column until the upper bed of the column has stabilized.
Example 1
A column for flash chromatography is manufactured with 50 g of spherical and porous silica gel having particle size of 25-40 μm.
Column length: 85 mm.
Silica gel: 50 g of spherical and porous silica gel of 70 Å pore size.
Recipient: syringe body of 150 ml volume and a diameter of 37 mm
Take the 150 ml syringe body and place a porous frit in the bottom of the syringe body.
Pour 50 g of spherical and porous silica gel in the column.
Add a second porous frit on top of silica bed.
Press on the top frit while vibrating the whole with vibrator or a vibrating table.
Wait until the bed has stabilized and does not move downwards.
a) Results Obtained
Operational Conditions:
Eluent: Ethyl acetate/Hexane.
Flow: 35 ml/min.
Detection: UV 254 nm
Gradient: A: Hexane/B: Ethyl acetate.
FIG. 1 illustrates the main substance that has been injected.












Time
% A
% B

















0
100
0


5
100
0


5.1
90
10


10
90
10


10.1
80
20


15.0
80
20


15.1
70
30


25
70
30









FIG. 2. illustrates the chromatogram obtained.
Number of plates on the main peak: 684.
K′: 10.
Working pressure: 16 psi.
Asymmetry of main peak: 1.75.
FIG. 3 shows, for the purpose of comparison, a chromatogram of a same column and in the same conditions, but filled with irregular silica gel, having particle size of 15-35 μm, in accordance with the prior art.
Number of plates of the main peak: 156.
K′: 10.5.
Working pressure: 43 psi.
Asymmetry of main peak: 5.88.
c) Comparative Table














Column with spherical and
Column with irregular and



porous silica gel
porous silica gel


















Number of plates
684
156


K′
10
10.5


Working pressure
16 psi
43 psi


Asymmetry of the main peak
1.75
5.88









Although specific embodiments of the invention have been described and illustrated, the invention is not to be limited to the specific forms or arrangements of parts so described and illustrated. The invention is limited only by the claims.

## Claims

1. A method for purifying a product comprising:
performing a flash chromatography process by:
introducing an eluent with at least one product to be purified into a flash chromatography column pre-filled with a spherical and porous silica gel having particle size between 3 and 45 μm and pores between 30 and 300 Å;
causing the eluent to flow through the pre-filled column; and
obtaining a separation of the at least one product to be purified.

2. The method of purifying a product of claim 1 wherein the flash chromatography column contains between 10 mg to 1 kg of the spherical and porous silica gel.

3. The method for purifying a product according to claim 1 wherein the flash chromatography column is adapted to purify synthetic products in quantities comprised between 10 mg to 100 g.

4. A method for purifying a product comprising:
performing a flash chromatography process by:
introducing an eluent with at least one product to be purified into a flash chromatography column pre-filled with a semi-spherical and porous silica gel having particle size between 3 and 45 μm and pores between 30 and 300 Å;
causing the eluent to flow through the pre-filled column; and
obtaining a separation of the at least one product to be purified.

5. The method for purifying a product of claim 4 wherein the flash chromatography column contains between 10 mg to 1 kg of the semispherical and porous silica gel.

6. The method for purifying a product according to claim 4 wherein the flash chromatography column is adapted to purify synthetic products in quantities comprised between 10 mg to 100 g.

7. A pre-filled flash chromatography column for purifying a product, comprising
a plastic tube or syringe body; and
spherical and porous raw silica gel having particle size predominantly between 3 and 45 μm and pores between 30 and 300 Å placed inside the plastic tube or syringe body.

8. The pre-filled flash chromatography column according to claim 7 wherein the flash chromatography column contains between 10 mg to 1 kg of the spherical and porous silica gel.

9. The pre-filled flash chromatography column according to claim 7 adapted to purify synthetic products in quantities comprised between 10 mg to 100 g.

10. A pre-filled flash chromatography column for purifying a product, comprising
a plastic tube or syringe body; and
semi-spherical and porous raw silica gel having particle size predominantly between 3 and 45 μm and pores between 30 and 300 Å placed inside the plastic tube or syringe body.

11. The pre-filled flash chromatography column according to claim 10 wherein the flash chromatography column contains between 10 mg to 1 kg of the semispherical and porous silica gel.

12. The pre-filled flash chromatography column according to claim 10 adapted to purify synthetic products in quantities comprised between 10 mg to 100 g.

13. A pre-filled flash chromatography column for purifying a product, comprising
a low-pressure glass tube or syringe body; and
spherical and porous raw silica gel having particle size predominantly between 3 and 45 μm and pores between 30 and 300 Å placed inside the low-pressure glass tube or syringe body.

14. The pre-filled flash chromatography column according to claim 13 wherein the flash chromatography column contains between 10 mg to 1 kg of the spherical and porous silica gel.

15. The pre-filled flash chromatography column according to claim 13 adapted to purify synthetic products in quantities comprised between 10 mg to 100 g.

16. A pre-filled flash chromatography column for purifying a product, comprising
a low-pressure glass tube or syringe body; and
semi-spherical and porous raw silica gel having particle size predominantly between 3 and 45 μm and pores between 30 and 300 Å placed inside the low-pressure glass tube or syringe body.

17. The pre-filled flash chromatography column according to claim 16 wherein the flash chromatography column contains between 10 mg to 1 kg of the semi-spherical and porous silica gel.

18. The pre-filled flash chromatography column according to claim 16 adapted to purify synthetic products in quantities comprised between 10 mg to 100 g.