CS223732B1 - Column for liquid mainly high-pressure chromatography - Google Patents

Abstract

The invention relates to a liquid column, in particular high pressure high pressure chromatography dividing efficiency. The essence of the column according to the invention resides in that it consists of a glass tube, optionally hardened by a coating of potassium ions, filled with sorbent, which is enclosed in it made of a porous material or mesh and embossed clad in a metal or plastic sheath in which it is fastened and sealed with terminals for connecting to a chromatograph while being filled and the sealed glass tubes are optionally associated with the appropriate number of tires, spacers with holes, nuts and two endings.

Description

The present invention relates to a column for liquid chromatography, in particular high pressure chromatography with high separation efficiency.

The essence of the column according to the invention consists of a glass tube, optionally cured by a surface layer of potassium ions, filled with a sorbent enclosed therein by closures provided with porous material or mesh screens and inserted into a metal or plastic sheath in which is fixed and sealed with terminals for connection to the chromatograph, whereby the filled and closed glass tubes are optionally connected by means of an appropriate number of sheaths, apertures with holes, nuts and two terminals.

The invention relates to a column for liquid chromatography, in particular high pressure chromatography.

In liquid chromatography, metal columns (tubes) filled with finely divided sorbents are used to achieve high separation efficiency. In the chromatographic process, the solvent is usually passed under considerable pressure. The most common column material is stainless steel, which guarantees good mechanical properties of the column, sufficient pressure resistance and, in most cases, satisfactory corrosion resistance, which may be caused by liquids used as mobile phases or even by the analyzed compounds themselves. The columns are sealed with elements of metal or a suitable plastic. The design of the terminals must ensure that the dead volumes at the inlet and outlet of the column are kept to a minimum, and that during the actual chromatographic process, undesirable washing of the sample does not occur when the liquid flows through the column.

For this purpose, there are many design solutions that meet these requirements, but they also exhibit some negative effects inherent in liquid chromatography itself, due to the very nature of the concept and materials used hitherto.

First of all, the use of metal columns is limited by the corrosion stability of the material itself (stainless steel), which is very good in most organic solvents, but is not suitable for organic acids, halogenated hydrocarbons and their derivatives. and salts customary in reverse phase chromatography, ion exchange chromatography, affinity and gelo gel chromatography of biopolymers In addition, a mixture of sensitive biologically active compounds that are increasingly separated by liquid chromatography may irreversibly change the sample upon contact with metal.

No less serious are the problems with the precision machining of metallic materials, since most of the usual designs of columns are relatively complex. High quality smooth inner tube surface is a prerequisite for successful filling and use of columns. This is reflected in the relatively high production costs of making the metal column. In most cases, the conventional design has a single-purpose use and a limited lifetime, and the entire column needs to be replaced if the chromatographic mode changes or the efficiency decreases.

The design principle analogous to metal columns was also used in the production of glass columns (for example, the Czech author's certificate No. 183 468). Glass columns have a number of advantages in liquid chromatography. The main one is high chemical resistance to aggressive mobile phases or separated compounds. Equally important is the high quality of the inner surface of the tubes, which minimizes the zone washing due to unevenness of the inner surface. On the other hand, the great brittleness of the glass, the low pressure resistance and the need to shape the glass columns for attaching the end pieces complicate the use of the previously known glass column designs in high performance liquid chromatography. Solutions applying a metal sheath to compensate the internal column pressure due to external pressure are very demanding and expensive.

SUMMARY OF THE INVENTION The present invention relates to a column for liquid chromatography, in particular high pressure chromatography, consisting of a glass tube preferably cured with a surface layer of potassium ions, filled with a sorbent and enclosed therein with closures provided with porous material or mesh screens. The glass tube is inserted into a sheath which does not come into contact with the solvent and can therefore be made of metal or plastic. The tubes are fastened and sealed in the housing, which is the supporting structural element, by means of terminals which serve for connection to the chromatograph. The filled and closed glass tubes are optionally connected in series by means of an appropriate number of shells, apertures, holes, nuts and two endings to form a column whose length is the sum of the lengths of the individual tubes.

Fig. 1 is a simplified cross-sectional view of a column according to the invention consisting of a glass tube 1 provided with closures 2 with a porous partition 3 and inserted into a housing 4 on which threads 6 hold the endings 5 with capillary holes through which the mobile phase enters and exits . The metal rings 10 of the closure 2 made according to FIG. 2 are sealed to the ends of the glass tube 1 and a seal 7 made of plastic (preferably polytetrafluoroethylene) is inserted into the front opening of the closure, which fixes the porous partition 3. steel, polytetrafluoroethylene, or glass, or a fine metal mesh. The rings 10 have an outer diameter such that they slide through the housing 4. After the terminals 5 have been removed, the threads 6 abut the seal 7 of the closure 2 and the column is ready for use.

The closure 2 of the tube 1 can also be formed by a cylindrical ring made of metal according to FIG. 3, which has shaped internal walls with recesses and is filled with a cone-shaped insert of plastic (polytetrafluoroethylene).

The inner diameter of the cylindrical portion of the liner 8 is smaller than the outer diameter of the glass tube 1 and a porous partition is provided in the liner

3. After pressing the glass tube into the closure, the plastic fills the recess in the metal ring 10 and the tube is fixed by applying pressure.

Another type of closure of tube 1 is shown in Fig. 4 and consists of a plastic plug 9 with a drilled hole, which fixes the porous partition 3 and fits with its widened end into the metal ring 10. In both last cases, the mechanism her comfort223732

The same as in the case of caps sealed to the tube.

The individual columns provided with the jacket 4 can be connected to each other in series as shown in Fig. 5. The columns are connected to each other by an intermediate piece 11 with an opening for the mobile phase passage that abuts the seal 7 and the jacket is connected by a nut 12.

The high performance liquid chromatography columns of the present invention have a number of advantages over the currently known metal and glass columns. In addition to the high chemical resistance of the glass and the perfect inner surface of the tube, the possibility of visual monitoring of the chromatographic separation and possibly of the filling quality by means of one or more visors in the jacket is a great advantage. In a single shell, a simple, tool-free operation can replace glass tubes filled with different sorbents as required for each type of chromatographic analysis. The columns according to the invention also overcome the above-mentioned disadvantages of the prior art glass column design solutions. Relatively brittle glass tube is placed in a rigid protective jacket during work, low pressure resistance of glass can be increased by chemical reinforcement and it is not necessary to widen the glass tube edges, because when using the column . The ability to exchange tubes in a single jacket brings a significant reduction in the cost of a set of columns packed with different sorbents. When replacing the original column with a new one, you only need to purchase a glass inner tube filled with the necessary sorbent. Joining columns in series makes it easy to create variable assemblies on a modular principle, including the inclusion of short protective columns.

The columns according to the invention are not only economical for the user but also for the manufacturer. By eliminating the number of machining operations required for each individual column, the labor is reduced and the cost of the metal material is also reduced. The construction of the columns according to the invention makes it possible to substantially increase the proportion of mechanization and automation in their production and filling with the sorbent.

The invention is illustrated and illustrated by the following examples without being limited thereto.

Example 1

The chromatographic column was made according to FIG. 1. Tube 1 is made of SIAL type borosilicate glass with an inner diameter of 3 mm and a wall thickness of 2.5 mm. The tube is 100 mm long. The closures 2 made according to FIG. 2 are sealed to the tube 1 and the porous partitions 3 are made of stainless steel meshes 3 mesh and fixed with a Teflon seal 7. The outer casing 4 is made of a brass tube with an internal diameter of 12 mm and a wall thickness 2.5 mm, along which two visors are milled against each other. The ends of the sheath are provided with external threads 6 on which brass terminals 5 with stainless steel inserts are provided with a bore and an external thread for receiving connecting capillaries. The column is packed with microparticular spherical silica gel having a particle size of 5 µm at a pressure of 40 MPa and achieves an efficiency of 25,000 theoretical plates per meter of column length. It was found in pressure tests of the empty column that after treatment of the glass tube by surface diffusion of potassium ions, it resists to 80 MPa without destruction.

Example 2

The column is made analogously to Example 1 and consists of a thick-walled calibrating tube 1 made of SIMAX glass having an inner diameter of 3.57 mm, a wall thickness of 2.3 mm and a length of 100 mm, chemically cured by a potassium ion coating. However, the closures 2 were made according to FIG. 4; they consist of a Teflon plug 9, a metal ring 10 and an interposed partition 3 of porous Teflon. The teflon plug 9 with its widened edge is fixed by the ring 10, which also serves as a guide when sliding into the sheath 4, which is made of an aluminum alloy (a tube with an outer diameter of 15 mm and a wall thickness of 2.5 mm). The housing 4 is provided with a series of circular visors with stainless steel ends 5 that abut the expanded edge of the Teflon plug 9 and seal the column tube. The column showed a pressure resistance of 60 MPa in pressure tests and, after loading with 5 μΐη spherical silica gel with modified octadecyltrichlorosilane, showed an efficiency of 20,000 theoretical plates per meter of length.

Example 3

The column was made analogously to Example 2, but the closures 2 of Figure 3 were used. After loading with spherical silica gel with a particle size of 10 μΐη, the column exhibited an efficiency of 15,000 theoretical plates per meter of length.

Example 4

Two 150 mm and 40 mm long glass tubes 1 are used, the inner diameter is 3 mm and the wall thickness is 2.5 mm. Both are strengthened by diffusion of potassium ions. The tubes are provided with closures 2 according to Example 1, perforated sheaths 4 of aluminum and provided with terminals 5 also according to Example 1. The tubes are filled at a pressure of 35 MPa with spherical silica gel o; size 5 μπι with modified octadecyltrichlorosilane. After loading, the columns were connected in series by means of a nut 12 and an intermediate piece 11 with an orifice (made of stainless steel) and sealed at both ends with aluminum ends with stainless steel inserts. This system was used for reverse phase chromatography and its efficiency was 40,000 theoretical plates per meter of length. In this case, the short column protects the column itself from the substances which deactivate the sorbent. In some cases, instead of the stainless steel liner that forms part of the inlet terminal 5, the column was directly connected to the LCI 20 injection valve (Laboratory Instruments, Prague), the fitting of which was the same type as the liner used.

Example 5

The column is the same as in Example 1, except that for a particularly corrosive environment, the protective jacket 4 is made of a 14 mm outer diameter titanium tube and a 2 mm wall thickness.

Example 6

The column is analogous to Example 1, except that for a particularly demanding embodiment, the protective jacket 4 of the column and the terminal 5 are made of stainless steel.

Example 7

The column has the dimensions and construction of the same as in Example 1, except that the material of the jacket 4 is polyvinyl chloride, or alternatively polypropylene, polyester and polyamide. Holes for visual monitoring of the chromatographic process are not milled in the tube. The terminals 5 are aluminum, lined with stainless steel. At the test overpressure of 30 MPa, the columns provided with these jackets were stable.

Example 8

The column is made according to Example 1 except that the column jacket 4 is not perforated and is provided at its upper and lower ends with tubes for supplying the tempering medium to the space between the jacket and the glass tube. The column is packed with 10 μΐη spherical silica gel and used for high performance liquid chromatography at 80 ° C. Water is used as the tempering medium.

Claims (7)

Column for liquid chromatography, in particular high pressure chromatography, characterized in that it consists of a glass tube (1), optionally cured by a surface layer of potassium ions, filled with a sorbent enclosed therein by closures (2) provided with partitions (3) of porous material or a mesh and embedded in a metal or plastic sheath (4) in which it is fastened and sealed by end pieces (5) for connection to the chromatograph, the filled and closed glass tubes (1j being optionally connected by an appropriate number of sheaths (4), intermediate pieces ( 11 with a hole, nuts (12) and two terminals (5). Column according to claim 1, characterized in that the cap (2) of the tube (1) is formed by a plug (9) with an opening and a widened edge, said plug (9) having a partition (3) of porous, material or stainless steel. the mesh and plug (9) with its widened edge fits into the shaped metal ring (10). Column according to claim 1, characterized in that the cap (2) of the tube (1) is formed by metal rings (10) adhered to the outer end of the glass tube (1) and a plastic gasket (7) is inserted into its opening. preferably of polytetrafluoroethylene, the recess of which is a partition (3) of porous material. Column according to claim 1, characterized in that the closure (2) of the glass tube (1) is formed by a metal ring (10) with shaped inner walls, which is provided with an insert (8) of tapered plastic into which a partition is inserted. (3) of porous mass or mesh. 5. The column of claim 1, wherein the jacket (4j) is a metal selected from the group of stainless steels, aluminum and its alloys, brass, titanium or plastic selected from the group of polyamides, polypropylene, polyvinyl chloride, polyester, phenolformaldehyde and urea-formaldehyde. resins. 6. The column according to claim 1, characterized in that the jacket (4) is provided with two openings for the inlet and outlet of the tempering medium. A column according to claim 1, characterized in that the column jacket (4) is provided with at least one opening for visual monitoring of the column load.