EP2502064A1

EP2502064A1 - Supporting devices for capillary and nano hplc columns

Info

Publication number: EP2502064A1
Application number: EP09805871A
Authority: EP
Inventors: Cosimo Manzo
Original assignee: Avantech Group SRL
Current assignee: Avantech Group SRL
Priority date: 2009-11-18
Filing date: 2009-11-18
Publication date: 2012-09-26
Also published as: WO2011061769A1

Abstract

There is described a supporting device (11) for capillary and nano columns used in liquid chromatography, wherein adapter means are provided to hold a column in position in the housing element and to ensure fluid-tight seal of the column regardless of its length and/or of its diameter. Separate embodiments describe adapter means for columns of different diameters, but of predetermined length; adapter means that can be adjusted in length; a coiled column; and multiple columns connected in series.

Description

"SUPPORTING DEVICES FOR CAPILLARY AND NANO HPLC COLUMNS"

FIELD OF THE INVENTION

The present invention relates to supporting devices suitable to contain capillary and nano columns for liquid chromatography and, in particular, for High Pressure Liquid Chromatography, also known as HPLC.

BACKGROUND ART

High Pressure Liquid Chromatography is a chromatography technique which allows the separation of two or more compounds present in a solvent, using the equilibrium of affinity between a "stationary phase" positioned inside the chromatography column and a "mobile phase" that flows through it. A substance with higher affinity to the stationary phase with respect to the mobile phase will employ a longer time to pass through the chromatography column (retention time) with respect to a substance with low affinity to the stationary phase and high affinity to the mobile phase.

A detector (generally UV, mass spectrometer or MS, etc.) is applied to the end of the chromatography column and, with the aid of subsequent data processing, this allows continuous analysis at the column outlet and consequent identification, also quantitative, of the substances injected into the column inlet mixed together, and separated during their passage along the chromatography column according to appropriate operating methods.

The HPLC technique (cap-HPLC and nano-HPLC) offers numerous advantages due, for example, to the small dimensions of the columns with respect to those used in other chromatography techniques and also due to the possibility of using small quantities of the compound to be analyzed, while ensuring high accuracy and precision and, above all, easy interface with mass spectrometers.

According to the type of compounds to be analyzed using HPLC, it is possible to select the most suitable type of column and eluent.

In the case in which the mass spectrometer is used as a detector, the most suitable columns for HPLC analysis, particularly in the field of proteomics, have proved to be those with an internal diameter in the region of 50-500 μηι, also called nano and capillary columns. In general, HPLC systems with capillary columns and MS detection are used for the separation and identification of biomolecules, typically proteins and polypeptides. In recent years, a significant increase has been observed in the use of HPLC instruments based on capillary columns and mass spectrometers as detectors (cap-HPLC/MS and nano-HPLC/MS), due to the considerable increase in studies and research activities in the field of proteins and biomolecules in general.

Although having numerous advantages, capillary and nano columns for HPLC nonetheless have the characteristic of being delicate and/or very fragile, and therefore difficult to handle, both due to their extremely small dimensions and due to the material with which they are made, often fused silica. When they are used as is, they must be inserted, positioned and secured in the instrument for performing HPLC analysis. Although these operations are considered routine in the case of conventional columns, in the case of capillary columns they are often broken and require to be replaced, resulting in even considerable increases in costs.

To overcome the aforesaid drawbacks, some supporting devices for HPLC capillary columns have been designed and are currently available on the market; these supporting devices have a hollow cylindrical housing made of rigid material (PEEK or steel), with an internal diameter and length suitable to accommodate the column to be used. At each of the two opposite ends of the housing, which are appropriately threaded, it is possible to position a filter or a sealing capsule, a support for the filter or sleeve, suitable to be screwed to the end of the housing, a ferrule and an end nut to close the system, suitable to be screwed to the support for the filter or sleeve. Once the housing has been assembled with the column inside it, the column is protected and therefore less exposed to breakages or damages in general, thereby facilitating its installation in the instrument.

Although the supporting systems for capillary columns according to prior art ensure greater protection of the column with respect to any accidental breakages, they do not solve the problem of having to replace the column completely if it should nonetheless be accidentally broken or, a much more frequent occurrence, if it should become clogged, for example at the inlet with respect to the direction of flow. In fact, whether the column is used as is or it is used with the aid of a support system according to prior art, very often when the mixture of compounds is injected, waste materials, coming both from the mixture and from the solvents used as mobile phase, can accumulate at the inlet of the column. Although mobiles phases are highly purified before their use, given the dimensions of the capillary columns, any waste materials, even if present only in traces, frequently accumulate at the inlet and cause clogging of the column. Moreover, once waste materials are present in the column, its subsequent use is compromised given the risk of these materials being at least partly drawn in during later analyses, with the risk of polluting subsequent samples.

In all the situations described above, the capillary column must be completely removed and replaced with a new one. As capillary columns are characterized by their considerable costs, also due to the difficulties encountered in their preparation, complete replacement thereof implies a considerable expenditure.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a supporting device for capillary and nano columns, in particular for capillary and nano columns for HPLC, which is adjustable in length, so that it can also accommodate columns of different lengths and small dimensions.

Another object of the present invention is to provide a supporting device for capillary columns, in particular for capillary and nano columns for HPLC, which is suitable to accommodate columns with a smaller diameter than the internal diameter of the device.

Yet another object of the present invention is to provide a supporting device for capillary columns, in particular for capillary and nano columns for HPLC, which allows said columns to be easily re-used even in the case in which they have been subjected to clogging or damages of other kind.

These and other objects and relative advantages which will be more apparent from the description below are achieved with a supporting device for capillary and nano columns according to claim 1.

The supporting device in general comprises at least one housing element equipped with a seat for at least one column and at least one pair of unions connected to the ends of the housing element. Each of the unions houses at least one sealing capsule and one ferrule abutting against the capsule for sealed connection of the column to a liquid chromatography instrument.

The supporting device advantageously includes adapter means to hold a column in position in the housing element and to ensure fluid-tight seal of the column regardless of its length and/or of its diameter.

According to a first embodiment, the adapter means can include a pair of ferrules equipped with an axial through hole into which end portions of the column are inserted! The ferrules have at least one end shaped to abut with seal in the seats of corresponding shape of the sealing capsules housed in the unions.

The ferrules are inserted at the ends of the housing element and held in position by sleeves screwed onto the threaded ends thereof.

The unions are in turn connected indirectly to the ends of the housing element by screwing onto corresponding external threaded portions of the sleeves.

Advantageously at least one ring nut is provided, screwed onto the external threaded portion of each sleeve, capable of abutting when screwed against the union to prevent (accidental) mutual unscrewing between union and sleeve.

This allows the device to be adapted to any diameter of the column housed therein. In fact, it is sufficient to appropriately select the ferrules and the sealing capsules with through holes of appropriate internal diameter to house a column of any external diameter in the device.

In a second embodiment of the device, in alternative to or in combination with the first embodiment, the housing element includes at least two parts. The adapter means in this case include at least one intermediate sleeve that connects by screwing two of the threaded ends of the two parts forming the housing element.

A ring nut is also provided, screwed onto a threaded end portion of at least one of the parts forming the housing element, capable of abutting during screwing against the intermediate sleeve to prevent mutual unscrewing between the parts forming the housing element and the intermediate sleeve.

This embodiment allows the device to be adapted to house columns of different length, for example when it is necessary to shorten a column already used to remove a short clogged section without introducing dead spaces that might deteriorate the separation.

Between the possible embodiments of the device according to the invention, the seat for the column can, for example, be formed by an internal axial cavity which opens only at the ends thereof. The seat can in any case include at least one intermediate opening to place the internal axial cavity in communication with the external environment.

In other words, the device according to the present invention is, for example made of metal and is provided, preferably and above all when its length exceeds the order of a few centimetres, with openings or "windows" of various shape. Given that, in the majority of cases, the columns must be kept at a temperature above the ambient temperature during HPLC analysis, the device of the invention is made of metal to facilitate the diffusion of heat inside and the transmission of heat to the column in a homogeneous manner.

More in detail, a supporting device according to the present invention includes a housing element that has a hollow cylindrical shape and can be produced of variable length, for example between 1 cm and 1 m, and also with variable internal diameter, for example between 1 mm and 1 cm, for the capillary column to be inserted therein.

In the case in which the column has a diameter even significantly smaller than the diameter of this device, it can in any case be easily secured to the ends of the device by the ferrules, and remain thus secured and held in the required position, without undergoing any damage and also ensuring the necessary fluid-tight seal.

The immediate advantage is given by the fact that, with a limited number of supports available, it is possible to use a same support for a very large number of columns, even with internal/external diameter differing greatly from one another, without it being necessary to use a specific supporting device for each diameter of capillary column used.

In fact, given the characteristics of the capillary columns and the characteristics of the substances that are typically analyzed and/or separated with these columns, even small differences in the diameter of the columns can result in very significant variations in the analysis results, especially in terms of sensitivity. Using a supporting device according to the present invention it is thus possible to use a wide range of capillary columns even with diameters differing greatly to one another, with a limited number of supports.

A further advantage offered by the device according to the present invention is represented by the fact that the device is also adjustable in length. In the case in which clogging occurs at the inlet of the capillary column, due to impurities present in the mixture to be analyzed and/or in the solvents forming the mobile phase or used to convey the mixture, it is possible to cut off the clogged part of the column and consequently shorten the device without introducing significant dead spaces. In fact, as the device is adjustable in length, it can be shortened by a part corresponding to the section of column removed.

At this point the column thus "shortened" can be positioned once again inside the same device and re-used, without having to be completely eliminated and replaced. The supporting device according to the invention is therefore a versatile device, as it can be used not only with capillary columns with diameters differing greatly from one another, but also with columns of small dimensions in length, both with respect to the original dimensions of the column and with columns of different lengths.

In practice, the use of the supporting device according to the invention allows both re-utilization of a capillary column that has been reduced in length, and use of columns of different length without having to replace the device. Therefore, the device according to the invention is adjustable in length according to the length of the column that one wishes and/or requires to use.

In a further embodiment, the housing element can alternatively include a frame to support at least one capillary column in coiled configuration. The housing element in this case includes a pair of internally hollow arms connected to the unions. Each of the arms can be slidingly positioned with respect to the frame and can be locked in position with screw means.

In some cases, HPLC technology provides for the use of columns of particular length, which cannot be positioned inside the instrument unless provided in the form of a "coil", i.e. in turns wound about themselves in the form of a "spring" or "spiral", in order to occupy a limited space.

In this case, i.e. when it is necessary to use long capillary columns, wound about themselves, the supporting device according to another embodiment of the present invention is produced in the form of a frame equipped with two arms at opposite ends.

Each arm allows the inlet and the outlet of the column to be connected to the instrument to perform HPLC analysis, and preferably includes the system already illustrated above which allows the supporting device to be adjusted as a function of the length of the capillary column, with the same advantages illustrated above.

According to another aspect of the present invention, a support assembly is provided for a plurality of capillary or nano columns used in liquid chromatography and connected in series with one another.

The assembly comprises a plurality of housing elements connected in series with one another by screwing and each equipped with a seat for at least one column, and with a pair of unions connected to the free ends of the housing elements positioned at the opposite ends of the series. Each of the unions houses at least one sealing capsule and one ferrule abutting against the capsule for sealed connection of the column of each end of the series with a liquid chromatography instrument. Adapter means are advantageously provided to hold each column in position in the respective housing element and to ensure fluid-tight seal of the columns connected in series regardless of their length and/or of their diameter.

The assemblies thus produced therefore have two or more housing elements connected by screwing them together using intermediate sleeves with appropriate threads. This allows two or more housing elements to be mutually combined to house therein two or more types of different columns, for example a pre-column followed by one or more capillary columns connected in series with one another.

In this case, the intermediate sleeves also have the same characteristics found at the ends of a single housing element such as the one described above, i.e. each end can be connected to the end of another housing element or to the union for connection to the chromatography instrument. Also in this case, each of the housing elements of the assembly can be formed of two parts so that it is adjustable in length, thus making it possible to house capillary columns that are subjected to variations in their length, for the reasons explained above. The support assembly that provides for connection in series of at least two housing elements is particularly advantageous when separation of the mixture to be performed using HPLC technology requires the use of columns with different characteristics, for example the combined use of an ion exchange column and of a reverse phase column.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the present invention will be more apparent from the description below, provided by way of example with reference to the accompanying drawings, wherein:

- Figure 1 is a front view, in partially disassembled condition, of the components of a supporting device for capillary columns according to prior art;

- Figure 1 A is an enlarged view, in longitudinal section, of some components of the device of Figure 1 ;

- Figure 2 is a front view, partially in cross section and in unassembled condition, of a supporting device according to a first embodiment of the present invention;

- Figure 2A is an enlarged view, in longitudinal section, of some components of the device of Figure 2;

- Figure 3 is a view in assembled condition of a supporting device adjustable in length according to another embodiment of the present invention;

- Figure 4 is a schematic view in longitudinal section of the components of a further embodiment of the supporting device according to the present invention in which coiled capillary columns can be housed;

- Figure 4A is an enlarged view, in cross section along the plane A- A, of a detail of Figure 4;

- Figure 4B is an enlarged view, in cross section along the plane B-B, of a detail of Figure 4; - Figure 5 is a view in assembled condition of a support assembly according to the present invention- in which it is possible to install several columns connected in series with one another; and

- Figure 5A is an enlarged view, in longitudinal section, of some components of the device of Figure 5.

MODES FOR CARRYING OUT THE INVENTION

Figures 1 and 1 A show a supporting device 1 for capillary columns according to the prior art and, respectively, an enlarged view in longitudinal section of some components thereof.

The prior art device 1 comprises a housing element 2 of hollow cylindrical shape suitable to accommodate therein a capillary column 50. The housing element 2 can be provided with an opening 5 to place the internal cavity in communication with the external environment, for example to allow uniform heating of the column housed in the housing element 2 for the entire length thereof, and visual inspection of the column inside it.

Both ends of the housing element 2 comprise a threaded portion 3 onto which a union 6 is screwed. This union comprises a first internally threaded portion 6a and a second externally threaded portion 6b, the first of which allows connection of the union 6 to the threaded portion 3 of the housing element 2.

The threaded portion 6b of the union 6 receives screwed thereon a nut 9 which causes locking of a ferrule 10, or similar coupling means known in the art, at the end of the supporting device. The union 6 is shaped internally to allow housing of at least one sealing capsule 4 and, if necessary, also a filter (not shown).

The ferrule 10 is internally hollow and generally has a truncated-cone shaped end portion to allow fluid connection of the end of the capillary column 50 with the liquid chromatography instrument, and therefore passage of the fluid to be analyzed.

In fact, when all the components of the supporting device 1 are connected to one another, the capillary column is ready to be handled in safety, reducing the risk of damages, and can thus be easily housed inside the instrument.

As represented in detail in Figure 1 A, the sealed connection between the column

50 and the ferrule 10 is produced by a truncated cone shaped portion 7 made in one piece with the support 2 and inserted by pressure into the sealing capsule 4, on the opposite side with respect to the ferrule 10.

In practice, the prior art proposes a column 50 fully incorporated in the support 2, which is also shaped at the ends to ensure the necessary fluid-tight seal between the column and the chromatography instrument to which it must be connected. Therefore, in the case in which it is necessary to use a column with different diameter or to shorten this column to remove any clogging, the prior art requires replacement of the entire assembly formed of the column and of its supporting device.

The supporting device for capillary columns according to the present invention is instead adaptable to different types of columns of different diameter and/or length, thus allowing a smaller assembly of supporting devices to be used with a wide variety of columns, or allowing the same device to be re-used with a same column that has been reduced in length.

Figure 2 shows a first embodiment of a supporting device 11 for capillary or nano type columns 50, provided with adapter means that allow columns of different diameter, but of predetermined length, to be housed.

In particular, some components at one of the ends (left end) are represented in unassembled condition and in longitudinal section, while at the opposite end the supporting device is represented in assembled condition. In any case, as the device is exactly symmetrical with respect to a plane perpendicular to its longitudinal axis, it is evident that exactly the same components represented in unassembled condition are also present in assembled condition, even if they are not visible.

The supporting device 11 comprises a housing element 12, inside which a longitudinal seat is provided, for example a cylindrically shaped cavity, suitable to house a capillary column 50. Openings 55 can be provided along the housing element 12, in a number variable as a function of the length of the housing element 12, to allow uniform diffusion of heat and, if necessary, visual inspection of the inside of the cavity of the housing element 12 that accommodates the column 50. A threaded external surface portion 13 is present on the end parts of the housing element 12. The supporting device according to the invention comprises a union 16 equipped internally with a seat 16c in which a sealing capsule 14 is housed. Contrary to the case of prior art devices (Figure 1), the union 16 is not mounted directly on the threaded end portions 13 with which the housing element 12 of the device is equipped.

In fact, the device according to the present invention comprises a connecting sleeve 15 interposed between the union 16 and the housing element 12. In particular, the connecting sleeve 15 comprises a first internally threaded portion 15a having pitch and dimensions compatible with the threaded end portion 13, and a second externally threaded end portion 15b having pitch and dimensions compatible with the internal thread of the union 16.

The union 16 in turn comprises an internally threaded portion 16a, intended to be screwed onto the connection sleeve 15 and an externally threaded portion 16b, onto which the nut 19 is finally screwed to allow locking of the ferrule 10.

Moreover, a locking ring nut 20 is also screwed onto the threaded portion 15b of the connecting sleeve 15 to prevent accidental loosening between the connecting sleeve 15 and the union 16. The ring nut 20 is in fact screwed onto the sleeve 15 until it abuts against the union 16, thus acting as "counter nut".

All the components 15, 16, 19 and 20 are in any case equipped in a known manner with at least one knurled, or similar, outer surface portion, to facilitate the manual operation thereof.

The adapter means in this case include a pair of ferrules 17, each housed partly in a seat 18 of the housing element 12 and partly in a seat 15c of the sleeve 15, in a position that allows the truncated-cone shaped end of the ferrule 17 to project on the outside through a hole 15d of the sleeve 15.

The enlarged view of Figure 2A shows in greater detail the components that ensure seal in the assembled part of the device of Figure 2. Each ferrule 17 includes an axial through hole into which the respective end portion of the column 50 is inserted, and a truncated cone shaped end designed to abut in the seat of corresponding shape of the respective sealing capsule 14 housed in the union 16. To adapt the supporting device 11 according to the invention to columns with different external diameter, it is sufficient to select the ferrules 17 and the seal capsules 14 with a through hole of appropriate diameter, without any change to the other components of the device.

As observed previously, prior art supporting devices do not allow the column to be re-used if it has been reduced in length, for example in the case in which an end portion is removed to eliminate clogging or deposits of impurities that occur prevalently at the inlet end of the capillary column.

In fact, by removing the end portion of the column affected by clogging, it can no longer be inserted in the supporting device maintaining a continuous flow of fluid, and therefore cannot be re-used as the dimensions of the supporting device remain the same.

Figure 3 shows another embodiment of a supporting device 21 according to the invention, in which the housing element is composed of two parts 22 and 23 mutually connected by an intermediate sleeve 25. In this manner, besides providing the possibility of housing columns of different diameter from one another, the supporting device 21 of this second embodiment can be adjusted in length, thus allowing a column to be re-used even if it has been reduced in length to eliminate clogging.

The part 22, at the end thereof coupled with the intermediate sleeve 25, includes an externally threaded portion 24 having a much greater length with respect to the thread of the other end, which has a thread (not shown) with a length substantially similar to the one indicated with 13 in Figure 2. This latter end is in fact designed to be coupled with the same components 15, 16, 19 and 20 and the respective adapter means 10, 14 and 17 already described with reference to the embodiment of Figure 2.

The mutual screwing position between the intermediate sleeve 25 and the part 22 is also locked through a ring nut 20 acting as counter nut, thus offering a high possibility of variation of the length of the supporting device 21 as a function of any reductions in length of the column 50.

The part 23 illustrates by way of example two openings 55 that allow uniform diffusion of heat along the entire column 50 and any necessary visual inspections, but further openings can also be provided in the part 22. The threaded ends of the part 23 are substantially similar to those indicated with 13 in Figure 2 and are respectively coupled to the intermediate sleeve 25 and to the components 15, 16, 19 and 20, so that they also house the aforesaid adapter means 10, 14 and 17 described above with reference to the embodiment of Figure 2.

Figure 4 and the Figures 4A and 4B of some details show a further embodiment of a supporting device 31 according to the present invention, in which the housing element is produced in the form of a frame to allow housing of a coiled column 45 (shown schematically with dashed lines).

The supporting device 31 includes a pair of shaped plates 32 disposed according to two parallel planes. The plates 32 are mutually constrained and equipped with openings 40 to promote air circulation around the column 45 and thus ensure uniform heat transmission thereto.

At opposite ends of the frame formed by the plates 32 two hollow arms 35 are provided, through which the ends of the column coiled between the two plates 32 are made to pass. At the free ends of each of the arms 35, a threaded end portion 33, similar to the one already indicated with 13 in Figure 2, is provided, to which the components 15, 16, 19 and 20 are coupled, so that they also house the aforesaid adapter means 10, 14 and 17, already described with reference to the embodiment of Figure 2.

As shown in greater detail also in the view of Figure 4 A, each of the arms 35 is housed sliding in a block 36 mounted integral with the two plates 32 and locked in position by a screw 37. Besides allowing a certain degree of adjustment of the dimension of the device 31 , this also allows further possibility of adaptation to any reductions in the length of the column 45.

In the supporting device 31, the column 45 is coiled and retained along a plurality of pins 38, preferably disposed in angularly equidistant positions along a circumference, one of which is represented in detail in the enlarged view of Figure 4B. Each pin 38 is secured to the plates 32 by means of screws 47 and includes a transverse slot 41 open at a gap 42. All the gaps 42 are oriented towards the inner space delimited by the pins 38, so that the coils of the column can be easily inserted into the slots 41 to be positioned against the inner wall of each slot and thus remaining locked in position along the pins 38.

Figure 5 shows a support assembly 61 produced according to the principles of the present invention, in which different types of columns are connected in series with one another regardless of the type and diameter thereof, for example capillary columns, nano columns and/or pre-columns.

The assembly 61 includes for example a first housing element 62 for a pre- column, followed by a housing element 63 for a capillary or nano column, in turn followed by a further housing element 64 for another capillary or nano column.

Coupled at the free ends of the assembly 61 are the components 15, 16, 19 and

20 to house the aforesaid adapters 10, 14 and 17, already described with reference to the embodiment of Figure 2.

In the intermediate couplings between two subsequent housing elements, besides the components 15, 16 and 20, a sleeve 65 is also disposed to allow each housing element 62 and 63 to be connected to the union 16 immediately subsequent. In this case, as shown in Figure 5 A, fluid-tight seal is produced through two ferrules 17 inserted in the opposite seats of a sealing capsule 14, as shown for example in Figure 5A, for sealed connection between the columns 50' and 50" respectively present in the housing elements 63 and 64.

Various modifications can be made to the embodiments represented schematically herein without departing from the scope of the present invention. For example, the lengths of the various threaded portions can differ from those shown in the figures to ensure different adaptation solutions, just as the reciprocal shapes and/or dimensions of the various components can differ from those effectively shown.

Claims

1. A supporting device for a capillary or nano column used in liquid chromatography, comprising at least one housing element equipped with a seat for at least one column and at least one pair of unions connected to the ends of said housing element, each of said unions housing at least one sealing capsule and one ferrule abutting against said capsule for sealed connection of said column to a liquid chromatography instrument, characterized by including adapter means to hold a column in position in said housing element and to ensure fluid-tight seal of the column regardless of its length and/or of its diameter.

2. The device according to claim 1, wherein said adapter means include a pair of ferrules equipped with an axial through hole into which the end portions of said column are inserted, said ferrules having at least one end shaped to sealingly abut in the seats of corresponding shape of the sealing capsules housed in said unions.

3. The device according to claim 2, wherein said ferrules are inserted at least at the ends of said housing element and held in position by sleeves screwed onto the threaded ends of said housing element.

4. The device according to claim 3, wherein said unions are connected indirectly to the ends of said housing element by screwing onto corresponding external threaded portions of said sleeves.

5. The device according to claim 4, wherein at least one ring nut is provided screwed onto the external threaded portion of each sleeve, said ring nut being capable of abutting against said union to prevent mutual unscrewing between said union and said sleeve.

6. The device according to claim 1, wherein said housing element includes at least two parts and wherein said adapter means include at least one intermediate sleeve that connects by screwing two of the threaded ends of said at least two parts.

7. The device according to claim 6, wherein at least one ring nut is provided screwed onto a threaded end portion of at least one of the parts forming said housing element, said ring nut being capable of abutting during screwing against said intermediate sleeve to prevent mutual unscrewing between at least one of said two parts forming said housing element and said intermediate sleeve.

8. The device according to claim 1, wherein the seat for said at least one column in said housing element is formed by an internal axial cavity which opens only at the ends thereof.

9. The device according to claim 8, wherein the seat of said housing element includes at least one intermediate opening to place said internal axial cavity in communication with the external environment.

10. The device according to claim 1, wherein said housing element includes at least one frame to support at least one capillary column in coiled configuration.

11. The supporting device according to claim 10, wherein said housing element includes a pair of internally hollow arms connected to said unions and wherein each of said arms can be slidingly positioned with respect to said frame and can be locked in position with screw means.

12. A support assembly for a plurality of capillary or nano columns used in liquid chromatography and connected in series with one another, characterized by including a plurality of housing elements connected in series with one another by screwing and each equipped with a seat for at least one column; at least one pair of unions connected to the free ends of the housing elements positioned at the opposite ends of the series, wherein each of said unions houses at least one sealing capsule and one ferrule abutting against the capsule for sealed connection of said column with a liquid chromatography instrument; and adapter means to hold each column in position in the respective housing element and to ensure fluid-tight seal of the columns connected in series regardless of their length and/or of their diameter.