WO1994028408A1

WO1994028408A1 - Method of continuous analysis of volatile organic compounds in an atmosphere to be analyzed and corresponding concentration unit and chromatograph

Info

Publication number: WO1994028408A1
Application number: PCT/FR1994/000636
Authority: WO
Inventors: Liberto Torres; Franck Amiet
Original assignee: Chromato-Sud
Priority date: 1993-06-01
Filing date: 1994-05-31
Publication date: 1994-12-08
Also published as: FR2706037A1; FR2706037B1

Abstract

Method of continuous analysis of volatile organic compounds contained in an atmosphere to be analyzed, unit for concentrating these compounds and chromatograph comprising such a unit. According to the invention, the concentration unit includes, in particular, a trap (15) consisting of an internally vitrified metal tube (16) adapted to contain a solid absorbent (35), a six-way valve (12), injection means (30a), detection means (30b) and a chromatrographic column (13). The unit further comprises electric power supply means (22) connected to the metal tube (16) and adapted to supply power capable of producing thermal energy so that the temperature gradient required for the thermodesorption of the organic compounds is obtained in at most 30 seconds.

Description

PROCESS OF CONTINUOUS ANALYSIS OF ORGANIC COMPOUNDS

VOLATILES CONTAINED IN AN ATMOSPHERE TO BE ANALYZED,

CONCENTRATION MODULE AND CORRESPONDING CHROMATOGRAPHER

The present invention relates to a process for continuous analysis of volatile organic compounds contained in an atmosphere to be analyzed, as well as a module for the concentration of these compounds and a chronograph comprising such a module. In terms of environment and pollution, the study of atmospheres (free or confined) is of great importance.

With regard to the composition of atmospheric air, it is known that human and industrial activity modifies it, not at the level of the majority compounds (nitrogen, oxygen, ...), but at the level of the compounds present in l 'trace amounts, such as Volatile Organic Compounds (VOCs) of biogenic and / or anthropogenic origin (pesticides, hydrocarbons, oxidants, aerosols, ...). However, VOCs can play a role in the biosphere-atmosphere balances as well as in the radiative balances of the planet and in the chemistry of the atmosphere.

With regard to confined atmospheres, such as those of workshops, hospitals, food storage rooms, etc., it is also necessary to set up devices for the analysis and control of VOCs liable to harm human safety (or health) and product quality. Thus, there are a large number of harmful or suspicious products, the subject of standards as to the accepted exposure limit concentrations.

The problem at present is that the most reactive VOCs are often present at concentrations of the order of the part per billion (ppb) or even lower, and that the existing devices making it possible to measure such weak concentrations are very bulky and therefore difficult to transport between two sites. Indeed, these devices, such as for example that described in the article in volume 329 of the journal "JOURNAL OF CHROMATOGRAPHY", pages 339-405, comprise a first system of preconcentration on adsorbent, a second system of cryofocusing on capillaries suitable to reconcentrate the compounds released during thermodesorption, means for heating the capillaries with a view to thermodesorption of the latter, and finally, an analysis and detection module. Due to the "heaviness" of these devices, it turns out in practice that their use is relatively limited because of the cost that it generates.

It should be noted however that there are portable devices such as for example that described in patent EP 091 928.

According to this patent, the analysis method consists in carrying out a concentration of the compounds to be analyzed by adsorption on a solid adsorbent, then a rapid thermodesorption in order to inject them into a chromatographic column for their analysis. According to this patent, the air taken for analysis is used as carrier gas throughout the concentration and then in the chromatographic column. The major drawback of such a device lies in the fact that the air which circulates in the analysis column has only been purified of the contaminants retained in the adsorbent. Assuming that all of these contaminants have been retained. However, in the air, there are other contaminants and these will disturb or even distort the analysis made in the chromatographic column.

In addition, such a method has the drawback of continuing to supply product contaminating the adsorbent during the thermodesorption period. What still disturbs the measurement.

Another drawback of the method according to this patent lies in the fact that the circulation of air at analyze is performed by a suction pump. As a result, the air flow rate is poorly controlled and very difficult to regulate, which creates dead volumes and flow resistances throughout the analysis chain. The present invention aims to overcome the aforementioned drawbacks of known devices, and has as its first objective to provide an easily transportable device.

Another objective of the invention is to prevent the carrier gas from disturbing the analysis by the contaminants which it may contain.

Another objective of the invention is to provide a device allowing easy regulation of the circulation of fluid in the column in order to avoid any disturbances due to dead volumes and flow resistances.

To this end, the present invention relates to a method for analyzing volatile organic compounds contained in an atmosphere to be analyzed, of the type consisting in:

- take a determined volume of the atmosphere to be analyzed,

concentrating the volatile organic compounds present in the atmosphere to be analyzed by trapping them in an adsorbent element subjected to sweeping by the atmosphere to be analyzed,

- inject trapped volatile organic compounds by thermodesorption into a chromatographic analysis column, - analyze the injected volatile organic compounds,

- And cool the adsorbent element and the column, then repeat all of the previous steps for a new sampling and analysis cycle. According to the invention, this process is characterized in that:

- using a metal tube sheathed internally with a thickness of inert material not thermally insulating, to contain each adsorbent element,

- Thermodesorption is carried out by electrically supplying each metal tube with an electric power supply capable of producing heat energy such that the temperature gradient necessary to achieve said thermodesorption is obtained in a period of time at most equal to 30 seconds.

Thanks to the design of the trap, such a process makes it possible to obtain practically simultaneous thermodesorption of all the trapped compounds, thus avoiding having to reconcentrate them again, for example by cryofocusing, and simplifying the device which can be reduced to dimensions allowing easy transport.

According to another characteristic of the invention: a) in a first phase, called the sampling phase: - the atmosphere to be analyzed is sampled and preconcentrated according to a first circuit,

- and simultaneously, the chromatographic column is scanned with a carrier gas according to a second separate and independent circuit from the first, b) and in a second phase, called analysis:

- The volatile organic compounds are analyzed by sweeping with the carrier gas all of the first and second circuits placed in communication.

Thus, in the sampling phase, two independent circuits are formed: on the one hand a first circuit comprising the adsorbent where the atmosphere to be analyzed circulates by means of a suction pump, and on the other hand, a second circuit comprising the chromatographic chain swept by the pure carrier gas. Thus, during this sampling phase, the VOCs of the atmosphere to be analyzed are adsorbed on the adsorbent which is isolated from the chromatographic chain, while the pure carrier gas purges the chromatographic chain and stabilizes the signal (signal substantially flat, without background noise). During the analysis phase, a new circuit is made in order to put the pure carrier gas in communication with the adsorbent and with the chromatographic chain. Rapid heating of the adsorbent is then implemented to carry out the thermodesorption of the trapped compounds: the carrier gas scans the adsorbent and drives the VOCs to the chromatographic column where the analysis is carried out. During the analysis, the adsorbent is cooled to room temperature, and a new cycle (concentration, thermodesorption, analysis) can be automatically initiated.

By virtue of such arrangements, the purity of the carrier gas is guaranteed, and better measurement accuracy is obtained since the injection of the contaminants is avoided during the thermodesorption period.

Advantageously, the carrier gas used is blown under pressure. Therefore, the dead volumes and the flow resistances are eliminated. A uniform and constant regulation of the carrier gas flow rate is also ensured over the entire cycle.

The present invention also relates to a module for the concentration of volatile organic compounds present in an atmosphere with a view to their analysis, of the type comprising: - at least one means forming a trap suitable for retaining the volatile organic compounds,

a means of heating each trap associated with command and control means,

- A means of suction of the atmosphere to be analyzed adapted to circulate the aspirated atmosphere through at least one trap.

According to the invention, this module is characterized in that: - each trap consists of a metal tube internally sheathed with a thickness of inert non-thermally insulating material, containing an adsorbent element, - the heating means of each trap include electrical supply means electrically connected to the metal tube and adapted to provide an electrical power capable of producing heat energy such that the temperature gradient necessary for the thermodesorption of organic compounds is obtained in a period of time at most equal to 30 seconds.

In addition, according to another characteristic of the invention, the concentration module comprises:

- a multi-way valve adapted to present at least two positions:

. a first position, called the sampling position, in which a first circuit is established between the suction means and the trap, and a second circuit is established simultaneously, between a source of pressurized carrier gas and an injection orifice to a chromatographic column, said first and second circuits being distinct and independent,

. and a second position, called analysis, in which the first and second circuits are put in communication,

- And management and control means of the permutations of the multi-way valve between the first and the second position.

In the sampling phase, the multi-way valve is placed in a first position suitable for ensuring that the trap is swept by the atmosphere to be analyzed while carrier gas is directed towards the chromatographic column. In the analysis phase, this same valve ensures in a second position, the scanning of the trap and the chromatographic chain by the carrier gas.

Advantageously, during the sampling phase, the adsorbent contained in the trap is swept away in a first direction of circulation while, during the analysis phase, it is swept by the carrier gas in a direction opposite to the first. This sweeping by the carrier gas in the opposite direction makes it easier to expel the VOCs trapped by the adsorbent. In fact, VOCs tend to be trapped in the sampling phase at the start of their progression in the adsorbent. However, in the analysis phase and after heating of the trap, the carrier gas directed in the opposite direction allows a relocation of the trapped compounds and an easy expulsion of these since they do not have to cross all of the adsorbent to be extracted.

The present invention also relates to a chromatograph characterized in that the chromatographic column is produced by winding a metal tube around a core and is in the general form of a thin cylinder.

The advantage of the chromatograph according to the invention lies in the fact that the chromatographic column also has its own heating and cooling means and that it can therefore operate at different temperatures completely independently of the temperature of the means. injection and detection, or that of the trap.

Advantageously, this results in a better separation of the products contained in the atmosphere to be analyzed and therefore a better sensitivity of the analysis.

Other objects, characteristics and advantages of the present invention will emerge from the description which follows, by way of nonlimiting example, with reference to the appended drawings in which:

- Figure 1 is a schematic plan view showing the concentration module and the chromatograph according to the invention, - Figure 2 is a simplified pneumatic diagram,

- Figure 3 is a schematic plan view illustrating the sampling phase of the process according to The invention,

- And Figure 4 is a schematic plan view illustrating the analysis phase of the method according to one invention. According to the embodiment shown in FIG. 1, the chromatograph 10 according to the invention comprises:

a concentration module 11 comprising a trap 15 and a six-way valve 12, a low-power pump P,

- a chromatographic column 13

- And electronic means 14 for managing and controlling all of these elements.

The trap 15 is constituted by a metal tube 16 vitrified internally.

Inside this trap is placed an adsorbent element 35, for example a porous polymer marketed under the name of "Tenax TA". This adsorbent is held in place in the trap by two glass wool plugs 17 rendered inert by silylation.

At each end of the trap, connections 18 connect it with pipes 19 and 20. These pipes are also connected to the six-way valve 12.

The trap is also provided with two electrical connectors 21 in contact with the metal tube 16 on the one hand, and with a transformer 22 on the other hand. A thermocouple 36 for controlling the temperature prevailing inside the trap is also provided.

The concentration module 11 according to the invention is provided with means 14 for monitoring and controlling the valve 12.

The valve 12 actuated by a pneumatic cylinder 27 makes it possible to produce two different circulation patterns. This valve receives, in addition to the lines 19 and 20, a line 23 for supplying carrier gas GV on which are interposed a valve 28 with flow or pressure regulation and a pressure gauge 29, a line 24 for supplying the atmosphere to be analyzed, a line 25 evacuation to a vent 38 on which is mounted the pump P and a flow regulator 37, and an injection pipe 26 to the chromatographic column 13.

As shown in Figures 3 and 4, this six-way valve is adapted in a first so-called sampling phase to present a first position in which an atmosphere to be analyzed is taken via line 24. This atmosphere arrives at valve 12 where it is directed towards the pipe 20 and crosses the entire trap 15. At the outlet of the trap the atmosphere is then directed via the pipe 19 to the valve 12 then towards the pump P and outside via the pipe 25.

Thus, a first circuit is created in which the sampled atmosphere circulates in the trap 15 in the direction of the arrow F and is then discharged. During this first phase, a second circuit is activated in which carrier gas (GV) is introduced under pressure into the valve 12 via the line 23 and then via the injection line 26 through the entire column 13. This second circuit is independent from the first.

The fact that the carrier gas is blown under pressure ensures a constant and adjustable flow through the entire chromatograph. The pump P is only present to ensure the evacuation of the sampled atmosphere to the outside. This pump can therefore be of low power.

In a second phase, after permutation of the valve 12 (FIG. 4) which then has a second position, the atmosphere taken off through the pipe 24 is discharged directly through the pipe 25 and the pump P. On the other hand, the carrier gas introduced under pressure via line 23 is directed via line 19 through trap 15 in the direction of arrow G, then via line 20 to valve 12 from where it is redirected to column 13, via line 26.

During this second phase, the trap and the column are thus continuously swept one after the other (in series), by the same carrier gas.

It will be noted that the column is thus never directly crossed by the atmosphere to be analyzed.

The operation of this concentration module is described below. In a first phase, the atmosphere to be analyzed is aspirated and then passes through the trap 15 according to arrow F, as previously described. During the passage of the atmosphere to be analyzed in the trap 15, the VOCs contained in this atmosphere are retained by the adsorbent 35. Thus, during the entire sampling phase, the VOCs accumulate in this adsorbent. This phase continues for a predetermined time so that a predetermined volume of atmosphere to be analyzed is taken. During this entire phase, a carrier gas circulates in the column according to a circuit independent of that of the atmosphere to be analyzed. This carrier gas can be nitrogen, or any other pure gas which does not disturb the chromatographic analysis, such as for example argon, hydrogen, helium, neon or any other rare and inert gas. .

When the predetermined volume of atmosphere to be analyzed has been taken and in the case where the carrier gas is not nitrogen, the valve 12 is swapped in second position and therefore, the carrier gas (GV) is injected in line 19 for a few moments, to remove the traces of nitrogen present in the adsorbent before the thermodesorption phase.

During this so-called purge time, none of the VOCs trapped in the adsorbent is extracted. As soon as this purging is completed, the trap is heated, and for this the metal tube 16 is supplied with current. The rise in temperature inside the trap is very rapid and advantageously at most equal to 15 seconds. By way of example, a transformer having the following characteristics: primary voltage 220 V, secondary 150 V, 2 V, makes it possible to obtain a rise in temperature of a value less than 0 ° C. up to 270 ° C. seconds.

A transformer with the following characteristics: primary voltage 220 V, secondary 300 A, 3 V, allows a rise in temperature from a value below 0 ° C to 400 ° C, also in 15 seconds.

This rise in temperature is controlled by thermocouple 36. During thermodesorption, the VOCs trapped in the adsorbent are extracted almost simultaneously. However, the trap and the column are swept by the same flow of carrier gas. In the trap, this carrier gas moves in the direction of the arrow G opposite to the direction of that of the arrow F in the sampling phase. Therefore, the VOCs released by the trap 15 are carried by the carrier gas GV to the column 13 to be analyzed there. When the thermodesorption is complete, the heating of the trap is stopped. When the trap is at room temperature, the six-way valve is again swapped to return to the first position. The cooling phase is carried out by Venturi effect (or Vortex) and / or by using Peltier effect elements and / or by air circulation. Once cold, a new sampling and analysis cycle is initiated.

As a variant, it will be noted that one can use several traps in parallel, each having its own specificities concerning the determination of particular VOCs. To this end, three different categories of elements can be used as adsorbent:

- carbon adsorbents, such as activated carbon, or those sold under the name Ambersorb, Carbotrap, ...,

- porous polymers such as those sold under the name Porapaks, Chromosorbs, XADs, Tenax, ..., - molecular sieves of the Zeolite, Silicagel, Alumina type, etc.

It will further be noted that by combining these different adsorbents, the selectivity of trap 15 can be improved.

The present invention relates not only to the concentration module described above, but also to a chromatograph associated with such a module.

As shown in FIG. 1, this chromatograph comprises the module 11 and the six-way valve 12 already described as well as injection means 30a and detection 30b associated with a first heating means 33, and a chromatographic column 13 associated with a second heating means 31, the first and second heating means being independent of each other. It should be noted that this chromatograph can have several distinct detection means 30b.

The chromatograph also includes electronic management and control means 14 adapted to automatically manage all of the sampling and analysis cycles. These electronic means 14 are constituted by. a set of conventional cards and are managed by a microprocessor. This microprocessor manages not only the general automation of the chromatograph, but also the permutations of the valve 12 as well as the heating of the trap 15 and the heating means 31 and 33.

Such a chromatograph is portable. Its weight and size are low and it is therefore possible to move it and carry out all the analyzes in the field. In addition, as shown schematically in Figure 2, this chromatograph is divided into two chambers. An uninsulated enclosure 1 mainly containing the trap 15 and the electronic means 14, and a thermally insulated enclosure 2 mainly containing the valve 12, the injection 30a and detection 30b means and the column 13.

Such a chromatograph is also intended to be placed in places inaccessible to humans prolonged (polluted, dangerous atmosphere and / or irradiation, ...).

It will be noted that one of the advantages of this chromatograph resides in the fact that the heating of the column 13 is independent of that of the injection means 30a and of detection 30b and, of course, completely independent of that of the trap 15. This allows better selectivity of the measurement.

The temperature gradient applied to the column varies for example from sub-ambient to 130 ° C. This heating is obtained by contact of the column 13 with a heated aluminum block 31 which constitutes the first heating means 31. Such a heating has the particularity of being direct and very fast. The chromatographic column 13 used can be of the capillary type or not, and is metallic. This column is formed by winding a metal tube around a core. Each lateral end of the core is covered with a disc 34 ensuring the cohesion of the assembly. The column thus formed has a generally cylindrical shape and is thin. Peltier elements 32 are carried by one of these discs 34 (or both) and provide cooling of the column. This cooling can also be obtained by Vortex effect and / or by air circulation.

In the same chromatograph, it is possible to use a plurality of columns 13 whose internal diameters are different or not. Of course, it is easy if necessary to replace a column by another better suited to determining the desired VOC (s), because the columns are removable.

It should be noted that the entire device operates continuously in a fully automatic manner.

To improve the accuracy of the measurement, a "blank" cycle is carried out cyclically (for example every ten analysis cycles). Such a cycle is carried out without trapping VOCs and makes it possible to determine the cleanliness of the trap and to take it into account. The analysis method according to the invention makes it possible to analyze continuously, automatically the VOCs contained in an atmosphere to be analyzed. This process consists in: - taking a determined volume of atmosphere to be analyzed,

- concentrating the VOCs present in this atmosphere by passing them through at least one trap 15 comprising at least one adsorbent element 35, - injecting by rapid thermodesorption

VOCs trapped in a column 13 for chromatographic analysis,

- analyze the VOCs injected into the column, - and cool the adsorbent element and the column 13 to then repeat the set of steps above.

In addition, this process consists of: a) in a first phase, called the sampling phase:

- take and concentrate the atmosphere to be analyzed according to a first circuit,

- and simultaneously, sweep the chromatographic column with a carrier gas according to a second separate and independent circuit from the first, b) and in a second phase, called analysis:

- analyze the VOCs by sweeping with the carrier gas all of the first and second circuits put in communication.

It will be noted that, while the analysis is carried out in the chromatographic column, and when the valve 12 is swapped into the first position, that is to say when the trap is cooled, a new sampling step can then be initialized even that the analysis step of the previous cycle has not been completed.

It will also be noted that the cooling of the trap is carried out during the analysis phase, and that this Cooling can advantageously be controlled so as to trap the compounds at a predetermined constant temperature.

It should also be noted that when the chromatograph according to the invention is placed in a polluted atmosphere to be monitored automatically, it is provided with an alarm signal which is activated as soon as the threshold concentrations of VOCs are exceeded.

It should also be noted that the data relating to all the analyzes carried out are stored by the means 14, so that they can be processed subsequently or at the end of the analysis. This data can easily be transferred to a computer for any necessary calculations. . Of course, the present invention is not limited to the embodiment described and encompasses any variant within the reach of ordinary skill in the art. Thus, the chromatographic column can be non-metallic and / or have a shape other than that shown.

Claims

CLAIMS 1/ - Process for analyzing volatile organic compounds (VOCs) contained in an atmosphere to be analyzed, said process being of the type consisting of: - taking a determined volume of the atmosphere to be analyzed,

- concentrate the volatile organic compounds present in the atmosphere to be analyzed by trapping them in at least one adsorbent element (35) subjected to scanning by the atmosphere to be analyzed,

- inject the trapped volatile organic compounds by thermodesorption into a chromatographic analysis column (13),

- analyze the injected volatile organic compounds,

- and cool the adsorbent element and the column (13), to then resume all of the steps indicated above, said process being characterized in that: - a metal tube (16) is used internally sheathed with a thickness of inert non-thermally insulating material, to contain each adsorbent element (35),

- thermodesorption is carried out by electrically supplying each metal tube (16) with an electrical supply power capable of producing heat energy such that the temperature gradient necessary to carry out said thermodesorption is obtained in a period of time at most equal to 30 seconds.

2/ - Method according to claim 1, characterized in that each metal tube (16) is electrically supplied so that the time period for obtaining the temperature gradient necessary for carrying out thermodesorption is less than 15 seconds.

3/ - Method according to one of claims 1 or 2, characterized in that: a) in a first phase, called levy :

- the atmosphere to be analyzed is taken and concentrated according to a first circuit,

- and simultaneously, the chromatographic column (13) is scanned with a carrier gas (GV) according to a second circuit distinct and independent of the first, b) and in a second phase, called analysis:

- the volatile organic compounds (VOCs) are analyzed by scanning with the carrier gas (GV) all of the first and second circuits placed in communication.

4/ - Method according to claim 3, characterized in that during the sampling phase the adsorbent is swept with a fluid moving in a first direction (F) of circulation, and during the analysis phase the adsorbent is swept according to a second direction (G) of circulation opposite to the first.

5/ - Method according to one of claims 1 to 4, characterized in that the metal tube (16) and the chromatographic column (13) are heated independently.

6/ - Method according to claim 4, characterized in that the chromatographic column (13) is cooled using Peltier effect elements (32), the temperature gradient for this column varying from sub-ambient to 130° C.

7/ - Method according to one of the preceding claims, characterized in that the column (13) and the metal tube (16) are cooled using Peltier elements (32) and/or by the Vortex effect and/or by the 'air.

8/ - Method according to one of the preceding claims, characterized in that it is carried out continuously automatically.

9/ - Concentration module for volatile organic compounds present in an atmosphere with a view to their analysis, of the type comprising:

- at least one means forming a trap (15) adapted to retain volatile organic compounds (VOC), - means (22) for heating each trap (15) associated with command means (14) and control means (36),

- a suction means (P) of the atmosphere to be analyzed adapted to circulate the aspirated atmosphere through at least one trap (15), said module being characterized in that:

- each trap (15) consists of a metal tube (16) internally sheathed with a thickness of inert, non-thermally insulating material, containing an adsorbent element (35),

- the heating means of each trap comprise electrical power supply means (22) electrically connected to the metal tube (16) and adapted to provide electrical power capable of producing heat energy such as the temperature gradient necessary for the thermodesorption of the organic compounds is obtained in a period of time not more than 30 seconds.

10/ - Concentration module according to claim 9, characterized in that the electrical supply means consist of a transformer (22).

11/ - Concentration module according to one of claims 9 or 10, characterized in that it comprises:

- a multi-way valve (12) adapted to present at least two positions:

. a first position, called sampling position, in which a first circuit is established between the suction means (P) and the trap (15), and a second circuit is established simultaneously, between a source of carrier gas (GV) under pressure and a chromatographic column (13), said first and second circuits being distinct and independent,. and a second position, called analysis position, in which the first and second circuits are placed in communication,

- and means of management and control (14) permutations of the multi-way valve between the first and the second position.

12/ - Concentration module according to claim 11, characterized in that the multi-way valve (12) is adapted during the sampling phase, to direct the atmosphere to be analyzed into the trap (15) in a first direction (F) circulation and during the analysis phase, to direct the carrier gas (GV) into the trap

(15) in a second direction (G) of circulation opposite the first.

13/ - Concentration module according to one of claims 9 to 12, characterized in that it comprises means (32) for cooling the trap.

14/ - Concentration module according to claim 13, characterized in that these cooling means consist of Peltier elements (32) and/or Vortex effect devices and/or air.

15/ - Concentration module according to one of claims 9 to 1, characterized in that the adsorbent element (35) contained is held in place in the trap

(15) by two glass wool plugs (17) made inert by silylation.

16/ - Concentration module according to claim 15, characterized in that the adsorbent (35) is a carbonaceous adsorbent and/or a porous polymer and/or a molecular sieve.

17/ - Concentration module according to one of claims 9 to 16, characterized in that it comprises at least one trap (15). 18/ - Module according to one of the claims

11 or 12, characterized in that the valve (12) is a six-way valve associated with heating means (33).

19/ - Chromatograph of the type comprising a concentration module (11) according to claims 9 to 18, characterized in that it further comprises:

- a metallic chromatographic column (13) provided with a first heating means (31) capable of allowing said column to be heated with a gradient of temperature,

- injection means (30a) and detection means (30b) associated with a second heating means (33), said first and second heating means being distinct and independent of each other,

- and control and control means (14) of the different heating means (31, 33), the injection means (30a) and detection means (30b) and the chromatographic column (13). 20/ - Chromatograph according to claim

19, characterized in that the heating means (31) consist of a block of aluminum associated with heating elements and/or Peltier effect elements.

21/ - Chromatograph according to one of claims 19 or 20, characterized in that the chromatographic column (13) is produced by winding a metal tube around a core and is in the general form of a cylinder of thin.

22/ - Chromatograph according to claim 21, characterized in that it comprises a plurality of columns (13).

23/ - Chromatograph according to one of claims 19 to 22, characterized in that each column is removable. 24/ - Chromatograph according to one of claims 19 to 23, characterized in that it comprises a plurality of distinct detectors (30b).