JPH0239743B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to gas chromatography,
More specifically, it relates to a method and apparatus for introducing a sample into a gas chromatograph. The present invention can be applied to the analysis of trace contaminants in solid, gaseous, and liquid mixtures of organic and inorganic compounds.

Methods are known in the art for injecting a sample into a pressure-filled evaporator within a gas chromatograph that is continuously blown through with a stream of inert carrier gas. The sample is introduced by piercing the syringe needle through a septum of self-sealing material sealing the inlet of the evaporator, thus injecting the liquid sample into the evaporator. The sample vapor produced in the evaporator is carried by a carrier gas to the chromatography column.

The accuracy of known gas chromatograph chromatographic analyzes using sample injectors is critical due to the septum made of a self-sealing material such as silicone rubber used to pierce the injector needle and close off the evaporator inlet. affected by There are two main problems that arise in connection with the use of self-sealing septa. One is the contamination of the chromatographic equipment with septum material, which prevents analysis in sensitive instruments during temperature programming, and the second is the insertion of the syringe needle dozens of times. This causes the bulkhead to lose its self-sealing ability. It also gives "ghost peaks" in the chromatogram during column temperature programming even without sample introduction. There are at least four reasons for bulkhead contamination. They are caused by the fact that the septum emits gaseous substances due to the high temperature in the evaporator, and that some of the septum material is carried by the syringe needle and enters the evaporator together with the sample. , the emission of volatile components of pieces torn from the septum, and the effects of residues from the previously used sample absorbed by the septum due to back-diffusion of volatiles in the evaporator. ,
and septum material reacting with the sample in the syringe needle, resulting in build-up and residual effects of previous sample.

Since 1967, patents have been granted in various countries for inventions related to structures for preventing the accuracy of chromatography measurements from being degraded due to the above factors. Typical of such inventions are strips of inert material, such as polytetrafluoroethylene, which are exposed within the evaporator and are moved after piercing the bulkhead and shield. This relates to a bulkhead shield provided on the surface of a bulkhead, and this was established in 1971.
U.S. Patent No. 3581573, Cl, 73−
There are some such as those disclosed in 422.

Another invention is the 1972 U.S. Patent No.
This is disclosed in Japanese Patent No. 3,635,093, and has a structure in which a metal shield having a hole is slidably disposed between the partition wall and the inside of the evaporator. The hole is properly aligned with the inlet in the head of the evaporator before piercing the septum with the syringe needle, and then aligned with the hole drilled in the septum so that the septum is completely isolated from the heating area of the evaporator. be shifted from

Inventions that attempt to prevent partition walls from adversely affecting the results of chromatographic analysis include:
U.S. Patent No. 3939713, issued in 1976, Cl.
73-422. An improved feature of the invention is that by rotating the head of the evaporator after each sample injection, the septum is completely shielded from the interior of the evaporator.

However, the inventions cited so far partially solve the problems that arise with partition walls. These configurations may prevent contamination due to septum volatiles, but do not prevent the ingress of some of the septum material introduced into the evaporator, e.g. carried by the syringe needle. . Additionally, other problems such as pressure sealing in the partition wall were not resolved at all.

To reduce the drawbacks of self-sealing septa, new devices have been developed that introduce sealed samples into capsules of inert metals such as aluminum, gold, etc. This arrangement is such that the capsule is introduced into the evaporator through the inlet, pierced with a hollow needle, and the contents of the capsule, after heating, are transferred to the chromatographic column in a manner that exposes the capsule to a flow of transport gas. (U.S. Pat. No. 3,783,794, issued in 1974, Cl.
73-422).

The problem with this device is that it has a complex structure with a fairly large number of elements subject to friction.

More recently, a method of introducing a sample into a gas chromatograph has been proposed in which a liquid sample is injected into the evaporator of the gas chromatograph through an inlet sealed with a rotatable shutoff valve. That is, before inserting the syringe needle into the evaporator, the pressure in the evaporator is relieved, and when the needle is withdrawn from the evaporator after sample injection,
The rotatable valve is arranged to reseal the inlet.

However, this device has the disadvantage that the rotatable valve is located close to the evaporator heating area. The valve is also intended to reliably seal and close the evaporator inlet without lubrication solely by the engagement of the abrasive surfaces. However, this adversely affects the reliability of the gas chromatograph. This is especially a problem when analyzing substances with high boiling points exceeding 450°C. Another disadvantage is that only syringes must be available as sample carriers, which limits the range of substances that can be analyzed since only liquid or gaseous samples can be introduced with syringes. It is.
(See K. Grob and K. Grob II, 1978, Journal of Chromatography, No. 151, p. 311).

An object of the present invention is to provide a method and apparatus for introducing a sample into a gas chromatograph, which prevents staining substances from entering the analysis sample and allows highly reliable and accurate chromatographic analysis results to be obtained. It is to be.

This is a method in which an analyte sample is introduced into the evaporator of a gas chromatograph with a sample probe or carrier, and the vapor of that substance is then transferred into the chromatography column of the gas chromatograph by a flow of carrier gas. The evaporator of the tograph is sealed only during sample injection, after the evaporator is physically connected to the sample carrier, and the analyte vapor is passed from the evaporator through a flow constrictor of constant cross-sectional diameter to the chromatographic process. , and the evaporator is then vented to the atmosphere.

This method is advantageous in that the evaporator is sealed only during sample injection, and the vapor is transferred to the chromatography column through a constant cross-section flow constrictor before opening the evaporator to the atmosphere. Unless a sample of It is scavenged by a portion of the carrier gas stream entering the column inlet. In other words, it is blown away. This prevents contaminants from entering the injected sample and makes the chromatographic analysis more reliable and accurate.

A device for carrying out the method according to the invention, for example a liquid sample is injected into an evaporator by a sample probe or carrier such as a hypodermic syringe, and the physical volume of the part of the syringe inserted into the evaporator, e.g. a needle thereof; is somewhat smaller than or approximately equal to the internal volume of the evaporator. A liquid sample introduced into the evaporator rapidly increases in volume after evaporation, creating an overpressure sufficient to transfer the sample from the evaporator through the flow constrictor into the carrier gas stream that enters the chromatography column. A vapor having a .

Preferably, the analyte is conveyed from the evaporator into the chromatography column by a flow of carrier gas, which is provided after sealing the evaporator. After the transfer of the vapor from the evaporator to the chromatography column, the flow of carrier gas supplied to the evaporator is shut off and this flow is then directed downstream of the flow restrictor to the inlet of the chromatography column.

According to the invention, there is further provided an apparatus for carrying out the method of the invention as described above, in which the sample carrier comprises a passage leading to the evaporator itself, a conduit for conveying the carrier gas to the evaporator, and a conduit for conveying the vapor of the substance under analysis to the evaporator. The evaporator is periodically connected to the evaporator, with a passageway for transporting the chromatography column from the chromatography column to the chromatography column. According to another feature of the invention, a flow of constant cross-sectional diameter is provided between the passage leading the sample carrier to the evaporator and the passage carrying the vapor of the substance under analysis from the evaporator to the column of the chromatography. While a constrictor is provided, the sample carrier is equipped with a sealing element that sealingly engages the sample carrier with the evaporator during sample injection.

The main advantage of this device for sample injection is that it does not use a self-sealing septum, and that contaminants and volatiles from the septum cannot enter into the sample material. The aim is to improve the reliability and accuracy of chromatographic analysis. In marked contrast to prior art devices, the sample injector according to the invention does not include polished moving elements such as gate valves, slide valves, etc., which are normally located near the heating region of the evaporator. This improves the reliability of the device, especially in the high-temperature (above 400° C.) atmospheres that occur in the evaporator. Also,
Various known types of sample carriers can be used with the device, such as syringes, pipettes, ampoules, etc., ie a wide variety of different sample substances can be introduced by the device of the invention.

In a less complex modification of the device according to the invention, in which a known conventional gas chromatograph can be used as is without modification, it is possible to place the sample carrier in an evaporator and to provide a passageway leading to the evaporator. An elongated capillary constant cross-sectional diameter flow constrictor is used.

In another modified form of the sample injector, the constant cross-section flow restrictor is part of the passageway that excludes the vapor of the substance under analysis from the evaporator and into the chromatography column. It is placed at the outlet of the evaporator. This modification is particularly advantageous for use with temperature programmable chromatography columns. The flow restrictor may preferably be placed within the furnace of the column.

Another example of a sample injection device uses a tubular flow constrictor or flow restrictor filled with particulate absorbent. The absorbent is the same as that used in chromatography columns.
This modification is preferably used in conjunction with a gas chromatograph equipped with a device for flushing or blowing away heavy sample components to speed up the chromatographic analysis of lighter components.

One preferred embodiment of the apparatus includes a flow divider attached to the carrier gas supply tube, with one outlet tube of the flow divider directing the sample vapor from the evaporator into the chromatography column upstream of the flow constrictor. The outlet pipe is equipped with a shutoff valve. Another outlet tube of the flow divider passes through a passageway that rejects sample vapor from the evaporator and into the chromatography column downstream of the flow constrictor.
and has an adjustable flow restrictor. This device is intended for a carrier gas to carry the substances under analysis from the evaporator into the chromatography column, thereby increasing the reproducibility of sample injection.

Additionally, this embodiment includes another controllable isolation valve located in the outlet pipe with an adjustable flow restrictor from the flow divider.

A further modification of the device is contemplated for the purpose of injecting a sample in a gas phase that is in thermodynamic equilibrium with the liquid or solid material being analyzed. That is, a hollow elongate needle with a pointed end extending from the evaporator serves as a passageway for the sample carrier to the evaporator. The sample carrier is generally an ampoule partially filled with the analyte, the top or neck of which is closed by a septum, or membrane, of self-sealing material. The interior of the ampoule is opened to the evaporator at the moment the introduction of the gas phase sample begins by the needle piercing the self-sealing septum.
The ampoule is moved towards the end of the sharpened needle. To prevent vapor condensation, the hollow needle is preferably enclosed within a temperature-controlled housing and the tip of the needle extends therefrom.

In order to increase operational reliability during injection of the metered liquid sample, the sample carrier is in the form of a capillary with a closed end attached to a holder, the capillary having a transverse hole adjacent to the closed part. . The capillary tube also includes a sealing sleeve of inert deformable material. This structure is particularly advantageous for introducing small liquid samples (up to 1 microliter), since it prevents fractionation of sample components.

By providing the capillary holder with a spring-biased grip in the form of a flexible plate with a corrugated hooked end, the reliability of the device is increased, while retaining the structure described so far. The head portion of the evaporator has a collar that securely engages the corrugated end of said plate, the head collar tapering outwardly, and the tapered portion of the head collar extending longitudinally or axially therealong. It has a group that extends to . Furthermore, an electric microswitch is placed in close proximity to the head of the evaporator to automate the sample injection process. The structure also includes a control device for controlling the isolation valve, the control device being electrically connected to the microswitch,
One of the spring-biased grip plates has a rib that cooperates with the microswitch at the point of operation when the passage is sealed before passing the sample carrier to the evaporator.

Alternatively, to introduce a sample of solid material,
The sample carrier has a rod-like shape made of ferromagnetic material, and the body of the evaporator is surrounded by an induction coil.

Disclosed below are various embodiments of sample injection devices according to the present invention. The method according to the invention comprises:
It will be better understood by considering the structure and mode of operation of the device.

Referring to Figures 1 and 2, there are two operating positions: before injecting the sample (first
A preferred embodiment of the simple construction of the sample injector is shown in the position shown in FIG. 2) and during injection (FIG. 2).
Indicated collectively by numbers 1, 2, and 3 are:
evaporator, sample carrier, and chromatography column, respectively. The chromatographic column 3 may be of known construction and is a tube 4 of glass-like inert material filled with a particulate absorbent 5. The sample carrier 2 forming part of the sample injection device may also be of known design and in this modification is generally a syringe with a glass-like, transparent material body 6, the internal passage of which extends in the axial direction of the syringe. It is provided with an axle 7 which can be moved vertically along the path. The hollow needle 8 opens into the body 6 of the syringe, the internal passage of which is actually an extension of the internal passage of the body 6.

The evaporator 1, which is essential to the sample injector used here, includes a cylindrical body made of an inert, heat-resistant material, such as stainless steel, and a heater 10. Inside the body 9 of the evaporator 1 there is a tubular element 11 forming a passage for the sample carrier 2 into the evaporator 1 . In the embodiment disclosed here, the communication between the sample carrier 2 and the vaporizer 1 is obtained by inserting the hollow needle 8 of a hypodermic syringe inside the tubular element 11, the size of the tube 11 being: Preferably, the internal volume of the needle 8 is as equal as possible to the internal volume of the tube 11, but is sized such that the needle 8 is placed with a minimum clearance to the internal wall of the tube 11. The tube 11 has a sealing ring 12 of soft material, such as aluminum or copper, which sealingly engages towards the head 13 of the body 9 of the evaporator 1 by means of a coupling nut 14. It's like being under pressure. Sealing ring 12 may be engaged to tube 11 by welding or the like. Inside the evaporator 1 there is a capillary, constant cross-sectional diameter flow constrictor 1 as an extension of the tubular element 11.
5 is provided. A conduit 16 for conveying an inert carrier gas, such as nitrogen, to the evaporator 1 is placed in communication with the evaporation chamber. Conduit 16 includes a controllable isolation valve 1, such as an electromagnetically controlled valve.
A bypass pipe 17 having a diameter of 8 is provided. Inside the evaporator 1, the vapor of the substance being analyzed is removed from the evaporator 1 into the chromatography column 3 in an annular gap created between the wall of the body 9 and the tubular element 11. There is a tube 19 forming a passageway through which the In the embodiment shown in FIGS. 1 and 2, the chromatographic column 3 is actually an extension of the passageway for removing vapors from the evaporator 1, and is made of an inert fibrous material such as glass fiber. It is separated from the evaporator by a filter 20. A sealing element 21 is provided for pressure sealing the location of the tube 19 where it extends from the evaporator 1 . This sealing element 2
1 is connected by means of a coupling nut 22 to the cylindrical body 9 of the evaporator 1 facing the column 3 of the chromatography.
is pressed into sealing engagement with the end face of the. Alternatively, other known suitable sealing elements may be used to create a pressure seal between tube 19 and evaporator 1. The details of the sealing element 23 in this embodiment include a guide 25 for aligning the needle 8 with the tubular element 11 when inserted into the interior of the evaporator 1, and a metal cup. It has an annular sleeve of deformable material such as rubber surrounded by 24.

The embodiment of the sample injector according to the invention described above operates as follows.

Prior to sample injection, a stream of carrier gas is continuously conveyed along conduit 16 to evaporator 1;
From there the bulk of the gas enters column 3 of the chromatography and is given a tendency to flow to a detector (not shown as it is not relevant to the invention and its construction and use are well known to those skilled in the art). ing. A small portion of the carrier gas, ie on the order of 1 to 3 milliliters per minute, is discharged from the flow constrictor 15 via the tubular element 11 to the atmosphere. The introduction of the sample is carried out by means of a syringe 2,
And for this purpose, the needle 8 of the hypodermic syringe is inserted into the passage of the tubular element 11 until the end of the tube 11 extending from the vaporizer 1 is pressure-tightly sealed by the sealing element 23. The length of the tube 11 is chosen in such a way that the tip of the needle 8 can penetrate into the heating region of the evaporator 1 at the moment when the pressure-sealing position is achieved. The temperature of the heating region is maintained at or above the vaporization point of the analyte mixture. Once a pressure seal is established between the tubular element 11 and the sealing element 23, the liquid sample is injected into the heating region of the vaporizer 1 by pushing the stem 7 of the hypodermic syringe 2. The instantaneous evaporation of the sample in the passage of tube 11 creates an overpressure of approximately 10 to 20 times or more than the pressure of the carrier gas at the inlet of column 3 of the chromatography. The pressure difference between the pressure in the passage of tube 11 and the pressure at the inlet of column 3 of the chromatograph directs most of the sample vapor from the passage of tube 11 through constrictor 15 into the extension of column 3 of the chromatograph. The sample vapor, which is forced to flow in and then dragged along by the carrier gas flow, enters the chromatographic column 3 for analysis. The amount of sample received by the chromatography column 3 is determined by the resulting pressure difference, the resistance of the constrictor 15 and the retention time of the syringe needle 8 in the tubular element 11. In order to increase the amount of sample transferred into the column 3 of the chromatography, the isolation valve 18 is activated following injection of the sample.
is automatically switched from the position shown in FIG. 1 to the position shown in FIG. 2, and the carrier gas is allowed to escape to atmosphere or flow along bypass pipe 17 into a buffer vessel (not shown). The position of valve 18 at this point (FIG. 2) reduces the pressure at the inlet of column 3, thus allowing the amount of sample to be forced from the passage of tube 11 through constrictor 15 into column 3 of the chromatography. It has the effect of increasing After the sample is injected, the needle 8 of the syringe is inserted into the tube 1.
It is extracted from passage 1. This is accompanied by a loss of pressure sealing in the evaporation chamber 1, with the result that the valve 18 is automatically switched from the position shown in FIG. 2 to the position shown in FIG. With the position of the valve 18 at this point,
A stream of carrier gas is caused to be conveyed continuously along conduit 16 into the evaporator 1, with the majority of the flow passing through conduit 19 to column 3 of the chromatography so that the sample is separated into its components. Meanwhile, a small portion of the flow is discharged to the atmosphere through the constrictor 15 and the passage of the tubular element 11, thereby cleaning sample residues.

Therefore, in the sample injection device example described above, the introduction of the vapor of the sample to be analyzed is caused by the pressure difference between the pressure generated in the passage of the tubular element 11 during evaporation of the sample and the pressure at the inlet of the column 3 of the chromatography. It is characterized by the fact that it is possible to Cleaning the components with a carrier gas escaping to the atmosphere prevents sample vapor from adhering to the components, thus ensuring that subsequent analyzes are not influenced by previous samples, which can improve the accuracy of the analysis. Increase.

Next, a sample injection device according to another embodiment of the present invention, in which the same elements are indicated by the same numbers, will be described with reference to FIGS. 3 and 4. Figures 3 and 4 generally show the two working positions of the sample injection device. The embodiment shown in these drawings is a combination of schematic and cross-sectional views, and is located between the passage formed by the tube 19 for eliminating the vapors of the analyte mixture and the column 3 of the chromatography. The flow restrictor 315 has a predetermined cross-sectional diameter.
Additionally, the carrier gas conduit 16 includes a flow regulator 26 and a flow divider 27 placed in series. One outlet tube 28 of the flow divider 27 removes analyte vapor from the evaporator 1 and passes it through a flow constrictor 315 to the chromatography column 3.
and is provided with a shutoff valve 29, such as an electromagnetically controlled valve. Another outlet pipe 30 of the flow divider 27 directs the steam to the evaporator 1
This leads to a passageway for removal to column 3 of the chromatography. This outlet pipe 30 is connected downstream of a flow restrictor 315 and is provided with an adjustable flow restrictor 31 . A detector 32, such as a flame ionization detector, is attached to the outlet of the chromatography column 3.

The embodiment of the sample injector according to the invention shown in FIGS. 3 and 4 operates as follows.

Prior to liquid sample injection (FIG. 3), the flow of carrier gas enters the outlet tube 30 of the flow divider 27 from the flow regulator 26 and then through the adjustable flow constrictor 3.
1 to the inlet of column 3 of the chromatography. The majority of the flow enters the chromatography column 3 (at a rate of 20 to 30 milliliters per minute) and then to the detector 32. The remainder or small portion of the flow (from 1 to 3 milliliters per minute) enters the evaporator 1 via the flow constrictor 315 and is then discharged to the atmosphere through the tubular element 11. In this path of the carrier gas, valve 29 is closed and the optimum flow rate is at chromatographic column 3.
while a small portion of the carrier gas flow cleans the evaporator 1. A sample is then taken by means of a syringe 2, which serves as a sample carrier, and a predetermined measured quantity of the liquid mixture to be analyzed is introduced.

The syringe 2 is equipped with a sealing element 23 at the point of contact of the needle 8 with the syringe body 6, the sealing element 23 being a rubber sleeve that allows it to be slipped onto the needle 8 of the syringe 2 before sample injection. It is becoming. Syringe 2
The needle 8 is then carefully inserted into the passageway of the tubular element 11. For this purpose, the passage usually has a diameter larger than the outer diameter of the needle 8.

The needle 8 is inserted far enough into the passageway of the tube 11 so that the rubber sleeve 23 completely blocks the entrance to the passageway.

Following this, valve 29 is switched to the position shown in FIG. In this position the valve 29 is open such that the flow of carrier gas exiting the flow divider 27 passes along both of its outlets 28 and 30, one of the carrier gas flows passing through the outlet 30 and an adjustable flow It passes through a squeezer 31 and enters column 3 of chromatography. Another carrier gas stream enters the evaporator 1 through the outlet 28 and from there moves along the path of the tube 19 and into the constrictor 315.
It enters column 3 through column 3. By pressing the stem 7 of the hypodermic syringe 2, the liquid material to be analyzed is
It is injected into the passage of a tube 19 placed in the heating region of the evaporator 1. The liquid sample mixture is then evaporated, whereby the vapor is entrained by the flow of carrier gas entering the evaporator 1 from the outlet 28 of the flow divider 27 and the flow constrictor 315.
It is carried through column 3 of chromatography, separated at the outlet of column 3 of chromatography,
Then, it is detected by the detector 32. After the sample is injected and the sample mixture is separated into components in column 3 of the chromatography, valve 29
is closed (FIG. 3) and the hypodermic needle 8 can be withdrawn from the passageway of the tubular element 11. The sample injector is thus connected to the outlet 3 of the flow divider 27.
A major part of the carrier gas stream leaving the chromatography column 3 enters the chromatography column 3, and a small part is returned to the operating mode shown in FIG. The passages of tubes 19 and 11 are thus cleaned. i.e. eliminate sample residue.

Gaseous samples can likewise be injected by means of the syringe 2, in which case the rubber sleeve 23 serves as a protective shield that closes off the transverse hole made in the needle before injection.

Next, FIG. 5 shows yet another embodiment of the sample injector of the present invention. FIG. 5 shows, partly schematically and partly in section, a sample injector intended for injecting a fraction of a liquid mixture sample consisting exclusively of light mixture components. The heavy components are not injected into the chromatography column 30, but are discharged to the atmosphere via the evaporator 1.

The elements in Figure 5 that are the same as those in Figures 3 and 4 are
The embodiment shown in FIG. 5, designated by the same numerals, differs from the embodiment of FIGS. It is a filled tube. An absorbent similar to that used to pack chromatography column 3 or any other suitable absorbent can be used as the absorbent for flow restrictor 515. Another feature of this embodiment that differs from the embodiment shown in FIGS. 3 and 4 is that the outlet tube 30 extending from the flow divider 27 is connected to the valve 30 when the valve 29 is in the open position.
Another controllable shut-off valve 34 is provided which operates simultaneously with the shut-off valve 29 so that the shut-off valve 29 is in the closed position and vice versa.

The embodiment shown in FIG. 5 operates as follows.

The internal pressure of the evaporator 1 is sealed by the tubular element 11.
This is achieved prior to sample injection by blocking the passageway of the syringe 2 with a rubber sleeve-shaped sealing element 23 slipped over the hollow needle 8 of the syringe 2. Following this, a liquid sample is injected into the passageway of tube 19. Valve 29 is opened while valve 34 is closed. The flow of carrier gas exiting the outlet 28 of the flow divider 27 is conveyed to the evaporator 1 and draws analyte vapor along the passage of the tube 19 to the flow restrictor 515. Separation of the sample mixture into two or more fractions or components then occurs in flow restrictor 515. This is because the restrictor 515 tube contains particulate absorbent. After the light fraction has been transferred from the flow restrictor 515 to the chromatography column 3, a switching between valves 29 and 34 takes place, with valve 29 assuming the closed position and valve 34 open. Following the changeover, needle 8 of syringe 2
By withdrawing the evaporator 1 from the passage of the tubular element 11, the pressure of the evaporator 1 is released, thus moving the sealing element 23 away from the entrance of the passage of the tube 11. With this mode of operation, the outlet pipe 3 of the flow divider 27
The carrier gas flow leaving from 0 and entering the inlet of column 3 of the chromatography (the path of the carrier gas flow is shown by the dashed arrow) is divided into two streams. One stream enters column 3 of the chromatography, carrying with it the lighter fractions of the analyte mixture along the length of the column, and forming separate emission bands at the outlet of column 3. ) in the form of a detector 32 for further separation and detection. Another flow of carrier gas is through flow restrictor 515.
The particulate absorbent 33 is flushed out and the heavy fraction, which is not analyzed, is discharged to the atmosphere via the passages of tubes 19 and 11. The cleaning of the particulate sorbent filling the flow restrictor 515 ensures that all light fraction components are forced from column 3 of the chromatography into the detector 32 and all heavy components are forced out of the flow restrictor 515 and into the atmosphere. It will continue until it is removed. The modifications described so far of the sample injector according to the invention include:
Prevents heavy fractions of the mixture under analysis from entering the chromatography column, thereby reducing the time required for the chromatography analysis.

Referring now to Figures 6 and 7, there is shown, partly schematically and partly in cross-section, a sample in the gas phase which remains in equilibrium with the liquid or solid sample to be analysed. Another embodiment of a sample injector according to the invention is shown, adapted to inject. FIG. 6 shows the embodiment in a state before sample injection. FIG. 7 shows a state in which the gas phase is being injected. The embodiment of FIGS. 6 and 7 differs from the embodiment shown in FIG. 5 in that the passage connecting the evaporator 1 to the sample carrier 2 is formed by a hollow needle 35 extending from the evaporator 1. , the pointed end 36 of the needle 35 is well spaced from the evaporator 1.
The needle 35 is surrounded by a temperature-controlled housing 37 equipped with a heating wire 38 . The pointed end 36 of the hollow needle 35 is fixed to the housing 37 and extends a distance therefrom. The sample carrier has the form of an ampoule 39 partially filled with the liquid or solid substance to be analyzed. Ampoule 3
The top or neck of 9 is hermetically closed by a septum or membrane 41 of self-sealing material such as silicone rubber, the surface of which is covered by a layer of polytetrafluoroethylene. Ampoule 3
9 is placed opposite the pointy end 36 of the hollow needle 35 and is equipped with a plurality of similar ampoules 39 along its periphery partially filled with the liquid or solid sample to be analyzed. It is rigidly mounted in a retainer 42 in the form of a rotatable cartridge. The ampoule 39 is arranged such that the pointed end 36 of the hollow needle 35 pierces the septum 41 made of self-sealing material, thereby communicating the internal volume of the ampoule 39 to the evaporator 1. It is held in a retainer 42 which is movable axially towards 36. Inside the holder there is placed a heating wire 43 intended to maintain a predetermined temperature inside the ampoule 39.

In that preferred embodiment of the sample injector according to the invention shown in FIGS. 6 and 7, the flow constrictor 15 has the form of a capillary tube extended by a hollow needle 35, the constrictor being placed in the evaporator. ing. Outlet pipe 2 of flow divider 27
8 leads to the interior of the hollow needle 35 via a valve 29, while the outlet 30 of the flow divider 27 connects to the interior of the evaporator 1 via a valve 34 and an adjustable flow restrictor 31.
It opens into a passage of tube 19 which serves to convey the sample vapor into the column 3 of the chromatography. Alternatively, another variant is possible in which the flow constrictor 15 is placed outside the evaporator 1 and serves as part of the passage of the tube 19 that excludes the sample vapor from the evaporator 1 to the column 3 of the chromatography. be.

This embodiment of the sample injection device according to the invention operates as follows.

Before sample injection, the holder 42 of the ampoule 39
is at the lowest position indicated by the broken line in FIG. At this point valve 29 is closed and valve 34
is open. The carrier gas is conveyed into the interior of the evaporator 1 from the outlet pipe 30 of the flow divider 27 . The majority of the carrier gas flow enters the chromatography column 3 through the passage of tube 19, while a small portion (from 10% to 30%) passes through the passage of tube 19 and enters the constrictor 15. The liquid is then inserted into the hollow needle 35 and released into the atmosphere. This operating position is the hollow needle 35
The pointed end is axially aligned with the ampoule 40 so that it rests just above the septum 41 of the ampoule 40. Upon receiving a signal from a programming device (not shown), holder 42 of ampoule 39 is raised to its uppermost position. The pointed end 36 of the needle 35 pierces the septum 41 of the ampoule 39 and enters the interior of the ampoule 39, which is filled with sample vapor. At this moment, receiving a signal from the programming device, valve 29 opens while valve 34 closes. The carrier gas (FIG. 6) flows along the outlet tube 28 of the flow divider 27 and into the passageway of the needle 35. The carrier gas follows the passage of the needle 35 and enters the chromatography column 3 through the flow constrictor 15. The carrier gas also travels along the path formed by the inside of the needle 35 and into the ampoule 39 where it passes through the needle 3.
The pressure is approximately equal to the pressure at the entrance of passage No. 5 (in this case, from 2 atm to 4 atm). The carrier gas is then saturated with vapor of the liquid to be analyzed within the interior of the ampoule 39. After sample injection, valves 29 and 34 automatically assume the position shown in FIG. 7 upon receiving a signal from the programming device. That is, valve 34 is opened and valve 29 is closed.
In this position of the valve, the pressure value at the inlet of the chromatography column 3 is essentially lower than the pressure value in the internal volume of the ampoule 39, and the difference in these pressure values is passed to the adjustable flow restrictor 31. Determined by the pressure difference thus created, the mixture of steam and gas is then transferred from the interior of the ampoule 39 to the needle 35.
and the constrictor 15 to enter the chromatography column 3. The amount of vapor and gas entering the column depends on the time of exposure. After a preselected period of time ranging from 5 seconds to 30 seconds, upon receiving a signal from the programming device, valves 29 and 34 are switched to the positions shown in FIG. 6, with valve 29 in the open position and valve 34 in the open position. Closed. The flow of carrier gas carried from the outlet tube 28 of the flow divider 27 into the passage of the hollow needle 35 serves to prevent the flow of vapor and gas mixture from entering the column 3.
After the sample injection has taken place, a signal received from the programming device causes the ampoule holder 42 to be lowered and subsequently (with a delay of less than one second) valves 29 and 34 to the position shown in FIG. 7 (valve 26 closed). , valve 34
is open}. At this position of the valve,
The carrier gas flows from the flow divider 27 to its outlet pipe 30.
, and enters column 3 of the chromatography for separation, while a small portion of the gas stream, between 10% and 20%, enters constrictor 15 and passes through the passage of needle 35 to the atmosphere. is released. The carrier gas escaping to the atmosphere cleans the needle 35 passage of previous sample residue as the needle 35 passage is heated to a temperature that prevents condensation of sample mixture vapor. The separation of the components of the sample mixture is carried out by the ampoule holder 42,
This is done simultaneously by turning a predetermined angle in order to place another sample ampoule 39 towards the pointed end of the hollow needle 35. The subsequent injections of the sample can thereby be carried out in the order described so far.

Referring now to FIGS. 8 and 9, there is shown, partly schematically and partly in cross-section, another preferred embodiment of an apparatus for injecting a liquid sample into a gas chromatograph; There, a micropipette is used as a sample carrier. The same elements of the device as shown in the previous drawing are
indicated by the same number. The sample carrier of the apparatus of FIGS. 8 and 9 is in the form of a capillary tube 44 made of an inert, heat-resistant material such as glass or stainless steel. The solid or solid end 45 of the capillary tube 44 is connected to the retainer 46, while the transverse hole 47 is directly adjacent to the blind end 45 of the capillary tube 44. The capillary tube 44 further includes a sealing member 2 in the form of a sleeve of deformable inert material such as rubber.
It has 3. The capillary retainer 46 is connected to the spring 48
a grip 49 biased by the grip 4;
9 has the form of a plate of flexible material, such as steel, with a corrugated hooked end 50. The evaporator 1 has a head 51 which extends away from its heating area and is rigidly connected to the tubular element 11, the passage of which, together with the passage within the head 51, connects the capillary tube 44 to the evaporator. Works to insert inside. The head 51 of the evaporator 1 further comprises a collar 52 in which the corrugated end 50 of the spring-biased grip 49 engages firmly. The collar 52 is arranged on its side facing towards the inserted capillary when the capillary 44 is introduced into the passage of the head 51 of the evaporator 1 and further into the passage of the tube 11 and when this passage is It has a tapered surface that acts as a guide for the hooked end 50 of the grip 49 when sealed against pressure escape by sealing engagement with the sealing element 23. The tapered collar 52 further extends vertically therethrough;
and is provided with a groove 53 (FIG. 9) intended for releasing the hooked end 50 of the grip 49 in order to depressurize the evaporator 1 after the sample has been injected into the gas chromatograph. Head 5 of evaporator 1
1, there is a microswitch 45 electrically connected to a control device 55 which controls the operation of the shutoff valves 29 and 34, and which is generally a timed relay. Spring biased grip 4
From one of the plates 9 extends a rib 56 which cooperates with a microswitch 54 when pressurizing or depressurizing the evaporator 1.

Another feature of this embodiment that differs from the previously described embodiments is that the outlet pipes 28 and 30 of the flow divider 27
Flow restrictors 57 and 58 of constant cross section are connected in parallel with the isolation valves 29 and 34, respectively, acting as a bypass for the flow. Furthermore, the flow divider 27
A device for monitoring the pressure therein, for example a pressure gauge 59, is connected to the outlet pipe 28 of.

The embodiment described herein operates as follows.

Sample fluid is delivered into the calibrated passage of capillary tube 44 by capillary forces. Movable sealing element 23
closes the lateral hole 47 of the capillary tube 44. Initially, i.e. before injecting the sample into the evaporator 1, the valve 29
is closed, while valve 34 is open. The carrier gas passes along the outlet pipe 30 of the flow divider 27 and enters the interior of the evaporator body 9, from where the bulk of the gas flow, between 30 and 60 milliliters per minute, is transferred.
Up to milliliters are transported into the chromatographic column 3 along the passage of tube 19, while a small fraction, from 1 milliliter to 5 milliliters per minute, is transported through the flow constrictor 15 and the passage of tube 11 and the evaporator. 1 and is released into the atmosphere through the head 51 of 1. At the same time, a small portion of the flow sent through the flow restrictor 57, between 1 and 2 milliliters per minute, is blown through a portion of the outlet pipe 28 of the flow divider 27, downstream of the valve 29, to release the gas to the atmosphere. act in order to

At the moment of sample injection, the capillary tube 44 is inserted into the channel of the head 51 of the evaporator 1 and moved as far as possible. The movable sealing element 23 thereby closes the entrance to the passage of the head 51 of the evaporator 1 with which it is pushed towards the head 51 and in sealing engagement therewith;
The corrugated end 50 of the spring biased grip 49 is
It is fixed to the collar 52 of the head 51 of the evaporator 1. A rib 56 extending from one of the plates of grip 49 is forced into engagement with a microswitch 54 to close its contacts, and a control device 55 has electrically controlled valves 29 and 34 as shown in FIG. Send a signal to both valves so that they can be switched to the position shown in . In this position of the valve, most of the flow of carrier gas proceeding along the outlet pipe 28 of the flow divider 27 is directed to the head 51 of the evaporator, which is placed opposite the lateral hole 47 of the capillary tube 44.
, a measured amount of liquid sample flows into the passage of tube 11 where it evaporates and its vapor, entrained by the flow of carrier gas, then passes through flow constrictor 15 and tube 11 . After passing through 19 passages, it is transported to the column for separation and detection at the outlet of column 3 of the chromatography. Following sample injection, a small portion of the carrier gas flow is
Via a flow restrictor 58 of constant cross-sectional diameter and an adjustable flow restrictor 31 it passes into the internal volume of the body 9 of the evaporator 1, whereby the sample vapor is directed into the outlet tube 30 of the flow divider 27. work to prevent the spread of Upon completion of the injection, as indicated by an optical signal indicator (not shown) electrically connected to a control device 55 that regulates the operation of isolation valves 29 and 34, the retainer 46 of the capillary tube 44 closes the grip 49. is turned counterclockwise, as best seen in FIG. 9, until the plate is aligned with the group 53 of the evaporator head 51. At the same time, the rib 56 of the grip 49
releases the contacts of microswitch 54 to switch valves 29 and 34 to their initial positions before sample injection (valve 29 closed, valve 34 open), and the capillary tube then closes to the head 51 of the evaporator. , thereby releasing the pressure in the evaporator 1. This position of the valve ensures that while a stream of carrier gas is conveyed from the outlet 30 of the flow divider 27 into the evaporator 1 and further along the path of the tube 19 into the column 3 of the chromatography, a small portion of the stream is , from 1 to 5 milliliters per minute is discharged to the atmosphere via the flow constrictor 15 and the passages of the tube 11 and the evaporator head 51, the carrier gas thus discharged flushing sample residues from the passages.

Sample injection can then be resumed, with subsequent liquid samples being injected in the order previously described.

The pressure gauge 59 is used to check the tightness of the passage in the evaporator head 51 after the sealing element 23 is pushed towards it into sealing engagement with the evaporator head 51 during sample injection. Useful for If the needle of the pressure gauge 59 changes its position after the grip 49 has stuck to the collar 52 of the evaporator head 51,
This indicates that appropriate pressure tightness could not be obtained. To correct this situation and completely seal the evaporator,
The position of the head 51 relative to the body 9 of the evaporator 1 must be adjusted or the sealing element 23 must be replaced.

Another embodiment of the sample injector shown in FIG. 10 is intended for injecting solid sample material. Referring to FIG. 10, the sample injector includes a sample carrier 2 made as a bar member 60 of ferromagnetic material, while an induction coil 61 is used instead of the heating wire of the previous preferred embodiment.
It is fitted into the body 9 of the evaporator 1, i.e. it surrounds it.

A ferromagnetic rod 60 is attached to a retainer 62 by sliding the sealing element 23 onto it. A sample of solid material is dissolved in a volatile solvent and a measured amount of the solution is applied to the end face of the ferromagnetic rod 60, such as by a syringe. The sample thus applied is then dried in a stream of inert gas or by an infrared radiator so that the solvent vapor is swept away leaving a thin film of solid material on the surface of the rod 60. . The rod 60 is then installed in the evaporator and sealed by the sealing element 23 to the tube 11.
Block the entrance to the passageway. Valve 29 is opened such that pyrolysis of the sample of solid material is effected by pulses of high frequency current induced by coil 61. Valve 34 remains closed during this operation. At the valve position shown in FIG. 10, all of the carrier gas flow exiting the flow divider 27 carries the gaseous and vaporized products of pyrolysis along the entrained outlet tube 28 into the passageway of the tube 11. , into the column 3 of the chromatography via the flow constrictor 15 and the passage of the tube 19. After the products of pyrolysis are sent to chromatography column 3, valve 2
9 and 34 are switched so that valve 29 assumes a closed position and valve 34 opens. At the same time, the entire flow of carrier gas is diverted to flow divider 2.
7 along its outlet pipe 30 and, via an open valve 34, an adjustable flow restrictor 31, and through the passage of valve 19 into the chromatography column 3. The rod 60 is then withdrawn from the passage of the tube 11 and a small portion of the carrier gas escapes through the flow restrictor 15 to the atmosphere.

The use of a sample injector according to the present invention prevents errors in chromatographic analysis that commonly occur when septa are used in prior art sample injectors. In other words, the method and apparatus proposed here eliminate "ghost peaks" that overlap the peaks of the components being analyzed.
Eliminate the appearance of This further helps prevent particles of barrier material from entering the internal volume of the evaporator. Another advantage of the sample injection device according to the invention is that the device consists of largely standard conventional elements and can be used with any known suitable gas chromatograph without substantial modification to its installation. Low manufacturing cost. Finally, the sample injector according to the invention is capable of injecting samples in various phases, such as liquid, gas, and gas phase.

Disclosed herein were various embodiments of the invention. However, it will be apparent to those skilled in the art that various changes and modifications may be made to such embodiments without departing from the spirit and scope of the invention.

[Brief explanation of drawings]

FIG. 1 shows a sectional view of the sample injection device according to the invention in its simplest form at the moment just before sample introduction; FIG.
FIG. 3 shows another embodiment of the sample injection device at the point of its operation just before sample injection; FIG. 3 showing the apparatus of FIG. 3 with a carrier inserted therein, FIG.
6 shows a modified version of the device according to the invention having a flow restrictor in the form of a tube filled with particulate absorbent, FIG. 6 partly schematically and partly in section. 7 shows an embodiment of a device according to the invention intended to introduce a gas phase in equilibrium with a liquid or solid phase at the moment just before sample introduction; FIG. 5, FIG. 8 shows an embodiment of the device according to the invention with a sample carrier in the form of a pipette, and FIG. 9 shows a partial top view of FIG.
and FIG. 10 shows an embodiment of the device according to the invention, intended for introducing solid samples.
In the drawing, reference numeral 1 is an evaporator, 2 and 39 are sample carriers, 3 is a chromatography column, 6 is a syringe body, 9 is an evaporator body, 11 is a passage connecting the sample carrier to the evaporator, and 19 is a steam 15,315 is a flow constrictor, 23
is a sealing element, 27 is a flow divider, 28 and 30 are outlet pipes of the flow divider, 29 and 34 are controllable shutoff valves, 3
1 is an adjustable flow constrictor, 35 is a hollow needle, 3
6 is the pointed end of the needle, 37 is a temperature controlled housing, 39 is an ampoule, 41 is a septum, 44
is a capillary, 45 is an end of the capillary, 49 is a grip, 50 is a hooked end of the grip, 51 is the head of the evaporator, 52 is a collar, 53 is a vertical groove, 54 is a micro switch, 55 is a control device, 56 is a rib, 60 is a bar,
61 is an induction coil, 62 is a retainer, and 515 is a flow restrictor. Table of reference numbers used in the claims of the invention: 1...evaporator, 2...sample carrier, 3
...chromatography column, 11 ... passage leading the sample carrier to the evaporator, 15, 31
5,515...Flow constrictor of constant cross section, 19...
... Passage for eliminating steam, 23 ... Sealing element, 27
... Flow divider, 28 ... Flow divider outlet pipe, 29 ...
Shutoff valve, 30... Outlet tube of flow diverter, 31... Adjustable flow constrictor, 34... Shutoff valve, 35... Hollow needle, 36... Pointed end of needle, 39... Ampoule, 41 ... Partition wall, 44 ... Capillary, 45 ... End of capillary body, 46 ... Retainer, 47 ... Horizontal hole, 4
9...grasp, 50...hooked end of the grip, 5
1...Evaporator head, 52...Brim, 53...Vertical groove, 54...Micro switch, 56...
Rib, 60... Rod, 61... Induction coil, 62...
retainer.

Claims (1)

[Claims] 1. A method of injecting a sample into a chromatographic column of a gas chromatograph, wherein the sample is evaporated in an evaporator connected to the chromatographic column, and then introduced into the evaporator. In the chromatographic injection method of the sample, the sample is carried to the chromatographic column by a carrier gas, in which a passage is provided in the evaporator, the passage being open to the atmosphere at one end and serving as a constrictor facing the chromatographic column at the other end. flowing a carrier gas downstream of the constrictor and allowing the carrier gas to flow into the chromatographic column; introducing a sample into the passageway and evaporating it while cutting off communication with the atmosphere in the passageway; The evaporated sample is drawn from the passage through the constrictor by means of a pressure difference due to the pressure at the time of sample introduction being higher than the pressure created by the flow of carrier gas downstream of the constrictor, and the carrier gas further directs the evaporated sample through the constrictor. and then cleaning the inside of the passage by opening the passage to the atmosphere and discharging the carrier gas to the atmosphere through the passage. . 2. A device for injecting a sample into a chromatography column of a gas chromatograph, which includes a first passage for injecting the sample, a change chamber for changing the sample to a vapor state, and two pipes for supplying a carrier gas, namely a first pipe connected to the change chamber and a second pipe communicating with the column of the chromatography; a shutoff valve provided in the first pipe; and a second passageway for introducing steam into the column of the chromatography. and having an evaporator in periodic communication with the sample carrier, wherein a flow restrictor 315, 515 is arranged before the second passage at the outlet of the change chamber, and the sample carrier 2 During the sample injection period, during the conversion of the sample into vapor, and during the transfer of the sample vapor to the column of the chromatography, the first passage 11 for sample injection into the evaporator 1 is sealed and sealed. An apparatus for injecting a sample into a gas chromatograph, characterized in that it is equipped with a sealing element 23 that closes in a fluid-tight manner, and that the change chamber is formed directly in the first passage 11. 3 A device for injecting a sample into a chromatography column of a gas chromatograph, which comprises a first passage for injecting the sample, a change chamber for changing the sample to a vapor state, and two pipes for supplying a carrier gas, namely a first pipe connected to the change chamber and a second pipe communicating with the column of the chromatography; a shutoff valve provided in the first pipe; and a second passageway for introducing steam into the column of the chromatography. and comprising an evaporator in periodic communication with a sample carrier, wherein a flow stream is introduced into the second passage ahead of the point of connection between the inlet of the column 3 of the chromatography and the second tube. A constrictor 315, 515 is installed so that the sample carrier 2 is free from the evaporation during the injection of the sample, during the conversion of the sample into vapor, and during the transfer of the sample vapor to the column 3 of the chromatography. The sample is characterized in that it is equipped with a sealing element 23 that airtightly and liquid-tightly closes the first passage 11 for injecting the sample into the sample container 1, and the change chamber is formed directly in the first passage 11. A device that is injected into a gas chromatograph. 4. In the device according to claim 3,
The flow constrictor 315 is placed at the outlet of the evaporator 1 to be part of the first passage 11, through which the sample vapor is rejected from the evaporator 1 to the column 3 of the chromatography. A device for injecting a sample into a gas chromatograph, characterized by: 5. The apparatus according to claim 3 or 5, wherein the flow constrictor is configured to contain particulate absorbent 3.
Apparatus for injecting a sample into a gas chromatograph, characterized in that it is made as a tube 515 filled with 3. 6. The device according to any one of claims 3 to 6, wherein the first pipe 16 for supplying the carrier gas is provided with a flow divider 27,
One outlet 28 of the flow divider 27 leading to the second passage 19 rejecting vapors from the evaporator 1 to the column 3 of the chromatography is located substantially upstream of the flow restrictor 315, 515. he,
and has a controllable isolation valve 29, while another outlet 30 of said flow divider 27 communicates with said second passage 19 substantially downstream of said flow restrictor 315, 515 and has an adjustable flow restrictor. An apparatus for injecting a sample into a gas chromatograph, characterized in that it has a container 31. 7. In the device according to claim 6,
Injecting the sample into a gas chromatograph, further comprising a controllable shutoff valve 34 placed in the outlet pipe 30 of the flow divider 27, with the adjustable flow restrictor 31. device to do. 8. In the device according to claim 7,
A hollow needle 35 is used as a passage for the sample carrier into the evaporator 1, the needle having a pointed end 36 extending away from the evaporator 1.
while said sample carrier 2 is made as an ampoule 39, the upper part or neck of which is hermetically covered by a septum 41 of self-sealing material, said ampoule 39 being constructed as an ampoule 39 at a point immediately prior to sample introduction. The needle 35 is moved towards the pointed end 36 of the hollow needle 35 so as to pierce the septum 41 of self-sealing material to communicate the internal volume of the flask 39 to the evaporator 1. A device for injecting a sample into a gas chromatograph, characterized by: 9. In the device according to claim 8,
The hollow needle 35 is enclosed in a temperature controlled housing 37 and the pointed end 3 of the needle
A device for injecting a sample into a gas chromatograph, characterized in that 6 extends from the device. 10. The apparatus according to claim 7, wherein the sample carrier 2 has a capillary tube 44 attached with a hermetically closed end 45 to a holder 46.
and further characterized in that it has a transverse hole 47 adjacent to said hermetically closed end 45 and is further characterized in that said capillary tube 44 is provided with a movable sealing sleeve 23 of inert deformable material. A device that injects a sample into a gas chromatograph. 11. The device according to claim 10, wherein the retainer 46 of the capillary tube 44 comprises a spring-biased grip 49 in the form of a plate of flexible material with a corrugated hooked end 50. While the evaporator has a head member 51 with a collar 52 adapted to securely engage the corrugated end 50 of the plate, the collar 52 of the head 51 of the evaporator 1 is tapered. Apparatus for injecting a sample into a gas chromatograph, characterized in that it has a surface, through which longitudinal groups 53 extend. 12. The device according to claim 11, which comprises an electric microswitch 54 placed in close proximity to the head member 51 of the evaporator 1;
The spring biased grip 4 is provided with a control device 55 for controlling the valves 29, 34, electrically connected to the microswitch 54.
9, one of the plates 9 has a rib 56 which cooperates with the microswitch 54 while the passage 11 leading the sample carrier 2 to the evaporator 1 is sealed against pressure escape. A device that injects a characteristic sample into a gas chromatograph. 13. The device according to claim 7, wherein the sample carrier 2 has the form of a rod 60 of ferromagnetic material rigidly attached to a holder 62, and the evaporator body 9 is provided with an induction coil 61. A device for injecting a sample into a gas chromatograph, characterized by: