DE2139992A1 - METHOD AND DEVICE FOR SAMPLING AND APPLYING A SAMPLE INTO AN ANALYZER - Google Patents

Description

_{Γ Γ} . - * 5602 LANGENBtFiG (RhId.), Den

■ core L ·. lUeisse Bökenbusch 41

_η . - <Phone (02127) 1319

Dipl.-Phys. Jürgen tfJeisse Telex 8516895 O 1 OQQQO

Patent Attorneys Z. I O <J <J v » ei

Patent registration

Bodenseeitferk Perkin-Elmer & Co. GmbH, 777o Überlingen (Lake Constance)

Method and device for taking samples and for applying a sample to an analysis device .

The invention relates to a method for taking samples and for giving up a sample in an analysis device, in which the sample is taken up by sorption by a sampling device and from this is expelled into the analyzer.

Sampling by adsorption is known per se. With gas chromatographic Analyzes are known guard columns that are filled with an adsorbent and through which you can at low temperature passes a larger measured amount of the gas to be analyzed. Then the guard column becomes a gas chromatograph brought and switched into the flow path of the carrier gas. By heating the guard column, that which is adsorbed in the guard column is then adsorbed Sample gas expelled and transported by the carrier gas into the separation column of the gas chromatograph, where the actual Analysis takes place. The guard column is a column packed with adsorbent granular material. Sampling takes place by that by means of special devices a gas flow through

309808/1069

the guard column is generated. This procedure is relatively complex.

There are so-called capillary columns for gas chromatographic analysis known. These are columns with a very small diameter but great length that do not contain a granular separating substance are packed, but in which the separating substance forms the wall of a freely continuous channel. For example, can

^ the wall of such a column with a separating substance Liquid coated. Such separation columns are very sensitive, but on the other hand have only a very low capacity, i.e. they are only suitable for processing relatively small amounts of sample. If, therefore, in the usual way a liquid Sample is introduced into the inlet part of the gas chromatograph by means of a syringe, then usually this inlet part a flow divider is connected downstream, which divides the sample and carrier gas flow in a defined ratio, so that only a certain Fraction of the sample and carrier gas is added to the separation column. The requirement of this flow division brings one unwanted loss of carrier gas with it. On the other hand, when dosing with a syringe, relatively large amounts of sample are required.

) irrelevant, which are then not exploited at all. Smaller sample quantities but cannot be handled reliably with conventional methods.

by means of injection syringes

The known dosage / has the disadvantage that errors by the manual Handling during sampling and dosing can occur. The sample composition can be sorption or fractionated Evaporation or be falsified by the flow division.

309808/1069

The invention is based on the object of a method for taking samples and for applying a sample to an analysis device to create, in which errors excluded by different manual handling during sampling and dosing as well as a falsification of the sample composition. Sampling should be simple and without complicated apparatus Aids (pump) may be possible. In addition, it should be possible to properly dose the smallest sample quantities.

The method according to the invention is characterized in that the sorption of the sample during sampling on the surface a solid shaped body takes place and this shaped body for sample application is introduced into a heated inlet chamber of the analyzer.

The surface of the shaped body can be used to take gaseous samples exposed to the sample gas for a defined period of time. This sample gas can, for example, add to the atmosphere be a specific place where air pollution is to be examined.

When examining liquid samples, the sample gas can be the vapor space above a liquid sample. It then becomes an adsorption on the shaped body in accordance with the vapor pressures of the individual components of the liquid above the liquid level occur.

It is of course also possible to dose liquid samples directly, by dipping the shaped body into the liquid, pulling it out again and allowing excess sample adhering to drip off. Powdered too In appropriate cases, samples can be used in this

309808/1069

In the case of ceramic metering rods, the surface adhesion is reinforced by electrical charges can be. When sampling solid substances according to the invention, it is a prerequisite that these substances are extremely finely powdered Form exist so that they adhere evenly to the surface of the molded body, and that they also as possible evaporate completely in the heated inlet chamber of the analyzer.

The shaped body is advantageously made after sampling in a gas-tight vessel to the analyzer with the inlet chamber transported.

It should also be recommended that with a similar shaped body on which no sorption of sample took place, a Reference measurement is made. In this way, interfering components can be determined and taken into account.

The shaped body can be heated according to a program in the inlet chamber of the analyzer.

The invention further makes it possible that the analyzer is a gas chromatograph with capillary column, to which the entire ψ is conducted from the molded body in the inlet chamber desorbed sample (without flow divider). This possibility, which not only simplifies and saves carrier gas, is created in that the method according to the invention allows extremely small samples to be metered without any handling difficulties.

30980 8/1069

2139932 5 -

The invention also relates to a device for carrying out the described method.

According to the invention, this device is characterized by

(A) a shaped body for sampling with a sorbent surface, which sits on a shaft, which with a ring seal on its circumference and a sealing plug and a handle on its the molded body the opposite end is provided,

(b) a heatable inlet chamber on the analyzer, which is guided by a guide channel through which the molded body is introduced and in which the shaft is guided, is separated by a closure member which is from the molded body is pressed when-the ring seal of the shaft causes a seal of the guide channel to the outside.

The shaped body can be a cylindrical pin. This pin can be provided with thread grooves to increase the surface. A recess can be provided between the pin and the shaft. However, the shaped body can also consist of several coaxially inside one another arranged pipe pieces are formed, also to increase the surface.

In an advantageous embodiment of the invention Device, the closure member is a piston which is in the cylindrical inlet chamber coaxial with the guide channel guided and through the molded body from a first, guide channel-side End of the same to dom the second, opposite end

- 6 309 80 8/1069

is movable. A transport gas channel from the piston opens into the inlet chamber near the second end is released in its end position. A transport gas outlet leads from the inlet chamber near the first end, and at the second end of the inlet chamber an outlet channel to the analyzer is provided in which the transport gas outlet flows out.

Initially, the piston is on the first. end of Inlet chamber. The transport gas inlet is connected to the outlet

ψ nal in connection. When the shaped body is inserted, the piston is pushed past the transport gas outlet and the latter is released. First, however, the piston still blocks the connection between the transport gas inlet and the transport gas outlet, so that the transport gas flows directly to the outlet channel. When the shaped body is practically completely within the inlet chamber, the piston moves past the transport gas inlet and blocks the connection between the transport gas inlet and the outlet channel. The transport gas now flows along the shaped body from the transport gas inlet to the transport gas outlet and via this to the outlet channel. So it is now the desorbed sample from the shaped body through the trans-

k port gas taken and transported into the exit channel.

The molded body advantageously contains a coupling piece, which automatically couples when inserted with a coupling counterpart of the piston, the coupling when pulled out of the molded body is automatically releasable when the piston reaches the first end of the inlet chamber. It gets that way ensures that the piston when pulling out the molded body

- 7 309808/1069

after dosing has taken place again at the first end of the inlet chamber is taken so that the above; described Initial state is reached again »

Another possibility is that the closure body is formed by a lock flap which is in a the inlet chamber upstream lock chamber is arranged, and that two ring seals on the shaft on both sides the lock chamber when the molded body is moved into the inlet chamber.

The inlet chamber can be coaxial with the guide channel and, depending on its shape and dimensions, on the cylindrical shaped body adapted and only slightly larger than this. In the from a recess between the shaped body designed as a pin and the annular space formed in the shaft can open at least one transport gas inlet, while on the guide channel opposite side of the inlet chamber is provided an outlet channel. This results in a very small dead space the inlet chamber. The transport gas flows from the annular space evenly over the entire surface of the pin, which is designed as a pin Shaped body to the exit channel. In this way you get a very quick and concentrated removal of the desorbed Sample material on the analyzer (e.g. a gas chromatograph).

Another possible embodiment is characterized in that the closure member is a valve body which is guided in the cylindrical coaxial to the guide channel inlet chamber and cooperates with a valve seat of which is or can be lifted by the mold body, that on the outer surface des'Ventilkörpers axial grooves are provided that have a

30 9808/1069

-Q-

Allow port gas to pass between the valve body and the inlet chamber wall, and that laterally behind the valve seat Transport gas inlet opens and at the one facing away from the guide channel An exit channel is provided at the end of the inlet chamber.

In order to switch off the interaction between metal surfaces and sample, the inlet chamber can advantageously be equipped with a Ceramic lining.

Furthermore, the device according to the invention can be characterized by a container for receiving and transporting of the molded body, this container being closed by the stopper on the shaft and the molded body by the Shaft is held freely in the container. The stopper can fulfill a further function, namely by being a container to be completed with a liquid sample and the shaped body above the liquid surface in the vapor space holds.

"The materials used for the sorption zone of the shaped body are based on the respective tasks. The sorption zone of the shaped body can consist of metal, of glass, "quartz" or a ceramic material. The surface of the sorption zone of the shaped body can be coated with a film of a high-boiling liquid. Furthermore, the surface the sorption zone of the shaped body be coated with a sorbent oxide layer.

The invention is explained in more detail below using a few exemplary embodiments with reference to the associated drawings:

30980Ö / 1069

Fig. 1 shows in section, schematically, an inlet part of an analysis device, preferably a gas chromatograph for use in the method according to the invention.

Fig. 2 shows an associated sampling device »

Fig. Jj shows a modified embodiment of the molded body for sampling.

FIG. 4 shows a section along the line IV / IV from FIG. 3.

Fig. 5 shows another form of the inlet part for the Implementation of the method according to the invention.

FIG. 6 shows a suitable one for the inlet part according to FIG Sampling device.

FIG. 7 shows a modification of the arrangement according to FIG.

8 shows a further embodiment of a sampling device and an inlet part for carrying out the method according to the invention.

Fig. 9 shows a sampling device according to the invention in a transport container.

In Fig. 1, an inlet part of a gas chromatograph is shown with a heated block Ίο, in which an inlet chamber 12 is provided with a cylindrical basic shape. To the

- 1o 309808/1 069

2139332

1ο -

Block 1o closes with a tubular extension 14 a guide channel 16 for the shaft 18 of the sampling device 2o (Fig. 2). The guide channel 16 is coaxial with the inlet chamber 12. In the inlet chamber 12 is a piston 22 from a first, right-hand end on the side of the guide channel 16 to a second, left-hand end Movable at the end. From the left end of the inlet chamber 12 there is an outlet channel 24 which leads to a gas chromatographic Separation column leads. In the vicinity of the left end of the k inlet chamber 12, a transport gas channel 26 opens laterally. However, the mouth of the transport gas channel 26 is so that the piston 22 in its left end position the transport gas channel 26 to the interior of the inlet chamber 12 releases. Near the right end of the inlet chamber 12 goes from this a transport gas outlet 28, which is guided in the block 1o and opens into the outlet channel 24.

The sampling device 2o contains a shaped body 5o which, in the embodiment according to FIG. 2, has the shape of a pin. This shaped body has a sorbent surface. This sorbent surface has the length a. The shaft 18 adjoins the molded body 3o. Ψ the shank 18 ring seals 32 are provided which create during insertion of the sampling device 2o into the guide channel 16 at the wall and effect a seal to the outside. ^{Sealing plugs 7} Λ and a handle 36 are seated on the end of the shaft 18 facing away from the molded body 3o.

According to the method according to the invention, the shaped body (pin) 3o with the sorbent surface is exposed to a gas sample. This can be done, for example, in the form that the trial

- 11 -

3 0 9808/1069
BATH ORIGINAL

213999?

taking device 2o is immersed in a vessel containing a sample liquid, the stopper 54 of this vessel closes and the shaft 18 holds the pin 3o above the surface of the sample liquid in the vapor space. The molded body with the sorbent surface is exposed to the sample gases for a defined period of time, so that on the surface a sorption of sample gases according to the steam pressure takes place above the liquid surface.

It is then the sampling device 2o in the guide channel 16 introduced. The molded body 3o then takes with his designed as a coupling member end 38, the piston 22 to the left with. The piston 22 initially prevents the passage of transport gas from the inlet 26 to the outlet 28 and thus a flow of transport gas over the molded body 3o (FIG. 1). That Rather, transport gas 26 flows directly to the outlet channel 24. When the molded body 3o has penetrated so far into the inlet chamber 12 is that its sorbent surface is fully in the inlet chamber 12, namely by the distance a (Fig. 1), then the piston 22 locks, as shown in dashed lines, the passage from the transport gas inlet 26 to the exit channel 24 and the transport gas flows on the molded body 3o

along to the transport gas outlet 28 and from there into the outlet channel 24. The heating of the inlet chamber results in a desorption of those bound to the molded body 3 ° by sorption Sample substance from the transport gas flow in the gas chromatographic Separation column is transported.

The piston 22 is provided with a coupling member, for example in the form of a U-shaped expanding spring 4o, which when moving forward the sampling device 2o to the left with the coupling

309808/1069

link 38 automatically couples. When the sampling device 2o is then pulled out again to the right, it takes the piston 22 with it until it is at the right end of the inlet chamber 12 strikes. The coupling is designed in such a way that it is then released again by pulling it. So it is the one original initial state reached before inserting the sampling device 2o again.

In order to increase the surface area of the shaped body, the shaped body can 3 from a plurality of mutually coaxial pipe sections 4-2, 44, 46 are formed.

Fig. 5 shows another embodiment of the inlet part a gas chromatograph. Corresponding parts are with the The same reference numerals are provided as in FIGS. 1 and 2. In the course of the guide channel 16 in the embodiment according to FIG. a lock chamber 48 is provided. In this lock chamber 48, a lock flap is 5 ° movable, which is in the idle state the guide channel 16 closes off from the lock chamber 48 and the inlet chamber 12.

On the sampling device is between the molded body 3o and Shank 18 an annular groove 52 is provided.

When inserting the sampling device 2o, the shaped body pushes 3o open the lock flap 5o. When the lock body 3o is fully in the inlet chamber 12, the ring seals are located 32 on both sides of the lock chamber, so that on the one hand a perfect seal of the lock chamber to the outside as well as the inlet chamber 12 against the lock chamber 48. In the ring bolts formed by the annular groove 52 is

- 13 309808/1069

Transport gas introduced via transport gas inlets 54-, 55. The inlet chamber 12 is adapted in shape and size to the molded body Jo and is only slightly larger than this the annular space formed by the annular groove 52 and along the lateral surface of the molded body 3o to an exit channel 2Ά- provided on the left side of the inlet chamber 12.

This construction results in a particularly small dead volume in the inlet chamber 12, so that the sample material is quickly and concentrated on the separation column when the molded body 3o enters the inlet chamber 12 and is heated will.

The inlet chamber 12 is advantageously provided with a lining 56 made of glass, quartz or ceramic material.

In order to increase the surface of the shaped body 3o, according to FIG 7 the shaped body with a thread groove 58 on its lateral surface be provided. Instead, of course, annular grooves or axial grooves lying axially one behind the other can also be provided v / earth.

In the embodiment according to FIG. 8, in which the same reference numerals are otherwise used for corresponding parts as in the other figures, in the inlet chamber 12 is a valve seat 6o is provided which cooperates with a valve body 62 which is guided axially displaceably in the inlet chamber 12. The valve body 62 has axial grooves 64 which ensure that after the valve body 62 has been lifted off the valve seat 6o transport gas

309808 / f06 ⁴ 9 ~

-H-

step between valve body 62 and inlet chamber wall and can reach an output channel 24. The transport gas enters the inlet chamber 12 via a transport gas inlet 66, which opens closely behind the valve seat 60.

Around the approach H with the iMhrungskanal 16 despite heating To keep the block 10 relatively cool, cooling fins 68 are provided on the extension 14.

Pig. 9 shows the holder of a sampling device 20 in a cylindrical transport vessel 70, the potting 34 tightly seals the transport container 70 and the shaft 18 holds the molded body 30 freely in the transport vessel 70.

The method and the device according to the invention offer various advantages. The sampling device 20 is insensitive to rough handling, in contrast, for example to the usual microliter syringes. Dosing amount and analysis result are independent of individual handling differences, which are unavoidable when syringes are dosed by different people, both to different Total sample quantities as well as different analytical results being able to lead. Reading errors are not possible during sampling. It can with an arrangement according to the invention the chemical interaction of the sample with metal can be avoided, as occurs when using microlitre syringes could occur if namely both a ceramic inlet chamber (or an inlet chamber with a ceramic lining) as well as a ceramic molded body 30 can be provided for sampling. It is possible to take extremely small amounts of sample conveniently and to dose precisely. It is therefore possible to divide capillary columns without flow control in gas chromatography. use. That

- 15 309808/1069

2139997

brings, for example, a considerable saving in carrier gas and eliminates sources of error. The small dead space in the technically easy to implement is of particular advantage Inlet part. By choosing the appropriate material for the surface of the Lormkörpers there is the possibility of selective Sampling. In many cases, this is associated with trace accumulation without the use of any auxiliary equipment. Gas samples, air samples, in particular, can be taken on the spot without auxiliary equipment such as pumps etc. taken v / earth. Falsification of the sample is therefore excluded.

- 16 309808/1 069

Claims (1)

Claims Method for sampling and for applying a sample to an analysis device, in which the sample by sorption of a Sampling device added and from this in the analyzer is expelled into it, characterized in that the sorption of the sample during sampling on the surface a solid shaped body takes place and this shaped body for sample application in a heated inlet chamber of the analysis | device is introduced. 2. The method according to claim 1, characterized in that the surface of the molded body for sampling gaseous samples is exposed to the sample gas for a defined period of time, 3. The method according to claim 2, characterized in that the sample gas is the vapor space above a liquid sample. 4-, method according to any one of claims 1 to J, characterized in, that, after sampling, the shaped body is transported in a gas-tight vessel to the analyzer with the inlet chamber will. 5. The method according to any one of claims 1 to 4, characterized in that that with a similar shaped body on which no Sorption of sample occurred, a reference measurement is made. 6. The method according to any one of claims 1 to 5 »characterized in that that the shaped body in the inlet chamber of the analyzer is heated according to a program. - 17 309808/1069 7. The method according to any one of claims 1 to 6, characterized in that that the analyzer is a gas chromatograph with a capillary column on which the whole of the shaped body sample desorbed in the inlet chamber (without flow divider) is passed. 8. Device for performing the method according to claim 1, marked by (A) a shaped body (3o) for sampling with sorbent Surface (a) which sits on a shaft (18) which is provided with an annular seal (32) on its circumference and a sealing stopper (34-) and a handle (36) at its end facing away from the molded body (3o) is, (b) a heatable inlet chamber (12) on the analyzer, which is guided by a guide channel (16) through which the molded body (3o) is inserted and in which the shaft . (18) is separated by a closure member (22, 5o, 62) which is pressed open by the molded body (3o) is when the ring seal (32) of the shaft (18) a Sealing of the guide channel (16) causes to the outside. 9. Apparatus according to claim 8, characterized in that the shaped body (3o) is a cylindrical pin (Fig. 2). 1o. Device according to Claim 9, characterized in that the pin is provided with thread grooves (58) to increase the surface is (Fig. 7) · - 18 - 309808/1089 213999? 13 - 11. Apparatus according to claim 8 or 9, characterized in that between the pin (3o) and the shaft (18) there is a recess (54-) is provided, 12. Apparatus according to claim 8, characterized in that the shaped body (3o) is formed by a plurality of pipe pieces (42, 44, 46) arranged coaxially one inside the other (FIG. 4). 13. Device according to one of claims 8 to 12, characterized in that that the closure member is a piston (22) which is coaxial in the cylindrical to the guide channel (16) Inlet chamber (12) guided and through the molded body (3o) from a first, guide channel-side end thereof is displaceable to the second, opposite end, and that in the inlet chamber (12) in the vicinity of the second end a transport gas inlet (26), which is released by the piston (22) in its end position, opens from the inlet chamber (12) in the vicinity of the first end a transport gas outlet (28) goes off and at the second end of the inlet chamber (12) Output channel (24) is provided to the analyzer in which the. Transport gas outlet (28) opens. 14. Apparatus according to claim 13, characterized in that the molded body (3o) contains a coupling piece (38) which when inserting with a coupling counterpart (4o) of the piston (22) automatically couples, the coupling being automatically releasable when the molded body (3o) is pulled out, if the piston (22) reaches the first end of the inlet chamber (12). 15. Device according to one of Claims 8 to 12, characterized in that that the closure body is formed by a lock flap (5o) which is located in one of the inlet chambers (12) - 19 - 309808/1069 upstream lock chamber (48) is arranged, and that two ring seals (32) on the shaft (18) on both sides the lock chamber (48) when the molded body (3o) is moved into the inlet chamber (12). 16. Device according to claims 11 and 15 »characterized in that that the inlet chamber (12) is coaxial with the guide channel (16) and according to shape and dimensions on the cylindrical Molded body adapted and only slightly larger than this and that in the formed by the recess (54) Annular space at least one transport gas inlet (54, 55) opens, while on the side of the inlet chamber (12) opposite the guide channel (16) an outlet channel (24) is provided (Fig. 5) ·. 17- device according to one of claims 8 to 12, characterized in that that the closure member is a valve body (62) which in the cylindrical to the guide channel (16) coaxial inlet chamber - (12) and interacts with a valve seat (60), from which it passes through the Shaped body (3o) can be lifted off that axial grooves are provided on the lateral surface (64) of the valve body (62), which allow a transport gas passage between the valve body (62) and inlet chamber wall, and that laterally behind the Valve seat (60) opens into a transport gas inlet (66) and at the end of the inlet chamber (12) facing away from the guide channel an output channel (24) is provided. 18. The device according to claim 8, characterized in that the inlet chamber (12) with a lining (56) made of ceramic is given away (Fig. 5 and 8). - 2o 309803/1 069 - 2ο - 19 · Device according to one of Claims 8 to 18, characterized through a container (7o) for receiving and transporting the molded body (3o), this container (7o) closed by the plug (34) on the shaft (18) is and the shaped body (3o) through the shaft (18) freely in the container (7o) is held. 20. Device according to one of claims 8 to 19, characterized in that that at least the sorption zone of the shaped body (3 °) consists of metal. 21. Device according to one of claims 8 to 19 *, characterized in that that at least the sorption zone of the shaped body (3o) consists of glass, quartz or a ceramic material. 22. Device according to one of claims 8 to 21, characterized in that that the surface of the sorption zone of the shaped body (3o) is coated with a film of a high-boiling liquid is. 23. Device according to one of claims 8 to 19 »characterized in that that the surface of the sorption zone of the shaped body (30) is coated with a sorbent oxide layer. 309808/1069 Blank page