Method And Apparatus For Collecting And Introducing A Sample Into An Analytical Instrument

Abstract

A sample is collected and introduced into an analytical instrument by sorbing the sample with a sorption material which is arranged as a surface of a sampling transportable body, positioning the sampling body in an inlet chamber of the instrument, heating the sampling body for causing desorption of the sample material, and conveying the desorbed material in a carrier stream to an analysis station of the instrument. A sampling collecting device comprises a sampling body including a sorption segment thereof having a surface arranged for sorption of sample material. The sampling body further includes an elongated segment which is coupled to the sorption segment, an annular seal extending about a circumference of the elongated segment and a sealing plug and handle located at an end of the body opposite to that of the sorption surface segment. An apparatus for receiving the sampling device and for introducing the sample therein includes an inlet chamber which is positioned near a guide channel and through which channel the sorption segment of the sampling body is introduced. The elongated segment is guided in the channel and a chamber closure member is provided which is actuated by the device when the annular seal on the elongated segment establishes a leak-proof seal between the guide channel and chamber. The chamber closure member is actuated by the sampling body for causing a carrier gas stream to flow over the sampling body and to convey a desorbed material to the instrument.

Description

This invention relates to analytical instruments. The invention relates more particularly to an improved method and apparatus for collecting a sample and for injecting the sample into an analytical instrument.

Various arrangements have been employed for collecting a sample for analysis and for introducing the sample into an analytical instrument. In one collecting and injection technique, the sample is drawn into a syringe and is then discharged into a flowing carrier gas stream of a chromatographic instrument. One form of separating column employed with a gas chromatographic instrument comprises a capillary tube of small diameter, but relatively large length. In this type of column, a separating substance is coated on an inner surface of the tube and defines the wall of a free-passage channel. The surface of such a column may be coated with a liquid acting as a separating substance. Although separating columns of this type are relatively sensitive, they have a relatively small sample capacity and are only suited for processing relatively small sample volumes. Handling of sample quantities of this small size is generally impractical and unreliable. Thus, when a liquid sample is introduced into the inlet section of a gas chromatograph employing a capillary column by means of a syringe, a stream splitting means is provided for dividing the sample and carrier gas stream in a defined ratio for providing that only a fraction of the mixture of sample and carrier gas is supplied to the separating column. This requirement for stream splitting results in an undesirable loss of carrier gas. Furthermore, the collection of dosed quantities of a sample by means of an injection syringe can be unreliable since during the sample taking and dosing, errors can be introduced as a result of manual handling. In addition, the sample composition can be altered by sorption, by fractionated evaporation, or by the flow division.

Another technique provides for collection of the sample by adsorption. In gas chromatographic analyses, for example, sample introduction columns have been employed which are packed with an adsorbent granular material through which a relatively large dosed volume of a gas under analysis is conveyed at relatively low temperature. This column is coupled to a gas chromatograph and is connected into the flow stream of the carrier gas. The sample introduction column is then heated and the sample gas which was adsorbed by the column material is then exhausted and is conveyed by the carrier gas to a separating column of the gas chromatograph where analysis takes place. Sample collection is provided with this arrangement through the use of means which convey a sample gas stream through the sample introduction column. This technique, however, undesirably enlarges the cost, size and space requirements of the apparatus.

Accordingly, it is an object of this invention to provide an improved method and apparatus for collecting and introducing a sample to an analytical instrument.

Another object of the invention is to provide a method of sample collection and injection in which errors due to different manual handling during sample taking and dosing and alterations in the sample composition are subsequently reduced.

Another object of the invention is to provide a relatively noncomplex means for collecting a sample by sorption.

A further object of the invention is to provide an improved means for collecting relatively small dosed sample quantities.

In accordance with the general features of the method of this invention, a sample is collected and introduced into an analytical instrument by sorbing the sample in a sorption material which is arranged as a surface of a sampling transportable body, positioning the sampling body in an inlet chamber of the instrument and heating the sampling body for causing desorption of the sample material. The sampling body is transferred in a gas-tight vessel to the inlet chamber of the analytical apparatus. In collecting gaseous samples, the surface of the sampling body is exposed to a sample gas for a predetermined period of time. For example, the sample gas may comprise the atmosphere at a specific location at which the air is to be examined for pollutants. In collecting liquid samples, the sample comprises the vaporized portion which occupies the vapor space above the liquid sample. An adsorption occurs in the sampling body in accordance with the vapor pressures of the individual components of the liquid above the liquid level. The method is further advantageous in that liquid samples may also be collected by wetting the sampling body in the liquid sample, and permitting adhering surplus sample to drip off the body. Powder type samples can be collected with this method by the use of ceramic dosing rods whose surface adhesion is increased by the application thereto of electric charge. In the collection of solid samples, it is necessary that the solid exist in fine-powdered or particulate form so that the particles will adhere uniformly to the surface of the sampling body and that they evaporate in the heated inlet chamber of the analytical apparatus without residue.

In accordance with another feature of the method of the invention, a reference sample is collected with a like sampling body, but upon which sorption of a sample material does not take place. In this manner, interfering components can be sensed and accounted for in the analysis.

The invention further permits the analytical apparatus to comprise a gas chromatograph having a capillary column to which all of the sample desorbed by the molded body in the inlet chamber is conducted, without flow division. This possibility not only involves simplification and a saving of carrier gas but also provides for the dosing of extremely small samples without difficulties of handling.

A sample collecting device in accordance with the invention comprises a sampling body including a segment thereof having a surface arranged for sorption of sample material. In accordance with more particular features of the invention, the sampling body further includes an elongated segment and an annular seal extending about a circumference of this segment, a sealing plug and a handle located at an end opposite to that of sorption surface segment. An instrument for receiving the device and for introducing the sample therein includes an inlet chamber which is positioned near a guide channel and through which the sorption surface segment of the sampling body is introduced. The elongated segment is guided in the channel and a chamber closure member is provided which is actuated by the device when the annular seal on the elongated segment establishes a leakproof seal between the guide channel and chamber. A sorption surface segment, in one embodiment comprises a molded body of generally cylindrical shape. This body is provided with raised portions for elevating the sorption surface above the supporting body. A recess is provided between this cylindrically shaped segment and the elongated segment which comprises a rod, for example. The sorption segment alternatively comprises a plurality of coaxially arranged tubes.

In a particular embodiment of an apparatus in accordance with the invention, the inlet chamber includes a first inlet aperture communicating with the guide channel and a second inlet aperture through which a carrier gas flows to the chamber. A first outlet aperture is provided which communicates with an outlet channel for conveying carrier gas from the chamber to the analytical instrument. A transfer channel is also provided which communicates between the chamber and the outlet channel. The closure member comprises a sliding piston valve which is reciprocally actuated in an inlet chamber of generally cylindrical configuration. The chamber is coaxially positioned with respect to the guide channel. The piston is translated by the device from a first position near the guide channel to a second opposite position. A flow path through the transfer gas channel is established when the piston is located at the second position while the flow path between the first inlet and first outlet of the chamber is interrupted. When the piston is translated to the first position, the flow path through the transfer channel is interrupted while a flow path between the first inlet and outlet apertures is established.

In operation, the piston valve is initially located at the first position in the inlet chamber and the transfer gas inlet is maintained in communication with the outlet channel. When the sampling device is introduced, the piston is moved past the transfer channel in the chamber so that the carrier gas continues to flow between the first inlet and outlet apertures to the outlet channel. When the sorption segment is positioned substantially within the inlet chamber, the piston has then been translated past the transfer chamber inlet and now blocks communication between carrier gas inlet and outlet channels to the chamber. The carrier gas then flows over the sorption segment from the first aperture to the transfer channel inlet and through the latter towards the outlet channel. A desorbed sample from the sorption segment is picked up, is carried along by the carrier gas, and is transferred into the outlet channel.

The sampling device includes a coupling means which, upon introduction into the guide channel, automatically engages a coupling means of the piston valve. The coupling means is automatically disengageable upon withdrawal of the device from the chamber, when the piston valve reaches the first end of the inlet chamber. With this arrangement it is ensured that, upon withdrawal of the device after sample introduction, the piston will be translated from the second to the first end of the inlet chamber and the initial valve conditions are reestablished.

Alternative to a piston valve arrangement, the apparatus includes a sluice chamber and an inlet chamber. The sampling device extends initially through the sluice chamber and then into the inlet chamber. Two annular seals are positioned on the elongated segment and are disposed on both sides of the sluice chamber, when the sorption segment is positioned substantially in the inlet chamber. In one embodiment, the inlet chamber is coaxial with the guide channel; it conforms in general shape and dimensions to the sorption segment of the sampling device; and it is only slightly larger than the latter. A carrier gas inlet extends into an annular space defined by a recess formed between the sorption segment and elongated segment and an outlet channel is provided to the instrument through the inlet chamber which is disposed opposite the guide channel. A relatively small inlet chamber dead space is thereof obtained. The carrier gas which flows from the annular space flows uniformly across the total surface of the sorption segment to the outlet channel. In this manner, a relatively rapid and concentrated injection of the desorbed sample material into the analytical apparatus is achieved.

In accordance with an alternative embodiment, the closure member comprises a valve body which is guided in a cylindrical inlet chamber. The inlet chamber is arranged coaxially with the guide channel. The valve body coacts with a valve seat from which it is unseated by the sorption segment. Grooves extending in an axial direction on the body of the valve provide a carrier gas passage between the valve body and inlet chamber walls. A carrier gas inlet aperture is positioned downstream from the valve seat and an outlet channel is provided at an opposite end of the inlet chamber.

In accordance with another feature of the invention, the sampling device is transportable with a sealed vessel which receives the sorption segment for transfer. This vessel is sealed by a plug means positioned on the elongated segment and this sorption segment is suspended in the vessel by the elongated segment. The plug means additionally provides for sealing a vessel containing a liquid sample and for supporting the sorption segment above the liquid surface in the vapor space.

These and other objects and features of the invention will become apparent with reference to the following specification and to the drawings wherein:

FIG. 1 is a sectional view of one embodiment of an inlet of an analytical apparatus for use with the method of the present invention;

FIG. 2 is a side view of a sampling device for use with the inlet of FIG. 1;

FIG. 3 is an enlarged view, partially in section of one embodiment of a sorption segment of the sampling device;

FIG. 4 is a sectional view taken along lines IV--IV of FIG. 3;

FIG. 5 is a sectional view of an alternative of the inlet for carrying out the method of the invention;

FIG. 6 is a side view of a sampling device for use with the inlet of FIG. 5;

FIG. 7 is an enlarged view of an alternative embodiment of a sorption segment of the sampling device of FIG. 6;

FIG. 8 is a sectional view of a further embodiment of an inlet for carrying out the method according to the invention; and,

FIG. 9 is a side elevation view, partially in section, illustrating a sampling device and transfer vessel.

Referring now to FIG. 1, an inlet section of an analytical instrument as for example, a gas chromatograph, includes a heated block 10 in which there is formed an inlet chamber 12. The chamber, for example, has a generally cylindrical shape. A tubular projection 14 is integrally formed with the block 10 and includes a guide channel 16 for receiving an elongated segment or member 18 of the sampling device 20 (FIG. 2). The guide channel 16 is positioned coaxially with the inlet chamber 12. A sliding piston valve 22 is positioned in the chamber 12 and is reciprocally translated between a first right end of the chamber 12, as viewed in FIG. 1, and a second left end. The chamber 12 includes a first outlet aperture and channel 24 leading to a gas chromatographic separating column. A first carrier gas inlet aperture and channel 26 is provided and terminates in the chamber 12 near the left end of the chamber. This aperture is positioned with regard to the aperture 24 so that when the piston 22 is located in its left end position and interrupts the flow to aperture 24, the carrier gas flows from channel 26 towards a carrier gas transfer channel 28 which is formed in the block 10 and which communicates with the outlet channel.

The sampling device 20 includes a sorption segment or member 30 which comprises a molded body having the shape of a stud as illustrated in the embodiment of FIG. 2. This molded body has a surface adapted for sorption of a sample material. The materials from which a sorption surface of the molded body is formed is dependent on the type of analysis sample being handled. The sorption surface of the molded body is formed, for example, of metal, of glass, of quartz or of a ceramic material. The surface of the sorption segment of the molded body may be coated with a film of high-boiling liquid. Furthermore, the surface of the sorption zone of the molded body may be coated with an oxide layer adapted for sorption. This surface capable of sorption has the length a as illustrated in FIG. 2. In order to increase the effective sorption surface area of the body, the sorption segment may be arranged as a plurality of tubular pieces or segments 42, 44, and 46 (FIG. 3) which are mounted coaxially with respect to each other. Additionally, in order to eliminate the possibility of interaction between metallic surfaces and the sample, the inlet chamber 12 is provided with a lining of ceramic material. A pair of annular seals 32, such as "O" rings are positioned on the segment 18 and engage the walls of the guide channel 16. A sealing plug 34 as well as a handle 36 are mounted on an opposite end of the segment 18.

In accordance with the method of the invention, the sorption segment 30 and its surface adapted for sorption is exposed to a gas sample. This is accomplished, for example, in a manner for providing that the sampling device 20 is immersed in a vessel 70 (FIG. 9) containing a sample liquid. The plug 34 provides a seal for this vessel and the segment 18 supports the sorption segment 30 above the surface of the sample liquid in the vapor space. The sorption segment with a surface thereof adapted for sorption is exposed to the sample gases for a predetermined period of time. Sorption of sample gases above the liquid surface occurs in accordance with the vapor pressures of the constituent gases. The sampling device 20 is then introduced into the guide channel 16 of the inlet section of an analytical instrument. A leading segment of the device engages and translates the piston 22 toward the left from a first to a second position. The device 30 includes a coupling member 38 for engaging the piston 22. The piston 22, when located at the first position, enables the flow of carrier gas from the inlet 26 to the outlet channel 24 both directly through the chamber and through the transfer channel 28 as illustrated in FIG. 1. The first position of the piston 22 can alternatively be selected for inhibiting the flow of carrier gas through the channel 28 and causing the carrier gas to flow directly through the chamber to the outlet aperture 24. When the molded body 30 has been advanced into the inlet chamber 12 by a distance for providing that its sorption surface is positioned completely within the inlet chamber 12, i.e., by the distance a (FIG. 1), then the piston 22, as is shown in dotted lines, will inhibit the flow of the carrier directly from the inlet 26 to the outlet channel 24. The carrier gas then flows over the molded body 30 to the transfer channel 28 and through this channel into the outlet channel 24. Heating of the inlet chamber causes a desorption of the sample substance from the molded body 30. The substance is then transferred by the carrier gas stream into the gas chromatographic separating column.

The piston 22 includes a coupling member in the form of a U-shaped expansion spring 40 which is automatically engaged by the coupling member 38 upon advancement of the sampling device 20 in the guide channel 16. As the sampling device 20 is withdrawn from the guide channel 16, it translates the engaged piston 22 to the first position at which the piston abuts the right end of the inlet chamber 12. The coupling means 38 and 40 are arranged for disengagement by exerting a pulling force on the knob 36. The initial condition of the piston 22, prior to introduction of the sampling device 20, is then restored.

FIG. 5 illustrates an alternative embodiment of the inlet section of an analytical instrument. Those components of FIG. 5 which perform functions similar to components of FIG. 1 bear the same reference numerals. In the embodiment of FIG. 5 a sluice chamber 48 is provided adjacent the guide channel 16. A pivotally mounted sluice valve 50 is provided. In an unactuated position, this valve seals the guide channel 16 from the sluice chamber 48 and from the inlet chamber 12. The valve is rotatable in a clockwise direction when actuated. An annular groove 52 is formed on the sampling device between sorption segment 30 and elongated segment 18. Upon introduction of the sampling device 20 into the guide channel 16, the molded body 30 forces the sluice valve 50 in a clockwise unseated position. When the molded body 30 is disposed completely within the inlet chamber 12, the annular seals 32 are located on both sides of the sluice chamber thereby sealing the sluice chamber against leakage to the channel 16 and sealing the inlet chamber 12, against leakage into the sluice chamber 48. Carrier gas is introduced through gas inlets 54 and 55 into the annular space provided by the annular groove 52. The inlet chamber 12 has a size and shape which is adapted for receiving the molded body 30. More particularly, it has a size only slightly larger than this body. When the molded body 30 is positioned in the inlet chamber 12, carrier gas flows through the inlets 54 and 55 into the annular space defined by the annular groove 52 and along the surface of the molded body 30 to the outlet channel 24. With this construction, a particularly small dead volume in the inlet chamber 12 is obtained so that the sample material is supplied rapidly and in concentrated form to the separating column when the molded body 30 enters the inlet chamber 12 and is heated. The inlet chamber 12 is advantageously provided with a lining 56 of glass, quartz or ceramic material.

An alternative embodiment of the inlet system is illustrated in FIG. 8. Those components of FIG. 8 which perform functions similar to components of FIGS. 1 and 5 bear the same reference numerals. The inlet chamber 12 of FIG. 8 includes a valve seat 60 and a valve body 62 which is guided for movement in an axial direction in the inlet chamber 12. The valve body 62 includes grooves 64 extending in a generally axial direction which permit a carrier gas flow between the valve body 62 and the inlet chamber walls towards the outlet channel 24. The carrier gas enters the inlet chamber 12 through a carrier gas inlet 66 which terminates near the valve seat 60. In order to maintain the projection 14 and the guide channel 16 relatively cool when heating the block 10, cooling ribs 68 are provided on the projection 14.

FIG. 9 illustrates the mounting of the sampling device 20 in the cylindrical transfer vessel 70. The plug 34 tightly seals the transfer vessel 70 and the elongated segment 18 supports and suspends the sorption segment 30 in the transfer vessel 70.

FIG. 7 illustrates a further embodiment of the sorption segment 30. In order to raise the surface of the segment 30, the molded body is, as illustrated in FIG. 7, provided with lands and valleys, or, for example, a threaded groove 58 on its surface. Alternatively, laterally spaced annular grooves or axial grooves are provided.

The described method and device according to the invention offer various advantages. The sampling device 20 is relatively insensitive to rough handling, in contrast, for example, to sampling devices of the microliter syringe type. The dosed volume and analytical result are substantially independent of individual differences in handling which are common problems in syringe dosing by different persons and which leads both to different total sample volumes and to different analytical results. Reading errors are avoided by the sample collection technique. In an arrangement according to this invention, the chemical interaction of the sample with metal such as it might occur when using microliter syringes, can be avoided through the use of both a ceramic inlet chamber, or an inlet chamber having a ceramic lining, and a ceramic sorption segment 30. In addition, it is possible to conveniently and accurately dose relatively small sample volumes. Therefore, capillary columns can be used in gas chromatographs without the need for flow division. This results in a considerable saving in carrier gas and eliminates other sources of error. The relatively small dead volume in the inlet section is of particular advantage. By the selection of particular material for the surface of the sorption segment, selective sample collection can be achieved In many instances, an enrichment of traces without the use of any auxiliary equipment is thus provided. Gas samples, particularly air samples can be taken on site without the need for auxiliary equipment such as pumps, etc. Therefore, sampling errors and variations are precluded.

While there have been described herein particular embodiments of the present invention, it will be apparent that various modifications can be made by those skilled in the art without departing from the spirit of the invention and the scope of the appended claims.

Claims

What is claimed is:

1. A method of collecting and injecting a sample material into an analytical apparatus comprising the steps of:

sorbing the sample material on the surface of a sorption segment of a generally transportable sampling device by positioning said segment of said device in a space above a liquid sample which space is occupied by the vaporized liquid sample;

introducing the sorption segment bearing the sorbed sample material into an inlet chamber of an analytical apparatus;

causing the desorption of the material from the sorption segment of the sampling device within said chamber; and,

conveying the desorbed sample material to an analysis station of the apparatus.

2. A method of collecting and injecting a sample material into an analytical apparatus comprising the steps of:

sorbing the sample material on the surface of a sorption segment of a generally transportable sampling device by positioning said sorption segment of said device in an environment for exposing said segment to the sample material;

positioning said sorption segment within a gas-tight vessel after sample sorption and then transporting the sample device to an analytical apparatus;

introducing the sorption segment bearing the sorbed sample material into an inlet chamber of an analytical apparatus;

causing the desorption of the material from the sorption segment of the sampling device within said chamber; and,

conveying the desorbed sample material to an analysis station of the apparatus.

3. The method of claim 1 wherein said sample material is desorbed by heating said sorption segment of said sampling device.

4. A method of collecting and injecting a sample material into an analytical apparatus comprising the steps of:

sorbing the sample material on the surface of the sorption segment of a generally elongated transportable sampling device;

introducing the sorption segment bearing the sorbed sample material into an inlet chamber of an analytical apparatus;

causing the desorption of the material from the sorption segment of the sampling device within said chamber; and,

conveying the desorbed sample material to an analysis station of the apparatus;

said apparatus including an inlet chamber and valving means for controlling the flow of a carrier gas from a source thereof through said inlet chamber to the analysis station of the apparatus, and said sampling device actuating said valving means during insertion of said sorption segment into said inlet chamber.

5. An improved arrangement for introducing a sample material into an analytical apparatus comprising:

an inlet chamber;

means for supplying a carrier gas to said inlet chamber;

means for conveying said carrier gas from said inlet chamber to said analysis station of said apparatus;

a sampling device including a sorption segment adapted for sorbing a sample material on a surface thereof; and,

means for introducing said sorption segment into said inlet chamber, said means including a valve for inhibiting the flow of carrier gas through said latter means to atmosphere, said valve arranged for actuation by said sampling device.

6. The apparatus of claim 5 including a carrier gas transfer flow channel communicating between said inlet chamber and a first outlet aperture of said chamber and said valve is arranged for diverting the flow of carrier gas about said sorption segment when said sorption segment is positioned within said chamber and through said transfer flow channel to the apparatus.

7. The apparatus of claim 6 wherein said inlet chamber is formed as a cylinder and said valving means comprises a piston which is reciprocated between first and second positions by the introduction and removal of said sorption segment from said chamber.

8. The apparatus of claim 7 wherein said piston is arranged for enabling the flow of carrier gas through said chamber directly to said instrument when said piston is located in said first position and for inhibiting the direct flow of carrier gas to said instrument and causing said carrier gas to flow over said sorption segment and through said transfer channel when said piston is located in said second position.

9. The apparatus of claim 8 wherein said piston inhibits the flow of carrier gas through said transfer channel when said piston is located in said first position.

10. The apparatus of claim 5 wherein said valving means comprises a sluice chamber positioned adjacent said inlet chamber, a normally seated sluice valve which seals said sluice chamber from an inlet aperture thereto and which is arranged to be actuated by the sampling device when said sampling device is introduced through said inlet aperture, means forming a passage between said sluice chamber and said inlet chamber for introducing said sorption segment into said inlet chamber, means for directing the flow of carrier gas over said sorption segment, and means for inhibiting the leakage of carrier gas from said inlet chamber through said sluice valve.

11. The apparatus of claim 5 wherein said sampling device includes means positioned thereon for establishing the gas-tight seal for inhibiting leakage of carrier gas from said inlet chamber.

12. The apparatus of claim 10 wherein said sampling device includes means positioned thereon for establishing the gas-tight seal for inhibiting leakage of carrier gas from said inlet chamber, and said gas leakage inhibiting means comprises means for inhibiting leakage of gas from said inlet chamber to said sluice chamber and for inhibiting leakage of gas from said sluice chamber to said inlet aperture.

13. The apparatus of claim 5 wherein said valving means includes an annular valve seat which is positioned within said inlet chamber and through which said sorption segment extends upon entering said chamber, said valve comprises a body which is normally seated at said valve seat for inhibiting flow of carrier gas from said chamber to a probe inlet to said chamber, said valve is arranged for displacement in the direction parallel to a longitudinal axis of said sampling device and said valve includes recesses formed on an outer surface thereof for providing a carrier gas flow passage between the outer surface of the valve and said inlet chamber when said valve is unseated.

14. The sampling arrangement of claim 5 wherein said sorption segment comprises a plurality of concentrically arranged tubes extending over a predetermined length and spaced apart radially, each of said tubes providing a sorption surface for sorbing and adsorbing a sample material.

15. The sampling arrangement of claim 5 wherein said sorption segment comprises a body having a surface portion thereof elevated with respect to other portions of the body.

16. The sampling arrangement of claim 15 wherein said sorption segment is formed by a plurality of lands and grooves formed in said sorption segment.

17. The sampling arrangement according to claim 5, in which:

said sampling device comprises, in addition to said sorption segment, a relatively elongated support segment attached thereto;

and means are positioned on said support segment for establishing a gas-tight seal between said segment at a wall of a body within which said segment is positioned.

18. A sampling device comprising:

a generally cylindrically shaped body having a relatively elongated support segment thereof and a relatively shorter sorption segment extending from said support segment;

said sorption segment having a surface thereof adapted for sorbing a sample material and for desorbing said sample material when said sorption segment is heated;

the surface of said sorption segment being coated with a film of a high-boiling liquid.

19. A sampling device comprising:

a generally cylindrically shaped body having a relatively elongated support segment thereof and a relatively shorter sorption segment extending from said support segment;

said sorption segment having a surface thereof adapted for sorbing a sample material and for desorbing said sample material when said sorption segment is heated;

the surface of said sorption segment being coated with a film of a high-boiling liquid.