Device for supplying samples for gas analysis

 

(57) Abstract:

The invention relates to analytical instrumentation. The device includes an inner tube, one end of which is open, while the other is connected through the detector by means of motive gas flow, an intermediate tube, one end of which is open, while the other has a plug, through which is threaded open end of the inner tube, outer tube, one end of which is open, while the other is docked with the open end of the intermediate tube, injector tube with the sample material, one end of which is placed in the outer tube with a gap relative to its inner walls, and the other is placed outside the outer tube. The injection tube has a channel gas-tight septum. The open end of the inner tube is passed through the intermediate tube and is installed inside the injector tube before the gas-tight partition, while the location for the sample is located in the annular channel between the inner tube and the walls of the injector tube. Moreover, the intermediate tube is connected through a pipe with a pump flow of carrier gas. The technical result of the present invention is expressed in increasing dostovesky the instrument, namely, devices for feeding the gas analysis of the gas samples and samples of volatile substances in the conditions of the analysis proceed in the gas phase, from solid and liquid materials, in particular, high-resolution qualitative and quantitative microanalysis of gas chromatography and mass spectrometry.

A device for supplying volatile materials from solid materials for analysis in a gas chromatograph (U.S. Patent N 5065614, MKI G 01 N 30/18, publ. 19.11.91 g), including removable injector tube with the sample material, one end of which is connected through quick release tight joints and flexible pipe to the source of the impulses of the flow of carrier gas, and the other end has a removable needle. The device is equipped with a thermal desorption unit, made of a material with high heat conductivity and having a channel located coaxial injector tube and the open end of the chromatographic column. Around the canal to the heating element. The injector tube with a needle equipped with a mechanism for reciprocating movement and fixing it accordingly in three positions: the injector tube with the needle withdrawn from the channel of thermal desorption unit (preparatory phase); inject the and in the channel of the chromatographic column (feed the sample into the chromatograph).

The disadvantage of this device is the narrow scope of its use in micro-analytical technique because of the large number of restrictions on the use, and the lack of representativeness of the sample due to a change in its qualitative and quantitative composition due to the duration of the interaction of its components with the heated solid material and with each other. The injector tube with the needle, due to the complexity of its construction, has a relatively large mass, resulting in its solid material may be quickly heated ( heating rate of not more than 100oC/min heating time of at least 0.5 min). This, on the one hand, it is not possible to combine the procedure of heating the solid material and sampling procedure the sample from the injector tube for analysis, and on the other hand can lead to a change in the qualitative and quantitative composition of the sample.

The closest technical solution (prototype) is a device for supplying gas analysis of samples of volatile substances from solid materials in the form of filter (US Patent N 5109710, MKI G 01 N 30/20, publ. 05.05.92 g) comprising an inner tube, which is a chromatographic column, one end of which is open, and etector with the environment; the intermediate tube, one end of which is open and the other end has a plug, through which is threaded open end of the inner tube; an outer tube, one end of which is connected with the open end of the intermediate tube, and the outer and intermediate tubes is provided with each of his pipe with a valve; a heating device and temperature control, located around the intermediate tube with the nozzle and part of the outer tube adjacent to the intermediate tube; an injector tube with the sample material, one end of which is perforated, provided with a perforated cover and placed in the outer tube with a gap relative to its inner walls, and its other end located outside the outer tube and connected through quick release tight joints and flexible pipe, to stimulate a flow of carrier gas; node isolation channel of the outer tube from the environment, representing the seal Assembly in the form of an elastic cuffs placed on the end of the outer tube, through which omitted the injector tube with the possibility of reciprocation without depressurization of the outer tube; a cooling device outer tube in the region of the node platnimum disadvantages for use, especially in micro-analytical techniques, namely:

due to the relatively long path from the location of the sample before entering the open end of the inner tube and the large contact surface of the sample components with the elements of the outer and intermediate tubes, there is an increase in the duration of feeding them into the inner tube and, accordingly, increase the width of the chromatographic peaks, and also changes the qualitative and quantitative composition of the reactive components of the sample;

when placing the sample in the injector tube environment penetrates, due to diffusion, in the outer, intermediate and inner tubes;

at the time of submitting samples for analysis of pollution from the field site seal outer tube penetrate, due to diffusion, intermediate and

inner tube;

the carrier gas flowing into the injector tube at ambient temperature, decreases the rate and final temperature of the material containing the sample, and the sample, which leads to an increase in the duration of supply of the sample components in the inner tube and, accordingly, increase the width of the chromatographic peaks.

All the above-mentioned disadvantages reduce the reliability of the C samples when the pressure in the sample is equal to or below the ambient pressure and the possibility of filing for analysis of gaseous samples that limits the scope of application of the device.

Object of the present invention is to provide such a device that would provide the feed gas analysis gas samples and samples of volatile substances in the conditions of the analysis proceed in the gas phase, from solid and liquid materials, when the pressure in the staging area samples both above and below and equal to the ambient pressure, would increase the reliability of the qualitative and quantitative analysis due to:

sample feeding the shortest path in the channel connecting the device with the detector, without intermediate contact of its components with most elements of the device;

in all modes with the exception of penetration into the channel connecting the device with the detector, the pollution of the elements of the device and the environment;

the possibility of a more rapid heating of the material containing the sample, and samples.

This task is solved in that the device for supplying samples for gas analysis, including the inner tube, one end of which is open and the other end connected through the detector by means of motive gas flow; an intermediate tube, one end of which is you is the Nuits tube one end of which is open and the other end connected with the open end of the intermediate tube; heating device and temperature control, located around the outer tube and the intermediate tube with the nozzle; injector tube with the sample material, one end of which is placed in the outer tube with a gap relative to its inner walls, and the other end is placed outside the outer tube; node isolation channel of the outer tube from the environment, according to the invention, the end of the injector tube, placed in the inner tube, is made open; the open end of the inner tube is passed through the intermediate tube and is installed inside the injector tube; in the channel of the injector tube, before the open end of the inner tube, installed gas-tight partition, while the location for the sample is located in the annular channel between the inner tube and the walls of the injector tube; node isolation channel of the outer tube from the external environment is made in the form of a booster flow of carrier gas connected through a pipe to the intermediate pipe.

Node isolation channel of the outer tube from the external environment can be further provided with a removable rotary tube, one congou end provided with a site seal, performed, for example, elastic cuff, through which missed the end of the injection tube located outside the outer tube, with the possibility of reciprocating movement of the injector tube without the depressurization of the rotary tube. When this Gating tube is connected through a pipe to pump gas stream, and around it in the area of the site seal is a cooling device, for example, in the form of a heat sink with forced ventilation. The booster flow of gas from the rotary tube can be made in the form of booster vacuum. When the pressure in the placement of the sample above the ambient pressure as the pump flow of gas from the rotary tube can be used, the valve connected with the environment.

New distinctive features of the prototype characteristics of the proposed device provide:

feed samples in the shortest way into the inner tube without intermediate contact of its components with the elements of the outer and intermediate tubes by placing the open end of the inner tube inside the injector tube;

submission of samples for analysis at a pressure in the layout area of the sample, as

above and below, and equal to the pressure R>
in all modes except penetration into the inner tube of the environment or the environment of a rotary tube through the open end of the outer tube and the outer tube by creating a flow of carrier gas from the pump flow of carrier gas through the pipe intermediate tube, an intermediate tube, the outer tube and through the open end of the outer tube into the environment or into the lock tube;

more rapid heating of the material containing the sample, and the sample due to the installation in front of the open end of the inner tube gas-tight septum and receipts to the sample heated carrier gas from the outer tube over the end of the injector tube, placed in the outer tube.

The invention is further explained in the description of specific variants of its implementation and the accompanying drawings, in which Fig. 1 is a diagram of an apparatus for supplying samples for analysis; Fig. 2 - diagram of the device for supplying the samples, equipped with a rotary tube; Fig. 3 - scheme of the mutual location of injection and drainage operations of sampling and sample preparation.

In Fig. 1, 2, 3 symbols "A" denotes a material containing the sample. In Fig. 1, 2 symbols Q1-Q3 marked the absolute znachenia.prosto for submitting samples for analysis according to the first embodiment includes the inner tube 1, representing a quartz capillary column for gas chromatography, the end 2 of which is open and the other end connected through the detector 3 to the pump gas flow (not shown), a vacuum pump. The intermediate tube 4 has an open end 5 and at the other end of the installed plug 6. Through the cover 6 is missing from the end 2 of the inner tube 1. The outer tube 7 has an open end 8 and its other end 9 docked with the end 5 of the tube 4. Node isolation channel of the outer tube 7 from the external environment is made in the form of pump flow 10 carrier gas connected, through a pipe 11, with the intermediate tube 4. The pump flow 10 carrier gas is a container with a carrier gas under pressure, fitted with a valve for regulating the gas supply. Around the tube 7 and the tube 4 with the pipe 11 posted by device 12 heating and maintaining the temperature made in the form of a massive block of stainless steel, equipped with electric heating element, temperature sensor and power supply unit (not shown). The injector tube 13 is made in the form of thin-walled tubes (outer diameter 2 mm, wall thickness - 0.15 mm) stainless steel. In the channel injectors by the relatively her inner walls, and the other end 16 is placed on the outside of the tube 7. The end 2 of the inner tube 1 is passed through the tube 4 and is installed inside the injector tube 13 and front wall 14. The gaseous sample or material "A", containing the sample, representing, for example, a glass fiber filter or sorbent in the form of a layer of polydimethylsiloxane deposited on the inner wall of the tube 13, placed in the annular channel between the inner tube 1 and the walls of the injection tube 13. The end 15 of the injector tube 13 is provided with a detachable cap PTFE (diagrams not shown), which are used to avoid prolonged contact of the sample contained in the tube 13, with the environment.

Option 2. According Fig. 2, the device for supplying samples for analysis according to the second variant is further provided with a removable rotary tube 17. One end of tube 17 is connected to the end 8 of the tube 7 by means of the detachable sealed connection 18, made in the form of an elastic cuffs. The other end of the tube 17 provided with a seal node 19, which is also made in the form of an elastic cuffs, skipped through which the end 16 of the tube 13 with the possibility of reciprocating movement of the tube 13 without depressurization of the tube 17. The tube 17 is connected through a PA is not shown) or with the environment. Around the tube 17 in the node area of the seal 19 is located, the device 22 cooling, made for example in the form of a heat sink with forced ventilation. At an operating pressure in the sample above ambient pressure tube 1 may be connected through the detector 3 with the environment.

To enable sampling and sample preparation device according to the first and second embodiment is equipped with a drainage tube 23 (Fig. 3) with the open end 24. The end 25 of the tube 17 is connected by means of a sealed connection 26 and a flexible pipe 27 (not fully shown) to the pump 28 of the gas flow. Booster 28 thread made for example in the form of a vessel with a valve containing a carrier gas or gaseous sample under pressure, or in the form of a vacuum pump (not shown).

The device operates as follows.

Option 1. Feed analysis is preceded by a procedure of selection, preparation and storage of samples. The gaseous sample is injected into the vessels. Aerosols from the air are selected on the filter by passing through it a certain amount of air, then put it in the injector tube 13. Pair of organic substances from the air taken in the sorbent, which sabatucci solvents selected from the sorbent, supplied with injector tube, by applying to it an aliquot of the solution and subsequent removal of the solvent from the adsorbent by passing through the injector tube 13 a sufficient volume of carrier gas. The necessary flow of carrier gas or air through the injector tube create by introducing it through the end 15 end 24 of the drainage tube 23 (Fig. 3) and turn on the pump 28. thread made in the form of a vessel with a carrier gas or vacuum pump, respectively. When storing samples of the end 15 of the tube 13 is closed by a plug. The number of injection tubes corresponds to the number of samples.

To maintain the device (Fig. 1) operable in all modes include: booster (not shown) of the gas flow (vacuum pump) connected through the detector 3 to the tube 1, which provides a continuous flow of gas from the device to the detector 3 through the open end 2 and the channel inner tube 1 with a flow rate Q1; served continuously with a flow rate Q2>Q carrier gas from the pump 10 into the pipe 11, the tubes 4, 7 and from the tube 7 through the end 8 into the environment, what prevents the penetration of the environment into the tube 1 through the end 8 and the tube 7. In addition, include the device 12 heating and maintaining the tempo of the 3 released from the cover plate; injected into the tube 13 through the end 15 (Fig. 3) the tube 23 and set the end 24 of the tube before the partition 14; include booster 28 carrier gas or gaseous samples; expect some time required to fill the gas pipe 27 and the tube 13; output tube 23 from the tube 13; turn off the pump 28 of the gas flow; place the end 15 of the tube 13 (depicted by the dotted line) before the end of the 8 outside of the tube 7. Stage of preparation for submission to the analysis of solid samples may include only the operations of removing the insert and placing the end 15 of the tube 13 before the end of the 8 outside of the tube 7, if the environment is present in the field of material "A", containing the sample, does not interfere with the analysis.

In the second stage, the stage of submitting samples for analysis, the tube 13 is rapidly injected inside the outer tube 7, the end 2 of the tube 1 is in front wall 14. The end 15 of the tube 13, as a result of contact with the walls of the tube 7 and the carrier gas, and thermal radiation, is heated together with the material "A" and the breakdown. Due to continuous leakage of gas from the tube 13 into the tube 1, the tube 13 through the end 15 is continuously supplied hot carrier gas from the tube 7, which provides a more rapid heating of the material "A" and samples, and delivery of components prabhudeva to heat the material "A" and trial and submission of the sample components from the annular channel between the tube 1 and the walls of the tube 13 through the end 2 of the tube 1. The duration of injection of the sample into the tube 1 can be reduced by preheating the tube 13 with the sample in the tube 7 and reduce the retention time of the tube 13 in the tube 7.

At the third stage, the stage of analysis of the sample injector tube 13 is removed from the tube 7. The sample components continue to move in the flow of the carrier gas inside the tube 1 in the direction of the detector 3. Stage of the analysis is finished and the device is ready for submission to the analysis of the next sample when the sample components from the tube 1 will arrive at the detector 3.

Option 2. Selection, preparation and storage of samples also perform as described in the first embodiment.

To maintain the device (Fig. 2) operable in all modes include: booster (not shown) of the gas flow (vacuum pump) connected through the detector 3 to the tube 1, which provides a continuous flow of gas from the device to the detector 3 through the open end 2 and the channel inner tube 1 with a flow rate Q1; served continuously with a flow rate Q2>Q1 carrier gas from the pump 10 into the pipe 11, the tubes 4, 7 and from the tube 7 through the end 8 of the tube 17, what prevents the penetration of the medium from the tube 17 into the tube 1 through the end 8 and the tube 7. In addition, include the device 12 nagode samples for analysis, the end 15 of the injector tube 13 is released from the cover plate; introducing tube 13 through the end 15 (Fig. 3) the tube 23 and set the end 24 of the tube before the partition 14; include booster 28 of the flow of carrier gas or gaseous samples; expect some time required to fill the gas pipe 27 and the tube 13; output tube 23 from the tube 13; turn off the pump 28 of the gas stream; introducing the end 15 of the tube 13 (shown dashed) in the tube 17 through the hub 19 and set before the end of the 8 outside of the tube 7; includes booster 21 gas flow with a flow rate Q3; expect to establish the working pressure in the tube 17. The device is operable under the condition Q2=Q1+Q3 and Q2 > Q1. In the second stage, the stage of submitting samples for analysis, the tube 13 is rapidly injected inside the outer tube 7, the end 2 of the tube 1 is in front wall 14. The end 15 of the tube 13, as a result of contact with the walls of the tube 7 and the carrier gas, and thermal radiation, is heated together with the material "A" and the breakdown. Due to continuous leakage of gas from the tube 13 into the tube 1, the tube 13 through the end 15 is continuously supplied hot carrier gas from the tube 7, which provides a more rapid heating of the material "A" and sample and the flow of the sample components in the inner tube 1 without contemprory and submission of the sample components from the annular channel between the tube 1 and the walls of the tube 13 through the end 2 of the tube 1. The duration of injection of the sample components in the tube 1 can be reduced by preheating the tube 13 with the sample in the tube 7 and reduce the retention time of the tube 13 in the tube 7.

At the third stage, the stage of analysis of the sample, the end 15 of the tube 13 is removed from the tube 7 into the tube 17. The sample components continue to move in the flow of the carrier gas inside the tube 1 in the direction of the detector 3. When all components of the sample from the tube 1 will arrive at the detector 3, the end 15 of the tube 13 is removed from the tube 17 and disconnect the booster 21 stream. Stage of the analysis is finished and the device is ready for submission to the analysis of the next sample. New distinctive features of the prototype characteristics of the proposed device provide:

reduction of duration of feed samples up to 1 second or less, which practically does not reduce separation efficiency of most types of capillary chromatographic columns;

the exception penetration of dirt into the chromatographic column of elements of the device and the environment in all modes of operation of the device, which reduces the accuracy of quantitative measurements.

Industrial applicability. The invention can be used in analytical instrumentation.


 

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