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WO1992015875A1 - Unite de commande pneumatique pour dispositif de transport d'analyseur - Google Patents

Unite de commande pneumatique pour dispositif de transport d'analyseur Download PDF

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Publication number
WO1992015875A1
WO1992015875A1 PCT/US1992/001641 US9201641W WO9215875A1 WO 1992015875 A1 WO1992015875 A1 WO 1992015875A1 US 9201641 W US9201641 W US 9201641W WO 9215875 A1 WO9215875 A1 WO 9215875A1
Authority
WO
WIPO (PCT)
Prior art keywords
sample
vial
gas
headspace
needle
Prior art date
Application number
PCT/US1992/001641
Other languages
English (en)
Inventor
Thomas B. Green
Gregory G. O'neil
Original Assignee
Tekmar Company
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Tekmar Company filed Critical Tekmar Company
Publication of WO1992015875A1 publication Critical patent/WO1992015875A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N35/00—Automatic analysis not limited to methods or materials provided for in any single one of groups G01N1/00 - G01N33/00; Handling materials therefor
    • G01N35/10—Devices for transferring samples or any liquids to, in, or from, the analysis apparatus, e.g. suction devices, injection devices
    • G01N35/1079—Devices for transferring samples or any liquids to, in, or from, the analysis apparatus, e.g. suction devices, injection devices with means for piercing stoppers or septums
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00—Sampling; Preparing specimens for investigation
    • G01N1/02—Devices for withdrawing samples
    • G01N1/22—Devices for withdrawing samples in the gaseous state
    • G01N1/2226—Sampling from a closed space, e.g. food package, head space
    • G01N2001/2229—Headspace sampling, i.e. vapour over liquid
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N35/00—Automatic analysis not limited to methods or materials provided for in any single one of groups G01N1/00 - G01N33/00; Handling materials therefor
    • G01N35/02—Automatic analysis not limited to methods or materials provided for in any single one of groups G01N1/00 - G01N33/00; Handling materials therefor using a plurality of sample containers moved by a conveyor system past one or more treatment or analysis stations
    • G01N35/04—Details of the conveyor system
    • G01N2035/0401—Sample carriers, cuvettes or reaction vessels
    • G01N2035/0406—Individual bottles or tubes
    • G01N2035/041—Individual bottles or tubes lifting items out of a rack for access
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N35/00—Automatic analysis not limited to methods or materials provided for in any single one of groups G01N1/00 - G01N33/00; Handling materials therefor
    • G01N35/02—Automatic analysis not limited to methods or materials provided for in any single one of groups G01N1/00 - G01N33/00; Handling materials therefor using a plurality of sample containers moved by a conveyor system past one or more treatment or analysis stations
    • G01N35/04—Details of the conveyor system
    • G01N2035/0439—Rotary sample carriers, i.e. carousels
    • G01N2035/0441—Rotary sample carriers, i.e. carousels for samples
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N35/00—Automatic analysis not limited to methods or materials provided for in any single one of groups G01N1/00 - G01N33/00; Handling materials therefor
    • G01N35/02—Automatic analysis not limited to methods or materials provided for in any single one of groups G01N1/00 - G01N33/00; Handling materials therefor using a plurality of sample containers moved by a conveyor system past one or more treatment or analysis stations
    • G01N35/04—Details of the conveyor system
    • G01N2035/0474—Details of actuating means for conveyors or pipettes
    • G01N2035/0482—Transmission
    • G01N2035/0487—Helix or lead screw
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
    • G01N30/02—Column chromatography
    • G01N30/04—Preparation or injection of sample to be analysed
    • G01N30/06—Preparation
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
    • G01N30/02—Column chromatography
    • G01N30/04—Preparation or injection of sample to be analysed
    • G01N30/24—Automatic injection systems
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
    • G01N30/02—Column chromatography
    • G01N30/26—Conditioning of the fluid carrier; Flow patterns
    • G01N30/28—Control of physical parameters of the fluid carrier
    • G01N30/32—Control of physical parameters of the fluid carrier of pressure or speed

Definitions

  • the invention relates to devices for trans ⁇ porting large numbers of samples to a sampling site preparatory to analysis of those samples.
  • Head space analysis techniques are employed to analyze for volatile components in largely non ⁇ volatile mixtures. For example, this analytical technique is used in determining the amount of alcohol in a known quantity of blood. The technique is also used for analyses of volatile components in other body fluids. Further applications include analysis of trace organic compounds in water samples, testing for the presence of solvents in drugs, for solvents or monomers in polymers, for fragrances in toiletries, for flavors or aromas in foods, and the like. It is desirable in these applications to have a transport device capable of transporting samples automatically at high rates to the analyzing instrument.
  • the transport device prefferably be programmed to automatically repeat the sampling of one or more vials one or a number of times. This feature is useful for improving the precision of the analysis.
  • the amount of volatile components in the gaseous headspace portion over a liquid sample in a closed vial is known to vary with the temperature of the liquid sample. Therefore, it is very important to maintain the temperature of the liquid sample within a very narrow range in the transport prior to analysis. Further, because the actual quantity of material in the headspace over a liquid sample is very small, any contamination from outside sources would substantially alter the analysis of the headspace gases. Therefore, the risk of outside contamination must be minimized during the sampling process. Also, because sample vials are made in various sizes, it is desirable that the transport device be able to accommodate different sizes. Summary of the Invention
  • the invention relates to a sample vial transport device having a rotatable heated platen with a plurality of chambers to hold sample vials.
  • the sample vials are loaded into the chambers by a vial transport which conveys the sample vials from a point above the individual chamber.
  • the platen therefore does not have to move axially to input a vial or to sample the vial contents, as discussed below. This significantly reduces the complexity of the vial transport mechanism. Vials from which samples have already been taken are ejected from the individual chamber by reversing the operation of the vial trans ⁇ port.
  • Sampling of the contents of the sample vial is done at a point removed from the vial inlet point.
  • the sample vial is rotated toward the sampling point, at which time the sample vial is brought into contact with a needle by mating means.
  • the needle extracts at least a portion of the contents of the vial for sampling by puncturing a septum in the cap of the vial.
  • the platen is preferably heated electrical ⁇ ly. Electrical heating is preferred over oil bath heating, which tends to introduce trace materials attributable to the oil into the analysis instrument and thereby alter the analysis results. Further, oil vapors condense on mechanisms and hold dirt. The oil baths need to be constantly stirred to maintain temperature uniformity, and they pose a greater safety hazard to the operator.
  • the vial from which a sample has been extracted then continues back to the inlet point within the chamber. At that time, it is either ejected from the platen by the vial transport or alternatively remains in the chamber for an additional rotation and sampling operation.
  • the transport device chambers are also capable of holding liner sleeves, or inserts, which permit sampling of different size vials.
  • the vials utilized have volumes of 5ml, 10ml or 20ml.
  • the needle is stationary and positioned above the platen and a second vial transport is utilized as the mating means to push the sample vial upward from the bottom of the chamber to cause puncturing of the septum with the needle.
  • a second vial transport is utilized as the mating means to push the sample vial upward from the bottom of the chamber to cause puncturing of the septum with the needle.
  • the needle can be movable to puncture the septum as an alternative embodiment.
  • the rate of transport of gaseous components from the liquid to the headspace of the vial is a function of the mean path length the components must travel through the liquid to reach the headspace. It has been found that mixing the vial contents dramat ⁇ ically reduces the mean path length and thus improves the transport rate.
  • the invention includes a mixing device having a vertically displaceable rod positioned below the platen which rises through the bottom of the platen to contact the sample vial bottom in a chamber between the inlet point and the sampling point.
  • the rod is preferably connected to a DC solenoid which is repeatedly ener- gized for short periods to cause the rod to pulse and thereby shake the sample vial in an up and down motion within the chamber. This mixing motion aids in equilibrating the concentration of the material to be analyzed in both the liquid and gas phases within the sample vial.
  • Fig. 1 is a side view of the transport device, taken in an axial cross sectional view through the unit with certain features out of position to aid in understanding the invention.
  • Fig. 2 is a side view of the device, taken with a different cross section, and showing all elevator rods in the retracted position.
  • Fig. 3 is a schematic of the carrier gas and sample flow patterns.
  • Fig. 4 is a top view of the transport device.
  • Fig. 5 is a schematic of the carrier gas and sample flow patterns modified to show a different arrangement of pressure and flow controllers from that depicted in Fig. 3.
  • the invention in its broader aspects relates to a transport device for conveying sample vials to a sampling location for effecting withdrawal of at least a portion of the vial contents for analysis thereof, comprising a platen which is rotatable around a central axis having a plurality of counterbored chambers, a heater for the platen, a first vial transport which operates to convey a vial into a chamber from a point above the chamber and the reverse, a needle for extracting at least a portion of the vial contents from the vial, and mating means for bringing the needle into contact with the vial con ⁇ tents to allow extraction thereof.
  • Fig. l shows the sample transport 2 having a platen 4.
  • the platen 4 is a cylindrical block made of heat-conducting material, preferably aluminum, which is manufactured preferably by combining the throughbored block 8 with the bored plate 10 and insulation plate 12.
  • the throughbored holes in block 8 run axially through the block and are positioned near the periphery of the block. These holes mate with the bored holes in plate io, the holes having a smaller diameter than those in block 8. Mating is facilitated by the use of dowel pins 14 in the bored plate 10 which key into mating holes in the block 8.
  • throughbored block 8 with bored plate 10 creates individual cham- bers 16 for holding a sampie vial 20 having a septum 22 within cap 23.
  • a single block can be counterbored to form the same chambers as are created by combining block 8 with plate 10.
  • the preferred embodiment is easier to manufacture and therefore of lower cost.
  • an encoder wheel 24 This wheel has a series of slots 26, an example of which are shown in Fig. 4, which are read by a photodiode transmissive switch assembly 28 to thereby provide a means both for determining the position of the platen 4 and for centering the cham- bers 16 over the various mechanisms, to be described in detail below.
  • the transmissive. switch 28 has a light generating element and a light detecting ele- ent, and the encoder wheel rotates between these two elements. Position is determined by the number and location on the encoder wheel 24 of slots passing light through to the detecting element at any one time.
  • a support plate 30 Below the encoder wheel 24 is a support plate 30.
  • Plate 12 is preferably manufactured from a machineable glass fiber, one example of which is known as MARINITE I. Ml-iRINITE I, manufactured by Johns- Manville Corp., Denver, CO is comprised of calcium silicate with inert filters and reinforcing agents. Alternatively, other materials meeting the require ⁇ ments of machineability and heat insulative ability may be used.
  • the platen 4 will include the throughbored block 8, bored plate 10 insulation plate 12 and support plate 30.
  • the insu ⁇ lation plate 12, support plate 30 and the encoder wheel 24 are bored to match the borings in plate 10.
  • the platen 4 with encoder wheel 24 is secured to the guide track 36 through screws 38 and spacers 40, several of which being depicted in Figs. 1 and 2.
  • Mating is facilitated by matching dowel pins 42 (only one shown) with mating holes in bored plate 10, insulation plate 12, encoder wheel 24 and support plate 30.
  • the guide track 36 in turn is supported on a ball bearing cage assembly 50.
  • the cage assembly 50 is retained in position below the guide track 36 by the inside shoulder of platen gear 52, which is secured to the bottom side of guide track 36.
  • the bearings comprising the ball bearing cage assembly 50 rest on a thrust washer 54, made preferably from hardened tool steel, which is positioned onto the bas plate 56 and maintained in position by pins (no shown) driven into the base plate 56 adjacent th outside diameter of the thrust washer 54.
  • a channel corresponding to the diameter and thickness of the thrust washer 54 could be cut into the base plate 56 and the washer positioned therein.
  • this operation requires additional machining and is not necessary to the effective operation of the sample transport.
  • the guide track 36 and therefore the platen 4, is caused to align properly around a single axis during rotation by the presence of roller wheels 60 mounted onto the base plate 56 by bolt and sleeve assemblies 64.
  • the roller wheel 60 mates with the edge of the guide track 36 along its periphery to maintain the proper orientation.
  • the platen 4 is caused to rotate by actuation of drive motor 66 having a drive gear 68 attached thereto which cooperates with the teeth on platen gear 52.
  • the throughbored block 8 and bored plate 10 are heated preferably by cartridge heaters 76.
  • the temperature of the block 8 and bored plate 10 is measured by temperature measurement probes 78. These probes preferably are thermocouples, but may be resistance temperature devices or other like device.
  • the cartridge heaters 76 may be easily removed for servicing by removal of an epoxy plug 80 secured to the platen 4 by platen bolt 82, which is shown in Fig. 2.
  • Sample vials 20 are lowered into the platen 4 and ejected therefrom by a first vial transport 86 consisting of an elevator rod 88 connected to a level winding screw 90 by screw follower 92.
  • the elevator rod 88 is displaced vertically by rotating level winding screw 90 through use of transport motor 94.
  • the elevator rod 88 contacts the bottom of sample vial 20 by travelling upward through aperture 100, which is of smaller diameter than chamber 16.
  • the aperture 100 is bored through bored plate 10, insulation plate 12, encoder wheel 24 and support plate 30.
  • the extent of travel of the elevator rod 88 is regulated by lower limit switch 96 and upper limit switches 97, 98 and 99.
  • Switch 97 stops the upward travel of the elevator rod 88 when the sample vial is to be manually loaded or unloaded.
  • switches 98 and 99 are used.
  • Switch 98 stops the elevator rod 88 at the auto load point, and switch 99 is for the auto unload, or eject, point.
  • the sample vial 20 shown in the center chamber position in Fig. 1 is mixed by the mixer device 102, consisting of an elevator rod 104 which rises vertically through aperture 100 by rotation of level winding screw 106 connected to the elevator rod 104 by screw follower 108. Rotation is effected by actuation of mixer motor 109.
  • the DC solenoid 110 located on the screw follower 108 and connected to the elevator rod 104 pulses the rod to provide the neces ⁇ sary mixing.
  • the solenoid 111 is supplied with a variable voltage input which varies the power supplied to the elevator rod 104. The higher the power, the further the vial 20 rises in the chamber 16 in response to the pulse. This variable voltage feature allows varying of the intensity of mixing.
  • the transport device 2 as presently configured is capable of accepting vials of 5, 10 and 20 ml volumes.
  • the figures show the 20 ml vials.
  • the smaller vials require liner sleeves, or inserts (not shown) , which support the cap 23 and maintain the septum 22 uniformly near the top of the throughbored block 8.
  • the inserts also have a hole in the bottom through which the elevator rods 104 and 88 travel. Because the caps of the different-sized vials will all be at approximately the same height in the chamber 16, it follows that the bottoms of the vials will rest different distances above the bottom of the chamber 16. During mixing, the elevator rod 104 raises the vial only about 1/16 inch above a rest position.
  • the elevator rod 104 must rise different lengths to contact and mix the vials.
  • the limit switches Ilia, b, c, d indicate the elevator rod 104 rest position, and mixing points for the 20ml, 10ml and 5ml vials, respectively.
  • the sample vial 20 in the right chamber is shown in Fig. 1 to be proximate to the needle assembly 112 and is in position for sampling.
  • the vial 20 is raised from a rest position to puncturing contact of the septum 22 with needle 114 by a second vial trans- port 118, which serves as the mating means to bring the needle into contact with the vial contents.
  • the second vial transport consists of an elevator rod 120 terminating with a rod tip 121 which is raised verti ⁇ cally to contact the bottom of the sample vial 20 (or insert supporting a sample vial) by rotation of level winding screw 122 connected to the elevator rod 120 by screw follower 124.
  • the rod tip has a larger diameter than the hole bored into the bottom of a vial insert to raise the combination of vial and insert.
  • the rod tip 121 contacts the bottom of vial 20 directly.
  • Rotation of the level winding screw is effected by actuating transport motor 126. After sampling is completed, the sample vial 20 is returned into the chamber 16 by reverse movement of the elevator rod 120.
  • the septum 22 is freed from needle 114 with the assistance of a wiper plate 128 which pushes against the sample vial cap 23 via spring 130 loaded against needle flange 132.
  • the wiper plate 128 is maintained in position relative to the needle 114 by means of guide rods 134.
  • the extent of travel of the elevator rod 120 is regulated by lower limit switch 136 and upper limit switch 138.
  • Fig. 2 shows the sample transport 2 with all elevator rods in the fully retracted position. It can be seen that the needle 114 is positioned directly above the platen 4. The close positioning of the needle assembly 112 to the top of the platen 4 permits the sample vials 20 to be sampled while only being lifted a short distance inside the chamber. This close arrangement of needle assembly 112 to the top of the platen 4 minimizes temperature fluctuation within the individual sample vials as the sample is with ⁇ drawn.
  • Fig. 4 shows the top view of the transport device and the relationship of the components.
  • the platen 4 has positioned near its outside circumference a plurality of chambers 16. Inside the circumference of the chambers are located the temperature measure- ent probes 78. Near the axis of the platen 4 are the cartridge heaters 76.
  • the various components com ⁇ prising the platen 4 are secured by the platen bolt 82.
  • Below the platen 4 at the nine o'clock position is the first vial transport 86.
  • the tip of the elevator rod 88 can be seen in position ready to rise through aperture 100.
  • the mixer device 102 At the twelve o'clock position below the platen 4 is the mixer device 102, with the tip of elevator rod 104 appearing in aperture 100. At the three o'clock position below the platen is located the second vial transport 118, with the tip of eleva ⁇ tor rod 20 showing. In phantom is depicted the needle flange 132 which is located over the chamber corre ⁇ sponding to the second vial transport 118.
  • FIG. 3 is a schematic showing one embodiment of the gas flow pattern into the sample transport, depicted in part as the heated zone 140 and separate platen heated zone 141, out the sample transport and then to the gas chromatograph.
  • Zone 141 is the platen 4 itself. The heating of this zone 141 has been generally discussed and will be described in more detail below.
  • the zone 140 is heated to prevent condensation in the lines between the needle 114 and the gas chromatograph.
  • the temperature in this zone is typically set about 10° to about 25"C higher than the platen 4 temperature.
  • Carrier gas typically helium enters gas inlet 142 from a tank controlled with a pressure regulator (not shown) .
  • the gas supply is split at T-connection 144.
  • the tubing and connections through 5 which the carrier gas flows are made from nickel alloy, copper, stainless steel, or other material which does not evolve any compounds which might affect the G.C. analysis and which is not permeable to compounds in the air which might diffuse through the 10 material and be carried to the G.C.
  • Carrier gas flows through first line 146 at a pressure set at the tank regulator, typically about 60 psi, to a gas chromato ⁇ graph flow controller 148.
  • the controller 148 is connected in line to pressure gauge 150.
  • Carrier gas 15 then flows into six port valve 152 having ports A, B, C, D, E and F.
  • the carrier gas flowing through the first line 146 ultimately enters six port valve 152 at port C, exits through port D and continues through the heated transfer line 154 into the gas chromatograph. 2 0 .
  • This flow of gas is always on to constantly purge the gas chromatograph.
  • This portion of the gas transport system including the lines, valves, regulators and the connections and fittings between first line 146 and heated transfer line 154 is the analyzing instrument 5 purge system.
  • the remaining flow of carrier gas after splitting passes through second line 156.
  • the carrier gas flowing through this second line is used to purge the needle 114 and to pressurize the sample vial 20 after the septum 22 has been punctured by needle 114.
  • This portion of the gas transport system including the lines, valves, regulators and the connections and fittings between second line 156 and needle 114 is the needle purge and vial pressurization loop. Pressure is adjusted by regulator 158 within a range of about 5 to about 30 psi, depending on the application. The flow is regulated by flow controller 160. Carrier gas flow through the needle 114 is turned on and off by a solenoid operated pressurization valve 162.
  • the flow controller 160 is set at a level sufficient to pres ⁇ surize the sample vial in a reasonable time, but not so high as to waste excessive amounts of carrier gas as the needle is being purged.
  • the valve 162 is open to constantly purge the needle 114. With the pressurization valve 162 on, and vent valve 164 off, carrier gas flows through T-connection 168 to inlet line 170 and then into the six port valve 152 at port A. The carrier gas flows from port A into port B, through sample loop 172, into port E, out port F and through the needle 114 into the sample vial 20.
  • the pressurization valve 162 is turned off and the pressure within the lines from that valve to the sample vial is allowed to equilibrate.
  • the vent valve 164 is opened to allow the vial gases, consisting of carrier gas and headspace contents, to vent.
  • Carrier gas with the headspace contents flows back through needle 114, into the six port valve at port F and into the sample loop 172 and out port A toward the vent valve 164.
  • the vent valve 164 is closed and the six port valve 152 is cycled.
  • the carrier gas in the first line 146 which remained on and flowed out port D to the gas chromato ⁇ graph, is now caused to flow through port C to port B after the cycling.
  • the carrier gas flows into the sample loop 172 and flushes the contents into port E which is now connected with port D.
  • the sensitivity of the instrument relates as to the minimum amount of sample which can be detected.
  • the precision of the instrument relates to the reproducibility of results after multiple runs of the same material. The higher the precision, the smaller the standard deviation over a series of runs for a particular sample.
  • the accuracy of the instrument directly relates to the extent of agreement between the analyzed physical properties for a particular sample and the actual physical properties of the sample. The closer the agreement, the more accurate the instrument.
  • the precision, accuracy and sensitivity of analysis of a specific run by the gas chromatograph is adversely affected by the variation of the concentration of sample to be analyzed in the carrier gas, and by the presence of trace amounts of residual sample from other runs.
  • the concentration of sample in carrier gas in the sample vial 20 and ultimately in the gas chromatograph also changes due to the variation in total volume of carrier gas added to the sample vial 20 per unit time.
  • a decrease in the flow rate due to a decrease in pressure set at the pressure regulator 158 opens the possibility that the amount of carrier gas purging needle 114 will be insufficient to completely remove any trace residual sample from an earlier run.
  • the flow rates within the analyzing instrument purge system and the needle purge and vial pressurization loop are only changed by adjustment of the flow controllers 148 and 160 respectively. Adjustment of the pressure by regulator 158 does not vary the flow in the needle purge and vial pressurization loop. Therefore, the flow rate during the needle purge step remains constant until the source of the carrier gas is exhausted. Further, the amount of gas supplied to the headspace in sample vial 20 during vial pressurization is constant per unit time regardless of the desired pressure in sample vial 20 as set at pressure regulator 158. Thus, the amount of carrier gas flowing from flow controller 160 through the intermediate connections to needle 114 is constant per unit time during the needle purge step, which substantially eliminates the risk of residual sample from previous runs affecting analysis of the particular sample due to insufficient purge flow.
  • Changing the arrangement of the pressurization gas control pneumatics namely with the flow controller 160 positioned upstream from the pressure regulator 158, provides the capability of sweeping carryover from the sample line with a constant and optimal volume of sweep gas regardless of as chromatograph run time. For instance, if it is determined empirically that a volume of 800 cubic centimeters (cc) of gas must sweep from flow controller 160, through inlet line 170, through six-port valve 152 at ports A and F, and out needle 114 in order to eliminate carryover, the flow controller 160 may be adjusted to the proper rate to achieve this goal. Thus, if 800 cc of gas is required, and the gas chromatograph run time is 10 minutes, a needle purge flow rate of 80 cc/min. will provide the necessary purge volume. A constant and sufficient sweep volume improves both the precision and accuracy of the gas chromatograph or other analyzing instrument through the elimination or reduction of carryover.
  • cc cubic centimeters
  • placing the pressure regulator 158 downstream of flow controller 160 permits independent control of the amount of gas that is added to the vial during vial pressurization.
  • This gas can be the same or different from the gas supplied at gas inlet 142 for the analyzing instrument purge system.
  • This arrangement permits utilizing the pressurization regulator 158 as a dilution control device.
  • the higher the pressurization setting on the pressure regulator 158 the greater the amount of pressurization gas introduced into the headspace of the vial.
  • the increased pressure produces a dilution effect on the headspace sample which may be demonstrated by analysis.
  • the pressure increases, assuming a fixed phase? ratio (volume of headspace gas/volume of liquid or solid in vial) , the amount of sample as determined by area count from the detection system decreases.
  • the decreased area count indicates a dilution of the headspace sample.
  • providing independent gas sources through gas inlets 142 and 180 permits the pressurization of vial 20 and subsequent sweeping of the needle purge loop with a gas other than the carrier gas supplied through gas inlet 142.
  • a gas such as carbon dioxide.
  • This gas may be impractical or uneconomical for use as a carrier gas for conveying sample along heated transfer line 154 to the gas chromatograph.
  • the modification disclosed above and in Fig. 5 permits a separate gas to be used as the carrier gas, supplied through gas inlet 142. This arrangement permits increased flexibility in matching the vial headspace contents to the vial pressurization gas to maximize sample removal while allowing for independent selection of the optimum carrier gas.
  • a transport device such as an autosampler
  • three key variables the flow rate or back pressure at the column of the gas chromatograph, the pressure exerted on the vial by the pressurization gas, and the standby flow rate to purge the transfer lines in the transport device between runs.
  • the analyzer transport device of this invention accomplishes independent control over these variables.
  • the analyzer transport device described above is used preferably for preparing samples for analysis using the headspace analysis technique, wherein the gaseous sample is heated to a set tempera ⁇ ture and the contents sent to a gas chromatograph.
  • the operable temperature range is typically room temperature plus 10*C to about 200 ⁇ C.
  • the above transport device can be automatically loaded and unloaded, and large numbers of samples can be pro ⁇ Ded without constant operator supervision.
  • the electrically powered functions of the device are controlled through a keypad or other similar type of control unit (not shown) which, among other functions, adjusts the sample vial processing rate through the transport device, adjusts temperature, severity and time of mixing, sampling order by use of the encoder wheel in combination with the photodiode transmissive switch assembly, and number of repetitions of analysis of the headspace contents of a single sample vial.
  • a keypad or other similar type of control unit (not shown) which, among other functions, adjusts the sample vial processing rate through the transport device, adjusts temperature, severity and time of mixing, sampling order by use of the encoder wheel in combination with the photodiode transmissive switch assembly, and number of repetitions of analysis of the headspace contents of a single sample vial.

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  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
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  • Sampling And Sample Adjustment (AREA)

Abstract

Le dispositif de transport (2) d'échantillons est destiné à être utilisé dans l'analyse d'échantillons selon la technique d'analyse de l'espace libre. Le dispositif comporte un plateau cylindrique (4) doté de chambres à épaulement (16) destiné à recevoir des flacons d'échantillon (20). On chauffe et on fait tourner le plateau (4) d'un premier point de transport (86) de flacon jusqu'à un point d'échantillonnage (118), puis en arrière afin d'éjecter le flacon d'échantillon (20). Le mouvement vertical des flacons d'échantillons (20) s'effectue au moyen de tiges élévatrices (88, 104 et 120) reliées à des vis de mise à niveau (90, 106 et 122) montées au-dessous du plateau cylindrique (4). On améliore la sensibilité, la précision et l'exactitude de l'instrument d'analyse recevant un mélange de gaz et d'espace libre d'échantillon provenant du flacon d'échantillon (20) en positionnant la première unité de commande d'écoulement (148) en amont du régulateur de pression (158), dans la boucle de purge de l'aiguille et de pressurisation du flacon. Ladite boucle est dotée d'une alimentation en gaz (142) indépendante de l'alimentation en gaz destinée au système de purge de l'instrument d'analyse.
PCT/US1992/001641 1991-03-01 1992-02-28 Unite de commande pneumatique pour dispositif de transport d'analyseur WO1992015875A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US66373591A 1991-03-01 1991-03-01
US663,735 1991-03-01

Publications (1)

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WO1992015875A1 true WO1992015875A1 (fr) 1992-09-17

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PCT/US1992/001641 WO1992015875A1 (fr) 1991-03-01 1992-02-28 Unite de commande pneumatique pour dispositif de transport d'analyseur

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EP (1) EP0573571A1 (fr)
AU (1) AU1459592A (fr)
WO (1) WO1992015875A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996001994A1 (fr) * 1994-07-11 1996-01-25 Tekmar Company Auto-echantillonneur modulaire a flacons
US5948360A (en) * 1994-07-11 1999-09-07 Tekmar Company Autosampler with robot arm
CN119469939A (zh) * 2025-01-14 2025-02-18 大连天亿技术服务有限公司 一种lng低温取样分析装置

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2032798A (en) * 1978-10-16 1980-05-14 Erba Strumentazione Method and chromatographic columns
JPS6361163A (ja) * 1986-09-01 1988-03-17 Hitachi Ltd ガスクロマトグラフの試料注入制御装置
WO1991013350A2 (fr) * 1990-03-02 1991-09-05 Tekmar Company Dispositif de transport d'analyseur
JPH03240809A (ja) * 1990-02-19 1991-10-28 Fuji Electric Co Ltd 定流量装置

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2032798A (en) * 1978-10-16 1980-05-14 Erba Strumentazione Method and chromatographic columns
JPS6361163A (ja) * 1986-09-01 1988-03-17 Hitachi Ltd ガスクロマトグラフの試料注入制御装置
JPH03240809A (ja) * 1990-02-19 1991-10-28 Fuji Electric Co Ltd 定流量装置
WO1991013350A2 (fr) * 1990-03-02 1991-09-05 Tekmar Company Dispositif de transport d'analyseur

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 012, no. 280 (P-739)2 August 1988 & JP,A,63 061 163 ( HITACHI LTD ) 17 March 1988 *
PATENT ABSTRACTS OF JAPAN vol. 016, no. 028 (P-1302)23 January 1992 & JP,A,3 240 809 ( FUJI ELECTRIC CO LTD ) 28 October 1991 cited in the application *

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996001994A1 (fr) * 1994-07-11 1996-01-25 Tekmar Company Auto-echantillonneur modulaire a flacons
US5948360A (en) * 1994-07-11 1999-09-07 Tekmar Company Autosampler with robot arm
US5998217A (en) * 1994-07-11 1999-12-07 Tekmar Company Method of introducing standards into a vial
US6040186A (en) * 1994-07-11 2000-03-21 Tekmar Company Vial autosampler with selectable modules
US6056921A (en) * 1994-07-11 2000-05-02 Tekmar Company Vial transporter having an elevator
US6143573A (en) * 1994-07-11 2000-11-07 Tekmar Company Modular vial autosampler
US6426225B1 (en) 1994-07-11 2002-07-30 Tekmar Company Method of calibrating a vial autosampler
US6544799B1 (en) 1994-07-11 2003-04-08 Tekmar Company Vial autosampler with vial stabilization member
CN119469939A (zh) * 2025-01-14 2025-02-18 大连天亿技术服务有限公司 一种lng低温取样分析装置

Also Published As

Publication number Publication date
EP0573571A1 (fr) 1993-12-15
AU1459592A (en) 1992-10-06

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