JPS63138261A - Movement detector - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Technical field to which the invention pertains] The present invention relates to high performance liquid chromatography (HPLC).
The present invention relates to a novel movement detection device suitable for use in the field.

[Prior Art and Its Problems] High performance liquid O-mography is one of the most widely used techniques in the field of analytical chemistry.

The purpose is to separate a mixture of substances by passing a solution of the mixture through a chromatographic column designed so that the separated components of the mixture elute from the column at different times. Separated components can be individually detected and quantified. Detection and measurement is generally accomplished by monitoring the UV absorption of the eluate at a predetermined wavelength, although many other techniques can be used for components with specific properties.

The compounds of this class do not exhibit strong UV absorption at readily available wavelengths, and in particular the compounds of this class have special properties such that they cannot be easily used in chromatographic detection methods. For example, alkanes do not exhibit UV absorption at wavelengths higher than 200 nm, do not exhibit specific electrochemical properties, and do not exhibit strong fluorescence emission. These compounds are difficult to detect with high sensitivity in the liquid phase.

In gas chromatography related separation techniques, several highly sensitive detection devices are commercially available.

One of these is the flame ionization detector (FID), which combusts components eluting from a chromatographic column into an inert carrier gas in a hydrogen-oxygen or hydrogen-air flame and releases the components during combustion. This method is suitable for the detection of most carbon-containing compounds, with a detection signal closely related to the number of carbon atoms passing through the detector. The main difficulty in using the technique is that the majority of liquid effluents suitable for use in HPLC contain carbon atoms and therefore generate large "background" signals when passed directly through the FID. .

FIDs can be incorporated into liquid chromatography detection devices if the carbon-containing solvent is removed from the column effluent before it is combusted in the FID, but this is not easy to achieve.

A conventional attempt to solve this problem has been the use of continuously moving wires. The wire is passed through the eluate and some of the eluate is retained as a coating on the surface. The wire is passed through a low temperature oven to evaporate the solvent, then the remaining components are vaporized and burned in a high temperature oven. The resulting carbon dioxide is then hydrogenated to methane, which is transferred into the FID for re-combustion. Prior to coating, the wire is generally cleaned in an oven at high temperature.

Although this movement of the wire is generally satisfactory and serves a useful purpose, it has a number of drawbacks, including: (1) The continuous movement and small diameter of the wire makes it impossible, if not impossible. However, it is difficult to collect the entire eluate, thus reducing the sensitivity of the detector.

(2) For the same reason, the amount of eluate retained in the wire depends on the viscosity of the eluate.

(3) The wire itself must withstand the high temperatures used in the vaporization/combustion and cleaning steps, which are often too high for the wire to withstand without deforming or breaking.

(4) The wire is a good heat conductor, and therefore it is difficult to maintain separate regions of high and low temperatures.

(5) The wire requires mechanical support, with inherent problems of contamination of the support material and recontamination of the wire.

(6) Because the eluate coating is directly exposed to high temperatures, boiling occurs with the risk of sputtering and loss of sample from the wire.

[Problems to be Solved by the Invention] An object of the present invention is to provide a novel movement detection device which does not have the above-mentioned drawbacks and is particularly suitable for (but not necessarily limited to) HPLC applications that are particularly suitable for computer control. There is a particular thing.

[Means for Solving the Problems] According to the present invention, there are provided: (a) means for supplying a liquid; (b) a means for distributing a liquid disposed in sequence through the liquid supply means; a plurality of movable spokes made of a thermally conductive refractory inorganic material; (c) a fluid disposed on the plurality of spokes;
one or more evaporators positioned for successive passage of the spokes; (d) a detector positioned for successive passage of the plurality of spokes after passing through the evaporator; e) one or more coolers positioned to pass said plurality of spokes after passing said detector; and (f) a stepper motor adapted to move said spokes in a series of discrete steps. and (g) a control device for the step motor, evaporator, and cooler.

The means for supplying the liquid may be a heatable supply tube. This can be achieved by providing an inner tube for passing liquid and an outer tube surrounded by a heating element. A moving wire is further attached to the supply tube, and its brush is brought into contact with the spoke.
Efficient movement of liquid can be ensured. Generally, the liquid is 0.01 Inl1/min ~20ml1/min
Move at a speed in the range n.

The device may include an evaporator located at the point where the eluate is supplied to the spokes.

This is combined with a feed tube heater to promote evaporation of the solvent as quickly as possible after it exits the feed tube.

The spokes are preferably silica rods, particularly preferably about 1 mm in diameter. Other refractory materials such as sapphire can also be used. These materials can withstand the high temperatures involved, be physically robust, and not significantly deform or expand. Since each spoke absorbs its own heat and there is no storage effect, there is almost no overall thermal stress.

These spokes rotate without direct contact with the detector head and therefore do not require seals. Furthermore, the generally low thermal conductivity retains the supplied heat where it is needed, and therefore temperature control is easily achieved.

Preferably, the liquid is deposited onto the spokes at or near their tips. The tip may be enlarged to increase the surface area available for liquid adsorption. These spokes can be set at a slight upward angle from the tip to reduce the possibility of liquid flowing towards the center.

The spokes project radially outward from the circular hub, which can be driven by a stepper motor.

Alternatively, you can attach the spokes onto the belt and make this belt two
The belt is suspended by two wheels, one of which is driven by a step motor, and the belt is moved so that the flat surfaces of the spokes protrude outward at right angles to the belt. Although more complex, this method has the advantage of being able to vary the spacing between the spoke ends, keeping the spoke ends close together when in the straight section of the belt between two wheels and suspended from these wheels. When the belt is in a curved section, it can be further spaced apart. Therefore, by locating the evaporator and cooler along a straight section of the belt, the ends are slightly separated in the vicinity of the evaporator and cooler, and by placing the detector along one of the wheels. The ends can be arranged to be widely separated in the vicinity of the detector.

As mentioned above, moving detectors are particularly suitable for use in HPLC analysis. In this case, the liquid supplied to the spokes is an eluent consisting of a relatively volatile solvent and a relatively non-volatile solute. The solvent can be a mixture of liquids with different volatilities. In this case, it is advantageous to use a number of evaporators operated under different temperature conditions to ensure a sequential and smooth evaporation of the solvent, leaving relatively less volatile sample components behind. This prevents violent boiling, such as occurs when only one evaporator is used and the lowest boiling component of the solvent is exposed to the temperatures required to vaporize the highest component.

A suitable evaporator consists of a hot air blower. Generally, a range of three is sufficient, one associated with the supply tube;
Each is designed to accommodate one or more spokes and operates at temperatures between 20 and 300°C. Each evaporation stage has separately defined operating temperatures and air flow rates, and these parameters can be optimized for specific sample types and eluate flow rates.

Suitable detectors include flame ionization detectors, flame photometric detectors, and nitrogen/phosphorous detectors. These have universal detection ability and are capable of detecting sulfur (e.g. present in petroleum products)
, nitrogen (also present in petroleum products and amino acids, peptides, proteins, dyes, drugs, etc.) and phosphorus (present, for example, in pesticides and petroleum additives) can be performed.

When the spoke enters the FID flame, the hot flame vaporizes and burns the residue on the spoke to generate and record the FID signal. Because the spokes are made of a non-thermal material, only the ends of the spokes reach the high temperatures associated with an FID flame, which is generally sufficient to remove residue from the spokes and ensure that they can be reused. It is.

However, a cleaning flame can also be incorporated after the FID. This includes a variety of compounds that are not fully and completely combusted in the FID (e.g. sugars, which have a tendency to carbonize, and heavy materials such as asphalt and bitumen, which have a tendency to form refractory coke). (petroleum residues).

A cooler is provided to reduce spoke humidity prior to eluent deposition. A suitable cooler consists of an air fan. In this case as well, it is desirable to have two or more in order to facilitate control. Two, each designed to accommodate three to five spokes simultaneously, are generally sufficient. Control is achieved by controlling the air flow rate.

The stepper motor can advance the spokes at any desired speed. Generally, speeds in the range of 4 steps per second to 1 step per 10 seconds are suitable.

It is important that the step motor does not rotate at a constant speed. The stepper motor moves in a series of discrete steps, and the time required to move the spokes in each step is short compared to the time the motor does not move, so that one spoke collects the eluate and several spokes for evaporative and cooling airflow to be queued and processed in one spoke FID. This step is preferably under control, such as computer control, and the step rate is one of the parameters that can be optimized to handle particular sample types and eluate flow rates.

Steps have many advantages over continuous movement: (1) They can be more easily controlled, especially computer controlled.

(2) The residence time in each step can be selected so that the desired operation can be carried out sufficiently.

(3) Detection occurs only when the spoke is in the vicinity of the detector, making it easier to feed the signal from the detector to further steps and decipher it.

(4) It is easier to clean the spokes afterwards.

Suitable stepper motors are commercially available.

Because of the large number of variables used (e.g., eluent flow rate, evaporator flow rate and temperature, condenser flow rate and step rate), an effective control system is required. This is best achieved by a suitably programmed microcomputer via a multi-function interface system.

The system can include automatic monitoring feedback and control loops. The signal from the detector is unexpectedly high,
In case of possibly incomplete evaporation of the solvent, the control system can be programmed to take a reversing action, for example by increasing the temperature and/or the flow rate from the evaporator.

This system can be used as an online monitoring and/or control device.

This system is suitable for use with conventional HPLC chromatographic columns using hydrocarbon solvents and is therefore particularly suitable for analyzing hydrocarbons of the type boiling in the range of 300° C. or above.

However, due to the flexibility of this detector, HPL
The use of C can also be extended to other systems containing lower boiling hydrocarbons. Other potential uses are for example drugs such as alkaloids, antibiotics, steroids and analgesics; biochemical compounds such as amino acids, bebutides, proteins, carbohydrates, lipids and vitamins; for example pesticides, petroleum products, petrochemicals. , industrial chemicals such as polymers and dyes; and environmentally hazardous compounds such as polycyclic aromatic compounds and chlorinated hydrocarbons.

Eluents are not limited to hydrocarbons and hydrocarbon mixtures. Other substances such as water and alcohols can also be used.

The mobile detection device may also act as an interface for introducing a sample from an HPLC column or from other sources into a spectrometer for elemental analysis.
can. Suitable spectrometers include mass spectrometers, pyrolysis mass spectrometers, spectrophotometers and plasma spectrometers.

A suitable plasma spectrometer is ICPAES (I
nductively coupled plasma
Atomic Emiss-ion Spectro
meters > , ICP-MS (ICP Ma
ssSpectrometers) and M I PA
E S (Hicrowa-ve Induced)
Plasma Atomic Emission Sp
electrome-telrs). The invention can be used in particular for: (a) the use of the spectrometers described above as elemental specificity detectors for high performance liquid chromatography (HPLC); (b) the use of these spectrometers to Sample (101
Use as an automatic sampling device for elemental analysis of Ii>.

In ICPAES, the sample is generally in the form of a solution. This solution is generally introduced into the plasma (generally argon gas) via a pneumatic atomizer and atomization chamber. This allows approximately 2-3% of the solution (as a fine mist in argon gas) to flow into the plasma. Droplets of solution are dried in a plasma (temperature 8000-1000 K), sample molecules dissociate and atoms are excited to higher atomic and ionic states. As these atoms and ions relax to their respective ground states, characteristic lines appear in the visible region of the spectrum and in the U
v region, the intensity of which is proportional to the concentration of the element in the initial sample. The intensities of these lines are generally measured using conventional monochromators or polychromators (although Fouriere transfer systems are now also available).

The plasma source in I CP-MS is substantially the same as that used in ICPAES. However, instead of observing the light emission from the plasma, the ions are extracted into a quadrupole mass spectrometer.

The advantages over ICPAES are as follows = (i
) The detection limit is about the second power lower in terms of flat type, (ii) All elements are detected almost simultaneously (the mass range can be operated in about 30 m5), (iii) The ratio of isotopes is measured. (useful for tracer research).

MIP (generally He) can be used as a feedstock for atomic emission spectrometry. Argon I
The main advantage over CP is that emission may be observed for non-metals that are difficult or impossible to excite using said techniques, such as hydrogen, carbon and halogens. However, the main drawback is that MIPs have very low resistance to solvents and require solvent removal before introducing the sample into the plasma.

Most previous attempts to interface plasma spectrometers with HPLC columns have introduced the effluent from the column into the plasma using conventional pneumatic atomizers and atomization chambers.

This has several drawbacks: (i) The transfer efficiency is only about 2-3% and therefore the sensitivity is low.

(ii> Volatile solvent extinguishes the plasma.

(iii) Increased dispersion within the spray chamber, leading to broader chromatographic peaks.

Although the problems associated with the first two of these problems can be alleviated to some extent by using a solvent removal device for the spray chamber, this has the effect of exacerbating the third problem.

As mentioned above, the mobile device is particularly suitable for interfacing with a plasma spectrometer.

According to another feature of the invention, therefore, there is provided a mobile detection device in which the detector is a hydrogen flame, the device comprising: (a) means for supplying a liquid; and (b) a means for supplying a liquid. (c) a plurality of movable spokes made of a refractory inorganic material of low thermal conductivity positioned to pass sequentially to distribute a liquid; (c) after the liquid has been distributed over the plurality of spokes; ,
one or more evaporators positioned so that the spokes pass in sequence; (d) a hydrogen flame positioned so that the spokes successively pass after passing through the evaporator; e) one or more coolers positioned to pass said plurality of spokes after passing said detector; and (f) a stepper motor adapted to move said spokes in a series of discrete steps. (Q) a control device for the step motor, evaporator, and cooler; and (h) a plasma spectrometer adapted to receive combustion products from the hydrogen flame.

The hydrogen flame is a modification of the FID described above. Air is supplied to the hydrogen flame via concentric tubes. As the spoke enters the flame, the hot flame vaporizes and burns the residue on the spoke. Combustion products are introduced into the plasma by a flow of helium or argon from below the flame. Once in the plasma, the analytes are atomized, ionized and excited to high atomic and ionic states. Analysis is carried out using conventional optical or mass spectrometers according to conventional methods.

A suction device may be provided between the hydrogen flame and the plasma if necessary. This creates a suction that sucks up the combustion products due to the pendury effect, providing further pressure to force them into the plasma fireball.

A motion detection device interfaced with a plasma spectrometer has the following advantages: (i) a motion efficiency of 100
Close to %.

(ii) The width of the chromatographic peaks is minimized.

(iii) with any common solvent, 0.01 d/
min~20m+l! /I! Flow rates in the range n can be used. (iv) Multiple elements can be measured simultaneously.

(V) Increased freedom from matrix effects.

(vi) analytes can be introduced into the plasma without solvent, thus allowing the use of MIP and IC
Reduce spectral interference problems in P-MS.

(vii) Applicable to most elements in the periodic table (including, for example, non-metals such as hydrogen, carbon and halogens).

Instead of depositing the eluate from the chromatographic column onto the spokes, a small sample (10 samples) for elemental analysis can also be deposited with a snake pet onto the spokes. This method has two main advantages: (i) Elemental analysis can be performed on extremely small amounts of sample.

(ii) introducing the analyte into the plasma without the use of a solvent, thus providing greater freedom from matrix effects and significantly increasing the sensitivity and allowing the use of MIPs to measure non-metals; do.

Traditional methods for this type of analysis involved electrothermal vaporization. However, this method is extremely slow as measurements cannot be taken during the evaporation step (typically about 60 seconds) or the cooling step (typically about 2 minutes) in the analysis cycle. The method according to the invention comprises using a first spoke while the second spoke is cooling down, the third spoke is in the evaporation process and the sample is being introduced into the fourth spoke. Advantageously, measurements can be taken.

This therefore significantly increases the analysis speed.

Furthermore, this movement detection device can be used for other applications in any of the forms described above or with slight modifications as follows: Effective in condensing and recovering components.

(ii) The ends of the spokes can be coated with adsorbents and/or selective membranes to selectively adsorb desired compounds.

[Example] Hereinafter, the present invention will be further described by way of example with reference to the accompanying drawings.

The movement detection device comprises a plurality of quartz rods 1 mounted on a central hub 2 to form a spoked wheel. In the device shown, there are 32 rods, each approximately 1 mm in diameter and 12 cm long. The hub 2 is formed from two grooved circular aluminum plates, and the rod 1
is sandwiched between them and held in place by a rubber seal.

This wheel is positioned between the upper baffle plate 3 and the lower substrate 4 to provide mechanical support for the equipment components.

Additionally, these plates also provide passage for evaporative and cooling airflow.

The wheel is mounted directly on the shaft of the stepper motor 5 and rotated in individual steps.

During rotation, each spoke sequentially connects the eluate supply tube 6
Move under and attach a droplet of eluate to its tip.

For an eluate flow rate of 1.2 d/min, the amount of curvature is 10 per spoke as the spoke moves at 2 steps per second.

Further rotation will cause the spokes to undergo different temperature conditions and/or
or a series of three evaporators 7 operated under air flow rate
The solute is left behind by evaporating the solvent from the eluate. The first evaporator is located adjacent to the supply tube.

The evaporator essentially consists of a heating member 8, a fan 9, and a temperature sensor 10. The evaporative heater is mounted below the substrate and blows air upward through holes in both the substrate and the top plate.

After passing through the evaporator 7, the spokes move into a modified flD11 where the tips of the spokes are exposed to a hydrogen flame.

The FID has a body 12, slots 13 for spokes, and inlets 14 and 15 for hydrogen and air, respectively.
It is composed of a collector 16 and a chimney 17.

The FID is mounted in slots cut into both the base plate and the top plate and positioned so that the spoke ends are directly above the flame jets 20 as shown in FIG. The slots 13 are only 1 mm larger than the diameter of the spokes to minimize the entry of external gases and steam into the flame area.

The heat of the hydrogen flame is sufficient to burn off the residue on the spokes and leave them clean for subsequent deposition and analysis.

However, before that, the two coolers 1
Cool at 8. These coolers are simply air fans 19 mounted under slots in the mounting plate 4.

Cooling fans are mounted directly on the board, and the air exhausted from each fan treats about four spokes at a time.

Above the top plate, a plurality of partition walls (not shown) maintain isolation between the warm airflow from the evaporation process, the airflow from the cooling region, and the area surrounding the FID.

A microcomputer (not shown) is a step motor,
Controls the operation of evaporators and coolers.

Referring to FIG. 4, reference numerals 1.12.13.14 and 15 are the same as above.

As the spoke 1 moves into the hydrogen/air flame 20, the hot flame vaporizes and burns the residue on the spoke.

The combustion products are introduced into the plasma by a flow of helium or argon supplied via passage 21 from below the flame.

If necessary, a suction tube 22 can be placed between the hydrogen flame 20 and the plasma. It has a central tube 23 for the combustion products and is surrounded by a concentric ring 24, which is supplied with an additional amount of helium or argon via a line 25. venturi nozzle 2
6 gives suction.

[Brief explanation of the drawing]

Figure 1 is a plan view of the movement detection device, Figure 2 is a longitudinal sectional view, Figure 3 is a detailed view of the detector, and Figure 4 is a schematic diagram of the plasma spectrometer interface equipped with a suction device if necessary. . 1... Rod 2... Hub 3... Baffle plate 4... Board 5... Step motor
6... Supply tube 7... Evaporator 8
... Heating member 9 ... Fan 10 ... Temperature sensor 11 ... Variable FID 12 ... Main body 13 ... Slot 14.15 ... Inlet 16
...Collector 17...Chimney 18...Cooler ]9...Fan 20...Flame
22... Suction tube 23... Central tube
24...Ring 26...Nozzle patent applicant The British Vitroleum
Company B, L, C. 2, °−゛−・. Applicant's agent Patent attorney Hama 1) Osamu, 'Yuo
・S+=,, : ,'

Claims (9)

[Claims] (1) (a) means for supplying liquid; (b) sequentially passing through this liquid supply means; liquid is dispensed. Fire resistant inorganic with low thermal conductivity Multiple movable objects made of materials spokes and (c) distributing liquid onto said plurality of spokes; These spokes are then One piece was positioned so that it would pass through or larger evaporator, (d) after passing through the evaporator, the so that several spokes pass in sequence a positioned detector; (e) after passing through the detector, the Position it so that several spokes pass through it. one or more coolers and, (f) a series of separate steps of said spokes; A step motor that moves to data and (g) The step motor, evaporator, cooling control device for the device and A movement detection device comprising: (2) The device according to claim 1, wherein the detector is a flame ionization detector. (3) The detector is a hydrogen flame, and (h) receiving combustion products from said hydrogen flame; Plasma Spect that can be inserted Claim No. The movement detection device according to item 1. (4) The apparatus according to claim 1, comprising an evaporator located at a point where the eluate is supplied to the spoke. (5) The device according to claim 1, wherein the spokes are silica rods. (6) The device according to any one of claims 1 to 5, wherein the spokes project radially outward from a circular hub driven by a stepping motor. (7) The device according to any one of claims 1 to 6, wherein the evaporator is a hot air blower. (8) The device according to any one of claims 1 to 7, wherein the cooler is an air fan. (9) An apparatus according to any one of claims 1 to 8, wherein the control device comprises a suitably programmed microcomputer.