JP3673885B2 - Sample injection device in liquid chromatography - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sample injection apparatus and a sample injection method for injecting a high-temperature sample or the like into an analysis means comprising an analysis column and a detector in liquid chromatography such as high performance liquid chromatography (hereinafter abbreviated as HPLC). It is about.
[0002]
[Prior art]
FIG. 7 shows an example of a general HPLC instrument configuration. 1 is a solvent, 2 is a liquid feed pump, 15 is a sample injection device, 4 is an analytical column, 12 is a column oven, and 5 is a detector. is there. In this way, the sample rides on the solvent flow from the sample injection device and is introduced into the HPLC flow path, and after being separated by the analytical column, its concentration and the like are measured by the detector.
[0003]
In HPLC, a normal analysis result cannot be obtained unless a sample is dissolved in a solvent used as a mobile phase. Particularly in the field of molecular exclusion chromatography (hereinafter abbreviated as GPC) for analyzing molecular weight distribution, the sample to be analyzed is often a synthetic polymer, and how to dissolve the sample in a solvent is an important issue. .
[0004]
In the case of a normal polymer, since it can be dissolved in a solvent at about 60 ° C., molecular weight distribution analysis is relatively easy. However, polyolefins such as polyethylene and polypropylene do not dissolve in a solvent at about 60 ° C. Therefore, conventionally, a high boiling point solvent such as o-dichlorobenzene (hereinafter abbreviated as ODCB) or trichlorobenzene (hereinafter abbreviated as TCB) is added, heated and dissolved at about 150 ° C., and then subjected to GPC to perform molecular weight distribution. It is common to perform an analysis.
[0005]
However, especially when performing analysis under a high temperature condition such as 150 ° C., the analytical column is placed in a column oven or the like and kept at a high temperature condition. This also needs to be kept at a high temperature so that the sample does not precipitate in the piping. Further, in order to prevent the sample once injected from being deposited by an analysis means or the like after the sample injection device, it is necessary to keep the portions other than the sample injection device at a high temperature.
[0006]
In order to respond to such a request, in the conventional HPLC apparatus, as shown in FIG. 6, there are a sample injection means (6-way rotary valve) 3 equipped with a sample 14, a sample suction needle 13 and a sampling loop 6, and a measuring means. The syringe 10 and the cleaning liquid container 11 are all placed in the oven 18 and kept at the same high temperature as the analytical column.
[0007]
[Problems to be solved by the invention]
As shown in FIG. 6, the conventional sample injection apparatus includes a sample injection means 3 equipped with a sample suction needle and a sampling loop 6, a measuring means 10 including a syringe, a cleaning liquid container 11, an oven 18, and the like. However, movable mechanical parts such as a sample aspirating needle and a syringe as a measuring means for sucking a certain amount of liquid are arranged under high temperature conditions to perform each operation. Since these movable machine parts perform operations such as vertical motion, left-right motion, and rotational motion, there is a problem that durability tends to deteriorate under high-temperature conditions, and as a result, malfunctions are likely to occur.
[0008]
In addition, the parts that make up the sample injection device that come into contact with liquid components such as samples, solvents, and cleaning liquids are made of fluorine such as polytetrafluoroethylene as a liquid contact material (sealing material) due to the relationship between solvent resistance and pressure resistance. Although a series of resins are frequently used, there is a problem that the strength of the resin is extremely lowered under a high temperature condition of 100 ° C. or more, which may cause liquid leakage.
[0009]
Furthermore, with regard to the cleaning liquid, since it is necessary to supply the needle with a high-temperature cleaning liquid in order to clean the sample suction needle contaminated with the sample while preventing the precipitation of the sample, the cleaning liquid container is arranged in the oven and the internal cleaning liquid is analyzed. However, there is also a problem that the cleaning liquid volatilizes under such a high temperature condition and may leak out of the apparatus.
[0010]
Therefore, the object of the present invention is to arrange only the minimum necessary machine parts under high temperature conditions, to prevent the occurrence of malfunction of these machine parts to a minimum, and to use the liquid contact parts used for these machine parts. An object of the present invention is to provide a sample injection device capable of preventing the strength of the material from being lowered and preventing the cleaning liquid from volatilizing and leaking out of the device.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, a sample injection device according to claim 1 comprises a sample injection means equipped with a sample suction needle and a sampling loop, a first heat exchanger, a second heat exchanger, and a metering device. A sample injection apparatus for introducing a sample into the analysis means by connecting an analysis means including a pump and a column to the sample injection means, and at least for sample suction of the sample injection means The portion other than the needle and the first heat exchanger are arranged under the same temperature conditions as the analytical means including the column, and at least the second heat exchanger, the measuring means and the washing liquid container are arranged at a temperature different from the above temperature. The sample injection device is characterized in that the sample injection means, the first heat exchanger, the second heat exchanger, the metering means and the cleaning liquid container are connected in series. The apparatus according to claim 2 of the present application is a sample injection apparatus in which the sample injection means is a six-way rotary valve in the above configuration. Further, the apparatus according to claim 3 of the present application cleans the needle by discharging the cleaning liquid in the cleaning liquid container heated by passing through the first heat exchanger from the sample suction needle before the sample is sucked from the needle. It is a sample injection device characterized by being able to.
[0012]
The sample injection method according to claim 4, which is made to achieve the above object, includes a sample injection means equipped with a sample suction needle and a sampling loop, a first heat exchanger, and a second heat exchanger. A sample injection apparatus for introducing a sample into the analysis means by connecting the analysis means including a pump and a column to the sample injection means, comprising a measuring means and a washing liquid container, and at least a sample of the sample injection means The portion other than the suction needle and the first heat exchanger are arranged under the same temperature conditions as the analysis means including the column, and at least the second heat exchanger, the weighing means, and the cleaning liquid container are under a temperature different from the above temperature. And the needle injection device, the first heat exchanger, the second heat exchanger, the metering means, and the cleaning liquid container are connected in series with the needle injection device. Before aspirating the sample, a sample injection method of the cleaning liquid in the cleaning liquid vessel was heated by passing through the first heat exchanger is discharged from the sample class cited needle, characterized in that heating the needle.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the sample injection apparatus of the present invention will be described in detail with reference to the drawings.
[0014]
FIG. 1 shows an example of a sample injection apparatus of the present invention. In the figure, 13 is a sample suction needle, 3 is a sample injection means (6-way rotary valve), 6 is a sampling loop, 16 and 17 are a sample injection means 3 including a sampling loop and a preheating loop (first heat exchanger). An oven for keeping 7 at the same temperature conditions as the analysis means (not shown), 8 is a cooling loop (second heat exchanger), 9 is a switching valve, 10 is a metering means (syringe), and 11 is a cleaning liquid container. Show. Here, the sample suction needle is immersed in the sample by a needle driving means (not shown). In the above example, the same solvent as the solvent fed from a liquid feed pump (not shown) is used as the cleaning liquid.
[0015]
The sampling loop is obtained by winding a pipe in a coil shape, and its capacity is appropriately determined according to the amount of sample to be analyzed. The preheating loop, which is the first heat exchanger of the present invention, and the cooling loop, which is the second heat exchanger, are obtained by winding a pipe in a coil shape, and heat exchange is performed when the liquid passes through the part. It is of the type that performs. A 1st heat exchanger is arrange | positioned under the high temperature conditions by an oven, and has a function which heats up a liquid to this temperature. In the case of this example, the second heat exchanger is arranged under room temperature conditions and has a function of bringing the liquid to room temperature. The second heat exchanger may be arranged in a cooler box, for example, in addition to simply being arranged at room temperature, and may be appropriately selected in consideration of the heat exchange efficiency and the like.
[0016]
The sample injection means 3 including the sampling loop 6 and the preheating loop (first heat exchanger) 7 are arranged in separate ovens 16 and 17, respectively, but may be arranged in the same oven. As the oven, an oven used in ordinary HPCL can be used. The temperatures in these ovens are managed under substantially the same temperature conditions as an analysis means including an analysis column (not shown), thereby preventing sample precipitation and the like.
[0017]
As shown in the above example, the present invention is suitably used in HPLC in which a particularly high-temperature sample must be used for analysis means such as an analytical column. As a case where a high-temperature sample must be supplied to an analytical column or the like in this way, for example, the case where GPC is performed on the above-described polyolefin or the like (the sample needs to be about 150 ° C.) can be exemplified. However, the present invention exhibits its effect even when, for example, the sample is set to about 50 to 60 ° C. and used for an analytical column or the like. That is, the needle of the sample injection means, the metering means, and the cleaning liquid container are not arranged under such temperature conditions, but can be arranged at different temperatures, for example, room temperature conditions. The problem caused by volatilization can be prevented.
[0018]
The present invention can also be used in HPLC where a low-temperature sample must be supplied to an analytical column or the like. In this case, what is necessary is just to keep the temperature in an oven low in the said example. In this case, the first heat exchanger (preheating loop) functions as a cooling loop, and the second heat exchanger (cooling loop) functions as a preheating loop.
[0019]
Although FIG. 1 shows an example in which a six-way rotary valve is used as the sample injection means, the present invention is not limited to this example, and for example, an eight-way rotary valve can also be used. As the switching valve, an electromagnetic valve or the like used in normal HPLC can be employed. A syringe pump is used as the metering means, but other liquid feeding means can also be used. That is, the measuring means in the present invention is not particularly limited as long as it can perform sample suction, liquid feeding of the cleaning liquid to the sample suction needle, and the like.
[0020]
FIG. 2 shows details of a six-way rotary valve suitable as a sample injection means. The six-way rotary valve is composed of a fixed surface called a stator and an operating surface called a rotor. The stator has holes penetrating at intervals of 60 degrees, and the rotor has grooves alternately at intervals of 60 degrees. Therefore, although both are closely attached to form a flow path, it is possible to form two flow paths, that is, the flow path 1 and the flow path 2 by rotating the rotor 60 degrees.
[0021]
The sample injecting operation by the sample injecting apparatus of FIG. 1 includes four steps of a cleaning liquid suction step, a cleaning / heating step, a sample suction step, and a sample injection step. FIG. 3 shows the flow, and FIG. 4 shows the actual operation of the sample injection apparatus.
[0022]
The cleaning liquid suction step is performed in the flow path of FIG. In this step, the sample injection means (6-way rotary valve) is in a state where AB, CD, and EF are connected, and the switching valve is in a state where I-H is connected. In this state, the measuring means (syringe) is operated (pulling the plunger), and the cleaning liquid maintained at room temperature is injected into the means.
[0023]
The cleaning / heating process is performed in the flow path of FIG. In this step, the sample injection means (6-way rotary valve) is in a state where AB, CD, and EF are connected, and the switching valve is in a state where IG is connected. In this state, the measuring means (syringe) is operated (pushing the plunger), whereby the cleaning liquid in the means is transferred to the second heat exchanger (cooling loop), the first heat exchanger (preheating loop), and sample injection. The sample is finally discharged from the sample suction needle via the means. In this step, the washing solution is heated to the temperature while passing through the first heat exchanger (preheating loop) in the oven that is kept at the same temperature as the analytical column. In this way, the cleaning liquid is finally heated to the same temperature as the analytical column, that is, the temperature at which the sample can be dissolved, and is discharged by the sample suction needle. Thereby, a high temperature washing | cleaning liquid can be allowed to pass through about the needle for sample suction arrange | positioned on room temperature conditions. When the analysis is repeatedly performed, the needle can be washed without depositing the sample adhering to the needle in the previous sample suction.
[0024]
The sample suction step is performed in the flow path of FIG. In this step, the injection / injection means (6-way rotary valve) is in a state where AB, CD and EF are connected, and the switching valve is in a state where IG is connected. In this state, the dissolved high-temperature sample is placed under the sample suction needle, and the needle is lowered and inserted into the sample. The measuring means (syringe) is operated (pulling the plunger) to fill the sample in the sampling loop. At this time, the cleaning liquid in the sampling loop and the first heat exchanger (preheating loop) passes through the second heat exchanger (cooling loop) and returns to the metering means (syringe). The cleaning liquid in the sampling loop and the first heat exchanger (preheating loop) was kept at the same temperature as the analytical column because it was placed under a high temperature condition in the oven. The temperature is lowered while passing through the second heat exchanger (cooling loop) before returning.
[0025]
The sample injection process is performed in the flow path of FIG. In this process, the injection / injection means (6-way rotary valve) is in a state where BC, DE, and FA are connected, and the sample introduced into the sampling loop is sent to the analysis column for separation and detection. Is done.
[0026]
As is clear from the above description, if the sample injection apparatus and method of the present invention are used, the sample suction needle and measuring means having a large number of movable mechanical parts are used in the HPLC for analyzing the sample under high temperature conditions. There is no need to place it underneath. Moreover, since it is not necessary to arrange | position a washing | cleaning liquid also on this high temperature condition, the volatilization and the leakage to the exterior of an apparatus can be prevented.
[0027]
EXAMPLE The sample injection apparatus of the present invention shown in FIG. 1 was applied to high temperature GPC. The conditions of the high-temperature GPC are as follows: a commercially available refractometer as the detector, ODCB as the solvent (cleaning solution), polyethylene as the sample to be analyzed, a liquid flow rate by a pump (not shown) of 1 ml / min, and a commercially available analytical column A column (TSKgel GMH, manufactured by Tosoh Corporation, inner diameter 7.8 mm × length 30 mm × 3) and a measuring means (syringe pump) having a capacity of 1 ml were used. The sample was dissolved in a solvent heated to 150 ° C., and the temperature in the analysis column and ovens 16 and 17 was set to 150 ° C.
[0028]
Further, the amount of the sample used for analysis was 300 μl, and therefore the volume of the sampling loop was 300 μl. On the other hand, the capacity of the first heat exchanger (preheating loop) and the second heat exchanger (cooling loop) was 2 ml in order to enable sufficient heat exchange.
[0029]
First, the cleaning liquid suction step was performed with the sample injection means in a state where AB, CD, and EF were connected and the switching valve was connected in IH. That is, the plunger of the syringe was pulled to fill the 1 ml syringe with the cleaning liquid.
[0030]
Next, the cleaning / heating process was performed with the sample injection means in a state where AB, CD, and EF were connected and the switching valve was connected in IG. That is, the plunger of the syringe was pushed, 1 ml of the cleaning liquid was discharged from the sample suction needle to perform cleaning, and the sample suction needle was heated.
[0031]
Next, the sample suction step was performed with the injection valve in a state where AB, CD and EF were connected, and the switching valve in a state where IG was connected. That is, the dissolved sample was placed under the sample suction needle, the needle was lowered and inserted into the sample, the syringe plunger was drawn 0.5 ml, and the sample was filled in the sampling loop. Next, the sample injection means was brought into a state where BC, DE, and FA were connected, and 300 μl of the sample in the sampling loop was introduced into the analysis column. After the sample injection, the cleaning liquid suction step and the cleaning / heating step were performed, and the sample remaining in the sample suction needle was cleaned.
[0032]
The above analysis results are shown in FIG. In the figure, a is a refractometer signal, b is a pump pressure, and c is a sample injection time. If the injected sample is deposited in the flow path, the pressure applied to the column will increase or the refractometer signal will be greatly disturbed. If the sample is injected with the apparatus of the present invention, the pump pressure No increase was observed, and the detector signal was not disturbed. Thus, a good chromatogram was obtained without the sample being precipitated in the flow path.
[0033]
【The invention's effect】
As is apparent from the above description, according to the present invention, only the minimum required mechanical parts are placed under the same temperature conditions as the analytical column, and the weighing means and the washing liquid are placed under different temperature conditions. Usually, it can be placed under room temperature conditions. Therefore, when viewed as a whole sample injection apparatus, it is possible to minimize the occurrence of malfunctions of mechanical parts of the apparatus. Also, among the mechanical parts of the sample injection device, only the minimum necessary liquid contact materials (seal materials, etc.) used for parts that come into contact with the sample or solvent are different from the room temperature conditions as described above. Since it only needs to be arranged under conditions, it is possible to prevent the strength from being reduced to a minimum. Furthermore, since it is possible to arrange the cleaning liquid under room temperature conditions, it is possible to minimize the cleaning liquid from volatilizing and leaking outside the apparatus.
[0034]
The present invention is particularly suitable as an apparatus and method for injecting a sample into an analytical column under a high temperature condition exceeding 100 ° C. That is, even when such a high-temperature sample is injected, the sample suction needle, the metering means, and the cleaning liquid can be arranged at a temperature different from this, usually at room temperature.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a sample injection apparatus according to the present invention.
FIG. 2 is a view showing details of a six-way rotary valve suitable as a sample injection means in the sample injection apparatus of the present invention.
FIG. 3 is a diagram for explaining a sample injection method according to the present invention.
FIG. 4 is a diagram for explaining a sample injection method according to the present invention;
FIG. 5 is a chromatogram showing the results of an example in which sample injection was performed using the apparatus and method of the present invention.
FIG. 6 is a diagram showing an outline of a conventional sample injection device at a high temperature.
FIG. 7 is a diagram for showing a general HPLC apparatus configuration.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Solvent 2 Pump for liquid feeding 3 Sample injection apparatus 4 Analytical column 5 Detector 6 Sampling loop 7 1st heat exchanger (preheating loop)
8 Second heat exchanger (cooling loop)
9 Switching valve 10 Measuring means (syringe)
11 Cleaning solution (solvent)
12 Column oven 13 Sample suction needle 14 Sample 16, 17, 18 Oven

Claims (4)

A sample injection means equipped with a sample suction needle and a sampling loop, a first heat exchanger, a second heat exchanger, a metering means, and a washing liquid container, and an analysis means including a pump and a column in the sample injection means A sample injection apparatus for introducing a sample into the analysis means by being connected, wherein at least a portion other than the sample suction needle of the sample injection means and the first heat exchanger have the same temperature as the analysis means including a column Disposed under conditions, at least the second heat exchanger, the metering means and the washing liquid container are disposed at a temperature different from the temperature, and the sample injection means, the first heat exchanger, the second heat exchanger, A sample injection apparatus, wherein a measuring means and a cleaning liquid container are connected in series. 2. The sample injection apparatus according to claim 1, wherein the sample injection means is a six-way rotary valve. 2. The needle can be cleaned by discharging the cleaning liquid in the cleaning liquid container heated by passing through the first heat exchanger from the sample suction needle before the sample is sucked from the needle. Sample injection device. A sample injection means equipped with a sample suction needle and a sampling loop, a first heat exchanger, a second heat exchanger, a metering means, and a washing liquid container, and an analysis means including a pump and a column in the sample injection means A sample injection apparatus for introducing a sample into the analysis means by being connected, wherein at least a portion other than the sample suction needle of the sample injection means and the first heat exchanger have the same temperature as the analysis means including a column Disposed under conditions, at least the second heat exchanger, the metering means and the washing liquid container are disposed at a temperature different from the temperature, and the sample injection means, the first heat exchanger, the second heat exchanger, Before a sample is sucked from the needle by using a sample injection device characterized in that the measuring means and the cleaning liquid container are connected in series, the cleaning liquid container in the cleaning liquid container heated through the first heat exchanger is used. Sample injection method characterized by heating the needles to drain washing liquid from a sample class reference needle.

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