JPS6129760A - Simple on-column device - Google Patents

Abstract

PURPOSE:To simpify the device by heating the part between the outside periphery of a heating tank and the periphery of a sample introduction part by feeding a current directly or a flexible heating body. CONSTITUTION:The sample introduction part 1 is connected to a capillary glass column 4 put in the heating tank 3 through a stainless steel capillary tube 2 whose internal surface is inactivated while penetrating the heat insulation wall 6 of a gas chromatograph body 5. Carrier gas is admitted from a carrier gas support pipe 7 fitted to the introduction part 1, mixed with scavenger gas entered from a scavenger intake 8 through the introduction part 1, tube 2, and column 4, and sent to a hydrogen flame detector 9. When the tube 2 is heated by being fed with electricity, a lead wire 11 connecting with a transformer 10 is fitted to the tube 2 with a clip 12 and the other lead wire 13 from the transformer 10 is passed through a flow passage switch 14 and fitted to a slightly downstream point from a sample injection point with a clip 15; and the other from the switch 14 is fitted to an upstream point of the sample injection point with a clip 16. Thus, the device is simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus devised to facilitate on-column capillary gas chromatography, and more specifically to an apparatus in which an on-column injection port is prepared separately from the gas chromatograph body. .

Capillary gas chromatographs are widely used as analysis and separation means because of their excellent separation ability. However, the reproducibility of the obtained chromatographic peak ratios is not necessarily satisfactory, and especially for samples with a wide boiling point range, the low boiling point portion is actually much higher.
It has been found that the high boiling point part is low and the reproducibility is not particularly good. In the case of thermally unstable samples, there is also the disadvantage that part of the sample changes in quality due to the influence of heat from the sample evaporation section. On-column capillary gas chromatographs have improved on these points. However, in the on-column gas chromatography method, for example, when a sample containing a polar solvent is used in a non-polar column, or when a large amount of sample is injected, the shape of the peak becomes irregular. At that time, the initial temperature of the capillary column is the boiling point of the sample solvent! 710
If the temperature is increased by ~30°C, such inconveniences will be greatly alleviated. In general, the higher the temperature of the capillary column, the sharper the peak shape, which is preferable. Especially when the amount of sample injected is large and the initial temperature of the capillary column is low, the piping becomes sharp. However, in the on-column method, when injecting a sample, the needle tip of the sample injection syringe is inserted into the capillary column, and the tip is at least 15 mm deep into the heating tank containing the capillary column. It is necessary. Therefore, if the initial temperature of the capillary column is set higher than the boiling point of the sample solvent, the tip of the needle will be heated above the boiling point of the profiling medium, and fractional evaporation will occur during the sample injection operation, resulting in the reproducibility of peak ratios even in the on-column method. Sexuality becomes worse. As a way to avoid this problem, a method is already known in which the capillary column is partially forcedly cooled between the point where the needle tip reaches when injecting the sample and the wall of the heating tank (Japanese Patent Application No. 1983-
44991) o Furthermore, even if the temperature at the arrival point of the needle tip during sample injection is room temperature, there is an injection zone (in-jec on) between the sample injection point and the capillary column heating tank.
By providing a straight capillary column section called zone) that can perform rapid heating, the sample injection volume can be reduced to 8 P.
Even in the case of L, it has been announced that the peak becomes sharp and scales appear (J, V, 11inshaw, Jrand
F, J, Yang, )IRc & CC655
4 (1983)).

In the former case, when a large amount of a sample containing many high-boiling components is injected, it takes time to vaporize the sample, and a sharp peak cannot be seen. In the latter case, the liquid injected into the capillary column flows down into the heated injection zone. It is difficult to apply this method to a gas chromatograph with a top lid type heating tank. This method is also inappropriate because the injection zone must be attached to the front panel of a top-lid type gas chromatograph, because of the space on the front panel, and because the lees with the injection zone protrude about 20 cm from the front. Furthermore, this method requires that after the injection zone is heated, cooled air must be forced into the box to cool it down.

The present inventors have devised a simple device that solves these problems, can be applied to existing conventional gas chromatographs, and can thereby easily perform capillary gas chromatographs.

In addition to a conventional capillary gas chromatograph, the device according to the present invention includes at least a flexible capillary tube that connects a sample introduction section that can perform on-column operation and a capillary column in a heating tank of the gas chromatograph body, and a capillary tube for the capillary tube. Requires equipment that can conduct electrical heating along the curve. Although various structures of the on-column sample introduction section have already been announced, any of them can be used in the present invention, and the structure is not limited in any way. The material of the capillary column in the heating tank may be glass, fused silica, metal, etc.
There is no special difference between the capillary column and known capillary columns.

The material of the flexible cavity 2 Lee Cheap connecting between the capillary column and the on-column sample introduction part may be made of a material that is flexible and has a heat resistance of at least 150 to 200°C. It may be painted, but it is better to leave it bare.

At present, metal or fused silica is suitable as the material. If the capillary column in the heating tank is made of metal or fused silica, the easiest way is to use it as is, lead its end through the wall of the heating tank to the outside of the tank, and connect it to the sample introduction section. By connecting it, it can also serve as a flexible tube, and the present invention also includes such a case. In the on-column method, in order to avoid deterioration of the liquid phase in the cavity column due to evaporation residue of the injected sample, and to quickly move relatively high-boiling components in the injected sample to the capillary column in the heating tank, It is more preferable that the liquid phase is not applied to the capillary column between the portions connected to the sample introduction portion from outside the heating tank, that is, the capillary column is simply a capillary reach conduit. It is known to make a capillary column that is not coated with a liquid phase for the required length from the top of the column, but that method is complicated, so it is difficult to make a capillary column that is normally coated with a liquid phase. It is more convenient to carry out the present invention by connecting capillary tapes.The connection methods include a method using a heat-shrinkable Teflon pipe, a method using a connecting fitting, a method using silicone glue and a connecting pipe, etc. There is a Larger than the outer diameter of the syringe needle used for sample injection,
Same as normal on-column method, inner diameter 0.30~0
．． 35 mm is suitable. In addition, the length depends on the position of the tip of the cavitree column in the heating tank, the position of holes that need to be made in the heating tank, and the position of the sample introduction part. The sample introduction section of the simple on-column device based on the present invention, which usually has a length of 20 to 60 cm, can be placed on top of the heating tank, but it is usually convenient to use it by placing it on the right or left side of the main body of Gask Shimadura 7. At that time, the capillary chest will connect the cavity 2 column and the sample introduction section by making a hole in the side wall or back wall of the heating tank and passing through it. It is necessary to be able to
It is desirable that the sample can be cooled quickly at least from the sample introduction part to the injection point reached by the tip of the syringe needle when injecting the sample into the column. Unlike other parts of the capillary tube, the sample injection amount is, for example, 5 μm before the benign entry point, that is, about 5 to 30 mm in the direction of the sample introduction part.
If the amount is small as described below, it is necessary to be able to maintain the temperature lower than the boiling point of the solvent in the sample in order to avoid fractional evaporation of the sample in the injection needle during sample injection. It is also desirable to be able to heat that part of the sample after it is injected, especially in the case of samples containing high-boiling components. In many cases, there is no problem even if the device does not have this desirable function. The cavity chamber must be able to heat at least from the outside of the wall of the heating tank to the vicinity of the sample injection point, and if the heating tank has thick insulated walls, it must be able to heat from the inside of the insulation wall to the vicinity of the injection point. 0 Heating may be done by a heating method or a constant temperature method, but in the case of a heating method, it is desirable to set the initial temperature to a temperature higher than the boiling point of the additive and to heat it quickly, especially when large quantities are injected. . This is to prevent the plug or liquid of the injection sample from flowing into the capillary column without being vaporized. As described in the examples, it is not always necessary to use a metal capillary tube or metal thin tube as a method of heating with electricity, and various flexible heating methods can be used.Among them, this method is considered to be the simplest and best method. However, when the capillary chest is made of metal, the method is to apply a voltage of several volts to several 10 volts directly to it and heat it by direct current. By choosing the soaking position, the heating section can be selected as required. In addition to this direct heating method, there is also an indirect method in which a capillary tube is covered with a thin metal tube and electrically heated in accordance with the above-mentioned direct heating method, such as using a flexible heating element made of glass fiber and heating wire. There are methods etc. These metal capillaries
As for the type of metal for the pipe or thin metal tube, stainless steel is preferred because it has less heat transfer outside the energized section.Direct energization or indirect energization heating using a flexible heating element is a curved cabin reach, - In addition to the advantage of being able to easily heat it along the curve, it also has the advantage of allowing it to cool down in a short time if the electricity is turned off. When using the direct current heating method, it is often necessary to take into consideration electrical insulation from other parts of the device, but this can be easily done with very general knowledge, so the following examples are provided. The explanation of the electrical insulation method is omitted here, but one thing that is easy to forget about electrical insulation is that when the capillary reach is a metal capillary and is heated by direct current, the needle of the syringe used is This means that one made of fused silica should be used. If you use a metal needle, you will not be able to insulate it.

Next, examples will be given and the present invention will be explained for convenience in further understanding.

Example 1 Figure 1 shows an example of a simple on-column device according to the present invention attached to a gas cylinder capillary tube body, viewed from above. RA835 manufactured by Nippon Chromato Industries Co., Ltd., inner diameter 0, 35 mm, length 50 cm)
A gas chromatograph 27 is connected to a capillary glass column 4 housed in a heating tank 3 through a heat insulating wall 6 of a main body 5 of the gas chromatograph 2 . The carrier gas enters from the carrier gas supply pipe 7 attached to the sample introduction section 1, passes through the sample introduction section 1, the cavillary chamber 2, and the capillary column 4, and is mixed with the scavenger gas that enters the scavenger supply port 8. It is sent to the hydrogen flame detector 9. To heat the capillary tube 2 with electricity, the lead wire 11 connected to the transformer 10 is attached to the cavity tree tube 2 using a clip 12, and the other lead wire 13 from the transformer 10 is connected to the sample via the flow path switch 14. A clip 15 is also attached at a point slightly downstream of the injection point.

The other line from the flow diverter 14 is attached with a clip 16 at a suitable point upstream of the injection point.

Figure 2 shows an example of a gas chromatography column observed using the simple on-column device according to the present invention.The operating conditions are as follows.Capillary glass column 4: Inner diameter 0 .28 fitting length 25
m1 liquid phase methyl silicone rubber; Carrier gas: Nitrogen linear velocity 6 Q eg/sec; Initial temperature and temperature increase rate of heating tank 3 = 90°C, 10°C/min; Initial temperature of cavillary cheese 2: Clip 12 80°C between clips 15; initial temperature of injection point 60°C; heating rate of gear pillar reach 4-2: 20°C/min between clips 12 and 16; sample injection amount = 10
μt; Contents of sample: n-alkanes Cs, Cro,
Ctt, C14XC18% CIa, Cue and Co
The procedure for injecting an n-hexane solution sample into the cavillary chamber is to take a 10μ sample into a syringe fitted with a fused silica needle, and as shown in Figure 1, attach a needle thick enough to be penetrated by the fused silica needle. Insert the needle guide 17 into the septum rubber 18 of the sample introduction part 1, pass the tip of the needle of the syringe through the hole in the needle guide 17, reach the injection point of the capillary reach 2, and inject the sample in about 7 seconds. Then insert the syringe into the septum rubber 18 along with the needle guide 17.
The switching device 14 was switched from the position force 1 shown in the figure, and the temperatures of the cavillary cheese 2 and the heating tank 3 began to rise.

In FIG. 2, 19 to 27 are the solvent n-hexane,
Solute n-alkanes C8, Cso, C12, CIa
.

These are peaks based on C1a, Cta, CdoO, and C3.

FIG. 3 shows the chroma dog 2 flap that was observed when the cavity 2 reach up 2 in FIG. 1 was performed without heating. When compared with FIG. 2 based on the present invention, the heating effect of the cavity 2 reach-up of the simple on-column device of the present invention is obvious.
The temperature drop to ℃ was achieved only by cooling for about 90 seconds.

Example 2 FIG. 4 shows a diagram during gas chromatogram measurement when the cock-type sample introduction part 28 of the simple on-column device based on the present invention is provided above the heating tank 3.
The capillary column 4 is made of fused silica, and its head passes through a stainless steel thin tube 29 that penetrates the upper insulating wall 6 of the heating tank 3, and is fixed to the sample introduction part 28.
The other end reaches the detector 9, and the weight of the capillary column 4 is mainly supported by the support rod 30.

The lead wire 1 from the transformer 10 is connected to the stainless steel tube 29.
1.13 are tied to clips 15.12, respectively. The temperature of the stainless steel thin tube 29 is set in advance to a temperature higher than the boiling point of the liqueur in the sample, preferably 20 to 50° C. above the boiling point, and the temperature of the heating tank is set to an appropriate initial temperature for heating. When the amount of sample to be injected is small and it is necessary to avoid fractional evaporation during sample injection, the sample introduction part 28 should be moved from the state shown in FIG.
Raise the syringe by 3 cm, hold it in that position, open the cock, make sure that the tip of the syringe needle is in the middle of that 3 cm, inject the sample, then remove it and close the cock. Immediately thereafter, the sample introduction section 28 is returned to the state shown in Fig. 4, and the stainless steel tube 29 is heated rapidly and the heating tank 3 is heated at an appropriate rate. You can stop heating. For the next sample injection, if the sample introduction part 28 is lifted about 3 cm again, the sample injection point will be allowed to cool rapidly. If the amount of sample to be injected is large and the fractional evaporation can be ignored, the injection operation can be carried out in the state shown in FIG. 4. Needless to say, this example is an example in which a fused silica capillary column serves the function of the flexible capillary tube 2 shown in FIG. 1.

Embodiment 3 FIG. 5 shows an embodiment based on the present invention, in which the method of heating the stainless steel capillary cheese 2 shown in FIG. 1 of Embodiment 1 is a direct energization method. In this case, a capillary reach tube 2 is covered with a tubular member 31 made of glass fiber and a heating wire, and FIG. 5 shows the state immediately before sample injection. The heating tank 3 is set to a predetermined initial temperature, the temperature of the tubular object 31 is set to a temperature of 150 to 250°, and the temperature between the end on the lead wire 13 side and the sample introduction part is 3 to 250°.
Leave it for about 5 am. When injecting the sample, bring the tip of the syringe needle to the middle of the gap, inject the sample, and then
If necessary, pull out the tubular member 31 a little to eliminate the gap as much as possible.

As shown in the above-mentioned examples, according to the present invention, the temperature of the capillary column in the heating tank, the temperature of the part that transfers the sample, that is, the part that serves as the capillary reach screw, and the temperature of the sample injection point are controlled. Since the temperature can be selected independently, it has the advantage of being able to operate under optimal conditions.The heating of the capillary cheese or the part that serves as it is done directly or indirectly by energizing, so even if the part is curved. Heating is easy and cooling is quick. Moreover, the sample introduction part is provided separately from the gas chromatograph body, and the connection between it and the capillary column in the heating tank is easy even if the column is made of flexible material. Since it can be carried out by stretching it or by using a flexible capillary tube, any gas chromatograph can be easily converted into an on-column device. Furthermore, the simple on-column device according to the present invention is extremely useful since it is not inferior in performance to an on-column device in which the sample introduction section is attached to the main body.

4. Brief description of the drawings Figures 1, 4 and 5 show a simple on-column device or a part thereof based on the present invention. , 2... Capillary cheese, 3... Heating tank, 4...
Capillary column, 5...Gas chromatograph body, 6...Insulating wall, 7...Carrier gas supply pipe, 8...Scavenger gas supply port, 9... ...Detector, tJO...Transformer, 11.13...Lead wire, 12.15.
16... Clip, 14... Flow path switch, 17... Needle guide, 18... Septum rubber, 30... Support rod, 31...
FIGS. 2 and 3 are examples of gas chromatographs in which measurements were taken using an apparatus according to the present invention and an apparatus not according to the present invention, respectively. In the figure, 19...peaks due to solvent n-hexane, 20.21.22.23.24.25.
26 and 27... each n-alkane Cs,
C5oXCt*) Csa, C14, Cxs, C
Peaks due to xo and CH

Claims (5)

[Claims] (1) Prepare an on-column sample introduction section separately from the gas chromatograph body that includes a heating tank that houses the capillary column, and connect it and the capillary column in the heating tank using a flexible capillary tube that passes through the wall of the heating tank. Or, if the capillary column is made of a flexible material, connect one end of it to serve as a capillary tube, and at least connect the area near the outside of the heating tank and the area near the sample introduction part with a direct current or a flexible material. A simple on-column device characterized by having a structure that allows heating with a heating element. (2) Claim 1, in which the capillary tube is a stainless steel capillary, and the capillary tube is directly energized and heated.
Simple on-column device described in section (3) Make a hole in the side or back of the heating tank and connect the sample introduction part placed next to the gas chromatograph body and the capillary column inside the heating tank with a capillary tube covered with glass fiber and a heating element. Simple on-column device according to claim 1 (4) The capillary column is a fused silica or stainless steel capillary, which also serves as a capillary tube and is connected to the sample introduction part, and the area from near the insulation tank of the heating tank to near the sample introduction part is indirectly or directly heated by electrical current. A simple on-column device according to claim 1, which is configured to enable (5) A simple on-column device according to claim 1, in which a sample introduction part is provided in the upper part of the heating tank.