JPH03218457A - Method and device for injecting sample for split analysis - Google Patents

Abstract

PURPOSE:To improve the accuracy in the quantitative determination of a gas chromatogram by setting the distance from the front end of a needle for sample injection of quartz wool at a specified distance within a specific range. CONSTITUTION:A holding part 24 of the quartz wool 26 is provided by drawing a part of an insert 20 inserted into a body 10 of a sample evaporating chamber. The height of the amt. of the wool 26 which is packed in the insert 20 and is held in this part 24 is designated as B as shown in Fig. and the distance from the front end of the needle 28 up to the top end of the wool 26 when the needle of a microsyringe passes a septum 12 and is inserted into the insert 20 is designated as A. The greater part of a sample liquid released from the needle 28 migrates in the form of a liquid drop up to the wool 26 and evaporates by coming into contact with the wool 26 when the distance A is set constant within the range from several nm to about 30mm. The evaporating speed is, therefore, kept gentle and the gaseous sample having a uniform concn. is obtd. on the downstream side of the wool 26.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a sample injection method and sample injection*i using the split method in a capillary column gas chromatograph. 《Prior art》 In cavillary column gas chromatography. One method for obtaining sharp peaks is the split injection method, in which only a portion of the injected sample passes through the column, and most of the remaining sample is discharged. In a sample injection device using the split injection method, an insert is inserted into the sample vaporization chamber body, the inlet of the capillary column is inserted downstream of the insert, and the insert is often filled with quartz wool. The quartz wool is used to mix the vaporized sample gas and to prevent high-boiling residues from the sample from entering the capillary column.

Inserts filled with quartz wool include those that hold the quartz wool 6 in the narrowed part of the inner diameter, such as the insert 2 shown in Figure 3, and those that hold the quartz wool 6 in the narrow part of the inner diameter, as shown in the insert 4 shown in Figure 4. ; There is one that holds quartz wool 6.

(Problems to be Solved by the Invention) In conventional inserts, the distance from the inlet to the quartz wool 6 is not strictly determined, and this distance is set relatively long. Therefore, when inserting the sample injection syringe needle into the insert and injecting the sample, the distance between the tip of the syringe needle and the quartz wool 6 is long, and most of the sample liquid ejected from the needle flows into the heated insert. It vaporizes while moving, causing a sudden rise in pressure.

Furthermore, as the sample liquid evaporates while moving, the sample gas is distributed at a non-uniform concentration within the insert in the direction of gas flow. As a result, the reproducibility of peak areas in the resulting chromatograms deteriorates. Quantitative accuracy, such as reproducibility of peak areas, is affected by the distance from the needle tip to the quartz wool filled in the insert during sample injection. I understand.

The present invention aims to obtain a gas chromatogram with high quantitative accuracy by optimizing the distance from the quartz wool to the tip of the needle in the insert in the sample injection device.

(Means for Solving the Problems) In the present invention, an insert is inserted into the sample vaporization chamber body of a sample injection device for split analysis of a capillary column gas chromatograph, and the inlet of the capillary column is inserted on the downstream side of the insert. At the same time, the insert is filled with quartz wool, and the sample is injected while keeping the distance from the tip of the sample injection needle to the quartz wool constant in the range of several mm to about 30 mm.

The sample injection device for this purpose holds the quartz wool at a position where, when a predetermined amount of quartz wool is filled into the insert, the distance from the upstream tip of the quartz wool to the tip of the sample injection needle is from several mm to about 30 mm. There is a section to do this.

(Function) When injecting a sample, if the distance from the tip of the sample injection needle to the quartz wool is set to about 30 mm from a few mm, most of the sample liquid released from the needle will be transferred to the quartz wool while immersed in the liquid and then vaporized. do.

When the sample liquid is vaporized while in contact with the quartz wool, the vaporization rate becomes slow, and a sample gas with a uniform concentration can be obtained on the downstream side of the quartz wool.

(Example) FIG. 1 shows a sample injection device of one example. FIG. 2 shows the relationship between the insert and the needle in the same embodiment. Reference numeral 910 is the sample vaporization chamber body, the injection port septum 12 is attached to the upper end by the injection port fin 14, and the cavillary force is attached to the lower end. Ram 16 is attached. The sample vaporization chamber body 10 is provided with a carrier gas port 18 for supplying carrier gas.

A glass insert 20 is inserted into the sample vaporization chamber body 10, and an inlet of a collar 416 is inserted into the lower end of the insert 20. A split outlet 22 is rounded near the lower end of the insert 20 for discharging sample gas that has not been introduced into the column 16.

The insert 2o is provided with a holding part 24 for holding the quartz wool 26. The holding part 24 is an insert 20
The insert 20 is formed by partially narrowing so that the inner diameter of a portion of the insert 20 becomes narrower.

The amount of quartz wool 26 held in the holding part 24 and filled into the insert 2o is expressed by its height B, and the needle 28 of the microsyringe is
Let A be the distance from the tip of the needle 28 to the upper end of the quartz wool 26 when it is inserted into the insert 20 through the septum 12.

In this example, an insert 20 with an inner diameter of 4 mm is used, and the distance A between the lower end of the needle 28 inserted into the insert 2o using an automatic sample injection device and the quartz wool 26 is set to 5 to 8 mm.
Table 1 shows the reproducibility of the peak area of chromatograms obtained by varying the range of 0 mm.

Table 1? v is the variance/mean value expressed as %, 0■. ，
C2, . . . represent linear saturated hydrocarbons having the respective number of carbon atoms. It can be said that if C■ is 0.5% or less, the quantitative accuracy is high, and if it exceeds 1%, the quantitative accuracy is low. . According to the results in Table 1, when B is 5 mm, A is 5 mm, which is good, A is 35 mm, the quantitative accuracy is slightly degraded, and A is 80 mm, which is inappropriate.

Table 2 shows examples of reproducibility measurements when A is fixed at 5 mm and the amount of quartz wool 26 filled is varied.

Table 2 According to the results, when A is 5 mm, it is good if B is 5 mm, when B is 20 mm, the quantitative accuracy is slightly deteriorated, and when B is 40 mm, it is inappropriate.

A suitable value for A is a constant value in the range of 5 to 30 mm. B
A constant value in the range of about 5 to 20 mm is appropriate. More preferably, B is approximately 5 to 10 mm (assuming the inner diameter of the insert 20 is 4 mm, the value of B corresponds to 3 to 6 mg by weight of the quartz wool 26).

In the automatic sample injection device, the position of the lower end of the needle 28 inserted into the insert 20 is fixed, so the holding portion 24
When the position of the quartz wool 26 is fixed by
The distance from the lower end of 8 to the quartz wool 26 is always constant. Therefore, the present invention is suitable for use in automatic sample injection devices. However, the present invention can also be applied when manually injecting a sample. In the case of manual operation, if the needle 28 is inserted into the insert 20 until the lower end of the barrel of the microsyringe touches the injection port fin 14, the distance from the lower end of the needle 28 to the quartz wool 26 will always be constant.

In the embodiments shown in FIGS. 1 and 2, the inner diameter of the part that holds the quartz wool 26 in the insert 20 is partially reduced, but the inner diameter of the part that holds the quartz wool 26 is partially reduced. Instead of reducing the inner diameter, the insert 20 may have a part narrowed by sandwiching it from both sides, or may have a protrusion inside the insert 20, or may have a projection as shown in FIGS. 3 and 4. It is also possible to provide a step or a holding part so that the diameter becomes thinner so that the diameter of the ring can be reduced.

(Effect of the invention) In the present invention, the distance from the tip of the sample injection needle to the quartz wool in the insert of the sample injection device is set optimally, so that the sample liquid is vaporized in the quartz wool, and the vaporized sample gas is Since they are mixed uniformly, the quantitative accuracy of the obtained gas chromatogram is improved.

[Brief explanation of drawings]

Fig. 1 is a vertical sectional view showing one embodiment, Fig. 2 is a vertical sectional view showing an insert, column, and needle in the same embodiment, and Figs. 3 and 4 are vertical sectional views showing conventional inserts, respectively. be. 10... Sample vaporization chamber body, 12...
Septum, 16... Capillary column, 18
...Carrier gas population, 20...Glass insert, 22...Split outlet, 24
...Holding part, 26...Quartz wool,
28...Syringe needle.

Claims (2)

[Claims] (1) Insert an insert into the sample vaporization chamber body of the sample injection device for split analysis of a capillary column gas chromatograph, insert the inlet of the capillary column on the downstream side of the insert, and fill the insert with quartz wool. , an injection method in which the sample is injected while keeping the distance from the tip of the sample injection needle to the quartz wool constant in the range of several mm to about 30 mm. (2) Insert an insert into the sample vaporization chamber body of the sample injection device for split analysis of a capillary column gas chromatograph, insert the inlet of the capillary column on the downstream side of the insert, and insert a predetermined amount of quartz wool into the insert. When filling, the distance from the upstream tip of the quartz wool to the tip of the sample injection needle is several mm to 3 mm.
A sample injection device with a part that holds quartz wool at a position of about 0 mm.