JPH0570106B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas chromatograph, and in particular provides a gas chromatograph that enables analysis of dilute samples.

In gas chromatography, a capillary column (for example, 0.2 to 0.5 mmφ) is often used as the main column, but due to the column load due to the small internal diameter of the capillary column, the sample (solution) is usually reduced to 1/50 to 1/300. (split) into the capillary column. Therefore, if the sample is a dilute solution (low concentration component), analysis is often difficult in terms of detection sensitivity (for example, analysis of biological samples such as steroids and organic acids in urine). Of course, there is also a method of introducing most of the sample containing a solvent into a capillary column for analysis, but there is a risk that the capillary column will deteriorate due to a large amount of solvent.

This invention was made in view of these circumstances, and its specific configuration includes an outer cylinder, a sample vaporizing inner cylinder coaxially supported within the outer cylinder via a seal ring, and a sample vaporizing inner cylinder coaxially supported within the outer cylinder via a seal ring. a capillary column extending from one opening to the detector; a first carrier gas supply section attached to a portion of the sample vaporizing inner cylinder on the one opening side of the outer cylinder with reference to the seal ring; and a seal ring of the outer cylinder. a second carrier gas supply section and a sample heating temperature control means attached to a portion of the sample vaporizing inner cylinder on the other side of the opening, and an exhaust section attached to a portion of the outer tube near the other opening; and by operating the sample heating control means, the first and second carrier gas switching supply sections, and the exhaust section, the carrier gas is supplied from the first carrier gas supply section to the sample vaporization inner cylinder from one opening to the other. The carrier gas is guided in the direction of the opening to the exhaust section, and unnecessary components such as solvent in the sample solvent injected into the sample vaporization inner cylinder are discharged and removed from the exhaust section, and then the carrier gas is passed from the second carrier gas supply section to the exhaust section. This gas chromatograph is configured such that the sample solution is introduced into the sample vaporization inner cylinder from the other opening toward one opening, and the target component in the sample solution is vaporized and introduced into the capillary column.

That is, this invention adopts a capillary column as a sample separation column, and the structure for introducing the sample into the capillary column is a double cylinder structure in which an outer cylinder and an inner sample vaporization cylinder are connected using a seal ring. By arranging two carrier gas supply sections and a discharge section at specific positions in the multi-tube structure, it is possible to remove unnecessary components such as the solvent that make up the majority of the sample solution in advance and introduce only the target components into the capillary column. This makes it possible to analyze dilute samples with high sensitivity and prevents deterioration of the capillary column.

The present invention will be described in detail below based on embodiments shown in the figures. Note that this invention is not limited to this.

First, in Figure 1, the gas chromatograph G
comprises an outer cylinder 15 and a sample vaporizing inner cylinder (or glass insert) 7 coaxially installed inside the outer cylinder, 16 is a support ring for the inner cylinder, and 17 is a seal ring. 18 is the sample vaporization chamber of the inner cylinder 7, 6 is the silica wool filled in the vaporization chamber, and 9 is a capillary column (example: inner diameter 0.3 mmφ, length 25 m) extending from the rear opening 19 of the inner cylinder to the detector 10. ).
On the other hand, 5 is a septum installed in the front opening 20 of the outer cylinder 15, 21 is a septum holding plate, 22 is an exhaust part, 25 is a seal ring of the rear opening 24 of the outer cylinder 15, and 25 is a split near the opening 24. flow path,
26 refers to this supply section, which includes the support ring 16 and the seal ring 1.
This is the carrier gas supply section on the opposite side to 7.
In addition, 11 is a high flow path resistance, 27 is a variable flow path resistance,
1 is an on-off valve, 2 and 3 are on-off valves, 29 is a pressure regulator, 12 is a high flow path resistance (variable split resistance),
31 is a make-up gas (or scavenger gas) inlet, and 28 is a column tank.

Reference numeral 30 denotes a sample heating control cylinder installed around the outer cylinder 15 in a body wrapper, through which air or nitrogen cooled from the cylinder via a cooler can pass, and a heater 8 is wound around the outside of the cylinder. The temperature of the sample vaporization chamber 18 in the inner tube can be controlled by controlling the heater.

Thus, first, a certain amount of sample is taken into the microsyringe 4, and the sample solution is dropped through the septum 5 onto the sample vaporization chamber 18, that is, onto the silica wool 6 of the sample vaporization chamber. At this time, the temperature in the sample vaporization chamber 18 is set to a temperature at which only the solvent in the sample solution can evaporate (for example, room temperature to about 70°C, which of course varies depending on the solvent). Also, on-off valves 1 and 3 are closed,
The on-off valve 2 is open, and the carrier gas is supplied to the pressure regulator 8,
The sample solution passes through the interior of the inner cylinder 7 through the on-off valve 2, and then escapes to the outside through the on-off valve 1, whereupon the highly volatile solvent in the sample solution evaporates and is discharged to the outside of the system through the exhaust section 22.

Next, the on-off valves 1 and 2 are closed, the on-off valve 3 is opened to reverse the flow direction of the carrier gas in the inner cylinder 7, and at the same time the heater 8 is activated to open the sample vaporization chamber 18.
is rapidly heated (e.g., 300° C.) to vaporize the target component remaining in the silica wool 6, and send it to the capillary column 9, where it is detected by a detector 10 as appropriate. In this way, the analysis of the sample is performed only on the target components excluding the solvent, which accounts for most of the sample, and therefore, even if the sample is a dilute sample, highly sensitive analysis is possible.

Note that, after rapid heating, the sample vaporization chamber 18 is cooled by cold air in order to introduce the next sample.

Among the sample heating temperature control means adopted in the above examples, the heating means is a means of coating the outside of the inner cylinder (made of glass) with a metal film, or inserting a paramagnetic metal inside the inner cylinder and performing high-frequency heating. Of course, in either case, care must be taken to prevent the vaporized components from coming into contact with the metal surface and causing decomposition.

According to the present invention, since the split flow path is used as a carrier gas supply flow path during solvent removal, there is no need to separately install a carrier gas introduction pipe.Moreover, with such a simplified configuration, the solvent that occurs when a capillary column is used Problems such as column deterioration due to components can be resolved.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of a gas chromatograph according to the present invention. 7... Sample vaporization inner cylinder, 8... Heater, 9... Capillary column, 10... Detector, 22... Exhaust section, 25... Split channel, 26... Carrier gas supply section.

Claims (1)

[Scope of Claims] 1. An outer cylinder, a sample vaporizing inner cylinder coaxially supported within the outer cylinder via a seal ring, a capillary column extending from one opening of the sample vaporizing inner cylinder to a detector, and the outer cylinder. A split flow path attached to the opening side of the capillary column side of the sample vaporizing inner cylinder with reference to the seal ring of the cylinder, and a carrier gas attached to the opposite side of the split flow path with reference to the seal ring of the outer cylinder. a supply section, a carrier gas switching supply means for switchingably allowing carrier gas to flow sequentially through the carrier gas supply section and the split flow path, and an exhaust section attached to the outer tube on the opening side of the sample vaporizing inner tube opposite to the capillary column side opening. and a sample heating temperature control means disposed around the outer cylinder, and the carrier gas switching supply means first causes the carrier gas to flow through the split channel, eliminating the need for a solvent in the sample solvent injected into the sample vaporizing inner cylinder. The gas chromatograph is controlled so that the components are discharged and removed from the exhaust section, and then the carrier gas is caused to flow from the carrier gas supply section to the sample vaporization inner cylinder, and the target component in the sample solution is introduced into the capillary column.