JPS62192658A - Gas chromatograph provided with base line correcting means - Google Patents

Abstract

PURPOSE:To make heating-up analysis with a piece of column by changing the flow rate of a carrier gas flowing in a resistance pipe according to a column oven temp. without using the column for correcting the base line. CONSTITUTION:The column 4 and resistance pipe 12 are mounted in the column oven 2. Base line correctors 14, 18 consisting of tubes packed with packing materials and detectors 10, 20 respectively connected to the outlets of the correctors are mounted in a thermostatic chamber 8 for detectors. The outlet of the column 4 is joined with the outlet of the corrector 14 and is connected to the detector 10. The carrier gas is supplied through a mass flow controller 6 to the inlet of the column 4. The outlet of the resistance pipe 12 is connected to the inlet of the corrector 14 and the carrier gas is supplied through a flow rate controller 16 which maintains the specified pressure to the inlet of the resistance pipe 12. The carrier gas is further supplied through a flow rate controller 22 which maintains the specified pressure to the inlet of the corrector 18. The correction of the base line is executed by detecting the difference between the detection signals of the detectors 10, 20.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a gas chromatograph capable of performing temperature programmed analysis, and particularly to a gas chromatograph capable of correcting the baseline of a gas chromatogram.

(Prior Art) In order to shorten the analysis time using a gas chromatograph, a temperature-rising analysis method is used in which the temperature of a column is increased as one hour passes.

In temperature-programmed analysis, as the column temperature rises, the amount of liquid phase eluted from the column packing material increases. Therefore, in a single-flow method using only one column, the recording speed increases as the column temperature rises. The baseline of the chromatogram recorded on the meter increases.

In order to suppress such a rise in the baseline, conventionally, other columns of the same type are installed in the column oven, and a detector for detecting the effluent of the other columns is installed in the thermostatic chamber for the detector. The rise in the baseline is corrected by taking the difference between the two detectors installed.

(Problems to be Solved by the Invention) A conventional gas chromatograph for temperature-programmed analysis requires two columns of the same type. Columns deteriorate with use, so when replacing a column, two columns must be replaced.

An object of the present invention is to perform baseline correction without using a column for baseline correction, thereby making it possible to perform temperature-programming analysis with a single column.

(Means for solving the problem) In the gas chromatograph of the present invention, a column oven (two
) in which a column (4) and a resistance tube (12) are installed, and a first baseline correction device (14) consisting of a tube filled with a filler in a thermostatic chamber (8) for a detector; A first detector (10) connected to the outlet of the baseline correction device (14), a second baseline correction device (18) consisting of a tube filled with a filler, and this second baseline correction A second detector (20) connected to the outlet of the device (18) is installed, and the outlet of the column (4) is merged with the outlet of the first baseline correction device i2 (14) to perform the first detection. column (4).
), a carrier gas is supplied to the inlet of the resistance tube (12) via a mass flow controller (6), and the outlet of the resistance tube (12) is connected to the inlet of the first baseline correction device (14). Carrier gas is supplied to the inlet via a first flow regulator (16) that keeps the pressure constant, and a second flow regulator that keeps the pressure constant is supplied to the inlet of the second baseline correction device ID (18). A carrier gas is supplied through the detector (22), and the difference between the detection signal of the first detector (1o) and the detection signal of the second detector (20) is output.

(Example) FIG. 1 represents one embodiment.

2 is a column oven, and inside the column oven 2, a column 4 and a resistance tube 12 are installed.

As the resistance tube 12, one with a large resistance is used so that the flow rate changes greatly as the temperature of the column oven 2 changes.

Reference numeral 8 denotes an oven as a constant temperature oven for the detector, and inside the detector oven 8 there are a first baseline correction device 14, a first detector connected to the outlet of the baseline correction device 14, and a second FIDI O1. A baseline correction device 18 and an FID 20 as a second detector connected to the outlet of the baseline correction device I8 are installed. Baseline correction devices 1214 and 18 are the same.

As the baseline correction device 14.18, a tube filled with a filler, which is a carrier coated with a liquid phase and is generally used in gas chromagraphs, can be used. Baseline correction device 14.18
It is desirable that the liquid phase be one that can withstand as high a temperature as possible. For example, a silicon-based liquid phase such as 0V-101 (methyl silicon) is preferred. Liquid phase concentration is 10~
About 20% is preferable. Baseline correction device 14°1
The packing used in column 8 is not necessarily the same as the packing used in column 4.

The carrier gas entering column 4 passes through mass flow controller 6.
It is supplied through. Mass flow controller 6 and column 4
A sample introduction port 24 is provided between them. The flow path connected to the outlet of the column 4 merges with the outlet of the baseline correction device 14 and is connected to FIDIO.

Carrier gas is supplied to the inlet of the resistance tube I2 via a flow regulator 16 that controls the pressure to be constant. The outlet of the resistance tube 12 is connected to the inlet of the baseline correction device 14.

22 is a flow rate regulator that controls the pressure to be constant, and carrier gas is supplied to the inlet of the baseline correction device 18 through the flow rate regulator 22.

The carrier gas flow path through flow regulator 22 does not pass through column oven 2 .

The temperature of the detector oven 8 is usually set to be 30 to 70° C. higher than the column temperature (the temperature of the column oven 2). The detector oven 8 may be replaced with a constant temperature block.

Next, the operation of this embodiment will be explained.

Before raising the column temperature, the temperature of the detector oven 8 is raised to the set temperature. As a result, liquid phase vapor is generated from the baseline correction devices fi14 and fi18. The amount of liquid phase vapor from both baseline correction devices 14, 18 is determined by the carrier gas flow rate F+, which passes through the flow regulator 16.22, respectively.
Adjust by F=.

Thereafter, the temperature of the column oven 2 is raised to raise the temperature of the column 4. As the temperature of column 4 increases, the liquid phase vapor generated from within column 4 increases, and the liquid phase vapor acts in the direction of pushing up the baseline of the chromatogram, as shown in Figure 2 (A). .

On the other hand, since the temperature of the resistance tube 12 also increases at the same time, the flow rate of the carrier gas passing through the resistance tube 12 under pressure control decreases due to the increase in viscosity. Steam volume is column oven 2
As the temperature increases, the liquid phase vapor acts to lower the baseline of the chromatogram, as shown in FIG. 2(B).

Since the flow rate of the carrier gas supplied to the baseline correction device 18 is not affected by the temperature rise of the column oven 2, the amount of liquid phase vapor inside the baseline correction device 18 does not change.

Figure 2 (A) and (B) are FIDlo and FTD20
It is calculated by taking the difference between the outputs of

In this way, the increase in liquid phase vapor from the column 4 that occurs as the temperature rises in the column oven 2 and the decrease in liquid phase vapor from the baseline correction device 14 act to cancel each other out, and the Suppress line rise.

FID], the difference between the output of O and the output of FID20 is output as a chromatogram.

The parameters for correcting the baseline include the temperature of the detector oven 8, the difference between the set flow rates mFt and F2 by the flow rate regulators 16 and 22, the absolute flow rates of the set flow rates F1 and F2, the FIDIo of the detector, and the hydrogen of 20. There are flow rates, etc. For example, in Fig. 2, when the maximum temperature is reached, the contribution to raising the baseline by the liquid phase vapor from column 4 is Δ
The flow rates F+, F:: may be set so that the baseline lowering contribution Δ■2 due to the liquid phase vapor from the baseline correction device 14 is as equal as possible to the baseline lowering contribution Δ■2.

In the present invention, the column 4 may be a packed column or a capillary column. When using a capillary column, it is generally used in a single flow path system, so it is not possible to correct the baseline using two columns as in the past. Therefore, it is particularly effective to apply the present invention to a capillary column gas chromatograph.

The detector is not limited to FID, but may be other detectors such as TCD.

(Effects of the Invention) In the present invention, a column is not used for baseline correction, and the flow rate of the carrier gas flowing through the resistance tube is changed in accordance with the column oven temperature, thereby generating the amount of liquid phase vapor from the baseline correction device. The baseline was corrected by changing the . Therefore, although a correction column was required in the past, such a correction column is no longer necessary in the present invention, and only one column for difficult analysis is required for column exchange.

[Brief explanation of drawings]

FIG. 1 is a wave line diagram showing one embodiment of the present invention, and FIG. 2 (A
) and the same figure (B) respectively show the change in the baseline due to the amount of liquid phase vapor generated from the column as the yl-temperature increases, and
FIG. 3 is a diagram showing changes in the baseline depending on the amount of liquid phase vapor generated from the baseline correction device. 2...Column oven, 4...Column, 6...Mass flow controller, 8...Detector oven, 10.20...FID , 12...Resistance tube, 14.18...Baseline correction device, 16.
22...Flow rate regulator.

Claims (1)

[Claims] (1) Install the column and resistance tube in the column oven, and connect to the first baseline correction device made of a tube filled with filler in the thermostat for the detector and the outlet of this first baseline correction device. a second baseline correction device made of a tube filled with a filler; and a second detector connected to the outlet of the second baseline correction device; The outlet of the column joins the outlet of the first baseline correction device and is connected to the first detector, and the inlet of the column is supplied with a carrier gas via a mass flow controller, and the inlet of the column is connected to the outlet of the first baseline correction device. an outlet of the resistance tube is connected to an inlet of the first baseline correction device, and a carrier gas is supplied to the inlet of the resistance tube via a first flow regulator that keeps the pressure constant; A carrier gas is supplied to the inlet of the device via a second flow regulator that keeps the pressure constant;
and a gas chromatograph that outputs a difference between a detection signal of the first detector and a detection signal of the second detector.