JPS60142242A - Heat conduction type detector - Google Patents

Abstract

PURPOSE:To execute a detection which is not influenced by atmospheric temperatures by containing a single temperature detecting element in a vessel of a small capacity, heating it by applying a pulse voltage and executing data processing by detecting a resistance variation caused by inflow of a gas. CONSTITUTION:A pulse generating device 26 receives a command of a microcomputer 22, applies a pulse of a prescribed period to a metallic filament 29 and heats it. Also, an output waveform pattern of a carrier gas is stored in a memory 24 at every DELTAt time. An output waveform pattern in case when a sample gas passes through the metallic filament 29 is also stored at every DELTAt time. The microcomputer 22 compares successively an amplitude value at every DELTAt time stored in the memory. In the height, the width and the appearance time of a peak value, a difference based on thermal conductivity of the carrier gas and the sample gas appears. Accordingly, the amplitude value of every DELTAt time is compared successively and a peak value generating position is matched, a difference of the amplitude value is derived, it is outputted to a D/A converter 25, D/A-converted and outputted to a recorder 27. In this way, a detection can be executed without being influenced by atmospheric temperatures.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a thermal conduction type detector used in a gas chromatograph.

(b), Prior art A thermal conduction detector used to detect the concentration of gas eluted and separated from a gas chromatograph column consists of two or four cells formed in a metal block made of a metal material such as stainless steel. Two or four temperature detection elements are housed inside the metal block, and the metal block is always maintained at a constant temperature for measurement.

This thermal conduction type detector uses two or four temperature detecting elements to form a prism, flows a standard gas and a sample gas through these temperature detecting elements, and detects the change in resistance of the temperature detecting element due to the sample gas. Although it is detected by converting it into a voltage change, the characteristics change due to variations in the resistance value of the temperature sensing elements that make up the bridge, so it is necessary to perform matching operations to synthesize the characteristics of the temperature sensing elements. Since two or four temperature detection elements are housed in the cell, the volume of the metal block itself becomes large, and a large thermostatic chamber is required to house it. It takes a long time for the temperature to stabilize completely. Furthermore, since the volume of the cell itself provided in the metal block is relatively large, when a small amount of sample gas is supplied, the sample gas will diffuse into the cell, making it impossible to detect a sharp peak waveform. It has the disadvantage that it cannot be applied to capillary column analysis for microanalysis.

()→, Purpose The present invention solves the drawbacks of the prior art described above, and aims to reduce the size of the thermal conductor by using a single temperature sensing element, so that it can be used for analysis in a shorter time. Thermal conduction type detector records the chromatogram indicated by the amplitude difference in the output waveform pattern without having to match the characteristics of the temperature detection element to the extreme, and without being affected by fluctuations in ambient temperature. The purpose is to provide.

(d) 6 configurations FIG. 1 is a functional block diagram clearly showing the configuration of the present invention.

In the figure, in the present invention, a fine temperature detection element housed in a small volume container is brought into contact with gas flowing into the element, and the output waveform obtained from the resistance change is zumbling Δ every time using a sampling storage means. , the amplitude is memorized to form an output waveform pattern, the peak value generation position of the output waveform pattern is determined by the peak position detection means, the peak value generation position of the output waveform pattern is matched, and the output waveform ie It measures the amplitude difference between turns, converts it into an analog quantity, and records it on a recording device.

In the following, the invention will be explained in detail.

(E), Examples (Figs. 2 to 6) Fig. 2 shows a gas chromatograph system using the thermal conduction type detector of the present invention, and Fig. 3 shows the system of a gas chromatograph using the thermal conduction type detector of the present invention. One example is shown in Fig. 4, which shows the pulses and output waveforms applied to the thermal conduction detector described above, and Fig. 5, which shows the difference between the output Q-turn waveform caused by the carrier gas and the G-turn waveform of the sample gas. FIG. 6 shows a flowchart.

In FIG. 2, 1 is a carrier gas cylinder filled with an inert gas such as helium, and 2 is a carrier gas flow rate controller that controls the carrier gas to flow at a predetermined flow rate. 3 is a sample injection part, 4 is a separation column, and 5 is a thermal conduction type detector. The part 6 indicated by the dotted line is in a constant temperature bath.
The sample injection section 3, separation column 4, and thermal conduction type detector 5 are each maintained at a predetermined temperature.

In FIG. 3, υ is a thermal conduction type detector, which is housed in a small-volume container 2 made of metal or ceramic, etc., in a constant temperature bath 28 shown by a dotted line, and maintained at a constant temperature. Then, at the lower end of the small-volume container 211, a removable bag (not shown) is attached to the container 211.
It is connected to IF031. - The q-in 03o is connected to a column (not shown), and the carrier gas and sample gas from the column flow into the container 2 in the direction of the arrow, and are discharged through the pipe 3. Container 21. A metal filament 29 made of tungsten or tungsten-rhenium alloy is housed inside the metal filament 29. Both ends of the metal filament 29 have beams 32,...? 3 to the pulse voltage generator 26, and both ends of the metal filament 29 are connected to the amplifier 23 via beams 34 and 35. 24 is a memory, and an amplifier 23
The output waveform of the carrier gas input from
The output waveform and turn of the sample gas are stored in accordance with instructions from the microcomputer 22. 22 is a microcomputer, and the control signal transmission path shown by the dotted line is a pulse generator 26.
and the memory 24, and the glucose generator 2
6 receives a command from the microcomputer 220, generates pulses at a predetermined period, and applies the pulses to the metal filament 29 to heat it. In addition, a control command signal is applied to the memory 24, and the output waveform and turn of the carrier gas are stored in the memory 24 by zumbling Δ every time, and similarly, when the sample gas passes through the metal filament 29, The output waveform Δ is also sampled and stored at each time. Further, the microcomputer 22 sequentially compares the amplitude values obtained by sampling the output waveform pattern Δ of the carrier gas or sample gas stored in the memory 24 at each time. The shapes of these output waveforms and patterns are close to similar, but the height of the peak value,
Differences based on the thermal conductivity of the carrier gas and the sample gas appear in the width of the peak and the time at which the peak value appears. Therefore, the peak value generation position was determined by sequentially comparing the amplitude values of the output waveforms sampled every 71 hours, and the peak value generation positions of both were matched, and then the Δ of both was obtained by sampling every time. The differences in amplitude values are determined and sequentially output to the DA converter 25.

The DA converter 25 converts the output signal from the microcomputer 22 into an analog signal and outputs it to the recorder 27 at the next stage.

Next, the operation of the above embodiment will be explained with reference to FIGS. 4 and 5.

Carrier gas and sample gas from a column (not shown) communicating with the pipe 30 are transferred to the container 21. Passing through, Guia',?
1f: The Noyalus voltage generator 26 receives a control signal from the microcomputer 22 and discharges the Noyalus voltage shown in FIG. Give and heat this.

The carrier gas is in the container 21. When the carrier gas flows into the metal filament 29, the heat of the heated metal filament 29 is taken away by the carrier gas, causing a resistance change, and a signal due to this resistance change is sent to the amplifier 23 and amplified. This output waveform is shown in Figure 4 (
Shown in bl.

When the sample gas flows in, its thermal conductivity is lower than that of the carrier gas, so the rise is delayed and the peak value is different, as shown in Figure 4 (c+). is removed from the gold filament 29, causing a resistance change, and the signal due to this resistance change is sent to the amplifier 23.
4'lo memo') 241d, Fig. 4 fb)
When a waveform shown by K is input, Δ is sampled every time and its amplitude is memorized. Further, when the waveform shown in FIG. 4(c) is input, Δ is similarly sampled every time, and its amplitude value is stored. next,
The microcomputer 22 reads out the amplitude values obtained by sampling Δ shown in FIG. (Align the peak value generation position of output/F turn shown in bl and (c). Fifth
Although shown schematically in the figure, Figures 4(b) and (C
)'s output/Zo-turn waveforms, and subtract the amplitude values of both samples of Δ at each time to find the difference in the waveforms of the two outputs/Zo-turns shown by diagonal lines. It is.

In this way, the difference between the two waveforms is converted into an analog signal by the DA converter 25, and the waveform of the difference is recorded in the recorder 27 to record a chromatogram.

Next, FIG. 6 shows a flowchart 1 for controlling the thermal conduction type detector of the present invention. Note that ■ to ■ indicate each step of the flowchart.

In step (2), the thermal conduction type detector is activated, and in step (2), the pulse generator 26 is energized and the pulses heat the metal filament 29. In step (2), when the first gas flows in, the metal filament 29
The first output waveform generated by the thermal resistance change is sampled every time Δ, and is stored in the memory 24. In step (2), the second output waveform pattern generated by the change in resistance of the metal filament 29 due to the second inflow of gas is sampled at time m and stored in the memory 24. In Stetsuno ■, the peak value generation time in the first output turn waveform is determined by comparing the amplitude of Δ sampled at each time, and the peak value generation time in the second output turn waveform is determined using the same method. Get into position. In step ■, the first output /'? The peak value B generation device of the turn waveform is made to coincide with the peak value generation position of the second output/lean waveform. In step ■, find the difference between the amplitude value obtained by sampling Δ of the first output waveform pattern every time and the amplitude value obtained by sampling Δ of the second output waveform pattern every time. . In Stesoge (■), if the operation to make the difference has not been completed, return to Sten 7° and continue that operation, and when finished, return to Stetsuno (■). In step ■, the difference between the amplitude values of both output waveforms for each time is stored in the memory, in step ■, the digital quantity is converted to an analog signal, in step 0, it is recorded and displayed on a recorder, etc., and in Stellan 0■ finish.

(f) Effects As explained above, according to the present invention, a single temperature detection element is housed in a small volume container, a pulse voltage is applied to the container to heat it, and resistance change due to gas inflow is detected. However, since data processing is performed on this data, it is possible to quickly detect even trace gases flowing in, as in capillary column analysis, and there is no need to match the thermal response characteristics of each detection element. Moreover, even if the ambient temperature fluctuates, it applies a very short pulse to the detection element, so it is possible to perform detection unaffected by the ambient temperature, and the output waveform・You can easily output a chromatogram of the difference by comparing the amplitudes of P-turns.

[Brief explanation of drawings]

Fig. 1 is a functional block diagram of the present invention, Figs. 2 to 6 show embodiments of the present invention, and Fig. 2 is a configuration diagram of a gas chromatograph using the thermal conduction type detector of the present invention. , FIG. 3 is a configuration diagram of an embodiment of the thermal conduction type detector of the present invention,
Figure 4 shows the output waveforms applied to the temperature detection element. A waveform diagram, Figure 5 is an explanatory diagram that superimposes the output waveforms shown in Figures 4(b) and (c) and calculates the difference, and Figure 6 shows a flowchart.In the figure, 1←[carrier gas cylinder, 2 is a carrier gas flow rate control unit, 3 is a test 131 injection unit, 4 is a separation column, 5 is a thermal conduction type detector, 6 is a constant temperature bath, μ(d is a thermal conduction type detector,
22 is a microcomputer, 23 is a lifting device, 24 is a memory, 25 is an I) A conversion diagnosis, 26 is a pulse voltage generator, 27 is a recorder, 211 is a container, 28 is a constant temperature bath, 2
9 is a temperature detection element, and 32 to 35 are lead wires. Chapter 6 figure

Claims (1)

[Claims] (1) A fine temperature detection element housed in a small volume container, a pulse voltage generator that applies power to the temperature detection element in a semicircular manner, and a ZanF sampling storage means for storing zero rings; peak occurrence position detection means for determining peak occurrence positions from amplitude comparison of sampled and stored output waveforms; peak occurrence position matching means for matching peak occurrence positions; A thermal conduction type detector comprising amplitude difference detection means for detecting an amplitude difference between output waveform patterns whose generation positions are matched.