JPH0552834A - Calibration of process gas chromatograph - Google Patents

Abstract

PURPOSE:To obtain correct concn. even when the base line of an output value is changed by calculating the concn. of a component to be measured from the outputs obtained at the times when the component to be measured is present and absent in a sample using a specific formula. CONSTITUTION:An electrical breaker 6 is turned ON and a zero position signal S13 is generated in a photodetector 12. This signal S13 is processed by a waveform processing circuit 2 to become a signal V0 by an operation circuit 3 to be stored in a memory circuit 4. Next, the breaker 6 is turned OFF to set such a state that no zero position signal S13 is generated in the photodetector 12. A sample is analyzed in this state by a process gas chromatograph and, when a component to be measured is not detected by a flame photometer 11, a signal V1 is obtained as the output of the circuit 3 and, when said component is detected, a signal V2 is obtained as output. Since the relation between the concn. C of the component to be measured and the output V of the circuit 3 is C=f(V), the concn. C of the component to be measured is calculated using formula C=f(V2-V0)-f(V1-V0).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for calibrating a process gas chromatograph equipped with a flame photometric detector known by the abbreviation FPD.

[0002]

2. Description of the Related Art In a conventional process gas chromatograph, the following method has been used as a method for obtaining the concentration of a component to be measured. That is, a reference sample of known concentration is first analyzed, and then the corresponding output of the analysis value (integral value or peak height value) and the analysis value of the sample containing the measured component of unknown concentration are analyzed. The method of comparing and calculating is often used.

However, when a sample containing sulfur is analyzed using a process gas chromatograph having a flame photometric detector as a detector, since the sulfur and the output of the flame photometric detector are not linear, If the base line of the output value changes, the peak value of the output also changes, and the correct concentration of the measured component cannot be obtained.

[Problems to be Solved by the Invention]

The present invention has been made in view of the drawbacks of the conventional example, and an object thereof is to obtain the correct concentration of the measured component even when the base line of the output value changes. It is to provide a calibration method for such a process gas chromatograph.

[0005]

[Means for Solving the Problems]

<Means for Solving the Problems> The feature of the present invention for solving the above problems is that the output of the detector when the output of the detector is made electrically or optically zero in the calibration method of the process gas chromatograph. From V ₀ , the output V ₁ when the measured component does not exist in the sample, and the output V ₂ when the measured component exists in the sample, the following equation using f (V) as a function of V is used. The concentration C of the component to be measured is obtained by the above. _{C = f (V 2 -V 0} ) -f (V 1 -V 0)

[0006]

The present invention operates as follows. That is, first, the electrical or optical breaker is turned on, and the zero-level signal generated by the photodetector is waveform-processed by the waveform processing circuit and then processed by the arithmetic circuit to become the signal V ₀ . It is stored in the memory circuit. Next, turn off the electrical or optical circuit breaker, and in the state where the zero signal is not generated in the photodetector,
The sample is analyzed by the process gas chromatograph, and V ₁ is obtained as the output of the arithmetic circuit when the measured component is not detected by the flame photometric detector, and when the measured component is detected by the flame photometric detector. V ₂ is obtained as the output of the arithmetic circuit. Since the relationship between the concentration C of the component to be measured and the output V of the arithmetic circuit is C = f (V), the concentration C of the component to be measured can be calculated from the following equation.
Is calculated. _{C = f (V 2 -V 0} ) -f (V 1 -V 0)

[0007]

The present invention will be described in detail below with reference to the drawings. FIG. 1 is a block circuit diagram of an essential part of an embodiment of the present invention. In this figure, 1 is a detection unit, 11 is a flame photometric detector, 12 is an output of the flame photometric detector 11 for photoelectric conversion, and it is sent from a voltage power source 5 through an electrical breaker 6. photodetector that emits the zero position signal by the voltage signal S12, 13 is an amplifier for amplifying the output S ₁₃ of the photodetector 12, the waveform processing circuit 2 for waveform processing by receiving an output S ₁₄ of the detection unit 1, 3 An arithmetic circuit 4 that receives the output S ₁₅ of the waveform processing circuit 2 and performs operational amplification is denoted by 4, and a memory circuit 4 stores the values that are arithmetically amplified by the operational circuit 3.

Reference numeral 5 is a voltage power source for generating a zero-level signal to the photodetector 12 via an electrical breaker (eg switch) 6. In the embodiment of the present invention having such a configuration, first, the electrical breaker 6 is turned on (that is, made conductive), and the null signal S ₁₃ ′ is generated in the photodetector 12. The signal S ₁₃ ′ is waveform-processed by the waveform processing circuit 2 and then processed by the arithmetic circuit 3 to become a signal V ₀ , which is stored in the memory circuit 4.

Next, the electrical breaker 6 is turned off (that is, cut off) so that the photodetector 12 does not generate the zero-level signal S ₁₃ ′. In this state, the sample is analyzed by the process gas chromatograph, and when the measured component is not detected by the flame photometric detector 11, V ₁ is obtained as the output of the arithmetic circuit 3 and the measured component is the flame photometric detector 11. When it is detected at, V ₂ is obtained as the output of the arithmetic circuit 3.

Here, the concentration C of the component to be measured and the arithmetic circuit 3
Since the output V has a relationship of C = f (V), the concentration C of the component to be measured is calculated by the following equation. C = f (V ₂ −V ₀ ) −f (V ₁ −V ₀ ) ………………

In the above-mentioned conventional example, the concentration C of the component to be measured was calculated by the following equation. C = f (V ₂ −V ₁ ) ………………

FIG. 2 is a characteristic curve diagram showing the relationship between the concentration C of the component to be measured and the output V of the arithmetic circuit 3, wherein the horizontal axis represents the concentration C of the component to be measured and the vertical axis represents the output voltage. V is shown. Further, the curve A in FIG. 2 shows the above formula, and shows that the concentration C of the component to be measured can be accurately measured even if the voltage V ₀ corresponding to the null signal of the photodetector 12 fluctuates. ..

On the other hand, FIG. 3 is a block circuit diagram of another embodiment of the present invention. In the figure, the same symbols as those in FIG. 1 are used with the same meanings and duplicate explanations are omitted. Also, 13
Is an optical circuit breaker which is composed of, for example, a chopper and blocks the optical path between the flame photometric detector 11 and the photodetector 12.

[0014]

According to the embodiment of the present invention described in detail above, even when the detection sensitivity changes due to the fluctuation of the output (Isuru base line) when the measured component is not detected, It is possible to compare with the zero position optically or optically. Therefore, even if the base line of the output value changes, a process gas chromatograph calibration method that can obtain the correct concentration of the measured component is realized, and the process gas chromatograph can be calibrated accurately. Become.

[Brief description of drawings]

FIG. 1 is a block circuit diagram of an essential part of an embodiment of the present invention.

FIG. 2 is a characteristic curve diagram.

FIG. 3 is a block circuit diagram of a main part of another embodiment of the present invention.

[Explanation of symbols]

 1 flame photometric detector 2 waveform processing circuit 3 arithmetic circuit 4 memory circuit 5 voltage power supply 6 electrical breaker 11 flame photometric detector 12 photodetector 13 amplifier 14 optical breaker

Claims (1)

[Claims] 1. A method for calibrating a process gas chromatograph equipped with a flame photometric detector, wherein the output V ₀ when the output of the detector is electrically or optically zero and the component to be measured is present in the sample. F (V) is calculated as V from the output V ₁ when there is no measured component and the output V ₂ when the measured component exists in the sample.
A method for calibrating a process gas chromatograph, characterized in that the concentration C of a component to be measured is obtained by using the following equation that is a function of _{C = f (V 2 -V 0} ) -f (V 1 -V 0)