JPH05149944A - Toc meter - Google Patents

Abstract

PURPOSE:To enable a state of sensitivity change from initiation of measurement to be known and achieve calibration up to a full-scale concentration with a standard liquid. CONSTITUTION:A standard liquid is measured at each predetermined period by a measurement control part 1. A first-time standard liquid measurement value is stored in a first-time calibration value memory 3 and a most recent standard liquid measurement value is stored in a most recent calibration value memory 4. A TOC operation part 5 calculates a TOC value by using a calibration value of a most recent calibration value memory 4 from a measurement value of a sample. An analog output part 10 adjusts a full scale of an analog signal to a most recent span standard liquid value measuring the sample, sets to a position within 70-95 in range of the full scale in measuring the span standard liquid, and then also outputs the second or thereafter span standard liquid measurement value in reference to the first-time span standard liquid output value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a TOC meter for measuring TOC (total organic carbon) in a sample.

[0002]

2. Description of the Prior Art A TOC meter, which has a carrier gas supply section, a sample injection section, a combustion oxidation reaction section and a CO ₂ detection section, measures the TOC value in a sample and outputs an analog signal corresponding to the TOC value. There is a total. Some TOC meters have a function of measuring and automatically calibrating a standard solution in a predetermined cycle and outputting an analog signal corresponding to the TOC value of a sample. Such TOC
In the meter, the TOC value of the sample is obtained by calibration with the latest standard solution, and the standard solution is automatically calibrated (automatically calibrated sensitivity), and the next standard solution is measured and output as an analog signal. When the span standard solution is adjusted to the full scale of the recorder output, if the sensitivity changes to the + side, the output shakes the full scale of the recorder, and the recorder cannot read the recorded value. In order to prevent such inconvenience, a span standard solution having a lower concentration than full scale, for example, a concentration of 80% of full scale is used.

[0003]

Since the output signal of the standard solution measurement value is the measurement value in the state in which it was previously automatically calibrated,
It is difficult to determine how much the TOC meter sensitivity change has occurred since the first calibration. When a span standard solution with a concentration smaller than the full scale value of the recorder is used, the range between the span standard solution concentration and the full scale value is an uncalibrated region. For example, a TOC meter with a full scale of 100 ppm is 80 pp
When calibrated with the standard solution of m, the range of 80 to 100 ppm becomes an uncalibrated region. It is an object of the present invention to provide a TOC meter in which the state of sensitivity change from the start of measurement can be understood and which is calibrated with a standard solution to a full scale concentration.

[0004]

The present invention will be described with reference to FIG. A measurement control unit 1 is provided to control the measurement operation so as to measure the standard solution at each predetermined cycle,
An initial calibration value memory 3 for storing the first standard solution measurement value and a latest calibration value memory 4 for storing the latest standard solution measurement value are provided. The TOC calculation unit 5 calculates the TOC value from the measured value of the sample using the calibration value of the latest calibration value memory 4. The analog output unit 10 adjusts the full scale of the analog signal to the latest span standard solution value when measuring the sample, and sets it to a position within 70% to 95% of the full scale when measuring the span standard solution. The span standard solution measured value after the second time is also output based on the solution output value.

[0005]

[Function] The sample measurement value is measured in the calibrated state after each automatic calibration and is output as an analog signal. However, the standard solution measurement value is output in the uncalibrated state. You can see the change. Use full-scale span standard solution. When it is output to the recorder as an analog output, it is output as a value in the range of 70 to 95% of full scale, and even when the sensitivity changes to the + side, it is prevented from swinging from the full scale of the recorder.

[0006]

2 is a block diagram showing a configuration for realizing the control system of FIG. The output of the detection unit 2 is captured by an MPU (microprocessor unit) 7, and the automatically calibrated sample measurement value and the standard solution measurement values after the second measurement are output from the analog output unit 10 as analog signals. A memory 8 such as a RAM for temporarily storing the standard solution measurement value is connected to the MPU 7. The measurement control unit 1, the calibration value memories 3 and 4 and the TOC calculation unit 5 in FIG.
It is realized by the MPU 7 and the memory 8.

FIG. 3 shows a TOC meter of one embodiment. The sample flows into the flow-through type sample container 12 from the lower inlet, and the sample is discharged from the upper outlet. The sample in the sample container 12 is the sample injection part 14
A fixed amount is collected by and is switched to and guided to the TC reaction unit 16 or the IC reaction unit 18. The TC reaction section 16 is provided with a TC combustion tube filled with an oxidation catalyst, and a heating furnace is provided outside the TC combustion tube to heat the TC combustion tube. To the TC reaction section 16, pure oxygen gas or high-purity air from which CO ₂ and hydrocarbons have been removed is supplied from the carrier gas supply section 20 as a carrier gas at a controlled gas flow rate.
In the TC reaction section 16, all the carbon components in the supplied sample are converted into CO ₂ gas and guided to the measurement cell of the non-dispersion type infrared gas analyzer (NDIR) 22 of the CO ₂ detection section to be detected. In the IC reaction part 18, inorganic carbon is generated as CO ₂ gas, which is guided to the measurement cell of the NDIR 22 together with the carrier gas and detected. The sample injection unit 14 is a TC or IC
The standard solution 23 can also be injected for preparing (calibrating) the calibration curve.

In order to process the detected value of NDIR 22,
As shown in FIG. 2, the MPU 7 is provided, the MPU 7 calculates the TOC value from the TC value and the IC value, and the analog output unit 10 is connected to the MPU 7 to output the TOC value to the recorder. Has been done. Reference numeral 26 is a measurement value display / printing unit for displaying and printing the measurement values.

The operation of one embodiment will be described with reference to the flowchart of FIG. 4 and the output example of the recorder of FIG. Simultaneously with the start of measurement, the analog output value is set to 0 (step S1).
The analog output value is held in the memory until it is recalculated in step S8 or S9, and the value is stored in step S7.
The analog signal is output by. When the first calibration is completed (steps S2 and S3), the standard solution measured value is stored in the latest calibration value memory 4 (stored value is B) (step S).
4). Since this is the first standard solution measurement, it is also stored in the first calibration value memory 3 (the stored value is A) (step S
5, S6). Here, since the analog output value is not calculated, the analog output value set to 0 in step S1 continues to be output in step S7. This state is the state shown as in FIG.

Each time the measurement of the sample is completed, the procedure advances to step S9 through steps S2 and S3, and the calibration value B stored in the latest calibration value memory 4 is set to full scale,
The analog output value is calculated based on this, and step S
The value is output at 7. This state is the state shown as in FIG. When the second calibration is performed, the measured value is stored in the latest calibration value memory 4 in step S4 through steps S2 and S3 and the calibration value B is updated to the latest value (step S5), and then in step S8. The first span standard solution measurement value A is set to 0.8 of full scale, and the analog output value of the latest span standard solution is calculated based on it (step S8), and this value is output (step S).
7). This state is the state shown as in FIG. It shows that there is almost no change in sensitivity during the second calibration. During calibration, the standard solution is measured, for example, three times, and the sensitivity of the TOC meter is calibrated from the average value. In the sample measurement after the second calibration is performed, the TOC concentration is calculated from the measured value based on the calibration value B of the latest calibration value memory 4 and output as an analog signal. This state is the state shown as in FIG. After that, the calibration and sample measurement are repeated in the same manner. In the example of FIG. 5, it can be seen that the sensitivity is lowered for some reason during the third calibration.

In the example of FIG. 5, the span value at the time of initial calibration is set to 80% of the full scale of the recorder, but this is an example, and it may be set to another appropriate value. In addition, although an example in which the present invention is applied to the calibration method using only the span standard solution is shown in the examples, when the calibration is performed using two points, that is, the zero point and the span point, the span point is as described above. By using the method, the measured value of the zero standard solution can be adjusted to, for example, 20% of full scale so that the sensitivity can be recognized even when the sensitivity changes in the negative direction.

[0012]

In the present invention, the output signal of the sample measured value is output as a value calibrated by automatic calibration every time, but the output of the standard solution measured value is output in the uncalibrated state. The sensitivity change from the start point and the zero point change in the case of two-point calibration can be easily seen. Since the full-scale value and the span standard solution concentration match, the sample measurement is performed using the range confirmed with the standard solution.
Higher measurement reliability. Further, it is possible to prevent mistakes such as making a mistake in the concentration of the span standard solution.

[Brief description of drawings]

FIG. 1 is a block diagram showing the present invention.

FIG. 2 is a block diagram showing a configuration for realizing FIG.

FIG. 3 is a configuration diagram showing a TOC meter of one embodiment.

FIG. 4 is a flowchart showing the operation of the embodiment.

FIG. 5 is a waveform diagram recorded in the recorder as a result of the operation of the embodiment.

[Explanation of symbols]

 1 Measurement control unit 2 Detection unit 3 Initial calibration value memory A 4 Latest calibration value memory B 5 TOC calculation unit 7 MPU 8 Memory 10 Analog output unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroaki Matsuhisa 1 Nishinokyo Kuwabara-cho, Nakagyo-ku, Kyoto City, Kyoto Prefecture Shimazu Corporation Sanjo Factory

Claims (1)

[Claims] 1. A TOC meter which comprises a carrier gas supply section, a sample injection section, a combustion oxidation reaction section and a CO ₂ detection section to measure a TOC value in a sample and outputs an analog signal corresponding to the TOC value, A measurement control unit that controls the measurement operation so as to measure the standard solution at each predetermined cycle,
The first calibration value memory that stores the first standard solution measurement value, the latest calibration value memory that stores the latest standard solution measurement value, and the calibration value of the latest calibration value memory from the sample measurement value
The TOC calculator that calculates the OC value and the full scale of the analog signal are adjusted to the latest span standard solution value when measuring the sample, and 70% of the full scale when measuring the span standard solution.
To 95%, and a TOC meter equipped with an analog output section that also outputs the span standard solution measured values from the second time onward based on the first span standard solution output value.