JP2907269B2 - Automatic calibration method of automatic analyzer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention performs automatic calibration in an automatic continuous analyzer for environmental measurement and the like for performing automatic continuous measurement of liquid samples such as various kinds of industrial water and wastewater, and gas samples such as flue gas and air. It is about the method.

[0002]

2. Description of the Related Art In an automatic analyzer such as a TOC (total organic carbon) analyzer, a change in measurement sensitivity occurs during a long-term continuous analysis. Therefore, automatic calibration is performed at appropriate intervals to re-create a calibration curve. I do. In the automatic calibration, in order to re-create a calibration curve, a plurality of measurements are performed on a standard sample having at least one concentration. For example, 1
It takes about 5 minutes for each measurement, so that if the measurement is performed three times for one type of standard sample, the measurement for calibration requires about 15 minutes.

[0003]

Since the analysis of the original object cannot be performed during the automatic calibration, the shorter the time required for the automatic calibration, the better. If the measurement is performed a plurality of times on the standard sample as in the related art, the measurement time becomes long, which may hinder the original analysis. In addition, the consumption of the standard sample is accelerated by performing a plurality of measurements. Since the automatic analyzer for environmental measurement is operated unattended for a long period of time, the standard samples required for automatic calibration must be provided in or near the device.
When the consumption of the standard solution is fast, the maintenance frequency of the apparatus increases, which is not preferable. Therefore, an object of the present invention is to reduce the measurement time required for automatic calibration.

[0004]

[Means for Solving the Problems] In automatic calibration, instead of rebuilding a calibration curve, only one measurement using a standard sample is performed at an appropriate point or several points in the calibration curve, and the result is used in the previous measurement. If it is deemed not to be significantly different from the data at the time of calibration,
Continue the analysis using the data from the previous calibration. When one measurement result of the standard sample measurement is significantly different from the data at the time of the previous calibration, a plurality of measurements necessary for re-creating the calibration curve are performed.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail with reference to FIG. For example, in a TOC meter, calibration is performed by measuring a standard sample having a known concentration, that is, a calibration curve is recreated. When the operation of the analyzer is started, the standard sample is measured a predetermined number of times, for example, three times, calibration is performed, and then the continuous operation is started. In this example, the calibration is performed using a standard sample of one concentration in the calibration curve.

During continuous operation, the standard sample is measured once when it is time to perform calibration. It is determined whether or not the one measurement data is within a first allowable range with respect to the measurement data at the time of the previous calibration. The first allowable range is a reference value for determining whether or not the current measurement data can be considered to be significantly different from the measurement data at the time of the previous calibration, and is set in advance. If the current measurement data is within the first allowable range, it is determined that the distance is not significantly different, and the calibration curve based on the measurement data at the previous calibration is continuously used without performing any further measurement.

On the other hand, when the one measurement data is out of the allowable range, two additional measurements are repeatedly performed on the standard sample. The standard deviation SD and the coefficient of variation CV are calculated for a total of three measurement data, ie, one measurement initially performed and two additional measurements. CV (%) is a value expressed as CV = SD × 100 / average value. When SD and CV are within the set second allowable ranges, respectively, it means that the accuracy of the three repeated measurements is good and these measurement data are reliable. In that case, the average value of the three repeated measurement data is calculated, and if the average value is within the first allowable range as compared with the measurement data at the time of the previous calibration, the previous measurement data is also used. Use the previous calibration curve.
Only when the average value is outside the first allowable range, a calibration curve is re-created using the average value.

On the other hand, when SD or CV is not within the second allowable range, the reliability of the measurement data obtained by the current repeated measurement is low, and if the calibration is performed using the data, it becomes inaccurate. In this case, the calibration curve is not re-created, and the analysis is continued using the calibration curve at the time of the previous calibration.

[0009]

FIG. 2 shows an example of a TOC meter to which the present invention is applied. A portion in a region surrounded by a two-dot chain line indicates a portion housed in the TOC meter main body, and a portion outside the region indicates a portion mounted outside the TOC meter main body. In order to collect the aqueous solution sample or the standard sample 8, a micro syringe 14 is connected to the 8-port valve 6, and can be connected to any port of the 8-port valve 6. Aqueous solution sample is sample inlet 2
From the fluid to the drain 4, and the flow path branches off from the middle and is connected to one port of the 8-port valve 6 to measure the standard sample 8 for calibration and IC (inorganic carbon) The acid 10 to be added to the water and the diluent 12 used for dilution and washing are also connected to the respective ports of the 8-port valve 6. The other port of the 8-port valve 6 is connected to a TC combustion tube 18 provided with a catalyst for converting all carbon components in a sample or a standard sample into CO ₂ through a slide TC sample injection unit 22 driven by a motor. The connected flow path, the flow path connected to the drain 4 via the trap 15 for capturing the foam, the flow path directly connected to the drain 4, and the flow path for supplying the offline sample are respectively connected.

The carrier gas flow path 23 passes through a pressure reducing valve 24, an electromagnetic valve 26 for carrier gas, and a combustion tube 20 for purifying carrier gas provided with an oxidation catalyst for converting carbon components into CO ₂ .
Carrier / sparge gas passage 28 and carrier gas passage 3
Branched to 0. A pressure gauge 25 is provided in a flow path between the pressure reducing valve 24 and the electromagnetic valve 26. The carrier / sparge gas flow path 28 includes a mass flow controller 32 and a flow meter 3
The micro syringe 4 is connected to the micro syringe 14 via the electromagnetic valve 4 and the sparge solenoid valve 36, and is used to remove IC components from the sample collected in the micro syringe 14. The carrier gas flow path 30 includes a mass flow controller 38 and a flow meter 4
0, a CO ₂ absorber (soda lime) 42, a membrane filter 44, and a check valve 46, which are connected near the inlet of the TC combustion pipe 18. The TC combustion tube 18 and the carrier gas purification combustion tube 20 are housed in the TC furnace 16 and heated.

The outlet of the TC combustion tube 18 passes through a scrubber 48 for separating water, an electronic cooler 50 for removing moisture, a halogen scrubber 52 for removing halogen components, and a membrane filter 54, and a CO ₂ detector 56 of an NDIR optical system.
Led to. CO ₂ detector 56 includes a reference cell 56b encapsulating sample cell 56a and the inert gas is derived sample, after gas passing through the sample cell 56a is the CO ₂ is removed via CO ₂ absorber 58 , CO ₂ detector 56 is used as a gas for cleaning the space between the cell and the detection unit. Water generated by the electronic cooler 50 is discharged to the drain 4 via the drain pot 60.

The TOC meter shown in FIG. 2 is a TC measurement and a TOC measurement by an IC removal method, that is, a nonvolatile organic carbon (NP).
OC) measurement can be performed. In the case of the TC measurement, the sample collected in the micro syringe 14 is supplied to the TC combustion tube 18 as it is and measured. In the case of NPOC measurement, the sample solution is collected in the micro syringe 14 and then the acid 1
After 0 is added and the IC component is discharged to the drain by the sparge gas and removed, the sample solution is supplied to the TC combustion tube 18 and NPOC (= TOC) is measured.

When it is time to perform automatic calibration, the 8-port valve 6 is switched so that the micro syringe 14 is connected to the standard sample 8, and a certain amount of the standard sample 8 is collected in the micro syringe 14. 14
Is connected to the TC combustion tube 18 so that the
Is switched, and the standard sample is supplied to the TC combustion tube 18 for measurement.

[0014]

According to the present invention, a single measurement using a standard sample is performed at the time of automatic calibration, and it is determined that the measured data is not significantly different from the measured data at the time of the previous calibration curve re-creation. If this is possible, that is, if the sensitivity of the apparatus is considered to be stable over time, the analysis should be continued using the previous calibration curve as it is without performing the multiple measurements required for rebuilding the calibration curve. Therefore, the time required for the automatic calibration can be reduced, and the consumption of the standard sample can be suppressed.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating the present invention.

FIG. 2 is a configuration diagram showing a TOC meter as an example to which the present invention is applied.

[Explanation of symbols]

 6 8 port valve 8 Standard sample 14 Micro syringe 16 TC furnace

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroshi Kitamura 1 Nishinokyo Kuwaharacho, Nakagyo-ku, Kyoto City, Kyoto Prefecture Inside the Sanjo Plant, Shimadzu Corporation (72) Inventor Hideto Nakagami 1st Nishinokyo Kuwaharacho, Nakagyo-ku, Kyoto City, Kyoto Prefecture (72) Inventor: Yuko Yamaji 1st place: Nishinokyo Kuwabaracho, Nakagyo-ku, Kyoto, Kyoto Prefecture (72) Shimadzu Corporation, Sanjo Plant (58) Field surveyed (Int. Cl. ⁶ , DB name) G01N 35 / 00

Claims (1)

(57) [Claims] 1. A method of performing automatic calibration by measuring a standard sample at an appropriate interval with an automatic continuous analyzer, wherein a single measurement is performed on the standard sample at the time of automatic calibration, and the measurement data is calibrated in the previous time. If it is not significantly different from the measured data of the standard sample at the time of performing, the analysis is continued without using the calibration at that time and using the calibration curve data from the previous calibration. When the distance is significantly different, the measurement of the standard sample is repeated a predetermined number of times, and calibration is performed and the calibration curve is re-created only when the accuracy of the repeated measurement for the standard sample is within the allowable range. Automatic calibration method.