JPH09127131A - Automatic analyzing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an error in analysis data due to a malfunction in detecting the liquid level. SOLUTION: Plural electrodes 9 are disposed in a piping connected to a probe 3, and the electric conductivity of wash water is measured by the electrodes 9. According to the measured value, if the wash water reaches such a conductivity as to have an effect upon the capacitance type liquid level detection, an alarm is given to request replacement of washing water and washing in the piping, or the replacement of wash water and washing in the piping are automatically performed by a computer in the device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic analyzer equipped with liquid level detection, which is used for automatic chemical analysis of various liquids including blood and the like.

[0002]

2. Description of the Related Art As disclosed in Japanese Patent Laid-Open No. 64-41823,
In chemical analysis, a sample such as serum or a small amount of a reagent is collected (dispensed) for analysis. In this dispensing, a predetermined amount is sucked by a nozzle called a probe and is discharged in the reaction part.

Generally, in dispensing, the probe descends and the tip is submerged in the liquid. When the probe enters below the surface of the liquid more than necessary, the liquid adheres to the probe and the dispensing accuracy deteriorates. Not only this, the liquid adhering to the probe mixes with other liquids and deteriorates the accuracy of analysis, so the descent is stopped when the probe tip comes into contact with the liquid surface.

In general, a probe sucks and discharges a sample such as serum or a reagent, and then flushes cleaning water (pure water or the like) from a tube attached to the upper part of the probe and discharges it from the tip of the probe for washing. However, if the electric conductivity of this washing water is as high as that of tap water, the capacitance between the probe and the counter electrode changes due to the change in the tube when the probe moves up and down, as if the probe was in contact with the liquid surface. Such a signal change is detected. The signal change becomes a big problem in performing accurate liquid level detection.

Japanese Unexamined Patent Publication No. 64-41823 describes a liquid level detecting method for an object having a large dielectric constant and an object having a small dielectric constant of a liquid to be dispensed. No mention is made of the effect of the cleaning liquid.

[0006]

In Japanese Patent Laid-Open No. 64-41823, in order to clean the inside of the probe and the tip, the electric conductivity of the washing water present in the tube attached to the upper part of the probe is It does not describe that the capacitance between the probe and the counter electrode changes due to the movement of the tube when the probe moves up and down when it rises due to breeding. However, the change in capacity has been a major obstacle to reliably detecting the liquid level.

Therefore, when the electric conductivity of the washing water in the tube exceeds a certain level, it is necessary to replace the washing water or replace the washing solution in the tube.

An object of the present invention is to monitor deterioration of the cleaning liquid.

[0009]

In order to achieve the above object, the present invention provides a plurality of electrodes in a pipe connected to a probe, measures the electric conductivity of washing water by the electrodes, and measures the electric conductivity. When the wash water reaches the conductivity that affects the capacitance level detection based on the value, an alarm is output and a request to replace the wash water and wash the inside of the piping, or automatically by the computer in the device Replace the wash water and clean the inside of the piping.

That is, by using the above means, when the electric conductivity of the washing water in the tube connected to the probe exceeds a specified value, the analysis is interrupted and the washing water is replaced. Thereby, it is possible to prevent the error of the analysis data due to the malfunction of the liquid level detection.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below.

As shown in FIG. 2, the automatic analyzer comprises a probe unit 3 for dispensing a sample 1 such as serum and a reagent 2.
It has. The probe unit 3 can move in the X and Z directions. Further, in the probe unit 3, as shown in FIG. 1, cleaning water for cleaning the inside of the probe 3-1 and the tip is fed by the tube 4 connected from the upper portion of the probe 3-1 to the probe 3-1. Discharge from the tip of.

An automatic analyzer for blood or the like generally uses a nozzle called a probe 3-1 to dispense a small amount from a sample such as blood or serum that has entered a test tube or the like.

For dispensing samples and reagents, the probe 3 is used.
A liquid level detection function is provided to prevent -1 from entering below the liquid level more than necessary.

This liquid level detection is a function for stopping the probe 3-1 which descends when the probe 3-1 reaches the liquid level, which is caused by an excessive amount of liquid adhering to the probe 3. , Not only the dispensing accuracy is reduced,
This is a function to prevent the liquid adhering to other liquids from mixing.

There are various directions for detecting the liquid level. In the electrostatic capacity method therein, the change in the capacity formed by the probe 3-1 and the counter electrode 5 is detected by the electrostatic capacity detection circuit 6 and the liquid level is detected. This is a judgment method.

When the change in the capacity is normal, the change in FIG.
As shown in (a), the probe 3-1 is lowered and the liquid level 7
Since the whole liquid has the same potential as the probe 3-1, the capacitance changes greatly. However, if the conductivity of the washing water contained in the tube 4 connected to the probe 3-1 is high, as shown in FIG. 3 (b), when the probe 3-1 descends for dispensing. The tube also moves accordingly, and the capacitance between the counter electrode 5 and the liquid in the tube having the same potential as the probe 3-1 changes due to the change in the tube.

Therefore, it becomes impossible to accurately judge whether the capacitance change when the probe 3-1 reaches the liquid surface or the capacitance change due to the change of the tube 4.

As described above, since the tube 4 into which the cleaning liquid has been injected must be electrically insulated, when the capacitance type liquid level detection is adopted, for example, the electric conductivity is 20 μS / Cleaning water of less than cm should be used. However, even if the washing water of 20 μS / cm or less is initially adopted, the electric conductivity of the washing water is 1 due to the growth of microorganisms.
It may exceed 00 μS / cm.

Therefore, the electric conductivity of the wash water is measured, and when the wash water has a conductivity that affects the detection of the capacitance liquid level, an alarm is issued and the wash water is replaced based on the measured value. Also requires cleaning the inside of the piping. Alternatively, a method has been devised in which an internal computer automatically replaces cleaning water and cleans the inside of a pipe. A specific example will be described below.

Regarding the method of measuring the electric conductivity of the washing water, it is conceivable to provide two or more electrodes in the tube and measure the electric conductivity from the current flowing between the electrodes. It is difficult to provide electrodes inside the tube.

However, as shown in FIG.
For the piping of the tube 4 connected to 1, the block 8 for connection is often used at the joint. Therefore, two or more electrodes 9 are provided in the block, and the electric conductivity is measured from the current flowing between the electrodes by the electrodes.

In one embodiment of the measuring circuit, as shown in the electric conductivity determining circuit 10 in FIG. 1, the electrode 9 and the resistor R1 are connected in series, and the voltage of the resistor R1 is compared with the reference voltage V0. To do. When the electric conductivity of the wash water in the block 8 decreases, the voltage appearing in the resistor R1 increases, and when the reference voltage V0 is exceeded, the output of the determination circuit 10 changes from H to L. Although not shown, the computer controlling the probe 3-1 and the analyzer receives this signal and issues an alarm to request replacement of cleaning water and cleaning of the inside of the pipe, or automatic cleaning water Replace and clean the inside of the piping.

[0024]

As described above, by measuring the electric conductivity of the cleaning water of the automatic analyzer, when the electric conductivity of the cleaning water in the tube 3-1 exceeds the specified value. By interrupting the analysis and replacing the wash water, it is possible to prevent errors in the analysis data due to malfunctions in liquid level detection.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an automatic analyzer according to one embodiment of the present invention.

FIG. 2 is an explanatory diagram of a positional relationship between a sample, a reagent, and a probe unit of the analyzer according to the embodiment of the present invention.

FIG. 3 is a characteristic diagram showing changes in the output of the capacitance detection circuit.

[Explanation of symbols]

1 ... Sample, 2 ... Reagent, 3 ... Probe part, 4 ... Tube, 5 ... Counter electrode, 6 ... Capacitance detection circuit, 7 ... Liquid level,
8 ... Block, 9 ... Electrode, 10 ... Electrical conductivity determination circuit.

Claims (1)

[Claims] 1. An automatic analyzer for detecting a liquid level by detecting a change in capacitance between a probe and a liquid surface, wherein an electrode is provided in a pipe system of the probe for collecting a sample or a reagent, and the electrode is provided. An automatic analyzer characterized by having means for measuring the electric conductivity of the cleaning liquid in the piping system and a function of judging deterioration of the cleaning water based on the measured electric conductivity value.