JPH06180272A - Measuring method for liquid - Google Patents

Abstract

PURPOSE:To provide a measuring method for liquid that, even if a dispenser of any shape is employed as a measuring equipment, surely decides error of dispensation and attains the dispensation of high accuracy. CONSTITUTION:In a measuring method for liquid, when liquid is sucked up into a measuring equipment by suction provided by the action of a suction mean 4, such as a syringe, the suction error is decided through the measurement of inner pressure of the measuring equipment by way of a detecting means 7 and calculation thereafter. Then, with a liquid introduction inlet 8A of the measuring equipment submerged in liquid, a specified suction force per hour is applied to the inside of the above stated measuring equipment, and the suction is maintained for a specified period, so that liquid is dispensed into the measuring equipment, and during this process, the suction force is monitored and, when rate of change of negative pressure per hour exceeds a specified value, suction error is decided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a liquid measuring method adopted for dispensing a blood test or the like.

[0002]

2. Description of the Related Art When an analyte such as blood is dispensed into a large number of liquid containers, it is necessary to monitor whether a regular amount has been dispensed. In other words, when the lower end opening of the measuring instrument is clogged in the process of sucking the liquid in the test tube into the measuring instrument by the suction action, the amount of liquid in the test tube is insufficient, and air is sucked into the measuring instrument. For example, it is necessary to judge the failure of dispensing.

For example, when the test sample in the test tube is blood, the test sample is previously separated into a plasma component and other precipitated components by a centrifugal action due to a difference in specific gravity, and a separating agent having an intermediate specific gravity is used. By doing so, it is possible to separate and hold the two in the test tube, so when the measuring instrument is immersed in the separating agent having a large viscous resistance in the process of being sucked into the measuring instrument, or When febrin (fibrous material) in plasma is sucked and the lower end opening of the measuring device is clogged, the internal pressure of the measuring device is abnormally increased. Also, in the process of sucking the liquid into the measuring instrument, if the amount of immersion of the lower end opening of the measuring instrument into the liquid in the test tube is insufficient, the liquid level will drop and air will be sucked into the measuring instrument. The internal pressure drops abnormally.

Therefore, in the conventional measuring system, the internal pressure of the measuring instrument is monitored, and the deviation from the internal pressure model pattern prepared in advance is used to determine the abnormality, and the success or failure of the dispensing is determined.
The response of the pressure monitor shows considerable variations due to changes in the viscosity of the liquid, fluctuations in the suction negative pressure, and line resistance in the measuring instrument. Therefore, even if the internal pressure of the measuring device is abnormally increased or decreased due to an abnormality such as clogging or air intake, it is difficult to make a reliable determination, and it may be erroneously determined that the regular amount has been inhaled. Further, even if the determination clearance is narrowed to obtain a high dispensing accuracy, the variation in the response becomes an obstacle and the purpose cannot be achieved.

[0005]

Therefore, the inventor of the present invention
First, after the lower end opening of the measuring instrument is immersed in the liquid in the test tube at a certain depth, the suction action is performed by the action of the suction means, for example, the stroke action of the syringe, and when a preset time elapses (predetermined time). At the time of normal dispensing), the lower end of the measuring instrument is separated from the liquid, the head pressure of the liquid is known from the internal pressure indicated by the pressure monitor at that time, and it is determined whether or not it is far from the normal value. We propose a weighing method (see Japanese Patent Application No. 60-206028) for determining whether or not the dispensing has been performed. In this case, a dispenser having an elongated tubular portion to the extent that air is not replaced with respect to the inside is used for the measuring instrument, and the water head pressure is measured in this region.

However, in such a measuring system,
As mentioned above, since the head pressure is used as the standard for measurement,
As a dispenser, a special shape, that is to say with an elongated tubular part, must be adopted. For this reason, it cannot be adopted in a dispenser that uses a taper-shaped dispenser that is generally used.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is possible to reliably judge an error in dispensing regardless of the shape of a dispenser having any shape, and to achieve highly accurate dispensing. The present invention is intended to provide a liquid measuring system which is made possible.

[0008]

Therefore, in the present invention,
When the liquid is sucked up into the measuring instrument by the suction action given by the operation of the suction means such as a syringe, the error in the suction can be judged by measuring the internal pressure of the measuring instrument by the detecting means and calculating. In the liquid measuring method
With the liquid inlet of the measuring instrument immersed in the liquid, a predetermined suction force is applied to the measuring instrument per unit time, and this is continued for the required time to dispense the liquid into the measuring instrument. In the process, the suction force is monitored, and the suction error is determined when the rate of change of the negative pressure per unit time exceeds a predetermined value.

[0009]

Therefore, when the lower end opening of the measuring device (for example, dispenser) is immersed in the liquid, the suction operation of the above-mentioned suction means (for example, stroke operation of the syringe to the negative pressure side) is performed inside the measuring device. Although the liquid is sucked, the stroke operation amount is proportional to the liquid suction amount, so that proper dispensing can be performed by stopping the suction after the elapse of the set predetermined time. Moreover, during the suction process, the pressure inside the measuring instrument is sequentially monitored. Therefore, if the lower end opening is clogged or air is introduced during this period, the rate of change in negative pressure per unit time is increased. Increases sharply, is not affected by changes in the viscosity of the liquid, pipe resistance of the measuring instrument (the manufacturing accuracy of the dispenser varies considerably), and suction errors can be assuredly, and It can be judged early.

[0010]

EXAMPLES Examples in which the measuring method of the present invention is adopted for dispensing blood will be specifically described below with reference to the drawings. The configuration of an apparatus for implementing the liquid metering system according to the present invention is shown in FIG. In the figure, reference numeral 1 is a meter main body having a tapered portion at its tip, the inside of which is hollow, and a syringe (piston / cylinder type) 4 as suction means is connected via flexible tubes 2 and 3. ing. A T-shaped joint 5 is provided between the flexible tubes 2 and 3, and a diaphragm pressure gauge (strain gauge) 7 is connected to the T-joint 5 via a flexible tube 6. The measuring device main body 1 is provided with an elevating means composed of rack and pinion 1A and 1B so that the dispenser tip 8 detachably attached to the lower end of the measuring device main body 1 can be moved up and down. Has become. Then, by this, the lower end opening 8A of the dispenser tip 8 can be immersed in the subject (for example, centrifuged blood) contained in the test tube 9. In this example, the analyte is separated by a separating agent A into an upper plasma component B and a lower precipitation component C.

In this embodiment, the elevating means is adapted to be moved up and down by the forward and reverse rotations of the pulse motor 10.
The rotation and forward / reverse switching of the pulse motor 10 are controlled by a control unit 11 such as a computer. The control unit 11 takes in information from the pressure gauge 7 as a digital measurement signal via the A / D converter 12, and the syringe 4 controls
The drive means 13 driven by the command of the unit 11 performs a digital forward or backward operation, and captures the stroke operation amount as a pressurizing force or a negative pressure in the measuring instrument, which is A / It is captured as a digital measurement signal via the D converter 14.

The control unit 11 causes the measuring device to perform a series of dispensing operations according to a program from the outside, and the measuring method of the present invention is applied at this time. That is, FIG. 2 (routine for dispensing)
As shown in FIG. 3, when the dispensing start signal is output from the control unit 11, the information acquisition from the pressure gauge 7 is started, the pulse motor 10 is driven, and the meter main body 1 is lowered. Yes (step S1).
When the lower end opening 8A of the dispenser tip 8 comes into contact with the liquid surface of the subject (blood) in the test tube 9 and is immersed to a required depth, for example, the internal pressure change of the meter main body 1 is measured by a pressure gauge. Measurement is performed by means such as 7 and the analog signal is converted into a digital signal via the A / D converter and sent to the control unit 11 (step S3). The control unit 11 supplements the situation and outputs a stop signal for the pulse motor 10 (step S4).

Next, the control unit 11 commands the syringe 4 to perform a stroke operation for suction to the negative pressure side (step S5). Then, after the suction is started (at time t ₀ in FIG. 3), the control unit measures the unit time (t ₁ ,
_{t 2, t 3 ··· t r} ) determine the pressure P _n of the measuring body 1 of, for calculating the rate of change _{α (α = [P n -P} n-1]
/ P _n-1 , where P _n-1 is the previous measurement value (first measurement value for the first time) (step S6). Then, in the suction process, when the dispenser tip 8 is inhaled with a separating agent having a large specific gravity, or when febrin or the like in the plasma component B is clogged, or when air is inhaled, the pressure change rate is When a sudden change (a large change in the rate of change) occurs in α, when it exceeds a preset value β or −β ′, the control unit 1
1 determines the suction error (step S7).

If it is determined that there is an error, immediately after an appropriate measure (check in the test tube 9, discharge of the inhaled subject, replacement of the dispenser tip 8) (step S8) , Get out of this routine.
If such a situation does not occur and the predetermined time T elapses (up to the suction end time t _r ) (during this time, the syringe 4 achieves a predetermined stroke operation) (step S
9) Assuming that the dispensing has been accurately achieved, the pulse motor 10 is driven to rotate in reverse by the command of the control unit 11, the meter main body 1 is raised, and in a regular order,
For example, the dispensed specimen is discharged onto a predetermined petri dish portion of the microplate (step S10). In addition,
In this embodiment, the monitoring start time of suction in the control unit 11 is the same as the suction start time t ₀ , but the suction error in the control unit 11 is determined in the meter main body 1 and This is performed after removing a certain period until the pressure in the dispenser tip 8 shows a stable pressure change rate as a dead zone.

The pressure change during the suction action of the syringe 4 is
As indicated by a, b, and c in FIG. 3, the pressure change amount in the case of an error in suction is different from the specific gravity and viscosity of the subject, as shown in FIG. 3 (indicated by a dotted line in the figure). ), Because it changes abruptly, without being affected by the characteristics of such an analyte,
You can judge the error. Further, unlike the case of measuring with the head pressure, the measured value corresponding only to the passage resistance of the lower end opening 8A is not affected by the shape and material of the dispenser tip 8 (surface tension due to the difference in water repellency). can get.

[0016]

INDUSTRIAL APPLICABILITY The present invention has been described in detail above, and when the liquid is sucked into the measuring instrument by the suction action provided by the operation of the suction means such as a syringe, the error of the suction is prevented from occurring inside the measuring instrument. In the liquid measuring method in which the pressure is measured by the detecting means and calculated, the liquid is introduced into the measuring device with the liquid inlet of the measuring device immersed in the liquid per unit time. , A predetermined suction force is exerted, and while maintaining this for a required time, while dispensing the liquid to the measuring instrument, the suction force is monitored, and the negative pressure change rate per unit time exceeds a predetermined value. At this time, the suction error is determined.

Therefore, in the operation of the suction means, for example,
When the liquid is sucked into the measuring device by performing the stroke operation of the syringe to the negative pressure side, the stroke operation amount is proportional to the suction amount of the liquid, so that the suction can be stopped after the set predetermined time has elapsed. Therefore, proper dispensing can be performed. Moreover, during the suction process, the pressure inside the measuring instrument is sequentially monitored. Therefore, if the lower end opening is clogged or air is introduced during this period, the rate of change in negative pressure per unit time is increased. Rapidly increases, and is not affected by changes in liquid viscosity, pipe resistance of the measuring instrument (the manufacturing accuracy of the dispenser varies considerably), and the amount of liquid suctioned during dispensing The error can be reliably determined. In this way, no matter what shape of dispenser is used for the measuring instrument, it is possible to reliably and early determine an error in dispensing, and
Highly accurate dispensing can be achieved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an example of an apparatus for realizing a weighing method of the present invention.

FIG. 2 is a flowchart showing an embodiment of the weighing system of the present invention.

FIG. 3 is a time chart showing an example of the above-mentioned weighing method.

[Explanation of symbols]

 1 Meter main body 2, 3 Flexible tube 4 Syringe 5 T-joint 6 Flexible tube 7 Pressure gauge 8 Dispenser tip 8A Lower end opening 9 Test tube 10 Pulse motor 11 Control unit 12, 14 A / D converter 13 Drive means

Claims (1)

[Claims] 1. When sucking a liquid into a measuring instrument by a suction action given by the operation of a suction means such as a syringe, the error in the suction is calculated by measuring the internal pressure of the measuring instrument by the detecting means. In the liquid measuring method for determining, in a state where the liquid inlet of the measuring device is immersed in the liquid, in the measuring device, per unit time,
A predetermined suction force is exerted, which is maintained for a required time, and the suction force is monitored in the process of dispensing the liquid to the measuring instrument,
A liquid measuring method characterized in that an error in suction is judged when the rate of change in negative pressure per unit time exceeds a predetermined value.