JPH05126780A - Measurement of solution concentraton - Google Patents

Abstract

PURPOSE:To obtain a measuring method of solution concentration which enables a very quick measurement without losing accuracy of the measurement. CONSTITUTION:In a measuring method of solution concentration where the solution concentration is calculated from output voltage of sample solution using a measuring device of solution concentration by ion electrode method, measurements of sample solutions 2 or 4 are repeated succedingly to the first calibration by calibration liquid. One single output voltage C1 obtained from the calibration is used for solution concentration calculation of output voltages S1 and S2 of each sample 1 or 2 before and/or after the calibration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solution concentration measuring method for obtaining the concentration of a sample solution such as various body fluids in a clinical test or the like from the output potential of the electrode by the ion electrode method.

[0002]

2. Description of the Related Art The ion electrode method uses various ion-selective electrodes to quantify the concentration of the target ion from the output potential of the solution containing the target ion by a calibration curve method or other method. In addition to chlorine and various other ions, it is also applied to the analysis of various body fluids in clinical tests by combining an immobilized enzyme membrane with an ion electrode.

In such a conventional solution concentration measuring apparatus using the ion electrode method, in order to obtain accurate measurement data by calibrating the shift or drift of the electrode output potential in each measurement, conventionally, once for one sample solution. Was being calibrated. That is, as the measurement operation, the calibration operation is always repeated prior to the measurement of the sample solution, so that the calibration solution and the sample solution are alternately measured.

That is, the waveform of the output potential with time according to the conventional calibration and measurement is shown in FIG. 2, and one sample solution is measured after the output potential C ₃ of the one-point calibration with the internal calibration liquid is obtained. The output potential S ₅ is obtained. After that, the calibration and the measurement of each sample solution are repeated in the same manner, and the output potential C ₄ of the calibration solution, the output potential S _{6 of} the next sample solution, the output potential C ₅ of the calibration solution, and the output potential of the next sample solution are sequentially obtained. S ₇ is obtained.

In this way, the calibration liquid and the sample solution are alternately measured, and the output potential of the obtained calibration liquid is used (as a reference) to determine the concentration of the sample solution from the output potential of the sample solution immediately after the calibration. Is calculated. Speaking of the waveform of the output potential in FIG. 2, the concentration of the sample solution is calculated from the output potential S ₅ of one sample solution immediately after that using the output potential C ₃ of the calibration solution, and the output of the calibration solution is similarly calculated. The concentration of each sample solution is calculated from the output potential S ₆ of the next sample solution using the potential C ₄ and from the output potential S ₇ of the next sample solution using the output potential C ₅ of the calibration solution. ..

However, in such a conventional method, 1
Although there is a small time gap between the measurement of one sample solution and its calibration, accurate measurement can be performed, but it is necessary to perform one calibration before each measurement for each sample solution. There is a drawback that the time required to measure two sample solutions becomes long and the processing speed of concentration measurement is extremely slow.

[0007]

SUMMARY OF THE INVENTION In view of the above conventional circumstances, it is an object of the present invention to provide a solution concentration measuring method capable of measuring more rapidly than before without impairing the accuracy of the measurement.

[0008]

In order to achieve the above object, in the solution concentration measuring method for calculating the solution concentration from the output potential of the sample solution by using the solution concentration measuring device by the ion electrode method of the present invention, the calibration Measurement of 2 to 4 sample solutions is repeated after one calibration with a liquid, and one output potential obtained by the calibration is used to calculate the solution concentration of each 1 or 2 sample solution before and after the calibration. It is characterized by

[0009]

FIG. 1 shows an example of the waveform of the output potential along with time obtained by the calibration with the calibration solution and the measurement of the sample solution performed by the method of the present invention. After obtaining the output potential S ₁ by measuring one sample solution, one-point calibration with the calibration liquid is performed to obtain the output potential C ₁ . Subsequently, the two sample solutions are continuously measured, and the respective output potentials S ₂ and S ₃ are continuously obtained. next,
After calibrating with the calibration solution again to obtain the output potential C ₂ ,
Similarly, the measurement operation of two sample solutions is repeated with one calibration in between.

In this way, after one calibration with the calibration liquid,
One sample solution is continuously measured, and while repeating this operation, the obtained output potential of one calibration is used to calculate the concentration of each one sample solution before and after the calibration. In the example of FIG. 1, a reference calibration of the output potential S ₂ of one sample solution immediately after the calibration and the output potential S ₁ of one sample solution for the calibration immediately before using the output potential C ₁ calibration solution, The concentrations of these two sample solutions are calculated. Similarly, by using the output potential C ₂ of the next calibration solution, the concentration of each sample solution is calculated from the output potentials S ₃ and S ₄ before and after the output potential C ₂ , and the calculation is sequentially repeated.

By the method of the present invention, the frequency of calibration can be reduced as compared with the conventional method, and the reliability of the measurement data can be secured. Therefore, in the computer operation unit of the solution concentration measuring device, as shown in FIG.
If the calibration is set to be used to calculate the concentration of each sample solution before and after that, the number of calibrations can be halved compared to the conventional method, and it is accurate because there is no time gap between calibration and measurement. It is possible to measure various concentrations.

Although FIG. 1 shows an example in which one calibration with a calibration solution is used to calculate the concentration of each one sample solution before and after the calibration, the electrode itself used is stable and the drift of the electrode output etc. Under very few conditions, 3 or 4 sample solutions are measured after one calibration, and one output potential obtained by the calibration is compared with the solution concentration of the sample solution up to 2 before and after the calibration. It can also be used for calculation. However, the larger the number of sample solutions based on one calibration, the longer the time gap between calibration and measurement, which is not preferable.

[0013]

EXAMPLES As one specific example of the method of the present invention, the case where one calibration is used to measure the concentration of two sample solutions before and after the calibration will be described. The solution concentration measuring device used for the measurement was NA-888 as a sodium ion electrode and HC- as a reference electrode.
888 (both manufactured by Toa Denpa Kogyo Co., Ltd.) was set in the computer arithmetic unit in advance so that one calibration was used to calculate the concentration of each one sample solution before and after the calibration.

As the standard solution, four kinds of sodium aqueous solutions having the concentrations shown in Table 1 below were prepared, and an aqueous solution having a sodium concentration of 140.0 mmol / l was used as the calibration solution:

[Table 1] Solution concentration (mmol / l) Solution concentration (mmol / l) 120.0 145.0 135.0 160.0

First, the solution was measured, then calibrated with a calibrating solution, then the two solutions were measured, then calibrated again with the calibrating solution, and finally the solution was measured. By this operation, as the output potential of the ion electrode, as shown in FIG. 1, the output potential S ₁ corresponding to the solution, the output potential C ₁ of the calibration solution, the output potential S ₂ corresponding to the solution, and the output potential S corresponding to the solution are obtained. ₃ , the output potential C ₂ of the calibration liquid and the output potential S ₄ corresponding to the solution are obtained, and the output potential C ₁ of the calibration liquid is used by the computer arithmetic unit to calculate the output potentials S ₁ and S _{2 of the} solution and the solution. The concentration of the solution was calculated, and the concentration of both solutions was calculated from the output potentials S ₃ and S _{4 of the} solution by using the output potential C ₂ of the calibration solution. The measurement results are shown in Table 2 below.

For comparison, the same ion electrode, reference electrode, and calibration solution as described above are used, and the operation of measuring one solution after one calibration by the conventional method is repeated to determine the output potential of one calibration. The concentrations of solutions 1 to 3 in Table 1 were measured by using it only for measuring the concentration of one solution immediately after. The results are also shown in Table 2 below.

[0017]

[Table 2] measured concentration (mmol / l) solution method of the present invention conventional method 120.2 120.9 135.7 135.2 144.4 144.9 160.3 159.6

According to the method of the present invention, accurate measurement data can be obtained which is in good agreement with the conventional method in which calibration is performed once for each measurement of one solution, and the time required for measuring the concentration of the four solutions is obtained. In the conventional method, it was 144 seconds, whereas in the method of the present invention, it was possible to significantly reduce it to 108 seconds.

[0019]

According to the method of the present invention, it is possible to secure the reliability of the measurement data while reducing the frequency of calibration as compared with the conventional method and keeping the time gap between the calibration and the measurement of the sample solution small. Therefore, it is possible to measure the concentration more quickly and more accurately than before.

[Brief description of drawings]

FIG. 1 is a graph showing waveforms of output potentials of a calibration solution and a sample solution obtained over time by the method of the present invention.

FIG. 2 is a graph showing waveforms of output potentials of a calibration solution and a sample solution obtained over time by a conventional method.

[Explanation of symbols]

_{C 1, C 2, C 3} , C 4, C 5 calibration fluid output potential S _{1 of, S 2, S 3, S} 4, S 5, S 6, S 7 output potential of the sample solution

Front page continued (72) Inventor Tatsu Ueda 613 Kitairiso, Sayama City, Saitama Prefecture Toa Denwa Kogyo Co., Ltd. Sayama Plant

Claims (1)

[Claims] 1. A solution concentration measuring method for calculating a solution concentration from an output potential of a sample solution by using a solution concentration measuring apparatus by an ion electrode method, wherein 2 to 4 sample solutions are calibrated after one calibration. The solution concentration measuring method is characterized in that one output potential obtained by the calibration is repeatedly used to calculate the solution concentration of the sample solution of 1 or 2 before and after the calibration.