JPH0556819B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical field of the invention] The present invention relates to aqueous liquids, particularly biological body fluids (blood, blood, etc.).
The present invention relates to an ion activity measurement device for quantitatively analyzing the activity (or concentration) of a specific ion in urine, saliva, etc. using potentiometry. [Background of the invention] Liquids (tap water, river water, sewage, industrial wastewater, etc.)
There is already a known method for measuring the activity of specific ions contained in droplets of biological body fluids (blood, urine, saliva, etc.) using a sheet-shaped ion activity measurement device. . That is, a reference liquid and a test liquid are applied to the surface of each ion-selective layer of a pair of ion-selective electrodes that are electrically separated from each other, and then each ion is This method measures the ionic activity of the test liquid by measuring the potential difference between selected electrodes. An example of such an ion activity measuring instrument is
No. 52-142586, JP-A-56-6148, JP-A-58-
The ion activity measuring device described in No. 211648, etc. can be mentioned. These ion activity measurement instruments basically have 1
A pair of sheet-shaped ion-selective electrodes is arranged with the ion-selective electrode facing upward, and a liquid spotting hole (an opening for applying the standard solution and test liquid) is provided above the electrode. On each ion selective layer,
Ion activity is measured by applying a reference solution and a test solution using a pipette or the like through the solution spotting hole, and measuring the potential difference generated between both ion-selective electrodes. On the other hand, by incorporating multiple ion-selective electrode pairs into one ion activity measurement device, it is possible to measure the activities of multiple types of ions by applying a reference solution and a test solution once each. This is known from Japanese Patent Application Publication No. 58-211648. Although the method of measuring the ion activities of a plurality of species substantially simultaneously using a plurality of sheet-like ion-selective electrode pairs as described above is a simple and excellent method, it has been found that there are the following problems. i.e., a topical bandage as a porous liquid distribution member;
When using linen cloth, chilled cloth, silk cloth, filter paper, etc., the ionic activity in whole blood, whole blood diluted solution, or similar blood samples containing blood (especially red blood cells), Hemolysis occurs in the volume measuring device, and as a result, the measured ionic activity of the measured blood often differs from the ionic activity of the real object to be measured in the blood sample. The occurrence of such ion activity measurement errors is particularly noticeable when measuring the ion activity of potassium ions. Such measurement errors were detected, for example, as a discrepancy with the potassium ion activity measured in plasma or serum obtained by removing blood from the same blood sample. On the other hand, if pharmacopoeial gauze is used as a porous liquid distribution member, hemolysis of whole blood is relatively small, but it is easily deformed and is very difficult to cut to a certain size. Fabrics of synthetic polymer fibers, such as polyester fibers, also cause less hemolysis of whole blood, but the fluid develops slowly. These materials are therefore not suitable for use as liquid distribution members in ion activity measurement devices such as those described above for measuring the ion activities of multiple species substantially simultaneously using a single device. [Object of the Invention] An object of the present invention is to provide at least a pair of ion-selective electrodes that selectively respond to specific ions, a porous liquid distribution system capable of supplying a test liquid to one electrode of the pair of ion-selective electrodes. a porous distribution member capable of supplying a reference liquid to the member and the other one of the electrodes, and a porous bridge achieving electrical continuity between the test liquid and the reference liquid supplied to each ion-selective electrode. When a blood sample containing blood cell components such as whole blood is used as a test liquid in an ion activity measurement device, hemolysis occurs or is accelerated due to contact between the blood sample and the porous liquid distribution member. An object of the present invention is to provide a measuring instrument capable of reducing errors in measuring ion activity. In particular, the present invention is a potassium ion activity measuring device having the above-described configuration, and when a blood sample containing blood cell components such as whole blood is used as a test liquid, the contact between the blood sample and the porous liquid distribution member Another object of the present invention is to provide a measuring device that can reduce errors in measuring potassium ion activity due to hemolysis that occurs or is accelerated. The present invention provides at least a pair of ion-selective electrodes that selectively respond to specific ions, a porous liquid distribution member that can supply a test liquid to one of the pair of ion-selective electrodes, and a porous liquid distribution member that can supply a test liquid to one of the pair of ion-selective electrodes; An ion activity measuring device comprising: a porous distribution member capable of supplying a reference solution to each ion-selective electrode; and a porous bridge achieving electrical continuity between the test solution and the reference solution supplied to each ion-selective electrode. The ion activity measuring instrument is characterized in that a cellulose-based spunbond nonwoven fabric containing no binder is used at least as a liquid distribution member for supplying the test liquid. The ion activity measuring device of the present invention has a function of avoiding or delaying hemolysis in a blood sample, and therefore is effective in all ion activity measurements where the ions to be measured are contained in blood cell components. However, among the ions that elute into serum or plasma due to hemolysis of a blood sample, potassium ions are the component with the largest amount. Particularly remarkable effects are seen when used as an ion activity measurement device for potassium ions. The cellulosic spunbond nonwoven fabric substantially free of binder is preferably one made of long fibers made from cotton linters. For example, a nonwoven fabric manufactured by a spunbond method from a spinning solution obtained by dissolving cotton linters in a Schweitzer solution is preferred. Such nonwoven fabrics generally have 3
Capable of absorbing at least 10 times the weight of the member in blood per second. The thickness of the porous liquid distribution member used in the present invention is approximately
Approximately 100μ to 400μ is appropriate. The porous liquid distribution member used in the present invention is
It can also have a shape as described in No. 59-244200. The ion activity measuring instrument of the present invention can take various specific embodiments, but for example,
The structure described in No. 211648 can be used.
For example, as shown in FIG. 1, a sheet-like solid electrode pair 26 having an ion-selective layer on the upper surface, an electrical connection terminal portion 27, a support frame 28 that accommodates a plurality of solid electrode pairs, and water that covers the surface of the solid electrode pair. An impermeable sheet member 30, a liquid supply hole 31 provided in the water impermeable member 30, and a porous member 3 that distributes liquid to the liquid supply hole 31.
2. Two liquid storage tanks 34 each receiving a test solution and a reference solution, an upper lid 35 having a spotting hole 36 and an air vent hole 37, and a porous bridge 38 made of fiber that communicates between the spotting holes 36. Be prepared. The structure described in JP-A-60-155960, JP-A-60-260843 and JP-A-60-260844 can also be used. Further, the structure described in Japanese Patent Application No. 148564/1988 can be used. For example, as shown in Figure 2,
A pair of sheet-like solid electrodes 11a, 11b, 11 having an ion selective layer on the lower surface and electrical connection regions at both ends.
c, an upper frame 18 having a spotting hole 12 and an air vent hole 17 and housing a plurality of solid electrode pairs; a spotting hole 1;
Porous bridge 1 made of fibers connecting between 2
9. Water-impermeable sheet member 20 provided in contact with the lower surface of the ion-selective layer of the solid electrode pair; liquid supply holes 13, 15a, 15 provided in the water-impermeable member 20;
b, 15c, a porous member 16 that distributes liquid to the liquid supply holes 15a, 15b, and 15c, and a lower frame 21 that accommodates the porous liquid distribution member 16 in the recessed portion 14. The members (including liquid supply holes, recesses, etc.) other than the solid electrode pairs 11a, 11b, 11c, the upper frame 18, the porous bridge 19, the water-impermeable sheet member 20, and the porous liquid distribution member 16 are covered with One pair each is provided for the test solution and reference solution. The ion activity measuring instrument of the present invention is also disclosed in the patent application filed in 1983.
−180358, patent application No. 180359, patent application No. 1883-
A structure as described in No. 180360 can also be used. The ion activity measuring instrument of the present invention can also have a structure as shown in FIG. In the figure, 3
1a, 31b, 31c are sheet-like solid electrode pairs having an ion selective layer on the lower surface; 38 is an upper frame body having spotting holes 51 and housing a plurality of solid electrode pairs; 39;
40 is a water-impermeable member provided in contact with the lower surface of the ion-selective layer of the solid electrode pair; Liquid supply holes 33, 35a, 35
b, 35c are provided. 36 is liquid supply hole 3
A porous member for distributing liquid to 5a, 35b, and 35c, 41 is a lower frame body, and a porous liquid distribution member 36 consisting of four parts is housed in the recessed part 34. Further, the lower frame body 41 is provided with air vent holes 37a and 37b. The porous bridge 39 may pass through a position eccentric from the center point of the liquid supply hole. To measure ion activity using these ion activity measuring instruments, use three ion-selective electrode pairs that are selective for sodium, potassium, and chlorine ions, and separate the reference solution and test solution. When spotted in the liquid spotting hole, the reference liquid and the test liquid permeate the porous liquid distribution member, and are supplied to the surface of each ion-selective electrode through the liquid supply hole provided in the water-impermeable member. Ru. As a result, a potential difference is generated between the pair of ion-selective electrodes, so the potential difference can be measured with a potentiometer via electrical connection regions provided at both ends of the pair of ion-selective electrodes. As a solid ion selective electrode, JP-A-58-
No. 211648, JP-A-60-237351, JP-A-60-
No. 237352, JP-A-61-7460, JP-A-61-7461
The ion-selective electrodes described in Japanese Patent Application No. 61-7462 and Japanese Patent Application No. 60-232306 can be used. The ion selective electrode can be manufactured by the method described in JP-A-58-102146, JP-A-58-156848, and JP-A-60-243555. Example 1 (Comparison of degree of hemolysis) Size 1.8cm x 4cm made of the following materials (Table 1)
Each of the distribution members was placed in a centrifuge tube for plasma separation, and 500μ of heparinized whole blood was added to each tube.
After standing for 1 minute, the distribution member was removed and centrifuged to obtain plasma. The potassium ion concentration in the plasma obtained was measured using a flame photometer (Corning Model 460).
The results measured in Table 1 are shown in Table 1.

[Table] The data in Table 1 shows that even after Benliese GS303 (a cellulose-based sponbond nonwoven fabric containing no binder) or 100% polyester cloth was placed in contact with whole blood (sample containing blood cells), potassium ions in plasma remained The concentration does not change from the potassium ion concentration in the plasma of the control sample (a sample in which whole blood is not brought into contact with any foreign matter such as cloth), indicating that Benliese GS303 and 100% polyester cloth are less likely to cause hemolysis. On the other hand, in samples that had been in contact with medical bandages or Lapier S (synthetic fiber woven fabric), the concentration of potassium ions in the plasma increased, and these bandages and fabrics were found to cause hemolysis when they came into contact with blood cells. It can be seen that it is easy to cause Furthermore, when Benliese GS303 and 100% polyester cloth were examined for their spreadability (liquid sample transport speed), it was confirmed that the latter was significantly inferior in spreadability compared to the former. In addition, when we investigated the shaping properties (characteristics of whether or not it can be easily cut into a desired shape) of Benliese GS303 and 100% polyester cloth, we found that the former could be easily shaped into the desired strip shape, while the latter It was found that in order to shape the material into the desired strip shape, a particularly sharp cutter and advanced cutting techniques were required. Example 2 (Potassium ion concentration measurement) A potassium ion selective electrode was installed in the center position of the ion activity measuring device disclosed in Figure 1 of Japanese Patent Application No. 59-244199, and the distribution shown in the table below was carried out. A multi-item ion activity measuring instrument was created using this method. 50μ of heparinized whole blood was used as the sample solution, and 50μ of Calibrate Level-2 (Warner-Lambert Co., potassium ion concentration 4.9meq/l) was used as the reference solution.
Table 2 shows the results of measuring the potential value of the potassium ion selective electrode one minute after spotting.

[Table] In Table 2, Benliese means Asahi Kasei Corporation.
Co., Ltd.'s product name for binder-free cellulose-based spunbond nonwoven fabric, and the symbol and number that follow it refer to the product number. From the data in Table 2, it can be seen that Bemliese (cellulose-based spunbond nonwoven fabric without binder) does not cause hemolysis even when whole blood is transported in an actual ion activity measuring device, as in the preliminary test in Table 1. It can be seen that it is less likely to cause (blood cell destruction). On the other hand, it was confirmed that the medical bandages that were confirmed to be prone to hemolysis in the preliminary tests shown in Table 1 tend to cause hemolysis even when whole blood was transported using an actual ion activity measurement device. It was done. Example 3 A multi-item ion activity measuring device was manufactured using Benliese GS303 as the four liquid distribution members 36 of the ion activity measuring device shown in FIG. Calibrate Level-2 (Warner-Lambert Co., potassium ion concentration 4.9meq/l) 50μ as a reference solution
The potassium ion concentration was measured using whole blood collected with heparin or 50μ of plasma after centrifugation of the whole blood as a sample solution. As a result of measuring the potassium ion concentration of each of 100 sample solutions, there was no difference between the measured values of whole blood and plasma by more than 0.5 meq/l.

[Brief explanation of the drawing]

FIG. 1, FIG. 2, and FIG. 3 are exploded perspective views showing embodiments of the ion activity measuring instrument of the present invention.

Claims (1)

[Claims] 1. At least a pair of ion-selective electrodes that selectively respond to specific ions, a porous liquid distribution member capable of supplying a test liquid to one of the pair of ion-selective electrodes, and other components. An ion activity measuring device comprising a porous distribution member capable of supplying a reference liquid to one electrode, and a porous bridge achieving electrical continuity between the test liquid and the reference liquid supplied to each ion-selective electrode. An ion activity measuring instrument, characterized in that a cellulose-based spunbond nonwoven fabric containing no binder is used as at least the liquid distribution member for supplying the test liquid. 2. The ion activity measuring instrument according to claim 1, wherein at least one pair of ion selective electrodes is an ion selective electrode for measuring potassium ion activity. 3. Claim 1, in which a cellulose-based spunbond nonwoven fabric containing no binder is produced by a spunbonding method using a spinning solution prepared by dissolving cotton linters in Schuweitzer's liquid as a raw material.
The ion activity measuring device described in Section 1.