JPH0565026B2 - - 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 method using 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 are arranged with the ion-selective electrode facing upward, and liquid spotting holes (openings for applying the standard solution and test liquid) are provided.
A reference solution and a test solution are applied through the liquid spotting hole using a pipette, etc., and then they are brought into contact with the ion selective layer surface of each ion selective electrode using a porous liquid distribution member, and the liquid is applied between both ion selective electrodes. Ion activity is measured by measuring the potential difference generated. 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. In other words, when measuring ion activity, especially potassium ion activity, in whole blood, whole blood diluted solution, or similar blood samples containing blood cells (especially red blood cells), it is important to note that the blood sample has not undergone hemolysis in the ion activity measurement device. This caused the measured potassium ion activity to often differ from the true potassium ion activity in the blood sample. This was detected as a discrepancy with the potassium ion activity measured in plasma obtained by removing blood cells from the same blood sample. When a topical bandage, filter paper, or the like is used as a porous liquid distribution member, errors due to such hemolysis are large. It takes some time for the measurement liquid (sample liquid, reference liquid) to permeate into the liquid distribution member and reach the surface of each ion selection electrode, making it possible to measure the potential difference. The hemolysis is exacerbated by the longer this time and by the greater the amount (surface area) of the liquid distribution member in contact with the whole blood. Synthetic polymer fibers, such as polyester fiber cloth, are materials that are relatively unlikely to cause hemolysis of whole blood, but because the liquid develops slowly, potassium ion activity and other ion activities can be simultaneously measured using one device. When used as a liquid distribution member of an ion activity measurement device, it takes time for the liquid to spread, and there is a risk of hemolysis. For the liquid distribution member that supplies liquid to the potassium ion selective electrode, it is necessary to consider not only the material but also the arrangement and structure to prevent hemolysis. [Objectives of the Invention] The objects of the present invention are to shorten the time until stable potential measurement is possible after applying a sample solution or reference solution, to prevent the effects of hemolysis of blood, and to reduce the amount of ions in whole blood samples. An object of the present invention is to provide a method for measuring ion activity using an ion activity measuring instrument particularly suitable for measuring activity. [Structure of the Invention] The present invention provides a plurality of ion-selective layers that selectively respond to potassium ions and other ions, which are stacked on a pair of single electrodes that are electrically separated from each other and integrated. a sheet-like ion-selective electrode; an upper frame having a pair of spotting ports and a porous bridge for storing each sheet-like ion-selective electrode in a parallel arrangement with the ion-selective layer below; A pair of binder-free cellulose for distributing each of the test liquid and reference liquid spotted in a pair of spotting ports of a frame onto the surface of an ion selective layer on a single electrode of a pair of sheet-like ion selective electrodes. a porous liquid distribution member made of a spunbond nonwoven fabric, a lower frame housing the pair of porous liquid distribution members parallel to each other and intersecting with the sheet-like ion selection electrode; and a sheet. The surface of the ion-selective layer of the shaped ion-selective electrode and the surface of the porous liquid distribution member are interposed between the two so that they do not come into contact with each other, and the sample liquid and reference liquid spotted from the spotting opening are A water-impermeable electrode having a liquid receiving port for supplying the liquid to the liquid distribution member and a liquid supply port for supplying the test liquid and reference liquid distributed by the porous liquid distribution member to the surface of the ion selective layer of each sheet-like ion selective electrode. A reference solution is applied to one spotting port of an ion activity measurement device consisting of a magnetic member, and a blood cell-containing test solution is placed in the other spotting port, and the reference solution and the blood cell-containing test solution are mixed. After passing through the liquid receiving ports separately, the liquid is introduced into each of the porous liquid distribution members from the side of the cut portion, and is passed through the porous liquid distribution member onto a single electrode of each sheet-like ion selective electrode. A method for measuring ion activity is characterized in that the potential difference between the single electrodes of each sheet-like ion-selective electrode is measured in that state. The test liquid or reference liquid of the potassium ion selective electrode is supplied from the end of the porous liquid distribution member that supplies the liquid to the potassium ion selective electrode or the side surface of the cut section (or the end of the cut section) to which the sample solution is supplied. More preferably, the shortest distance to the contact area does not exceed 5 mm. The distance from the end of the porous liquid distribution member that supplies liquid to the potassium selection electrode to which the test liquid or reference liquid is supplied or the side of the cut section (or the end of the cut section) to the other end is 10 mm or more. It is more preferable that As the liquid distribution member, a cellulose-based spunbond nonwoven fabric containing substantially no binder is preferred, and one made of long fibers made from cotton linters is particularly preferred. 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 non-woven fabrics are generally capable of absorbing at least 10 times the weight of the component in blood in 3 seconds. The thickness of the porous liquid distribution member used in the present invention is approximately
Approximately 100μ to 400μ is appropriate. The natural fiber threads used for buritsuji include cotton,
As synthetic fibers such as silk, threads of polyester, polyamide (for example, nylon), etc. can be used. The porous liquid distribution member used in the present invention is
It can also have a shape as described in No. 59-244200. Although the ion activity measuring instrument of the present invention can take various specific embodiments, it can also have a structure as shown in FIG. 1, for example. In the figure, 10
Reference numerals 1, 102, and 103 denote a pair of sheet-like solid electrodes (consisting of a pair of single electrodes that are electrically separated from each other and are integrated) having an ion-selective layer on the bottom surface; 400 has spotting holes 410 and 420; have,
An upper frame housing a plurality of solid electrode pairs; 600 is a porous bridge made of natural or synthetic fiber yarn, such as polyester yarn, communicating between spotting holes 410 and 420; 200 is an ion-selective layer of the solid electrode pairs; It is a water-impermeable member provided in contact with the lower surface of the water-impermeable member 200.
20 and liquid supply holes 213, 223; 212, 2
22; 211, 221 are provided. 312
and 311 are liquid supply holes 213 and 212, 2
porous member for distributing liquid to 11, respectively; 322;
and 321 are liquid supply holes 223 and 222, 2
500 porous members for distributing liquid to 21, respectively;
is a lower frame body, which is a concave frame body and accommodates porous liquid distribution members 312 and 311 and 322 and 321 in concave portions 510 and 520, respectively. In the present invention, the length of the porous member 311 (or 321) that supplies liquid to the potassium ion selective electrode pair 102 is at least 8 mm, preferably 10 mm or more,
It is desirable that the shortest distance from the end of the porous member 311 (or 321) facing the liquid receiving hole 210 (or 220) to the liquid supply hole 212 for the potassium ion selective electrode pair 102 be 6 mm or less, preferably 5 mm or less. Air vent holes 532, 531; 542, 541 are provided in the lower frame 500. The porous bridge 600 may pass through a position eccentric from the center point of the liquid supply hole. Further, it is preferable that the porous bridge 600 is provided in close contact with the upper surface of the upper frame 400 between the spotting holes 410 and 420. The structure described in JP-A-60-155960, JP-A-60-260843 and JP-A-60-260844 can also be used. 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. To measure ion activity using these ion activity measurement instruments, for example, three ion-selective electrode pairs are used, one pair is a potassium ion-selective electrode pair, and the other electrodes are selective for sodium and chlorine ions. When the reference liquid and the test liquid are placed in the liquid spotting hole as a pair, the reference liquid and the test liquid respectively penetrate into the porous liquid distribution member on the side of the cut part (or the end of the cut part), The liquid is supplied to the surface of each ion selection electrode through a liquid supply hole provided in the water-impermeable member. As a result, a potential difference is generated between each of the pair of single electrodes within the ion selection electrode, so that the electric potential difference is generated between the pair of single electrodes within the ion selection electrode.
The potential difference can be measured using a potentiometer. 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-61-6461
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-59-102146, JP-A-58-156848, and JP-A-60-243555. [Effects of the Invention] The present invention can be used as a porous liquid distribution member in an ion activity measurement device for measuring potassium ions in blood cell-containing test fluids such as whole blood. Instead, a porous liquid distribution member made of cellulose-based spunbond nonwoven fabric that does not contain a binder with low hemolytic properties is used, and the liquid sample such as the test liquid is placed on the side of the cut part of the distribution member (at the end of the cut part). Since the test liquid containing blood cells such as whole blood can be permeated from the surface of the ion-selective layer of the sheet-like ion-selective electrode with little risk of hemolysis. Therefore, by using the ion activity measurement method of the present invention, potassium ion activity in blood cell-containing liquid samples such as whole blood, which is particularly susceptible to hemolysis, can be measured with high accuracy and reliability. I can do it. EXAMPLES Below, the present invention will be explained in more detail with reference to Examples. [Example] (1) Preparation of Ag/AgCl electrode A continuous vapor deposition film was prepared by depositing a silver layer with a thickness of 8000 Å on a polyethylene terephthalate (PET) film with a thickness of 180 microns, and was cut into a width of 24 mm. A groove with a depth of 70 microns was cut in the center of the film in the width direction using the tip of a knife. Also, 3 on both ends
A solution of polyvinyl chloride in a mixed solvent of toluene and methyl ethyl ketone (removable film-forming mask resist) was coated in a mm width and dried to form a protective film with a thickness of 30 microns. Hydrochloric acid 60mmol/,
After being immersed for 90 seconds at 30°C in an oxidative halogenation treatment solution containing 12 mmol of potassium dichromate, the electrode was washed with water and dried to produce a sheet-like Ag/AgCl electrode. (2) Preparation of sodium ion selective electrode A solution having the following composition was applied onto the above Ag/AgCl electrode and dried. Sodium chloride 6g Water 50g Ethanol 40g Thereafter, a solution having the following composition was applied so that the dry film thickness was 25 microns. Vinyl chloride vinyl acetate copolymer Polymerization ratio = 90:10 0.9g (VYNS manufactured by Union Carbide) Dioctyl sebacate 1.2g Methylmonensin 0.1g Sodium tetraphenylborate 0.002g Methyl ethyl ketone 5.0g Surfactant 1% (Shin-Etsu Chemical) made
SH510) 0.06g Next, the resist layer applied to both ends was gently peeled off to expose the silver-deposited surface as an electrical connection terminal. This was cut into a width of 5 mm and used as a sodium ion selective electrode. (3) Preparation of potassium ion selective electrode A solution having the following composition was applied onto the above Ag/AgCl electrode and dried. Sodium chloride 2.78g Potassium chloride 2.22g n-propyl alcohol 32g Water 96g Surfactant 1% (Shin-Etsu Chemical SH510) 0.06g On top of this, a solution with the following composition was applied to a dry film thickness of 30 microns, and both ends were coated. By peeling off the resist layer, a potassium ion selective electrode was completed. Vinyl chloride vinyl acetate copolymer Polymerization ratio = 90:10 0.9g (VYNS manufactured by Union Carbide) Dioctyl phthalate 2.4g Valinomycin 44mg Potassium tetrakis parachlorophenyl borate
6mg Methyl ethyl ketone 5.0g Surfactant 1% (Shin-Etsu Chemical)
SH510) 0.05g (4) Preparation of chloride ion selective electrode A chloride ion selective electrode was prepared by coating the Ag/AgCl electrode to a dry film thickness of 12 microns, and peeling off the resist layers at both ends. Polyvinyl butyral 1.0g trioctylmethylammonium chloride
1.0g Ethanol 7.0g Surfactant 1% (Shin-Etsu Chemical)
SH510)
0.04g(5) Assembling the ion activity measuring instrument As shown in the exploded view in Figure 1, one set of each diameter 4
Length 28 mm with liquid spot holes 410, 420 and two sets of air vent holes 431, 432; 441, 442
mm, in the groove part of the plastic frame 400 with a width of 24 mm,
A sodium selection electrode 103 is placed on one side, a potassium ion selection electrode 102 and a chloride ion selection electrode 101 are placed on the other side across the liquid spotting holes 410 and 420.
are housed in the direction in which the ion selective layer is exposed, and one set of liquid receiving holes 210, 220 and three sets of liquid supply holes 21 are arranged.
A double-sided adhesive tape 200 with 3,223; 212, 222; 211, 221 provided thereon was attached to the electrode and frame surfaces such that each row of liquid supply holes faced each of the electrode surfaces. The distance between the centers of the liquid receiving hole 210 and the liquid supply holes 213, 212, and the distance between the centers of the liquid receiving hole 220 and the liquid supply holes 223, 222 are 5.8 mm, respectively.
The distance between the centers of the liquid supply holes 222 and 221 and the distance between the centers of the liquid supply holes 222 and 221 were both 5.7 mm. Next is Asahi Kasei Corporation, which is a long-fiber cellulose nonwoven fabric.
A set of liquid distribution members 31 with a width of 2 mm and a length of 13 mm, made of Benliese GS303 (product name: cellulose spunbond nonwoven fabric containing no binder) manufactured by Manufacturer.
1,321, and another 1 with a width of 2 mm and a length of 7.3 mm.
A pair of liquid distribution members 312 and 322 are placed on top of the double-sided adhesive tape 200 through the liquid supply holes 210 and 22.
One end is located 1 mm from the center of 0,
It was fixed so as to cover each liquid supply hole. Further, a polystyrene support frame 500 having a pair of groove portions 510 and 520 is placed on top of the groove portion 51.
0.520 was attached so as to accommodate the liquid distribution member. The ion activity measurement device assembled in this manner is used with the liquid spotting hole facing upward. Figure 2A is a cross-sectional view of the above ion activity measuring instrument, Figure 2B is an enlarged view of the part indicated by X in Figure 2A, and Figure 2C is a plan view of the ion activity measuring instrument shown in Figure 1. Indicated. In FIG. 2B, 102a is a film support of a potassium ion selective electrode, 102b is a silver layer, 1002c is a silver chloride layer, 102d is an electrolyte layer, and 102e is an ion selective membrane layer. (7) Potential measurement In the sample liquid supply hole of the ion activity measurement device prepared as described above, 50μ of whole blood collected with heparin was added, and in the reference liquid supply hole, the following composition was used. The liquid is applied to each electrode at the same time, and the potential difference generated after one minute is measured at the terminals 113, 123 of each electrode;
112,122; 111,121 was measured using an Orion Microprocessor Model 901 (manufactured by Orion). For comparison, potentials were measured in the same manner using plasma obtained from the same whole blood sample by centrifugation. Table 1 shows the potassium ion activity (average value) determined using a calibration curve from 5 measurements of the potential difference of the potassium ion selective electrode 1 minute after spotting.
shows. 【table】

[Brief explanation of the drawing]

FIG. 1 shows that according to the present invention, when a liquid sample containing blood cells such as whole blood is used as a test liquid, not only Na ions and Cl ions but also K ions are detected, and plasma is used as a test liquid. Almost identical ion activity values were measured. In other words, it was confirmed that hemolysis does not occur even when a liquid sample containing blood cells such as whole blood is used as a test liquid. FIG. 1 is an exploded perspective view showing an embodiment of the ion activity measuring device of the present invention. Figure 2A is a cross-sectional view of the ion activity measuring device shown in Figure 1, Figure 2B is an enlarged view of the portion indicated by X in Figure 2A, and Figure 2C is a plan view of the ion activity measuring device shown in Figure 1. It is.

Claims (1)

[Claims] 1. A plurality of sheets in which an ion selective layer that selectively responds to potassium ions and other ions is laminated on a pair of single electrodes that are electrically separated from each other and integrated. an upper frame body having a pair of spotting ports and a porous bridge for accommodating each sheet-shaped ion selective electrode in a parallel arrangement with the ion selective layer facing down; an upper frame body; A pair of binder-free cellulose-based liquids that distribute the test solution and reference solution spotted at a pair of spotting ports onto the surface of an ion selective layer on a single electrode of a pair of sheet-like ion selective electrodes. a porous liquid distribution member made of a spunbond lower woven fabric; a lower frame body housing the pair of porous liquid distribution members in a positional relationship parallel to each other and intersecting the sheet-like ion-selective electrode; and a sheet-like structure. The surface of the ion-selective layer of the ion-selective electrode and the surface of the porous liquid distribution member are interposed between the two so that they do not come into contact with each other, and the sample liquid and reference liquid spotted from the spotting port are distributed between the porous liquid and the surface of the porous liquid distribution member. A water impermeable electrode having a liquid receiving port for supplying the liquid to the distribution member and a liquid supply port for supplying the test liquid and reference liquid distributed by the porous liquid distribution member to the surface of the ion selective layer of each sheet-like ion selective electrode. A reference solution is applied to one spotting port of an ion activity measurement device consisting of a member, and a blood cell-containing test solution is spotted to the other spotting port, and the reference solution and the blood cell-containing test solution are separated. After passing through the liquid receiving port, the liquid is introduced into each of the porous liquid distribution members from the side of the cut portion, and the liquid is passed through the porous liquid distribution member to form a liquid on a single electrode of each sheet-like ion selective electrode. 1. A method for measuring ion activity, which comprises making the ion selection layer reach the surface of the ion selection layer, and measuring the potential difference between the single electrodes of each sheet-like ion selection electrode in that state.