Electrolyte analyzing device and control method

Abstract

The objective of the present invention is to suppress the occurrence of dripping during electrode replacement in an electrolyte analyzing device that analyzes an electrolyte contained in a sample. Upon accepting an instruction to replace an electrode, the electrolyte analyzing device according to the present invention supplies air to an electrode flow passage via a liquid feed passage, thereby replacing liquid in the electrode flow passage with air and discharging the liquid in the electrode flow passage from the electrode flow passage (see fig. 2).

Description

Electrolyte analyzer and control method

[0001] The present invention relates to an electrolyte analyzer for analyzing electrolytes contained in a sample.

[0002] Flow-type analyzers including flow-type detectors are capable of continuously and repeatedly measuring multiple samples, and are therefore used in a wide range of fields, such as clinical testing of biological samples and testing of plant production processes. In particular, automatic biochemical analyzers used in clinical testing of biological samples such as blood and urine mainly use the ion selective electrode method, which uses an ion selective electrode (ISE), as a method for analyzing electrolytes (such as Na ions, K ions, and Cl ions).

[0003] A flow-type electrolyte analyzer measures the electrolyte concentration by aspirating the sample from a container using an aspirating nozzle and introducing the sample into the ISE, which is the sensor unit. Between sample measurements, an internal standard solution may be measured to perform a one-point calibration.

[0004] The ion-selective electrode method measures the electrolyte concentration in a sample by measuring the potential difference (electromotive force) between the reference electrode and the ISE using an ion-sensitive membrane whose potential changes depending on the electrolyte concentration. To measure the potential difference, the ISE and reference electrode must be electrically connected via the analyte. Furthermore, to accurately measure the potential difference, the ISE must be isolated from electrical noise sources.

[0005] The electrolyte analyzer described in Patent Document 1 is a device for measuring the concentration of a specific electrolyte contained in an electrolyte solution such as human blood or urine, and measures the concentration using an ion-selective electrode. A typical measurement method involves supplying a sample solution, such as serum directly or diluted with a specimen diluent, to the ion-selective electrode. The liquid junction potential between the ion-selective electrode and the reference electrode solution is then measured. Next (or prior to measuring the liquid junction potential), a standard solution is supplied to the ion-selective electrode, and the liquid junction potential between the standard solution and the reference electrode solution is similarly measured. The electrolyte concentration of the sample solution is calculated from the two liquid junction potential levels.

[0006] Japanese Patent Application Laid-Open No. 2015-215274

[0007] The conventional flow-type electrolyte analyzer described in Patent Document 1 does not drain the liquid present in the electrode flow path when replacing the electrode, which can sometimes cause dripping of the reagent when replacing the electrode.

[0008] The present invention has been made in view of the above-mentioned problems, and aims to suppress the occurrence of liquid dripping that occurs when electrodes are replaced in an electrolyte analyzer that analyzes electrolytes contained in a sample.

[0009] When an instruction to replace an electrode is received, the electrolyte analyzer of the present invention supplies air to the electrode flow path via the liquid supply flow path, thereby replacing the liquid in the electrode flow path with air and discharging the liquid in the electrode flow path from the electrode flow path.

[0010] According to the electrolyte analyzer of the present invention, it is possible to prevent the occurrence of dripping that occurs when electrodes are replaced. Other objects, configurations, advantages, etc. of the present invention will become apparent from the following description of the embodiments.

[0011] FIG. 1 is an overall schematic diagram of an electrolyte analyzer 1. FIG. 2 is a schematic diagram of an operation of replacing liquid in an ion selective electrode flow path with air. FIG. 3 is a schematic diagram of an operation of replacing liquid in a reference electrode flow path with air. FIG. 4 is a schematic diagram of an operation of replacing the inside of an ion selective electrode flow path with a cleaning liquid. FIG. 5 is a schematic diagram of an operation of replacing the inside of an ion selective electrode flow path with a cleaning liquid. FIG. 6 is a flowchart explaining an operation of the electrolyte analyzer 1 replacing liquid in an electrode flow path with air.

[0012] FIG. 1 is a schematic diagram of an overall configuration of an electrolyte analyzer 1 according to an embodiment of the present invention. The electrolyte analyzer 1 is a flow-type electrolyte analyzer using an ion-selective electrode. Seven main mechanisms are shown in FIG. 1: a sample dispensing section, an ISE electrode section, a reagent section, a reference electrode solution supply section, a specimen dilution solution supply section, a reagent preparation section, and a waste mechanism. Also shown is a control device 129 (controller) that controls these mechanisms and calculates and displays electrolyte concentrations based on measurement results.

[0013] The sample dispensing unit includes a sample probe 114 and a sample container 115. The sample probe 114 dispenses a sample (such as a patient's specimen) held in the sample container 115 and draws it into the automated analyzer. A specimen is a general term for an object to be analyzed that is collected from a patient's living body, such as blood or urine. The specimen may also be one that has been pretreated.

[0014] The ISE electrode section includes a dilution tank 111, a sipper nozzle 113, an ISE electrode 101, a reference electrode 102, a voltmeter 127, and an amplifier 128. The sample dispensed by the sample dispenser is discharged into the dilution tank 111. The discharged sample is diluted and stirred with the specimen dilution solution dispensed into the dilution tank 111 from a specimen dilution solution dispense nozzle 124. The sipper nozzle 113 is connected to the ISE electrode 101 by a flow path. The diluted sample solution aspirated from the dilution tank 111 is delivered to the ISE electrode 101 by this flow path.

[0015] The reagent section includes reagents required for measurement, reagent bottles containing the reagents, and a reagent suction nozzle 108 for aspirating the reagents from the reagent bottles. The reagent section may also include a degassing mechanism 107 and a filter 116. Four types of liquids are used as reagents for measuring electrolytes: a high-concentration reagent, a reagent diluent, a specimen diluent, and a reference electrode solution. In this embodiment, the high-concentration reagent is an internal standard solution with a concentration 31 times higher than normal, and the reagent diluent is pure water. The high-concentration reagent bottle 103 containing the high-concentration reagent, the reagent diluent bottle 104 containing the reagent diluent, the specimen diluent bottle 105 containing the specimen diluent, and the reference electrode solution bottle 106 containing the reference electrode solution are set in the reagent section. FIG. 1 shows this state. The reagent diluent bottle 104 containing the reagent diluent may be configured to automatically receive a supply of pure water, thereby eliminating the need to replace the reagent diluent bottle 104 during operation of the device. When cleaning the device, a cleaning solution bottle containing cleaning solution may be set in the reagent section.

[0016] The degassing mechanism 107 is a mechanism for preventing air bubbles from appearing in the reagent from being supplied directly to the dilution tank 111 or the reference electrode 102. The syringes for delivering the reagents create negative pressure in the flow paths to draw up the reagents from the bottles, which can cause gas dissolved in the reagents to appear as bubbles in the reagents. The degassing mechanism 107 prevents, to some extent, the reagents from being supplied to the dilution tank 111 or the reference electrode 102 with air bubbles still in them.

[0017] The filter 116 is a mechanism for trapping impurities (such as dust) contained in the reagent bottle.

[0018] The reference electrode solution supply unit includes a sipper syringe 110, a pinch valve 123, and solenoid valves 117, 121, and 122, and is responsible for the operation of supplying the reference electrode solution and the operation of supplying the sample solution to the ISE electrode 101. The reference electrode solution contained in the reference electrode solution bottle 106 is supplied to the reference electrode 102 by operating the sipper syringe 110 with the pinch valve 123 closed. When the pinch valve 123 is then opened, the diluted sample solution supplied to the ISE electrode flow path and the reference electrode solution supplied to the reference electrode flow path come into contact, establishing electrical continuity between the ISE electrode 101 and the reference electrode 102. The ISE electrode unit measures the concentration of a specific electrolyte contained in the sample based on the potential difference (liquid junction potential) between the ISE electrode 101 and the reference electrode 102.

[0019] As a specific example, an ion-sensitive membrane is attached to the ISE electrode 101, and its electromotive force changes depending on the concentration of specific ions (e.g., sodium ions (Na+), potassium ions (K+), chloride ions (Cl-), etc.) in the sample solution. This causes the ISE electrode 101 to output an electromotive force corresponding to the concentration of each ion in the sample solution. The control device 129 acquires the electromotive force between the ISE electrode 101 and the reference electrode 102 using a voltmeter 127 and an amplifier 128. The control device 129 calculates the ion concentration in the specimen from the electromotive force acquired for each ion and outputs (for example, displays) the result. The sample solution remaining in the dilution tank 111 is discharged by a waste liquid mechanism, which will be described later.

[0020] The specimen dilution liquid supply unit includes a specimen dilution liquid syringe 109, solenoid valves 118 and 120, and a specimen dilution liquid discharge nozzle 124. The specimen dilution liquid discharge nozzle 124 is installed with its tip inserted into the dilution tank 111 and is connected to the specimen dilution liquid bottle 105 through a flow path. A preheat 112 may be included in the flow path. The preheat 112 is a mechanism for suppressing the effect of temperature on the ISE electrode 101 by controlling the temperature of the reagent reaching the ISE electrode 101 within a certain range.

[0021] The reagent preparation unit dilutes the high-concentration reagent with a reagent diluent to prepare a predetermined concentration. The reagent preparation unit is equipped with one liquid delivery mechanism (liquid delivery syringe 136) in its flow paths. By operating this liquid delivery mechanism and the associated solenoid valves, the high-concentration reagent is delivered from the first flow path 141 and the reagent diluent is delivered from the second flow path 142 to the third flow path 143. The delivered reagents mix in the third flow path 143 and are finally delivered in a predetermined amount (the amount of liquid delivered per cycle) from the prepared reagent delivery nozzle 125 to the dilution tank 111.

[0022] The waste liquid mechanism includes a first waste liquid nozzle 126, a second waste liquid nozzle 130, a vacuum bottle 134, a waste liquid receiver 135, a vacuum pump 133, and solenoid valves 131 and 132, and discharges the sample solution remaining in the dilution tank 111 and the reaction liquid remaining in the flow path of the ISE electrode section.

[0023] The control device 129 can be configured as a computer including an arithmetic unit such as a central processing unit (CPU), a storage device such as a random access memory (RAM), and an input / output device such as an I / O port. The storage device and the input / output device are configured to be able to exchange data with the arithmetic unit via an internal bus or the like. The input / output device is connected to each of the above-mentioned mechanisms of the electrolyte analyzer, and the control device 129 controls the operation of each mechanism via the input / output device. The control device 129 controls each part of the liquid delivery mechanism, and therefore can also be considered as part of the liquid delivery mechanism.

[0024] The storage device may store a program that defines the operation of the electrolyte analyzer, and the control device 129 may control the operation of the electrolyte analyzer by executing this program. This program is read into the storage device and executed by the arithmetic device. In addition, an input / output device may be connected to the control device 129, and the electrolyte analyzer may receive input from a user via this input / output device and display measurement results.

[0025] A basic operation for measuring an electrolyte concentration will be described as an example of the operation of the electrolyte analyzer 1 shown in Fig. 1. The measurement operation is controlled by the control device 129.

[0026] The sample dispensed from the sample container 115 by the sample probe 114 of the sample dispenser is discharged into the dilution tank 111 of the ISE electrode. Then, the specimen dilution syringe 109 is operated to discharge the specimen dilution from the specimen dilution bottle 105 through the specimen dilution discharge nozzle 124 into the dilution tank 111. The sample is diluted with the specimen dilution in the dilution tank 111. As described above, a degassing process may be performed by the degassing mechanism 107 attached midway along the specimen dilution flow path to prevent bubbles from being generated due to temperature and pressure changes in the specimen dilution in the flow path. The diluted sample solution is sent to the ISE electrode 101 by the operation of the shipper syringe 110.

[0027] Meanwhile, the pinch valve 123 and the sipper syringe 110 operate to send the reference electrode solution from the reference electrode solution bottle 106 to the reference electrode 102. After the reference electrode solution has been sent, the pinch valve 123 is opened to bring the sample solution and the reference electrode solution into contact with each other, thereby establishing electrical continuity between the ISE electrode 101 and the reference electrode 102. The ISE electrode potential (liquid junction potential) relative to the reference electrode potential is measured by a voltmeter 127 and an amplifier 128.

[0028] In addition, before or after the measurement using the sample solution, the electrolyte concentration of the internal standard solution is measured in the same manner as in the measurement using the sample solution.

[0029] The control device 129 calculates the electrolyte concentration in the sample solution using the ISE electrode potential measured for the sample solution. At this time, calibration based on the ISE electrode potential measured for the internal standard solution can be performed to measure the electrolyte concentration more accurately. The specific calculation content of the calibration process can be designed appropriately by a person skilled in the art based on known techniques, etc.

[0030] The above series of analyses, including dispensing of the sample, measuring the electrolyte of the sample, and measuring the electrolyte of the internal standard solution before and after, constitute one analysis cycle. One sample is processed per cycle, and by repeating the cycle, electrolyte analysis of multiple samples is performed.

[0031] Conventional electrode replacement procedures have the problem of reagent dripping because the liquid in the electrode flow path is not drained. In the present invention, dripping can be prevented by replacing the liquid in the electrode with air when replacing the electrode in an electrolyte analyzer. By preventing dripping, measurement errors caused by liquid droplets remaining inside the ISE thermostatic chamber after electrode replacement can be avoided, and the user's need to wipe off the liquid after electrode replacement is eliminated, contributing to improved usability. The air replacement operation is performed in a series of operations on the ion selective electrode flow path and the reference electrode flow path.

[0032] 2 is a schematic diagram of the operation of replacing the liquid in the ion selective electrode flow path with air. The first liquid supply flow path 144, the second liquid supply flow path 145, and the third liquid supply flow path 146 are connected by a junction (a component having a T-shaped flow path connecting these). First, with the pinch valve 123 and the solenoid valve 122 open and the solenoid valve 117 closed, air is introduced through the suction nozzle by pulling the sipper syringe 110. By introducing air, the liquid in the ion selective electrode flow path is pushed into the first liquid supply flow path 144 and the third liquid supply flow path 146, and the inside of the ion selective electrode flow path can be replaced with air.

[0033] Figure 3 is a schematic diagram of the operation of replacing the liquid in the reference electrode flow path with air. The operation in Figure 3 is performed following the operation in Figure 2. First, the pinch valve 123 is closed, and the air drawn into the third liquid supply flow path 146 is pushed out to the second liquid supply flow path 145. By pushing the air in the third liquid supply flow path 146 out to the second liquid supply flow path, air is supplied to the flow path of the reference electrode, thereby replacing the liquid in the reference electrode flow path with air.

[0034] In addition to the above operations, reagents and samples can be removed from the electrode flow path by replacing the electrode flow path with a cleaning liquid (which may be water; the same applies below) before supplying air to the electrode flow path. Furthermore, by replacing the inside of the ion selective electrode flow path with a cleaning liquid before performing the air replacement operation, the inside of the ion selective electrode flow path can be cleaned and the risk of crystallization by the reagent can be reduced.

[0035] 4A to 4C are schematic diagrams illustrating the operation of replacing the inside of the ion selective electrode flow path with a cleaning solution. First, with solenoid valve 120 open and solenoid valve 118 closed, analyte dilution syringe 109 is operated to draw in the cleaning solution, introducing the cleaning solution into the syringe (FIG. 4A). Next, with solenoid valve 120 closed and solenoid valve 118 open, analyte dilution syringe 109 is operated to discharge the cleaning solution into dilution tank 111 (FIG. 4B). Next, with pinch valve 123 and solenoid valve 120 open and solenoid valve 117 closed, sipper syringe 110 is pulled, introducing the cleaning solution from the suction nozzle into the ion selective electrode flow path (FIG. 4C). Through these operations, the inside of the electrode flow path can be replaced with a cleaning solution. This allows the electrode flow path to be washed with the sample dilution solution (e.g., pure water). This procedure can be performed, for example, before FIG. 2.

[0036] 5 is a flowchart illustrating the operation of the electrolyte analyzer 1 to replace the liquid in the electrode flow path with air. This flowchart is started, for example, when the user instructs the control device 129 to replace the electrode in the maintenance mode of the electrolyte analyzer 1. Each step is performed by the control device 129.

[0037] The control device 129 outputs a message, such as a confirmation message asking whether or not to replace the electrode (S202). Upon seeing the message, the user inputs a response to the control device 129 indicating whether or not to replace the electrode. If the user cancels the electrode replacement (S202: NO), the flow chart ends and the process returns to the maintenance screen. If an instruction to replace the electrode is received (S202: YES), the control device 129 checks the remaining amount of consumables (S203). If there is an abnormality, such as a lack of remaining amount, an alarm is output and the device transitions to a standby state (S203: NO). The control device 129 performs the air replacement operation for the electrode flow path described with reference to FIGS. 2 and 3 (S204). Before S204, the cleaning operation described with reference to FIGS. 4A to 4C may be performed. The user replaces the ISE electrode 101 and the reference electrode 102 (S205). The control device 129 performs post-processing of this flow chart (e.g., recording an operation log) (S206).

[0038] <Summary of the Invention> When the electrolyte analyzer 1 receives an instruction from a user to replace the ISE electrode 101, it supplies air to the electrode flow path in the ISE electrode 101, thereby discharging any liquid remaining in the electrode flow path with the air. This reduces the possibility of an operator coming into contact with the liquid remaining in the electrode flow path when replacing the ISE electrode 101.

[0039] The electrolyte analyzer 1 sucks air from the first liquid feed flow path 144, draws the air into the third liquid feed flow path 146, and then pushes the air from the third liquid feed flow path 146 to the second liquid feed flow path 145, thereby supplying air to the electrode flow path in the reference electrode 102. These operations are performed by a liquid feed mechanism included in the electrolyte analyzer 1. Therefore, the above air replacement operation can be performed without providing a new mechanism for supplying air to the electrode flow path.

[0040] <Regarding Modifications of the Present Invention> In the above embodiments, it should be noted that the mechanisms for carrying out the operations described in FIGS. 2 to 4C (e.g., first liquid supply flow path 144, second liquid supply flow path 145, third liquid supply flow path 146, specimen dilution liquid syringe 109, sipper syringe 110, sipper nozzle 113, pinch valve 123, each solenoid valve, specimen dilution liquid discharge nozzle 124, etc.) operate as a liquid supply mechanism for supplying various liquids to the flow paths of electrolyte analyzer 1.

[0041] In the above embodiment, the consumable item in S203 is, for example, a liquid such as a reagent used in the analysis process, and one example of such a liquid is one whose remaining amount can be detected by a liquid level detection mechanism provided in the dispensing probe.The consumable item may also be any other consumable item whose remaining amount can be detected by the control device 129.

[0042] In the above embodiment, the syringes, valves, and flow paths connecting them constitute a liquid delivery mechanism that delivers liquid to the ISE electrode 101 and the reference electrode 102. The control device 129 controls each part of the liquid delivery mechanism by issuing operational commands to them, thereby performing the operations described above. The control device 129 can be configured using hardware such as a circuit device that implements its functions, or can be configured by a computing device such as a CPU (Central Processing Unit) executing software that implements its functions.

[0043] 1: Electrolyte analyzer 101: ISE electrode 102: Reference electrode 103: High concentration reagent bottle 104: Reagent dilution solution bottle 105: Sample dilution solution bottle 106: Reference electrode solution bottle 107: Degassing mechanism 108: Reagent suction nozzle 109: Sample dilution solution syringe 110: Sipper syringe 111: Dilution tank 112: Preheat 113: Sipper nozzle 114: Sample probe 115: Sample container 117, 118, 120, 121, 122, 131, 132: Solenoid valve 123: Pinch valve 124: Sample dilution solution discharge nozzle 125: Prepared reagent discharge nozzle 126: First waste liquid nozzle 127: Voltmeter 128: Amplifier 129: Control device 130: Second waste liquid nozzle 133: Vacuum pump 134: Vacuum bottle 135: Waste liquid receiver 136: Liquid delivery syringe 137: Branching portion 138, 139, 140: Solenoid valve 141: First flow path 142: Second flow path 143: Third flow path 144: First liquid delivery flow path 145: Second liquid delivery flow path 146: Third liquid delivery flow path

Claims

1. An electrolyte analyzer comprising: an electrode having an electrode flow path to which a liquid is supplied; a liquid delivery flow path connected to the electrode flow path and delivering the liquid to the electrode via the electrode flow path; and a liquid delivery mechanism that delivers the liquid to the liquid delivery flow path, wherein when the electrolyte analyzer receives an instruction to replace the electrode, the liquid delivery mechanism supplies air to the electrode flow path via the liquid delivery flow path, thereby replacing the liquid in the electrode flow path with air and discharging the liquid in the electrode flow path from the electrode flow path.

2. The electrolyte analyzer according to claim 1, wherein the electrodes are composed of: an ion selective electrode, which is supplied with a sample or an internal standard solution and measures the potential of the sample or the potential of the internal standard solution; and a reference electrode, which is supplied with a reference electrode solution and provides a reference for the potential measured by the ion selective electrode; and the liquid delivery flow path is composed of: a first liquid delivery flow path connected to the ion selective electrode and having one end into which the sample or the internal standard solution is introduced; a second liquid delivery flow path connected to the reference electrode and having one end into which the reference electrode solution is introduced; a junction connecting the other end of the first liquid delivery flow path with the other end of the second liquid delivery flow path; and a third liquid delivery flow path connected to the junction and discharging the liquid in the first liquid delivery flow path or the liquid in the second liquid delivery flow path; and the liquid delivery mechanism draws air introduced from the first liquid delivery flow path into the third liquid delivery flow path, and further pushes the air drawn into the third liquid delivery flow path out to the second liquid delivery flow path, thereby supplying air to the flow path provided with the comparison electrode.

3. The electrolyte analyzer according to claim 2, characterized in that the liquid delivery mechanism comprises: a pinch valve that opens and closes the first liquid delivery flow path; a sipper syringe connected to the third liquid delivery flow path; a first valve that is disposed between the junction and the sipper syringe and that opens and closes the third liquid delivery flow path; and a second valve that opens and closes a flow path connected to the sipper syringe on the opposite side from the junction, and the liquid delivery mechanism introduces air into the first liquid delivery flow path and draws the air into the third liquid delivery flow path by pulling the sipper syringe with the pinch valve and the first valve open and the second valve closed.

4. The electrolyte analyzer according to claim 2, characterized in that the liquid delivery mechanism comprises: a pinch valve that opens and closes the first liquid delivery flow path; a sipper syringe connected to the third liquid delivery flow path; a first valve that is disposed between the junction and the sipper syringe and that opens and closes the third liquid delivery flow path; and a second valve that opens and closes a flow path connected to the sipper syringe on the opposite side from the junction, and the liquid delivery mechanism closes the pinch valve and the second valve and opens the first valve, thereby pushing the sipper syringe to expel air that has been drawn into the third liquid delivery flow path into the second liquid delivery flow path.

5. The electrolyte analyzer according to claim 1, characterized in that the liquid delivery mechanism cleans the inside of the electrode flow path by supplying a cleaning liquid to the electrode flow path via the liquid delivery flow path before supplying air to the electrode flow path.

6. The electrolyte analyzer according to claim 2, further comprising a bottle for storing a cleaning liquid, wherein the liquid delivery mechanism comprises: a pinch valve for opening and closing the first liquid delivery flow path; a sipper syringe connected to the third liquid delivery flow path; a first valve disposed between the junction and the sipper syringe for opening and closing the third liquid delivery flow path; and a second valve for opening and closing a flow path connected to the sipper syringe on the opposite side from the junction, wherein the liquid delivery mechanism opens the pinch valve and the first valve and closes the second valve while pulling the sipper syringe, thereby drawing cleaning liquid into the electrode flow path via the liquid delivery flow path and cleaning the inside of the electrode flow path.

7. The electrolyte analyzer according to claim 6, further comprising a dilution tank that dilutes the sample by storing and mixing the sample and dilution liquid, the bottle storing the dilution liquid as the cleaning liquid, the liquid delivery mechanism further comprising: a dilution liquid syringe that draws the dilution liquid from the bottle, a dilution liquid discharge nozzle that discharges the dilution liquid into the dilution tank, and a sipper nozzle that draws the dilution liquid from the dilution tank, the liquid delivery mechanism discharging the dilution liquid into the dilution tank using the dilution liquid syringe and the dilution liquid discharge nozzle, and the liquid delivery mechanism drawing the cleaning liquid into the electrode flow path via the liquid delivery flow path by pulling the sipper syringe while the tip of the sipper nozzle is in contact with the dilution liquid.

8. A control method for controlling an electrolyte analyzer, comprising: an electrode having an electrode flow path to which a liquid is supplied; and a liquid delivery flow path connected to the electrode flow path and delivering the liquid to the electrode via the electrode flow path; the control method comprising the step of, when the electrolyte analyzer receives an instruction to replace the electrode, supplying air to the electrode flow path via the liquid delivery flow path, thereby replacing the liquid in the electrode flow path with air and discharging the liquid in the electrode flow path from the electrode flow path.

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