Reference Electrode Using Gelled Hydrophobic Ionic Liquid Junction
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Solution Overview
Problem
Conventional reference electrodes with highly concentrated KCl internal solutions suffer from liquid junction potential variations, contamination of sample solutions, frequent refilling needs, and clogging issues due to AgCl deposition in porous junctions.
Innovation Solution
A reference electrode utilizing a gelled hydrophobic ionic liquid as the liquid junction, composed of a hydrophobic salt with a melting point ≤100°C and low water solubility, which minimizes ion movement and prevents contamination and clogging, maintaining stable potential and reducing refilling frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a highly concentrated KCl solution is used as internal solution, then liquid junction potential variations are suppressed, but sample solution contamination occurs and refilling frequency increases
Solution Approach 1:
A gel bridge comprising a gel matrix and a quaternary ammonium salt is introduced as an intermediary between the internal solution and sample solution. The gel bridge allows ion conduction while preventing direct mixing, thereby maintaining reference potential stability without contaminating the sample solution with KCl.
Solution Approach 2:
The invention changes the physical state of the junction from liquid to gel, and selects a quaternary ammonium salt with specific properties (low solubility in water, appropriate melting point) to replace traditional KCl in the gel bridge. This parameter change enables the system to maintain ionic conductivity while eliminating unwanted ion migration into the sample.
2Ease of operation
If a porous plug is used as liquid junction, then ion conduction is enabled, but AgCl migration causes clogging and measurement failure
Solution Approach 1:
The invention changes the physical state of the junction from liquid to gel, eliminating the porous structure that causes clogging. The gel matrix provides a continuous phase for ion conduction without the pore structures that trap AgCl precipitates, thereby maintaining ease of operation while improving reliability.
3Reliability
If KCl flows continuously into sample solution, then liquid junction potential stability is maintained, but internal solution concentration decreases requiring frequent refilling
Solution Approach 1:
The gel bridge acts as an intermediary that permits necessary ion conduction for maintaining liquid junction potential stability while physically restricting the bulk flow of KCl into the sample solution. This prevents depletion of the internal solution, extending its service life without compromising measurement stability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The gelled hydrophobic ionic liquid effectively eliminates liquid junction potential variations, minimizes sample solution contamination, prevents clogging, and maintains long-term durability and accuracy in electrochemical measurements.
Implementation Method 1
the liquid junction is made by the use of a gelled hydrophobic ionic liquid... means a hydrophobic salt whose melting point is less than or equal to 100° C. and whose solubility to water is less than or equal to about several mM
Implementation Method 2
the liquid junction is made by the use of a gelled hydrophobic ionic liquid
Implementation Method 3
AgCl migrates from the internal electrode and deposits and adheres inside the porosity of the liquid junction
Data Source
AI summary
The present claimed invention is to provide a reference electrode wherein variations of a potential difference at a liquid junction can be removed almost completely, contamination of a sample solution can be minimized, a frequency to supply and replace an internal solution is lessened, the liquid junction is prevented from being clogged, high durability for a long term can be maintained and a measurement with high accuracy can be conducted, and comprises an internal electrode 21, an internal solution 22 that makes a contact with the internal electrode 21 and a liquid junction 23 that continues into the internal solution 22, wherein the liquid junction 23 is made by the use of a gelled hydrophobic ionic liquid.