Refillable, Combination pH Electrode with Double Junction

The triple ceramic inner junction allows a higher flow rate of electrolyte from the reference cell into the measurement sample. A typical pH electrode will have a single ceramic junction that provides a flow rate of 15 to 20 ?L/hour. The HI10433 has three ceramic junctions in contact with the sample providing for a flow rate of 40 to 50 ?L/hour. The increased flow provides a greater continuity between the reference electrode and the indicating electrode, making it suitable for non-homogenous solutions and samples with highly alkaline pH values. Built-in temperature sensor at the tip of the pH electrode allows for rapid determination of the sample temperature and a high-accuracy temperature reading. Spherical tip Provides maximum surface area for accurate measurements. Glass Body Features a non-porous glass body that is easy to clean and withstands harsh chemicals. Refillable The double junction reference design presents a silver-free electrolyte solution interacting with the sample, making the electrode less susceptible to clogging and guaranteeing a fast response and stable reading. Built-in temperature sensor Built-in temperature sensor at the tip of the pH electrode allows for rapid determination of the sample temperature and a high-accuracy temperature reading. Single Junction Versus Double Junction pH Electrodes Conventional electrodes are normally single junction. As depicted by the figure above, these electrodes have only a single junction between the internal reference wire and the external solution. Under adverse conditions, such as high pressure, high temperature, highly acidic or alkaline solutions, the positive flow of the electrolyte through the junction is often reversed resulting in the ingress of sample solution into the reference compartment. If this is left unchecked, the reference electrode can become contaminated, leading to complete electrode failure. Another potential problem with single junction electrodes is the clogging of the junction due to silver chloride (AgCl) precipitation. Silver can be easily precipitate in samples that contain Tris buffer or heavy metals. When the electrolyte solution makes contact with the sample, some AgCl will precipitate on the external face of the junction. The result is drifty readings obtained from the sensor. Hanna's double junction system, as the name implies, has two junctions, only one of which is in contact with the sample as shown in the figure. Under adverse conditions, the same tendency of sample ingress is evident. However, as the reference electrode system is separated physically from the intermediate electrolyte area, the contamination of the electrode is minimized. The likelihood of clogging of the junction is also reduced with a double junction electrode since the outer reference cell uses a fill solution that is "silver-freein.. Since there is no silver present, there is no precipitate that can form to clog the junction.