• HI1043B is a glass body, refillable, double junction pH electrode with a BNC connector. This electrode has a single ceramic junction in the outer reference cell and the pH sensing portion is made with high temperature glass.

• This design consideration is ideal for hydrocarbons, paints, solvents, high conductivity samples, strong acids and bases, and for measuring samples at elevated temperatures.

• Refillable electrode

• Double junction design

• High temperature glass

• Hanna Instruments offers a wide variety of pH electrodes that are designed for many different applications. The type of glass used for sensing pH, bulb shape, body material, type of connector, reference type, and the electrolyte used are just some of the design considerations.

• The HI1043B uses high temperature (HT) glass, spherical bulb, glass body, single ceramic frit, double junction and is refillable with 3.5M KCl.

Figure 1 Details:

High Temperature Glass Formulation Measuring pH at very high temperatures is harmful to the sensitive glass bulb and will shorten its life. A pH electrode with general purpose (GP) glass has a resistance of 100 megohms at 25°C, while HT glass has a resistance of about 400 megohms at 25°C. When the HI1043B is used at high temperatures, the resistance decreases and approaches that of GP glass. The HI1043B is suitable for samples from 0 to 100°C.

Figure 2 Details:

• Spherical Bulb

• The spherical bulb is for general purpose use. Other tip shapes include conical for penetration and flat tip for surface measurements.

Figure 3 Details:

• Glass Body

• The glass body is ideal for laboratory use. The glass is resistant to many harsh chemicals and is easily cleaned. The glass body also allows for a fast transfer of heat to the internal reference electrolyte. The mV generated by the reference cell is temperature dependent. The faster the electrode reaches equilibrium, the more stable the reference potential.

Figure 4 Details:

• Single Ceramic Double Junction Reference

• The HI1043B is a double junction design. pH electrodes are available as single junction or double junction. See below for a complete description of the differences. The junction, also known as a salt bridge, is a necessary component of the electrical circuit. The movement of ions must flow through the junction for a stable reading. The outer reference has a single ceramic frit. Ceramic is a porous material that is easily fused with the glass body and has a similar expansion coefficient. A single ceramic junction has a flow rate of 15-20 μL/hour. Other junction types are available with higher flow rates and made with different materials.

Figure 5 Details:

• Refillable

• The HI1043B is a refillable probe. Since it is a double junction pH electrode, the fill solution is HI7082 3.5M KCl. This solution does not contain any silver as with single junction electrodes. The absence of silver will prevent any silver precipitate from forming and clogging the junction. Clogging of the junction will result in drift and unstable readings.

Figure 6 Details:

• BNC Connector

• The HI1043B has a BNC connector. This type of connector is universal in that it can be used on any pH meter that has a female BNC probe input. Other types of connectors include DIN, screw type, T-type, and 3.5mm to name a few. These other types of connectors tend to be proprietary for a particular type of meter and are not interchangeable.

• Conventional electrodes are normally single junction. As shown in 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, high acidity or alkalinity solutions, the positive flow of electrolyte through the junction is often reversed, allowing the sample solution to enter the reference chamber. If left unchecked, the reference electrode may become contaminated, resulting in complete failure of the electrode. Another potential problem with single junction electrodes is the clogging of the junction due to silver chloride (AgCl) precipitation. Silver can easily precipitate in samples containing Tris buffer or heavy metals. When the electrolyte solution makes contact with the sample, some silver chloride will precipitate on the outer surface of the junction. The result is a drifting reading 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 for the sample to enter is evident. However, since the reference electrode system is physically separated from the intermediate electrolyte zone, contamination of the electrode is minimized. The double junction electrode also reduces the likelihood of junction clogging because the outer reference cell uses a “silver-free” fill solution. Since silver is not present, no precipitate that would clog the junction can form.