Product Overview

• HI1043P is a glass body, refillable, double junction pH electrode with BNC and pin connectors. The pin connector is used to enable the CAL Check function of HI2221, HI2222 and HI2223 benchtop meters. The electrode has a single ceramic junction in the outer reference cell and the pH sensing portion is made of high temperature glass.

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

• Refillable electrode

• Double junction design

• High temperature glass

• Hanna Instruments offers a wide variety of pH electrodes that can be used in many different applications. The type of glass used to sense pH, bulb shape, body material, type of connection, reference type and electrolyte used are just some of the design considerations.

• HI1043P uses high temperature (HT) glass, a spherical bulb, glass body, single ceramic frit, double junction, refillable with 3.5M KCl.

Figure 1 details:

• High temperature glass formulation

• Measuring pH at very high temperatures is detrimental 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 HI1043P is used at high temperatures, the resistance decreases and approaches that of GP glass. HI1043P 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 easy to clean. The glass body also allows heat to be transferred quickly to the internal reference electrolyte. The mV generated by the reference cell is temperature dependent. The faster the equilibrium, the more stable the reference potential.

Figure 4 details:

• Single ceramic double junction reference

• HI1043P is a double junction design. pH electrodes are available as single or double junction. See below for a complete description of the differences. The junction is also called a salt bridge and is a necessary part of the 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 easy to fuse with the glass body and has a similar coefficient of expansion. The single ceramic junction has a flow rate of 15-20μL/hour. Other junction types are available with higher flow rates and made from different materials.

Figure 5 details:

• Refillable

• HI1043P 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 lack of silver will prevent any silver precipitate from forming on the junction surface and clogging it. Clogging of the junction will result in drift and unstable readings.

Figure 6 details:

• BNC + pin connector

• HI1043P has a BNC and pin connector. The BNC connector is universal in that it can be used on any pH meter that has a female BNC probe input. The pin connector is used to enable the CAL Check function on the following benchtop pH meters; HI122, HI123, HI221, HI222, HI223, HI2221, HI2222 and HI2223.

Single junction vs. double junction pH electrodes

• 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, highly acidic or alkaline solutions, the positive flow of electrolyte through the junction is often reversed, resulting in the sample solution entering the reference chamber. If left unchecked, the reference electrode can become contaminated, leading to complete electrode failure. Another potential problem with single junction electrodes is 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 contacts the sample, some silver chloride precipitates 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 sample to enter is evident. However, since the reference electrode system is physically separated from the intermediate electrolyte region, contamination of the electrode is minimized. Double junction electrodes also reduce the likelihood of junction clogging because the outer reference cell uses a “silver-free” fill solution. Since silver is not present, no precipitate is formed that would clog the junction.