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The HI11312 HALO is a revolutionary pH electrode that incorporates Bluetooth Smart (Bluetooth 4.0) wireless technology with an application-specific design. This electrode has many features that makes it ideal for use in a wide variety of applications. These features include general purpose (GP) glass, spheric bulb, integrated temperature sensor, glass body, and double reference junction with silver-free electrolyte.

General Purpose Glass Formulation

General Purpose (GP) glass, as the name implies, is a standard glass formulation that is used for general use. A pH electrode with GP glass will have a resistance of 100 megaohms at 25℃ and is suited for measuring pH of samples that are at ambient temperatures. The HI11312 is suitable to use with samples that measure from -5 to 80℃ (23 to 176℉).

Spheric Glass Tip

The spheric bulb is for general purpose use within laboratory environments and applications that measure aqueous solutions due to its large surface area. Other tip shapes include conic for penetration and flat tip for surface measurements.

Built-In Temperature Sensor

HI11312 features a built-in thermistor temperature sensor that is in the tip of the indicating pH electrode. A thermistor temperature sensor provides for a high accuracy temperature reading and should be as close as possible to the indicating pH electrode in order to compensate for the effect that temperature has on the membrane potential as predicted by the Nernst equation. By having an accurate reading it is possible to provide a temperature compensated reading.

Glass Body

The glass body of the HI11312 is ideal for laboratory use and measurement of grab samples. The glass is resistant to many harsh chemicals and is easy to clean. 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, so the faster thermal equilibrium is reached, the steadier the reference potential.

Single Ceramic Double Junction Reference

The HI11312 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 necessary component of the electrical circuit. The movement of ions must flow through the junction for a steady reading. The outer reference has a single ceramic frit. The ceramic is a porous material that is easily fused with the glass body and has a similar expansion coefficient. A single ceramic junction allows the 3.5M KCl electrolyte to flow at a rate of 15 to 20 µL/hour.

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-free.” Since there is no silver present, there is no precipitate that can form to clog the junction.

Hanna Lab App

HALO pH electrodes can connect with HI2202 edge^blu meter or a compatible Apple or Android device running the Hanna Lab App.

The Hanna Lab App turns a compatible Apple or Android device into a full-featured pH meter when used with the Hanna HALO pH probe with Bluetooth Smart technology. Functions include calibration, measurement, data logging, graphing and data sharing. Measurement and logging of pH and temperature at one second intervals start as soon as the probe is connected. Measurements can be displayed alone on the display, with tabulated data, or as a graph. The graph can be panned and zoomed with pinch-to-zoom technology for enhanced viewing.

Five-Point Calibration

The Hanna Lab App incorporates a probe calibration using up to five pH buffers that are automatically recognized and temperature corrected to 25.0℃ during calibration.

Real-Time Data

Display of pH and temperature updated every second. Readings are automatically saved to a history file every hour, limited only by the available memory on the device.

Fluid, Dynamic Graphing

Measurement can be displayed with tabulated data or a graph on the display. The graph axes may be expanded using pinch-to-zoom technology for enhanced viewing.

Hanna Lab App Features/Benefits:

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