Hanna Best pH Electrode for Your Application

The Best pH Electrode for Your Application

Finding the right electrode for a specific application might at times look like a mind boggling exercise! In order to solve this problem, Hanna Instruments has divided the different electrodes into 7 main categories. You will then find the benefits of the two most common types of electrodes in each category together with a suggested part number. By following these charts, one can not only find the right electrode but also understand the reasons why one type is better than another.

BNC Connector VS. US Standard Connector
Glass Body Electrodes VS. Epoxy (Plastic) Body Electrodes
Conic-Shaped Tip VS. Sphere-Shaped Tip
Gel-Filled Electrodes VS. Refillable Electrodes
Double Junction Reference VS. Single Junction Reference
Triple Ceramic Junction VS. Single Ceramic Junction
Ceramic Junction VS. Open Junction

Electrode Comparison Charts


1. BNC Connector*	VS.		US Standard Connector*
Smaller (fits better on specially smaller or hand held meters).
Inexpensive (BNC connectors are widely used on TV sets).
Fastens better (due to the twisting mechanism).
* Connectors: Before looking at different types of electrodes, ensure that the male connector at the end electrode cable matches the female connector on the pH meter. The vast majority of modern pH meters take BNC.
** The B and U at the end of electrode part numbers denote BNC and US Standard Connectors.
	Figure 1
BNC Connector		US Standard Connector


2. Glass Body Electrodes	VS.		Epoxy (Plastic) Body Electrodes
Slightly faster (due to larger surface area of the bulb).			More rugged (the electrode stem and bulb are well protected).
Easier to clean (larger bulb surface area).			Costs less than glass electrodes.
Available in more shapes for special applications.
Stands higher temperatures (typically up to 100 Centigrade; plastic only up to 80 C).
*Glass-body/Plastic-body refers to the stem of the electrode
	Figure 2



3. Conic-Shaped Tip	VS.		Sphere-Shaped Tip
Easier to clean and maintain. Sample trickles down to the tip. Best for applications such as dairy.			A few seconds faster due to the larger surface area of the bulb.
The tip is more rugged, hence better for penetration.			Normally costs less.
Can last longer.
*Conic/sphere shaped refers to the shape of the membrane only

4. Gel-Filled Electrodes	VS.		Refillable Electrodes
Requires less maintenance. No refilling required.			Electrode could last longer if electrolyte is changed.
Resists higher pressure (+15-30 psi).			A different electrolyte, for example, silver-free or calomel for special applications can be used.
			Slightly faster response due to greater flow of electrolyte into the sample.
* Gel-filled/Refillable refers to the kind of electrolyte inside the reference chamber.

5. Double Junction Reference	VS.		Single Junction Reference
Protects the sample from having any silver contamination from the electrolyte.			Normally costs less. (The Hanna Double Junction Plastic Electrodes are however supplied at the same price as standard electrodes).
Almost no silver is deposited on outer ceramic as electrolyte is lost into sample hence no clogging from inside.
Protects the Silver wire from being contaminated due to prolonged use, or in highly acidic or alkaline samples.
Longer life.

	Figure 3



6. Triple Ceramic Junction	VS.		Single Ceramic Junction
Allow a higher outflow of electrolyte, hence less likely to clog.			Costs less.
Recommended for low conductivity samples due to higher outflow of KCl.
Slightly faster response.
* Triple Ceramic have 3 Ceramics as opposed to a single outer ceramic on the stem of elec.

7. Ceramic Junction	VS.		Open Junction
Lasts longer.			No clogging (with a conic membrane becomes the ideal electrode for food samples with protein or glucose content or any medium which clog normal electrodes)
Costs less.
Stands higher temperatures (Typically 80°C or higher whereas open junction max. Temp. Is around 50°C)			Faster.
Stands higher pressure.
* Open Junction means that there is no ceramic separating the sample from the electrolyte.