Which pH electrode should I choose? Camlab

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There’s so many to choose from! Camlab have a large range of pH electrodes each varying in terms of the internal junction, shape of the tip and the materials used. Everything from apple juice to heavy metals to cheese! There is an electrode to suit testing the pH of any particular sample.

For a quick glance, check out our pH electrode selection guide which gives a great overview of the electrodes you should and shouldn’t go for when testing particular substances.

pH Measurement

pH is a measurement of the concentration of hydrogen ions (H+) in a substance. The scale it is measured on a scale between 0 to 14. A reading of 7 is neutral, below this is acidic and above this is alkaline or basic.

TYPE

Double Junction – these electrodes have an additional salt bridge to prevent reactions between the electrode fill solution and your sample which would otherwise cause damage to the electrode junction. They are required to test samples that contain proteins, heavy metals or sulphides.

Liquid Junction – A liquid junction electrode creates a junction with a thin film of filling solution at the tip of the probe. They usually have a pump function to allow you to create a fresh junction for every use. They do need refilling regularly but offer the best performance increasing lifetime, accuracy and speed of response.

EpoxyTough – these electrodes are filled with gel rather than traditional liquid filled models, so you do not need to refill them.

Micro – this small, slim electrode means that you can test when you have only a small amount of sample, or your sample is in a small container.

COMPATIBILITY

You will need to know which connection type BNC, DIN or S7 your pH meter takes in order choose a compatible electrode (or vice versa). Some brands of meters have their own unique connection which limits you to using only their brand of electrodes. The quickest way to find the electrode connection is to use our quick guide.

SHAPE

What state is your sample in? If you are testing solids then the pointed spear tip electrodes allows you to pierce a solid to then take a reading. This is commonly used to test meat, cheese or soil. A flat ended electrode can be used to test the surface of a solid sample such as fabric, biological tissues and substances that will be hard to clean off such as pastes as these probes have no crevices.

REMEMBER

Electrodes need to be looked after and it’s essential to calibrate them as much as possible, ideally every day before use. Some units have a two point calibration, others a three point at pH 4, 7 and 10 using buffers. These act as a reference point for the meter to then use to test your sample’s pH.

Between uses your electrode should be stored in a 3.0M KCl (potassium chloride) solution. An electrode storage bottle will help ensure that the electrode tip is not damaged and that the solution doesn’t evaporate over time.

You can read our previous blog about cleaning electrodes here.

For more information on anything pH give us a call on 01954 33120 or contact us by email with the form below