Temerature measurement with Ph Sensor

Hello All,
I have bought a Ph sensor (Analog pH Sensor - Meter Kit | Arduino Official Store) available on Arduino website.
As we all know that Temperature play a vital role in pH measurement.
So i wanna ask you is it possible to calibrate this Sensor for different temperature?? i.e. i am going to calibrate it at 25 C but when i install with my device, The temperature is higher than room temperature.

Thanks in advances.

Actually I didn't :slight_smile:
Seriously, Its not clear what you are trying to do. Or perhaps how you want to do it.

It would seem if PH varies with temperature and you don't know the temperature then you can't make the conversion.
I see this as similar to trying to "calibrate" a humidity sensor to give you Dew Point without knowing the temperature.

Or maybe I don' t understand the question.

Whilst pH varies with temperature so does the neutral point. An increase in temperature will normally result in an increase in the concentration of H+ ions so the pH will fall (appearing to be more acidic) however the concentration of OH- ions will also increase so the neutral pH point will decrease from 7 to something lower depending on temperature and what is being measured.

At 100C the pH of neutral water is 6.14

So back to the OP original question, yes you can calibrate your sensor for use at a higher temperature provided the probe supports that temperature, in your case a quick glace at the spec seems to suggest it should work upto 60C where the pH of neutral water will be somewhere around 6.5.

20 degrees Celsius can be used as a standard as well.
All the calibration is doing is altering the slope of the mV output of the probe against pH.
There's a lot of information out there in Googleland on the subject.
You might be able to use the map() function to tweak the numbers.
The pH electrode output is well defined for standard temperatures.
Ideally, if you want to try it out, you will need a minimum of two buffer solutions and ideally three.
Yes, as others have said, knowing the temperature is vital to accurate results.
It depends on your application just how accurate you need to be.
or long term use, you will need some buffer solutions for occasional checks.

1 Like

Thank you for your reply.
could you please guide me how do i program temperature variation with pH sensor.

You need to find an equation linking ph to temperature , you can then either use the equation directly or have a lookup table .

In the past I’ve played on a spreadsheet to try out curve fits , look up tables , etc , to get an idea as to what accuracy I might get with various methods before programming .

Also worth looking at the spec of your probe to see how good any correction needs to be :
Spec sez :

  • Measuring Temperature: 0 - 60 ℃
  • Accuracy : ± 0.1pH (25 ℃)

So there is no point trying to be better than .1ph and also we don’t know how the accuracy performs at different temperatures from 25C as this is not stated !

It is pretty cheap , don’t expect too much!

Thanks for your Support.