Atlas Scientific PH probe results query

Other Hardware Home Automation
1

I am doing a project at home using the arduino uno board and the atlas scientific ph probe.

I did some initial testing to observe the results of the PH probe. I inserted the probe in 3 liquids of PH 4,7, 10 and collected readings at a interval of 1 second for 30 - 45 minutes.

Using those readings I plotted a graph of Ph vs Time. (results attached)

I have the following questions in case someone has used the same instrument before -:

  1. I never get a stable reading using the probe. Is this expected?
  2. If the answer to question 1) is true then how should one measure PH of a solution accurately.

The intention of my experiment is to see the variation in PH with varying temperature. Currently I am not sure how to understand the PH readings as they keep varying and sometime keeps jumping up and down.

Any help in understand this would be very helpful.

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2

Without knowing how you have the probe connected and what your software looks like, it's a bit difficult to know what you are doing.

Did you read the data sheet? This current (which can be positive or negative) is very weak and cannot be detected with a multimeter, or an analog to digital converter. This weak electrical signal
can easily be disrupted and care should be taken to only use proper
connectors and cables.

What interface board do you have between the probe and the Arduino? Are you allowing for both positive and negative current from the probe?

Paul