Standard method for measuring PH
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In production, there are often products for which it is necessary to control the pH of the solution. Using a pH meter presents many problems, such as the need for frequent calibration, as well as the tendency of ordinary pH meters to become damaged. Therefore, in production, when the requirements are not particularly strict, pH testing is generally carried out using pH test strips. So what is the proper way to use pH test strips? This is how I have always done the measurement: I insert a clean stick or tube into the reaction solution, leave it there for about 5 seconds before removing it; then I dip a small amount of the solution onto a test strip, and the pH value is obtained within 5 seconds (the time cannot be longer). I’m not sure if this is the standard method – please share your own experiences as well. This post was last edited by lifanwang on 2009-3-12 at 11:00
The two combinations: 1. Operating procedures; 2. Instruction manual. In summary: first read the instruction manual, then create the operating procedures, and finally follow them
It’s certain that PH test strips are inaccurate. Generally, it is 1~2 units higher than that of a pH meter. If strict requirements are imposed on the process, it is best to use a pH meter.
We have been using glass electrodes for measurements, as they offer high accuracy
The method you mentioned can be used, but I think you should stir the solution before dipping it to ensure it is uniform. However, pH test strips are rarely used as the error is too large; pH meters are generally used instead. When using any instrument, it is necessary to follow the operating instructions; improper use can easily damage the instrument. It is essential to maintain the instrument, and as long as the operations are carried out according to the guidelines, I believe the pH meter will have a decent service life.
It is recommended to use a pH meter, as it provides more accurate readings; test strips usually give values that are 1–2 units too high. However, when the requirements are not high, test strips can be used for measurement; but it is best to avoid using broad-range test strips covering 1–14 (as they have large errors). It is recommended to use precision test strips after knowing the pH range, such as those for 0–5 or 5–9. The method of using the test strip is more or less correct as you described, but your method is only applicable in environments such as laboratories. When using it on-site, the test strip is generally dipped into the solution; it is important to ensure that the flow rate of the solution is not too high, and the strip should be removed from the solution as soon as possible after dipping it in order to take a reading.