Checking pH meter calibration HCL >37%

[rwooduk]

Hi,

I've calibrated our pH meter using 4.01 and 7.01 buffer solution, but I'm not sure if the probe has dried out at some point. So I want to check the calibration, I have some HCl > 37% that I can use. Just a quick question, since pH is on a log scale so I have to make solutions every ten unit?

i.e. 1ml HCl + 100mL DI water
1ml HCL + 1000mL DI water
1ml HCL + 10000mL DI water

For large volumes of water would my pH meter even detect a change? Please could someone suggest a realistic range of diluted HCl values with which to check the calibration is correct or is the above correct?

Thanks for any advice

 

[Borek]

You can't properly check the calibration with diluted acid, you need buffers for that. Diluted acid pH is very approximate (not to mention the fact it won't work at all at pH 7.00).

 

[rwooduk]

Ok thanks again Borek! I think we have more buffer solutions other than those used to calibrate, I will attempt to make use of them

 

[Borek]

You can't calibrate the pH electrode too often

Seriously, I suggest checking it once a day. It may turn out the readings are quite stable, but its in no way guaranteed.