Recently, one of my pH meters has been giving strange pH readings after calibration. The pH of my CLAS has always been 3.6 or 3.7. When I restarted baking in March, the meter in question was reading the pH value correctly. But since then, it has been displaying abnormal readings, such as pH1.x, pH2.x, etc., while my second meter shows 3.6 / 3.7. The faulty meter's last reading of my CLAS's pH is 4.0. Although it is close to the normal value, it is still incorrect.
Any suggestions of what might cause the discrepancies, and how can I fix it?
Thanks,
Yippee
The sensors get fouled by stuff in the solution you are measuring. There are cleaning solutions for them that might help.
Even with proper maintenance, the electrodes are only good for a few years.
I agree, it's probably a soiled probe. If all else fails, try a 2% caustic soda solution (use appropriate PPE!) to clean it.
If no joy, I have the later yellow Chinese meter with two buttons on the front (one says cal). It has 2 point auto calibration with 2 buffers - no fiddling with a little screwdriver needed. It came from Ebay and seems to be surprisingly good for the money.
Lance
Hi, everyone:
Thank you for your reply. I found an article describing cleaning procedures that do not require a particular solution. I want to try the "general cleaning," which says:
" General Cleaning: Soak the electrode in 1:10 dilution of household laundry bleach in a 0.1 to 0.5% liquid detergent solution in hot water with vigorous stirring for 15 minutes. Place junction under warm, running tap water for 15 seconds. Drain/refill the reference chamber. Soak the electrode in storage solution for at least 10 minutes."
My questions regarding this procedure are:
1) Is this an appropriate method to clean my pH pen?
2) If so, am I supposed to mix two solutions (diluted bleach + liquid detergent solution) together to soak the pH pen?
3) If "yes" to 2), how much of each solution do I mix?
Thank you,
Yippee
Yipee, another option is a crumb broken off a dishwasher tablet, or a bit of powder or liquid dissolved in a little warm water.
Soak the probe for 30mins.
This is the least complicated method. I am going to try it.
Yippee
Hi, Lance:
I have some questions about mixing the solution:
The following tablet weighs 20g.
1. What ratio of water : tablet should I use?
2. What is the red "thing"?
3. Do I include it as part of the tablet weight?
Thank you,
Yippee
I would try 3g of tablet in 100ml warm water. The red blob is supposedly rinse aid - don't add any.
Lance