Today I planned to do a titration curve with my protein and check some ph points for future experiments.
I took a baseline with the NANOPure (tm) water just to see how the pH meter worked. Apparently our water is pH 5.8 +- 0.3 pH units, depending on the mood of the pH meter. But wait, turn off the stir bar and it shoots up 0.5 units. And if you use litmus paper, it's pH 4.7.
So I can't trust the paper or the meter or the water. No one knows the last time the machine was checked (years), but it should be every 6 months.
Here's hoping I don't have bad news for everyone tomorrow.
Update: a bit of reading reveals that our water is probably good. Dissolved CO2 hits exactly 5.8. The high resistance of pure water (no ions) makes pH meters freak out. I'm not sure yet what is up with the litmus paper. Need to get a direct resistance reading off the machine (should be above 18Mohms I believe). See if there are other tests to do. Or just a technician.
http://www.millipore.com/references/files/pmc_url/$file/highpuritywater.pdf
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