GreenD
National Hazard
Posts: 623
Registered: 30-3-2011
Member Is Offline
Mood: Not really high anymore
|
|
pH meter drift
I've never had a pH meter that hasn't drifted. Granted I've never bought a new one.
I've looked up a few articles and they all say replace them. Is that the case?
I also notice this:
1.My drifting pH meter does not drift if I stir the solution (the pH meter reads the exact same reading).
2.Giving my solution to someone's pH meter which does not drift gives me approximately the same reading as when I stire the solution
is this coincidence, or do you believe that the initial reading of the meter while stirring is actually the correct one, while letting it sit
stationary is drift from the real pH>?
|
|
|
bahamuth
Hazard to Others
Posts: 384
Registered: 3-11-2009
Location: Norway
Member Is Offline
Mood: Under stimulated
|
|
How fast does it drift, and how much?
Usually a good cleaning is the cure for drift and/or new saturated KCl inside it, if it is possible (be aware that some electrodes need sat. KCl
saturated with AgCl). The cleaning procedures may be found online if you search a little.
Any sufficiently advanced technology is indistinguishable from magic.
|
|
|
GreenD
National Hazard
Posts: 623
Registered: 30-3-2011
Member Is Offline
Mood: Not really high anymore
|
|
well I work with aqueous polymers (horrible fkrs to pH), which can swing from 1 to 12 (no joke). A good clean with IPA and H2O usually gets me to +/-
.4 which is still pretty large. In aqeuous formulas it can drift around .2
My real question, I guess, is this: Does the end number of the drift actually accurate and precise? Or is drift caused by some other phenomenon that
actually skews the number?
|
|
|
bahamuth
Hazard to Others
Posts: 384
Registered: 3-11-2009
Location: Norway
Member Is Offline
Mood: Under stimulated
|
|
You would need to test if the endpoint of the drift is close to the "true" value with a buffer of sorts.
I've actually dealt with an electrode which was so slow that it could take 20 min to get the endpoint reading which was close to a "true" value
determined by buffers..
Any sufficiently advanced technology is indistinguishable from magic.
|
|
|
GreenD
National Hazard
Posts: 623
Registered: 30-3-2011
Member Is Offline
Mood: Not really high anymore
|
|
Quote: Originally posted by bahamuth  | that it could take 20 min to get the endpoint reading which was close to a "true" value determined by buffers..
|
shit.
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
