axehandle - 28-1-2004 at 22:45
Sorry for spamming, but is EUR60 cheap for a _new_ digital PH-meter?
Organikum - 29-1-2004 at 07:48
depends on the electrode(s) you get with the thingie and the amount of calibration liquids.
axehandle - 29-1-2004 at 08:28
Don't know about the electrodes, and 100ml of calibrarion liquid costs almost as much as the meter itself.
Homemade Calibration Buffers
chemoleo - 29-1-2004 at 08:57
Wow, don't even think about buying them!!
You can make your own buffers, with a set pH, if you have the acid/base component of the buffer - i.e. Acetate and acetic acid, H-phosphate or
H2-phosphate etc.
Then you need to know the pK of each, and then u use the Henderson Hasselbach equation to calculate the pH according to
pH = pKa+ log[A-]/[HA].
MUCH EASIER:
check
http://www.bi.umist.ac.uk/users/mjfrbn/buffers/makebuf.asp
There you can choose lots of differnent buffer conditions, and it calculates the required amounts of acid/base - and the pH is SET!!
Hence - don't even think about buying them for 100 euros 
axehandle - 31-1-2004 at 15:19
Thank you! I never considered making my own buffer solution.