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Author: Subject: PH meter
axehandle
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[*] posted on 28-1-2004 at 22:45
PH meter

Sorry for spamming, but is EUR60 cheap for a _new_ digital PH-meter?



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Organikum
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[*] posted on 29-1-2004 at 07:48


depends on the electrode(s) you get with the thingie and the amount of calibration liquids.



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axehandle
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[*] posted on 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.



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[*] posted on 29-1-2004 at 08:57
Homemade Calibration Buffers

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 :):)



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[*] posted on 31-1-2004 at 15:19


Thank you! I never considered making my own buffer solution.



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