How accurate is your pH measurement?

Antom Technologies HOW ACCURATE IS YOUR pH MEASUREMENT?

This site is sponsored by Antom Technologies and ionode, in the interests of better pH measurement....

What if we said there's a good possibility that your pH electrode is wrong? Ready to put your pH electrode to the test ?

STEP 1			Place electrode in pH 6.88 buffer. Adjust meter to read pH 6.88.
STEP 2			Rinse electrode, and place in pH 4.00 buffer. Adjust meter to read pH 4.00
STEP 3			Accurately dilute 10mL pH 6.88 buffer to 100mL in a volumetric flask. Immerse electrode in diluted solution. You should read a pH of 7.06 +/- 0.02.

This test is based on that proposed by Illingworth (1981), and is similar to that contained in AS 2300.1.6-1989, which in turn references BS 2586. If your pH electrode has a porous reference junction and doesn't measure up to this simple test, then you need a new electrode.

If you work with dilute solutions (eg., natural waters, boiler feed water), or analyse sticky, gooey substances such as foods, emulsions, slurries or pastes, your electrode must pass this test if you want to obtain accurate results.

The answer to better pH measurement is to use an electrode with a clean, fresh, renewable reference junction. Electrodes with sleeve reference junctions are pre-eminent in this regard.

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