Re: [CH] Need Advice: pH Testing of Hot Sauces
Steve (snearman@erols.com)
Tue, 19 Jan 1999 04:24:34 -0500
As for the digital pH meter being "quite precise", you may want to do a
little more checking before the purchase. I have a "Cole Parmen" model
5941-00, made in Singapore. Think I paid about $65 for it 10 years ago. Any
way they are not as easy and quick to use as you may think. To be accurate
you need to calibrate it each time you use it and need a source of acid
that is known to be the same as what you want your final solution to match.
It is recommended that you check it at least once a day. They tend to
drift towards what you are checking and can give false readings. Normal
drinking has a pH of about 7 if you calibrate it to 7 when testing normal
water and the water in not 7 then a reading of 4 will not be 4 and may not
read 4 correctly even it the water is 7 (that's a far spread). After using
for sever hours in the 2-3 range (acid) then checking normal water again it
will read lower, say 6.4-6.8. If checking alkaloid solutions in the 11-12
range the meter will seat 7.6-8.0 in drinking water. It also needs to be
kept wet with your test base solution to maintain accuracy. You can use a
vinegar as your test base if you have confidence that it is truly 5% The
spread between 5 and 4 should not give much of a false reading. They are
advertised as easy to use and read, but "now you know the rest of the
story"...
Steve
>I just talked to a genetleman at a scientific supply company, who told me I
>needed to buy a digital pH meter (cost: $85.00, plus shipping).
>The salesman explained that the meter was quite precise (in .1 increments
>‚ which is good), ...
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