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From: "Tauno Voipio"
References: <3D905023.firstname.lastname@example.org> <email@example.com>
Subject: Re: ph meter using PIC??
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Date: Wed, 25 Sep 2002 09:58:38 GMT
NNTP-Posting-Date: Wed, 25 Sep 2002 12:58:38 EET DST
Organization: Sonera corp Internet services
"andy" wrote in message
> tom wrote in message
> > I wonder if there is a good infrared spectrometer way to do
> > this pH measurement? I was looking into that about 15 years ago
> > and never found the perfect spectral wavelength for it. The idea
> > here is that the aquarium liquid is sampled for its absorbtion
> > in a narrow band of the infrared. This band would be at a
> > wavelength of absorbtion of some indicator compound that is added
> > to the water in a known concentration. The abosorbtion of the
> > indicator compound would change, dependant on the pH. The
> > absorbtion would indicate the pH. This would allow a flow-through
> > pH meter that didn't use the old method of a semipermiable
> > barrier.
> > I saw some flow-through spectrometers being sold several years
> > ago. They didn't mention the ability to do pH, they were
> > mostly for juding organic matter content of the water.
> I was working on a flow through system years ago that was designed to
> measure organic matter in water. I beleive the same company was
> concurrently developing a similar method of measuring PH. Don't know
> if they succeeded. I honestly thought they were on to a winner but
> they don't seem to sell either system as yet. Maybe they are still
> working on it..
For a different approach to pH measurement, see:
tauno voipio @ iki fi
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