dbell@cup.portal.com (David J Bell) (08/11/90)
I'm looking for an inexpensive method of electronically measuring the concentration of copper ion in a water solution. I don't need great accuracy, even +/- 5 or 10% will be adequate. The level I'm reading will be on the order of 2 ppm, in the presence of a bunch of other "junk". I'd expect to get a low-level voltage or current which I could amplify and read with an A/D and microprocessor for a simple process control application. Long term stability of maybe a few percent and low cost are prime factors, with ruggedness not far behind... Thanks! Dave dbell@cup.portal.com
larry@kitty.UUCP (Larry Lippman) (08/11/90)
In article <32660@cup.portal.com>, dbell@cup.portal.com (David J Bell) writes: > I'm looking for an inexpensive method of electronically measuring > the concentration of copper ion in a water solution. I don't need > great accuracy, even +/- 5 or 10% will be adequate. The level I'm > reading will be on the order of 2 ppm, in the presence of a bunch > of other "junk". I'd expect to get a low-level voltage or current > which I could amplify and read with an A/D and microprocessor for > a simple process control application. Long term stability of maybe > a few percent and low cost are prime factors, with ruggedness not > far behind... You can measure copper (more specifically cupric) ion concentration using an specific ion electrode, available from Beckman, Corning, Orion, etc. There is, however, a problem of interference in the presence of mercury, silver, chloride and certain other ions. You will need a high input impedance electrometer circuit, as is used for pH measurement. With some care, such a circuit is not difficult to build for measurements which do not require great accuracy. Various application notes from vendors such as Analog Devices, Burr-Brown, etc. should give you example circuits. You won't like the price of the specific ion electrode, however. You're probably talking about $ 200.00, minumum. There are other methods of measuring specific ion activity, such as voltammetry, polarography, etc., but automatic interpretation of such measurements would require a microprocessor and a potential control device (potentiostat) under program control. Simply stated, you probably don't even want to know about these options due to their complexity. Larry Lippman @ Recognition Research Corp. "Have you hugged your cat today?" VOICE: 716/688-1231 {boulder, rutgers, watmath}!ub!kitty!larry FAX: 716/741-9635 {utzoo, uunet}!/ \aerion!larry