Hello Mike, What I describe is theoretically possible, but quite large and technical project in practical manifestation. I would not know how to prepare the color standards. They cannot be made with the reagents used in the test, because the final colors are unstable, particularly in bright light. The old guys who know how to do that probably disappeared with the advent of modern instrumentation. The color is magenta-purple and stronger chroma than dilute grape juice or wine. Perhaps a series of dilutions of potassium permanganate.
If you make the investment in labware necessary to do the chemistry--- probably about 3 to 4 hundred US, depending on the accuracy of the glassware, why not shop the net for a used spectrophotometer? I have seen several which will do the trick for about 400. You can get excellent really high-end but obsolete stuff for a bit more. The problem with all this type of equipment is that it often costs more to align and calibrate it that the machine itself. For example: my Spectronics 20 cost 400, freshly aligned by an experienced and qualified technician. Send one to Spectronics, and they will totally spiff it up for 500. That includes any repair short of it being run over by a truck or such. There is no single reagent that I know of that you can just titrate into any Ag solution and match a color, like the variety of acid-base indicator solutions or paper dip-tapes. I have just begun recording mS of my batches to plot against analyzed mg/L, more out of curiosity than anything else. Bruce Marx told me a couple of years ago that he had very poor correlation. When I get enough to make a graph I'll post it. I do not know enough about how ISE devices work to know if they will measure the PPM of CS. The following is my not-well-informed conjecture only: If they measure the charge of each clump, and each clump has a positive charge ,[ +1 not monatomic ,--- Bruce Marx---or +1, +2,or +3 ---Ivan---] not directly related to the number of atoms in the clump, then the meter will read the number of charged particles per unit solvent, but not the total amount of silver, i.e., the total number of silver atoms. If the ISE reads the valence charge of monatomic silver ions only they will still not measure the total silver present unless it is all monatomic ions, because of the above. If they read monatomic silver and count it as "1" and also read the charge on a clump of several ?---hundred, thousand, million---atoms and count it as "1, or 2, or 3" depending on the charge, it will be equally useless in measuring total PPM. And, knowing PPM, even with precision, is not very helpful in terms of effectiveness it you don't know anything about particle size. And I---still---without proof---tend to think that the smaller particles are more potent, and more of them means greater chance of contact with a pathogen. The latter---more chance of contact--- is very probably true. Comments on the ISE stuff solicited. We are also into the realm of how many Angeles can dance on the head of a pin: how many silver bits does it take to destroy [Can't kill 'em; my microbiology text says they aren't alive] one herpes simplex viron? Will a huge clump with a big charge do it, or is a single atom best? Hach: In the United States 1-800-227-4224 Outside: 970-669-3050 They will send you "Products for Analysis" and "Water analysis Handbook" if you ask, Free. Lots of good practical information and tweaky toys. [Forgive me Hach, but some of these folk may actually buy some stuff from you. The last guy I turned on to your company buys tons of silver reagents] tootles... James Osbourne Holmes [email protected] The Worlds Foremost Producer of Ironic [sic] Silver -----Original Message----- From: M. G. Devour [SMTP:[email protected]] Sent: Thursday, November 11, 1999 12:03 PM To: [email protected] Subject: RE: CS>wet chem James wrote: > What you are describing is the way it is done. You react the silver > with reagents which produce a color whose intensity varies with the > concentration available silver. ... > All it would take is a high-accuracy set of printed color patches > to get you in the ballpark with the Hach reagents. I think you > could judge it certainly to within 2 PPM and possibly within 1 PPM. Well, I guess I shoulda asked this question more often. You guys have been around for months now and I didn't know you knew! <grin> Do you have any contact info for Hach? I should investigate. Be well, Mike D. [Mike Devour, Citizen, Patriot, Libertarian] [[email protected] ] [Speaking only for myself... ] -- The silver-list is a moderated forum for discussion of colloidal silver. To join or quit silver-list or silver-digest send an e-mail message to: [email protected] -or- [email protected] with the word subscribe or unsubscribe in the SUBJECT line. To post, address your message to: [email protected] List maintainer: Mike Devour <[email protected]>
