We could save some money and get quicker results if some of us could do our own ppm testing. Here's a couple of ideas I'd like to discuss and, hopefully, refine enough to make work.
The first idea is to evaporate a quantity of CS to be tested, say 100 ml (1/10th of a liter), and weigh the residue. 100 ml of a 20 ppm CS will leave 2 milligrams of residue. To get resolution to 1 ppm would require sensitivity to 1/10th of a milligram. So, ideally, you'll need access to an analytic balance sensitive to tenths of milligrams. This is a cut above your most common lab balances which will only handle milligrams. This type will typically have the measuring pan in a glass enclosure to stop drafts from effecting it. Otherwise you'd have to evaporate a much larger sample. I see putting the CS in a bag, bottle or funnel and allowing it to drip slowly onto a piece of absorbent paper. The paper would be held with clips over a heatlamp or hot air blower to evaporate the water. If you can get hold of some IV drip fittings you'd have the ideal setup, but I assume we could kludge up something with more common materials as well. The paper would need to be weighed before and after, and the results would be the difference between the weights. Now, right off, there are problems with this method. One is taking care that body oils and dust don't contaminate the paper and cause it to weigh more than it is supposed to. You can take care to handle the paper with gloves or tweezers, and perhaps enclose everything to minimize accumulation of dust. Another problem is knowing the exact state the silver is in when you're weighing it. Is it pure silver? Silver oxide? We could try using a few drops of nitric acid to "digest" the silver to form silver nitrate, which is one of the few silver compounds that is readily soluble in water. Now of course, we'd have to find out how the left over acid reacted with the paper. It would be easy to do a test with just the nitric acid in distilled water, and see how much weight the paper gained, if any. If all the nitrate hangs around then we *might* just be able to subtract it out and call the balance silver. The chemistry could prove to be more complicated, however. Which brings us to the *other* possibility, which is an entirely chemical assay that uses pH or some other characteristic with reagents and an indicator to standardize and visualize the reaction and allow you to measure the silver present by quantity required. If anyone knows a chemist who could help us with that it could save us a lot of effort. So here are some ideas. If I've convinced you an in-house ppm test would be useful, I hope you'll help me get one of these ideas working, or suggest another. 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]>
