----- Original Message ----- From: Marshall Dudley <mdud...@execonn.com>
> Ivan Anderson wrote: > > > PPM reading was supplied by a silver Ion Selective Electrode. > > Water was Purified Water BP and read 1uS before electrolysis. > > Prior to purchasing our spectrophotometer and silver kit, I check into using a > silver ion selective electrode for measuring ppm. Thats odd, on the first of July you wrote: "I am intrigued by this device. Do you know where on the web I can find more information on it? We may want to acquire one to improve our testing ability. I have done some searching on the net for "silver ISE", but have not found any references." > I was told that it measures > the number of ions (amount of charge) assuming the normal mobility of silver > ions, and that silver colloid would not produce a correct measurement due to > there typically being less charge on each particle than the number of atoms in > the particle, and due to the mobility being different than for one ion. The ISE does not measure the number of ions but rather the activity of the ions in the sample in question. In biology this is the most important question. This activity can be can be extrapolated to the concentration of the sample by the use of appropriate standards. The mobility of the ions or particles does not really enter the equation as the sample should be stirred briskly, just short of creating a vortex. It is correct that colloids may be comprised of both charged and uncharged atoms, but as my readings to date have been within 2ppm of total recoverable silver assays as conducted by independant laboritories, I am confident that my readings are accurate, and that the charge on the colloid is probably the sum of the atoms it is comprised of. > To use it properly one has to digest the silver so that you have silver > nitrate first, then use the probe on the residual silver nitrate. This is > exactly the same process I have to go through with the spectrophotometer for > ppm measurements. > > I was wanting to verify that you were indeed digesting the colloidal silver > before using the probe. If so this is a very interesting set of curves. Well, no I don't use nitric acid, and I notice from later messages that you probaby don't need to either. Perhaps you can tell me about the method you are about to try, maybe it will work for the ISE as well, and we can swap a bit of data. > Thanks, > > Marshall Regards - Ivan -- 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: silver-list-requ...@eskimo.com -or- silver-digest-requ...@eskimo.com with the word subscribe or unsubscribe in the SUBJECT line. To post, address your message to: silver-list@eskimo.com List maintainer: Mike Devour <mdev...@id.net>
