I will have to get with Bruce on this. He is the one that put me onto Hach in the first place and at the time was using digestion. The method he used required sulfuric acid, and produces silver sulfate which is almost insoluable, so I went back to Hack and they gave me a procedure that uses Nitric Acid only.
I am calling Bruce now to see if he has changed his procedure. Marshall James Osbourne, Holmes wrote: > If I may interject.... > > Using the Hach silver chemistry, Bruce found that the digestion process, > which involves all sorts of nasty stuff, produced erratic results with CS. > This was verified by a Hach tech rep. present at Bruce's lab. > > They decided that the process works reliably without the digestion. That > is the method which I use to measure mg/L-PPM. I think it is also the > method used by Bob Berger. Bob, Bruce, and myself have very close results > with the same samples. > > If someone is doing the Hach test with digestion, can I send you a sample > to see how well they correlate. I will reciprocate with your sample if you > like. > > I have yet to get an ISE [R&D funding limitations]. I think the "charge > per cluster" theory is probably correct. Has anyone ever discussed this in > detail with an ISE manufacturer? > > James Osbourne Holmes > [email protected] > > -----Original Message----- > From: Marshall Dudley [SMTP:[email protected]] > Sent: Tuesday, October 12, 1999 9:19 AM > To: [email protected] > Subject: Re: CS>Graph comparison: ppm & conductivity. > > 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. 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. > > 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. > > Thanks, > > Marshall > > -- > 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]>
