Mike, I have a single chamber Spect. with a pair of matched cuvettes. When I bought it, I went to the library and got a video by UCLA on the use of spectrophotometers .(worthwhile).
I bought an Alfa standard Ag 1000ug/ml. The Ag in 5% HNO3. This is ionic silver. The prodecdure is to make a series of dilutions 10, 20, 30, 40, 50, and 60 ug/ml (ppm) 1. Place 1 cc of silver solution in a 50 cc graduate, and fill to 50 cc with RO or DW. 2. Mix the two pillows of Hach chemicals in a dry 1" dia. test tube then add the mix of item #1. 3. Place the bleach powder in the "blank" cuvette, and fill to the 25 cc level. wait 2 minutes for reaction to complete. 4. Place "blank" in test chamber and zero and balance to full scale. 5. Place the remainder of step #2 in the other cuvette, zero the meter then read the % absorbance at 550 nm. light frequency. Repeat for all of the dilutions. Plot this data as % abs on the "Y" axis and the concentration on the "X" axis. If the work is accurate there will be a straight line through the data points and the 0,0 point on the axis'. I had a perfect line from 0,0 through the 50 ppm dilution. I calculated the slope of the line as 22 (%abs/ ppm) So I use the procedures #1 to #5 to get a %abs reading wich is then multiplied by 22 for a 50/1 dilution. I have on ocassion gone as high a 200/1 to be able to read the concentration. The spec. will not read Ag0. To get that I have had AA's made for total silver and them they do an ionic test as was done by Frank Key when he reported that the sample was 99.4% ionic and 0.6% particulate. I have had tests done by Kimball labs (now retired) as well as Stephen Quinto. This test does not read Ag0 only Ag+. I hope this clarifies the issue as what I am doing is the plating industry standard for silver lost in wash water. "Ole Bob": -- The silver-list is a moderated forum for discussion of colloidal silver. Instructions for unsubscribing may be found at: http://silverlist.org To post, address your message to: [email protected] Silver-list archive: http://escribe.com/health/thesilverlist/index.html List maintainer: Mike Devour <[email protected]>
