Developer Starter for Xtol/EcoPro?

[Mr Bill]

I have done probably 100,000 chloride determinations, Corning pH meter in positive mV scale, silver billet and double junction reference electrode, titration with AgNO3 to a 323mV endpoint. There were no bromides or iodide present. (Livestock supplements)
I have no equipment any longer.

Can one distinguish Br- from Cl- with a potentiometer? Silver billet/bar etc???

100,000 of em... pretty impressive. Just a point of curiosity - was that to a fixed endpoint (323 mv)?

In the photo developers there are separate inflection points for bromide and iodide (and presumably chloride, if it were there). You had to record data for the entire titration and find the inflection points after the fact, more or less. As I recall something like a 15 or 20 minute (or more) procedure for the titration, and if you went too fast and didn't precisely get the inflection point then you had to do it over. My memory is really fuzzy but as I recall an analytical method, if there were any confusion about what you were seeing you could add some further known amount of one halide to move THAT inflection point away from the others. To clarify the methods, Kodak's H-24 motion picture manual has similar analytical methods.

Regarding chloride, I recall switching from Ektaprint 2/3 (older color paper process) to RA-4 (photo paper) which is silver chloride based. It seemed like a minor miracle that the process activity was no longer super sensitive to replenishment errors. Which suggests that chloride ion barely restrains the developer. So this is why I tend to disregard the KCl listed as being in the starter solution - I doubt that it will have much restraining effect (at least compared to KBr). Of course, I could wrong... only actual testing will answer this conclusively.

 

[mshchem]

That stuff is horrible.

Do you add Cholula Hot Sauce?

 

[mshchem]

100,000 of em... pretty impressive. Just a point of curiosity - was that to a fixed endpoint (323 mv)?

In the photo developers there are separate inflection points for bromide and iodide (and presumably chloride, if it were there). You had to record data for the entire titration and find the inflection points after the fact, more or less. As I recall something like a 15 or 20 minute (or more) procedure for the titration, and if you went too fast and didn't precisely get the inflection point then you had to do it over. My memory is really fuzzy but as I recall an analytical method, if there were any confusion about what you were seeing you could add some further known amount of one halide to move THAT inflection point away from the others. To clarify the methods, Kodak's H-24 motion picture manual has similar analytical methods.

Regarding chloride, I recall switching from Ektaprint 2/3 (older color paper process) to RA-4 (photo paper) which is silver chloride based. It seemed like a minor miracle that the process activity was no longer super sensitive to replenishment errors. Which suggests that chloride ion barely restrains the developer. So this is why I tend to disregard the KCl listed as being in the starter solution - I doubt that it will have much restraining effect (at least compared to KBr). Of course, I could wrong... only actual testing will answer this conclusively.

This was a salt assay (chloride). Titrated to 323 millivolts. Titrated with 1/10 molar AgNO3. I would buy Kodak silver nitrate crystals in 1 pound (454g) brown glass bottles. 20 pounds at a time. It was just under 100 dollars a pound.

 

[Mr Bill]

That sure is a lot to be dripping through a burette.