[kyleasdfjkl]

doing an extended essay...and am stumped on determination of aluminum...

experiment involves analyzing the amount of leeching from aluminum bottles, with the use of acids, but even the controls are not able to be reliably analyzed.

am currently using EDTA with zinc back-titration and eriochrome black TS as colorant, and ph 10 buffers...

is there something that is wrong with my materials? or procedural suggestions? specific problem is that end point is not at all clear plus the fact that when back-titrated, it goes over the original EDTA amount...

any help would be great...thx

[Borek]

Check this procedure description, perhaps it will give you some idea: EDTA titration of aluminum.

[kyleasdfjkl]

instead of ammonia...would it be acceptable to use NaOH...?  or would the sodium block the aluminum or zinc...?  or would it be ok if i had a known amount of NaOH?