Dave,

        In a former life I worked a bit with Ni-nitric acid reaction.  You
will find [counterintuitively in my opinion] that dilute nitric acid will
be more reactive than concentrated nitric acid, so be careful.

>Hello all,
>  I have been having problems with some of our new nickel tubes being used
>in a miniaturized conventional fluorination line for small (3mg) Qz
>samples. We have contamination problems, apparently from the machining and
>welding and I would like to know if users have followed a particular
>clean-up procedure. One that was suggested to me is 'nickel passivization'
>-- apparently a series of nitric acid treatments. This supposedly removes
>surface gunk and renders surfaces even more inert than machined nickel. Any
>observations about whether this is a good idea or not?
>  It seemed to me that the BrF5 would do a pretty good cleanup job after a
>standard solvent series, but I think the welding was done with a good deal
>of machine oil on the tube bore at the time. We now get high (>100%) yields
>in about 1/3 of our vessels and the d18-O values are too negative.
>
>  Many thanks for any suggestions.
>
>- David
>
>
>               David Dettman          [log in to unmask]
>               Dept. of Geosciences   ph. (520) 621-4618
>               Univ. of Arizona       FAX (520) 621-2672
>               Gould-Simpson Bldg.
>               Tucson, AZ 85721



********************************
Steve Nelson
Dept. of Geology
S389 ESC
Brigham Young University
Provo. Utah  84602

voice:  1-801-378-8688
FAX:  1-801-378-8143

"INTEL INSIDE" is a warning label
*********************************