Buffer precipitated??

[Kaj Stenberg]

Not being a chemist I do not understand why my buffer precipitated, any
help would be appreciated.

The buffer was:
20mM MOPS pH 7.5
200mM NaCl
2mM DTT

Clear and fine. I then added ZnCl2 (10mM) and a precipitate formed (pH
did not change). I assume the precipitate is zink-x. In that case adding
the zink as acetate salt won't help (?).
a) Why does it precipitate
b) how to get 10mM zink into the buffer

Thank you,
-- 
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Kaj Stenberg, Ph. D 
Department of Biosciences            tel. +358-9-708 59032
Division of Biochemistry             fax +358-9-708 59068
P. O. Box 56, Viikinkaari 5          e-mail kstenber at kruuna.helsinki.fi
FIN-00014 University of Helsinki     http://www.helsinki.fi/~kstenber/
Finland

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