anhydrous ampicillin

Richard Vernell rjv at
Tue Nov 4 17:48:00 EST 1997

The anhydrous ampicillin will dissolve readily in 10 mN NaOH.  I do this
routinely.  While I am not familiar with the structure, there must
be an acidic functionality on the ring that is titrated... only a
guess... but then it would be called free acid and not necessarily
anhydrous? Hmmmmm  None the less, it works!

Cornelius Krasel (krasel at
wrote: : colossus... <s535290 at> wrote:
: > I just got some anhydrous ampicillin to test the minimum inhibitory
: > concentrations of some bugs, but I was told to make a salt using some 
: > NaOH in order to dissolve it. Are there any of you who have ever had to
: > do this ?  I wasn't even told how concentrated the NaOH should be, or what
: > amounts to use. I've used the regular ampicillin which just dissolves in
: > water but this anhydrous stuff is the one that one is supposed to use when
: > testing MICs. It just doesn't dissolve like the regular stuff does.

: I've never done this, but it doesn't make sense to me. Basically, the
: "normal" ampicillin is the Na-salt of the "anhydrous" one. Therefore,
: correcting for the additional Na should do the trick with the "normal"
: amp.

: --Cornelius.

: -- 
: /* Cornelius Krasel, U Wuerzburg, Dept. of Pharmacology, Versbacher Str. 9 */
: /* D-97078 Wuerzburg, Germany   email: phak004 at  SP4 */
: /* "Science is the game we play with God to find out what His rules are."  */

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