Bob Ludwig ludwig at
Tue Jun 8 17:14:11 EST 1993

RE: Gentamicin sulfate

We have observed a >50% decrease in the potency of  two, different lots of gentamicin sulfate
recently purchased from Sigma Chemical Co. We have discussed this matter with Sigma, who
have been cooperative. As gentamicin costs some US$ 120 per 1 gram lot, this difference in
bioactivity is quite meaningful. 

Sigma, of course, simply resells this product, and trusts the bioassay of their supplier. 

If anyone else has had a similar, recent experience, or knows of an alternative vendor (with a
different primary supplier) with a more potent product, we would appreciate receiving this

Bob Ludwig
Prof. molecular biology & biochemistry
Sinsheimer Laboratories
University of California
Santa Cruz, CA 95064

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