[RASMB] A disturbing label..

[Matthew Hockin]

Since everyone here seems in some way connected to chemistry and we all rely
on the preparation of accurately made solutions I have become increasingly
concerned with a trend that now seems to be entrenched.

I went to make some new solutions and discovered that Sigma is now leaving
the MW of the compound off a number of its chemicals.

Read that again, its not a typo.  I called them and the individual I spoke
to was unsure why this was the case but suggested it may be part of an
effort to move to a uniform label convention with more safety information,
which I found completely unconvincing.  Do yourself a favor and look at some
of your recent orders and check to see if this is the case, maybe we just
got a bad batch as all ours come from the St. Louis facility.  Our bottles
of EDTA di-sodium salt, Potassium Acetate, and Potassium Chloride are all
missing this vital information (and I did not bother to look at more).  Not
sure how to use the bottle without it, although I am now noting this as very
common, I believe this started quite some time ago but was less frequent and
I wrote it off to error.  A simple pen fixes the issue but really, are we
now supposed to pretend that MW is an inconsequential detail to be looked up
each time its needed, to look up the MW of every chemical we order and
appropriately label the bottle, or to otherwise memorize some 100 or 200 or
more of the more commonly used chemicals?

Maybe its just me, but nothing irritates me more than to see a protocol with
g/L of compounds neglecting molar concentrations.  I suppose if this is how
you structure things the MW is indeed inconsequential, but its really
dangerous as the hydration state of the salt suddenly becomes a vitally
important part of the protocol as well as being quite exacting in providing
the exact formula, simple molar concentrations fix this for the most part
but do require that small detail of MW.  If this bugs you and you find it to
be the case on your new and recent Sigma orders it might be worth a phone
call, maybe if enough scientists bug them they will return to labeling
chemicals as they have been, i.e. as a chemistry reagent with useful
chemical information.

Matt Hockin
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