Chemical & Engineering News Digital Edition ... - IMM@BUCT

CHIP CLARK/SMITHSONIAN INSTITUTION
alin’s cross-linking mechanism may hinder
its DNA-preserving ability.
Perhaps the most significant drawback
of traditional preservatives is a dearth of
scientific records about them, making it
tough to rationally develop safer, better
alternatives, argues John E. Simmons, an
independent museum consultant and former
collections manager at the University
of Kansas’ Natural History Museum. AFIP
keeps records on the formulas of its preservatives,
and researchers there were engaged
in an active research program in preservation
during the 1940s and ’50s, Spatola says.
However, collections donated to AFIP from
elsewhere are less stringently cataloged.
Simmons contends that research programs
like AFIP’s have historically been
the exception rather than the rule. “In fluid
preservation the tradition has always been
to just try something out,” he says. Many
published preservative formulas reflect
traditions handed down in a given lab,
without much testing of specific variables
to look for improvements, Simmons says.
“There is a general preservation procedure
in place, but the people who prepared specimens”
in the past “often had their own
way of doing things,”
Dhody adds.
PICKLED Millions
of specimens are
kept in alcohol at
the Smithsonian’s
National Museum
of Natural History’s
storage area near
Washington, D.C.
The Smithsonian’s
giant squid
bucks that tradition—it
is a model of
meticulous record
keeping. Photographs
and extensive
documentation chronicle how the squid’s
soft body tissue was injected with formalin
by experts in northern Spain, where the
squid was caught. They also describe the
squid’s journey stateside, where it was
submerged in Novec and where the record
keeping continues apace.
NOVEC 7100 comprises two inseparable
isomeric hydrofluoroethers, methyl
nonafluorobutyl ether, CF 3 (CF 2 ) 3 OCH 3 ,
and methyl nonafluoroisobutyl ether,
(CF 3 ) 2 CFCF 2 OCH 3 . The fluid differs from
both formalin and ethanol in that it’s neither
a cross-linking agent nor a preservative, says
David A. Hesselroth, a 3M chemist. Instead,
Novec is a nonflammable, nontoxic, and
ozone-friendly storage medium for alreadypreserved
specimens, he says. Novec products
have been in use since the mid-1990s,
when they were developed to replace ozonedepleting
chlorofluorocarbons in applications
such as cleaning electronics.
Novec works by forming a chemical
envelope around preserved specimens,
explains Joseph Koch, marketing manager
for 3M’s electronics materials division. The
fluid has very low surface tension, so “it
completely spreads around a specimen’s
surface, displacing water in all the nooks
and crannies,” he says. Novec’s low water
solubility keeps the fluid from getting
cloudy over time, and it doesn’t leach color
from specimens the way alcohol does.
Musteen can vouch for that. “You can
still see the squid’s brick-red skin as clearly
as on the day it was caught, and the fluid
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WWW.CEN-ONLINE.ORG 27 NOVEMBER 3, 2008