[NHCOLL-L:1292] RE: testing fluid solutions

[Simmons, John E]

Concerning the issue that "Ideally, we'd periodically replace the solution,
rather than just 'topping off'..." I don't agree.  We know that in alcohol
(which is a solvent) a lot of proteins, lipids, pigments and what have you
are extracted from the specimen.  This means that the fluid around the
specimen is, in effect, part of the specimen, too.  Unless this fluid
becomes unsuitable for storage (e.g., too acidic or so badly discolored that
it discolors the specimen), we should  not change it, but rather top it up.
For topping up, I recommend using the formula published by Sendall and
Hughes to preserve alcohol concentration (Sendall, K. and G.W. Hughes.
1996.  Correcting alcohol concentrations.  Society for the Preservation of
Natural History Collections Newsletter 11(1):6-7).
 
I agree with Julian's analysis of the formaldehyde-in-alcohol issue.  I
think his suggestion for staging specimens is very appropriate.  Here is
what I am recommending in the new edition of "Herpetological Collecting and
Collections Management":

Transfer of Specimens from Fixative to Preservative
It has long been customary to remove specimens from the field fixative,
rinse or soak them in water in open containers (sometimes for several days),
and then place them directly in storage-strength alcohol preservative
(Simmons 1995).  There are several problems with this procedure.  Damage may
result from soaking specimens too long in water.  Once formaldehyde is
replaced with water, enzymatic activity in the tissues may resume (Taylor
1981a) and the water may reverse the chemical crosslinks, permitting
autolysis to occur.  Specimens will swell as they absorb water during
rinsing or soaking and shrink once they are placed in an alcohol
preservative solution.  Some workers have suggested transferring specimens
directly from the formalin fixative solution to the alcohol preservative
(Fink et al. 1979).  This also has several drawbacks, including severe
osmotic shock in going from nearly 100% water to 30% water, and the quantity
of formaldehyde that is released into the alcohol preservative.
Formaldehyde in the preservative will drive the acidification of the alcohol
solution, which will decalcify specimens and cause more severe color
changes, as well as pose serious health risks for people working with the
specimens.

Based on the studies available on shrinkage, swelling, and other effects on
specimens during transfer (e.g., Jones and Owen 1987, Lai 1963, Lafromboise
et al. 1993; see discussion in Simmons 1995); and considering the effects of
osmotic pressure changes on tissues (Steedman 1976); a more gradual transfer
of specimens from a solution of near 100% water (e.g., "10% formalin") to
30% water (70% ETOH) is recommended.  Following the protocol of Laframboise
et al. (1993), I recommend using steps of approximately 20% to stage
specimens from 10% formalin or water solutions to 70% ethyl alcohol.

Trace Amounts of Formaldehyde in Preservative Solutions
It is difficult (and probably undesirable) to completely remove the
formaldehyde fixative from specimens fixed in 10% formalin by washing.  As a
result, there will most likely be some trace amounts of formaldehyde in the
alcohol preservative.  One study found these amounts to average 0.07% in one
collection (Simmons and Waller 1994).  Trace amounts of formaldehyde in
preservative solutions can be detected by using formaldehyde test strips.
Test strips can be made by following the instructions in Waller and
McAlister (1986), or a commercial formaldehyde test kit may be purchased
(see Appendix III).  Trace amounts of formaldehyde are usually insufficient
to affect the quality of the preservative, however, in some cases
formaldehyde and other sources of acid (e.g., label paper) have been shown
to acidify alcohol solutions (Andrei and Genoways 1999, Van Guelpen 1999).

Transfer of Specimens between Alcohols
Specimens should not be changed from one type of alcohol to another,
especially specimens on loan from other institutions.  Changing a specimen
from one type of alcohol to another, particularly from isopropanol to
ethanol, may cause significant shrinkage and other damage (Jones and Owen
1987) and significantly alter the body proportions of the specimens (Lai
1963).  If it is necessary to change specimens from one alcohol preservative
to another, follow the protocol of Laframboise et al. (1993).

References:
Andrei, M. A. and H. H. Genoways.  1999.  Changes in pH in museum storage
fluids, I-effects of Resistal paper labels.  Collection Forum 13(2):63-75.  

Fink, W.L., K.E. Hartel, W.G. Saul, E.M. Koon, and E.O. Wiley.  1979.  A
report on current supplies and practices used in curation of ichthyological
collections.  American Society of Ichthyologists and Herpetologists ad hoc
subcommittee report, 63 pp.

Jones, E.M. and R.D. Owen.  1987.  Fluid preservation of specimens.  Pp.
51-63 in Genoways, H.H., C. Jones, and O.L. Rossolimo (editors).  Mammal
Collection Management.  Texas Tech University Press, Lubbock.  iv + 219 pp.

Laframboise, S., R.M. Rankin, and M.M.L. Steigerwald.  1993.  Managing
change: alcohol transfer at the Canadian Museum of Nature.  Pp. 28-33 in
Snyder, A.M. (editor).  The 1992 American Society of Icthyologists and
Herpetologists Workshop on Collections Care and Management Issues.  ASIH.
52 pp.

Lai, Y-C.  1963.  Effects of several preservatives on proportional
measurements of the fat-headed minnow, Pimephales promelas.  M.A. thesis,
University of Kansas, Lawrence.  40 pp.

Simmons, J. E.  1995.  Storage of fluid preserved collections.  Pp 161-186
in Rose, C. L., C. A. Hawks and H. H. Genoways (editors).  Storage of
Natural History Collections: A Preventive Conservation Approach. Society for
the Preservation of Natural History Collections, x - 448 pp.  

Simmons, J.E. and  R.W. Waller.  1994.  Assessment of a fluid-preserved
Herpetological collection.  Pp. 11-15 in Snyder, A.M. (editor).  The 1994
American Society of Ichthyologists and Herpetologists Workshop on Collection
Care and Management Issues.  American Society of Ichthyologists and
Herpetologists, Albuquerque.  20 pp.

Steedman, H.F.  1976.  Miscellaneous preservation techniques.  Pp. 175-181
in Steedman, H.F. (editor).  Zooplankton Fixation and Preservation.
Monographs on Oceanography, 4.  The Unesco Press, Paris.  350 pp.

Taylor, W.R.  1981a.  Preservative practices: water in tissues, specimen
volume, and alcohol concentration.  Curation Newsletter No 2:1-3.

Van Guelpen, L.  1999.  Larval fish preservation:  ethanol acidity from
Byron Weston Resistall label paper.  Curation Newsletter  12:12-14.  

Waller, R. and D.E. McAlister.  1986.  A spot test for distinguishing
formalin from alcohol solutions.  Pp. 93-99 in Waddington, J. and D.M.
Rudkin (editors).  Proceedings of the 1985 Workshop on Care and Maintenance
of Natural History Collections.  Life Sciences Miscellaneous Publications,
Royal Ontario Museum.  v + 121 pp.

--John

John E. Simmons
Collection Manager, Natural History Museum
and
Coordinator, Historical Administration and Museum Studies Program
University of Kansas
Dyche Hall
1345 Jayhawk Boulevard
Lawrence, Kansas 66045-7561
Phone 785-864-4508
FAX 785-864-5335
jsimmons at ku.edu

-----Original Message-----
From: Panza, Robin [mailto:PanzaR at CarnegieMuseums.Org]
Sent: Tuesday, October 23, 2001 1:56 PM
To: 'nhcoll-l at lists.yale.edu'
Subject: [NHCOLL-L:1289] RE: testing fluid solutions


>>>Julian.Carter at nmgw.ac.uk> 01-10-16 4:27:00 am
...found using the Paar density meter of more benefit. The density readings
Robin gave are similar to my own results. <<<

What bothers me is that we put specimens in ethanol-water after fixing in
formalin.  Even after soaking, there's some formalin leaking into the
storage solution, so it's ethanol-water-formalin.  If formalin is heavier
than water and ethanol is lighter, how can a densitometer measure proof?
When the density reads 70%, is the ethanol concentration actually higher
because the water-formalin is denser?  How much formalin contamination is
"ok"?  

Ideally, we'd periodically replace the solution, rather than just "topping
off", so we'd be removing trace formalin and accurately measuring the
ethanol content, but who can afford to do that frequently?

Robin K Panza                         panzar at carnegiemuseums.org
Collection Manager, Section of Birds          ph:  412-622-3255
Carnegie Museum of Natural History       fax: 412-622-8837
4400 Forbes Ave.
Pittsburgh  PA  15213-4008  USA