Difference between revisions of "Fluid Collection Monitoring"
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| − | Ethanol and water and mixed together form an azeotrope rather than a true solution, resulting in asymmetric evaporation rates. Ethanol evaporates faster from mixture than water, diluting preservative strength over time. When concentrations fall below desired levels, specimens are at risk of degradation. Ethanol’s preservative qualities diminish at concentrations <60%, and specimen cell autolysis, decomposition and deterioration may occur (Notton 2010). At low concentration strengths (<50%), ethanol loses its antiseptic properties, promoting bacterial and fungal growth (Waller and Strang, 1996). Specimens exposed to air from dropping preservative levels are vulnerable to desiccation, salt and solute deposition, and increased risk of mechanical injury. | + | Ethanol and water and mixed together form an azeotrope rather than a true solution, resulting in asymmetric evaporation rates <ref>Simmons, John E. 2014. Fluid Preservation: A Comprehensive Reference. Lanham, MD: Rowman & Littlefield, 347 pp. <ref>. Ethanol evaporates faster from mixture than water, diluting preservative strength over time. When concentrations fall below desired levels, specimens are at risk of degradation. Ethanol’s preservative qualities diminish at concentrations <60%, and specimen cell autolysis, decomposition and deterioration may occur (Notton 2010). At low concentration strengths (<50%), ethanol loses its antiseptic properties, promoting bacterial and fungal growth (Waller and Strang, 1996). Specimens exposed to air from dropping preservative levels are vulnerable to desiccation, salt and solute deposition, and increased risk of mechanical injury. |
==Topping Up== | ==Topping Up== | ||
Revision as of 17:35, 8 May 2019
Statement of Purpose
These links and documents contain information about best practices for monitoring fluid collections in natural history collections.
Introduction
Fluid collections should be monitored on a regular schedule to prevent excessive preservative evaporation, detect faulty seals on storage containers or changes in the quality of the preservative, and to maintain collections at desired concentration levels. Monitoring intervals will vary based on staff resources as well as the environmental stability within a particular collection store, however, a general guideline is to monitor fluid collections every six months.
Preventing Evaporation
Preservative evaporation within containers steadily occurs in any collection environment. Several measures can be implemented to slow evaporation rates, such as buffering the collection space from fluctuations in temperature and humidity through use of environmental controls, and placement of the store within an interior space rather than adjacent to exterior walls that are more vulnerable to climactic variation. Use of best practice housing materials can also reduce within-jar evaporation rates. Polypropylene lids are less prone to embrittlement than harder plastics such as Bakelite, and can be lined with a polyethylene or Teflon insert to act as a mild oxygen barrier. Use of a film layer (e.g., Teflon, Parafilm) between lid and container or Telfon tape wrapped along the threading on jar mouths can also slow evaporation rates [1]. Although common, rubber gaskets used with wire-bail jars are not recommended due to the fact that they may dissolve or embrittle when coming into contact with alcohol, risking contamination of specimens and preservatives in addition to negating the efficacy of the seal.
Risks of Evaporation
Ethanol and water and mixed together form an azeotrope rather than a true solution, resulting in asymmetric evaporation rates Cite error: Closing</ref> missing for <ref> tag- ↑ Simmons, John E. 2002. Herpetological Collecting and Collections Management. Rev. ed. Society for the Study of Amphibians and Reptiles Herpetological Circular 3. New York: Taylor and Francis.
