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<div>Dear Joachim,</div>
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<div>When a buffer like borax or a humectant like glycerol is added to ethanol 70 it might indeed significantly change the density of the fluid. However, dissolved animal fats and small excretions from the body likely lead to only a very slight offset in density.
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<div>In ethanol just about 2% of animal fat can dissolve, which will give a very minimal change in the density of the fluid (<1% EtOH), also because animal fat itself has a density which is in the same range as that of ethanol 50-60%. Also, most organic salt
excretions from the body don't dissolve very well in ethanol 70. <br>
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<div>Therefore, I believe density measurement by hydrometer, by digital density meter, or by using the Alcomon Indicator System are sufficiently accurate, convenient and very useful tools in collection management of fluid preserved specimens.<br>
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<div>Kind regards,</div>
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<div>Dries<br>
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<p class="MsoNormal"><span style="font-size:8.0pt; font-family:"Verdana","sans-serif"" lang="NL"><br>
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<p class="MsoNormal"><span style="font-size:8.0pt; font-family:"Verdana","sans-serif"" lang="NL">Andries J. van Dam | conservator<span style="color:#FF8000"></span></span></p>
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<p class="MsoNormal"><span style="font-size:8.0pt; font-family:"Verdana","sans-serif"" lang="NL">Museum of Anatomy | Leiden University Medical Center | Building 3 (V</span><span style="font-size:8.0pt; font-family:"Verdana","sans-serif"" lang="EN-US">3-32)</span></p>
<p class="MsoNormal"><span style="font-size:8.0pt; font-family:"Verdana","sans-serif"" lang="EN-US">P.O.Box 9600 | 2300 RC Leiden | The Netherlands</span></p>
<p class="MsoNormal"><span style="font-size:8.0pt; font-family:"Verdana","sans-serif"" lang="EN-US">Visiting address: Hippocratespad 21 | Tel: +31 (0)71 52 68356 | E-mail:
</span><span style=""><a href="mailto:A.J.van_Dam@lumc.nl" target="_blank"><span style="font-size:8.0pt; font-family:"Verdana","sans-serif"; color:blue" lang="EN-US">A.J.van_Dam@lumc.nl</span></a></span><span style="font-size:8.0pt; font-family:"Verdana","sans-serif"" lang="EN-US"></span></p>
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<p class="MsoNormal"><span style="font-size:8pt; font-family:Verdana,sans-serif" lang="EN-US">Scientific associate</span><span style="font-size:8.0pt; font-family:"Verdana","sans-serif"" lang="EN-US"> | Natural History Museum London |
</span><span style=""><span style="font-size:8.0pt; font-family:"Verdana","sans-serif"; color:blue" lang="EN-US"><a href="http://www.nhm.ac.uk/" target="_blank">http://www.nhm.ac.uk</a></span></span></p>
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<div id="divRpF781802" style="direction: ltr;"><font size="2" face="Tahoma" color="#000000"><b>From:</b> Nhcoll-l [nhcoll-l-bounces@mailman.yale.edu] on behalf of Joachim Händel [Joachim.Haendel@zns.uni-halle.de]<br>
<b>Sent:</b> Friday, May 29, 2020 8:16 AM<br>
<b>To:</b> irenefinkelde@gmail.com<br>
<b>Cc:</b> nhcoll-l@mailman.yale.edu<br>
<b>Subject:</b> [MOGELIJK SPAM ! *****] [Nhcoll-l] Antw: Re: Test for formalin<br>
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<div>Hi all,<br>
Dear Irene,<br>
<br>
Thanks very much for the interesting information.<br>
<br>
I heard about the use of digital density meters and I also know museums and collections that work with such devices.<br>
But I am still sceptical about this.<br>
What about the organic components, which are dissolved out of the preparations by the alcohol (fats, dyes, stomach contents of small animals ...)<br>
In this case it is no longer a pure water-alcohol solution and the density datas are falsified.<br>
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Allthe best<br>
<div>Joachim</div>
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<div><font size="2" face="Arial, sans-serif" color="#949494">-- </font></div>
<div><font size="2" face="Arial, sans-serif" color="#949494">Joachim Haendel</font></div>
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<font size="2" face="Arial, sans-serif" color="#949494">Center of Natural SciencesCollections<br>
of the Martin-Luther-University<br>
- Entomological Collection -<br>
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Domplatz 4<br>
D-06099 Halle (Saale)<br>
Germany<br>
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Phone: +49 345 - 55 26 447<br>
Fax: +49 345 - 55 27 248<br>
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<div><font size="2" face="Arial, sans-serif" color="#949494">Email: joachim.haendel@zns.uni-halle.de</font></div>
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>>> Irene Finkelde <irenefinkelde@gmail.com> 29.05.20 3.09 Uhr >>><br>
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<p class="MsoNormal" style=""><font style="" face="trebuchet ms, sans-serif" color="#00a389">Hi All</font></p>
<p class="MsoNormal" style=""><font face="trebuchet ms, sans-serif" color="#00a389"> </font></p>
<p class="MsoNormal" style=""><font face="trebuchet ms, sans-serif" color="#00a389">The paper test suggested by Dries and the NIWA test with marker, which bleeds in alcohol, are great because they are quick and simple – but they do not give quantitative results
of how much formalin/formaldehyde is in the fluid preservative, nor the concentration of the alcohol solution. For your purposes Mandy, this may not be necessary, but I thought I would share some methods for quantitatively determining formalin/formaldehyde
concentration in case anyone else on the list-serv is also looking for methods. </font>
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<p class="MsoNormal" style=""><font face="trebuchet ms, sans-serif" color="#00a389"> </font></p>
<p class="MsoNormal" style=""><font face="trebuchet ms, sans-serif" color="#00a389">For testing alcohol concentration, a digital density meter is really the most effective method. However, this is a very costly piece of equipment and many organisations do not
have budget to buy one. A hydrometer can be used if you have sufficient fluid volume. I have refined a method, initially published by Theresa Mayfield, that uses salts (potassium carbonate and sodium chloride) to distinguish between ethanol, isopropanol and
aqueous solutions (formalin). It requires a 2-4ml sample of fluid and can give a good indication of alcohol concentration. </font><font color="#00a389"><span style="font-family:"trebuchet ms",sans-serif">As highlighted by Rob, this is not a test for the presence
of formalin, but rather just that the solution is aqueous or an alcohol with water combination. This method is awaiting peer review, but if anyone has any queries please get in touch and I would be happy to share my research.</span></font></p>
<p class="MsoNormal" style=""><font face="trebuchet ms, sans-serif" color="#00a389"> </font></p>
<p class="MsoNormal" style=""><font face="trebuchet ms, sans-serif" color="#00a389">To determine the amount of formaldehyde/formalin in solution there are several methods available. I have tested three commercially available methods, and a titration method
to determine formalin concentration initially developed by Rob Waller and refined (very slightly) by myself. In testing these different methods, comparisons and assessments about the advantages and disadvantages of each method were made. </font></p>
<p class="MsoNormal" style=""><font face="trebuchet ms, sans-serif" color="#00a389"> </font></p>
<p class="MsoNormal" style=""><font face="trebuchet ms, sans-serif" color="#00a389">One of the first challenges is getting your head around the terminology we use when describing formalin, and this seems to vary between countries and institutions. What we often
call “10% formalin” is actually a dilution factor, from diluting a 1 part 100% formalin stock solution with 9 parts water. This 100% formalin stock solution is 37% by weight or 40% by volume formaldehyde gas in water. This means that “10% formalin” is 3.7%
(w/w) or 4% (w/v) formaldehyde gas in water, which is 40,000 mg/L formaldehyde.</font></p>
<p class="MsoNormal" style=""><font face="trebuchet ms, sans-serif" color="#00a389"><br>
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<p class="MsoNormal" style=""><font face="trebuchet ms, sans-serif" color="#00a389">The titration method, has the best resolution of the methods tested, only needs to be conducted once without the need for multiple dilutions, also gives results for titratable
acidity, and has a small sample size of 0.75ml. Due to the costs of equipment set up and materials for analysis, this would be a good method for institutions who want to quantify the amount of formalin/formaldehyde in solution in fluid preservatives and were
aiming to conduct many tests, which would reduce the overall cost per test.The paper that details the titration method and comparison to the commercially available methods, is also currently awaiting peer review, to be published later this year in Collection
Forum.</font></p>
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<p class="MsoNormal" style=""><font face="trebuchet ms, sans-serif" color="#00a389"><br>
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<p class="MsoNormal" style=""><font face="trebuchet ms, sans-serif" color="#00a389">Two types of commercially available formaldehyde test strips were tested (MQuant and Quantofix), and these give semi-quantitative results. As discussed on the listserv previously,
these test strips can be very challenging to use and require significant dilution and calculations to get accurate results. They measure in the range of 0mg/L to 100mg/L or 200mg/L. “10% formalin” (4% w/v formaldehyde gas in water) is 40,000mg/L so to get
results in the range that the test strips can read dilutions up to 1:1000 may need to be made. This can be time consuming and costly as often more that one test strip and dilution are required to get a result within the test strips range.
</font></p>
<p class="MsoNormal" style=""><font face="trebuchet ms, sans-serif" color="#00a389"> </font></p>
<p class="MsoNormal" style=""><font face="trebuchet ms, sans-serif" color="#00a389">A commercially available titration test kit, which uses the same chemical reaction as the titration method above, was also tested (Hach Formaldehyde Test Kit: Model FM-1). This
can test formaldehyde concentration in solution within the ranges of either 0.05 - 1% or 0.5% - 10% formaldehyde in solution (here is where terminology is important – what we often call “10% formalin” is 4% w/v formaldehyde gas in water).
</font></p>
<p class="MsoNormal" style=""><font face="trebuchet ms, sans-serif" color="#00a389">The solid reagent supplied with this test kit is insoluble in ethanol, which is an issue when testing for residual formalin in alcohol solutions. When I tested ethanol solutions,
I first dissolved the contents of the reagent sachet in 10ml demineralised water and added that to the sample before titration.
<span style="">Even though the sample was diluted the drops of titrant were still counted as though each drop represented 0.05% formaldehyde.</span><span style="">
</span></font></p>
<p class="MsoNormal" style=""><font face="trebuchet ms, sans-serif" color="#00a389">The resolution of the results with this commercially available method is not as great as the titration method above, and the sample size for the tests is significantly larger
(1ml or 10ml), however it is a simple to use method and all the required materials are supplied. I would recommend for people wanting to use this method to contact the supplier when ordering and request for a lid for the test vial, to avoid spills when mixing
the solid reagent with the fluid preservative sample using the manufacturer's published method.
</font></p>
<p class="MsoNormal" style=""><font face="trebuchet ms, sans-serif" color="#00a389"> </font></p>
<p class="MsoNormal" style=""><font face="trebuchet ms, sans-serif" color="#00a389">Methods to test fluid preservatives need a lot more research, and this will enable us to have a greater understanding of the fluid chemistry and the impacts on specimens long-term
preservation. </font></p>
<p class="MsoNormal" style=""><font face="trebuchet ms, sans-serif" color="#00a389">From a health and safety perspective it is important for us to quantify how much formaldehyde is in solution in fluid preservatives, be it from preservation in formalin or residual
in alcohol preservatives from initial fixation in formalin. </font></p>
<p class="MsoNormal" style=""><font face="trebuchet ms, sans-serif" color="#00a389"> </font></p>
<p class="MsoNormal" style=""><font face="trebuchet ms, sans-serif" color="#00a389">If anyone would like more information about any of these methods, they will hopefully be published later this year, but in the meantime I would be happy to discuss them with
you – please get in touch!</font></p>
<p class="MsoNormal" style=""><font face="trebuchet ms, sans-serif" color="#00a389"> </font></p>
<p class="MsoNormal" style=""><font face="trebuchet ms, sans-serif" color="#00a389">All the best,
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<p class="MsoNormal" style=""><font style="" face="trebuchet ms, sans-serif" color="#00a389">Irene Finkelde
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