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I'd also point to the good old Traille glass densitometers - the bigger ones are pretty accurate, though you need enough fluid for them to float in. The little "pocket" ones are less precise, but are cheap and do not go out of calibration.</div>
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<div style="font-family:Tahoma; font-size:13px"><b>Paul Callomon</b><br>
<i>Collection Manager, Malacology and General Invertebrates</i><br>
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<font face="Verdana"><b>Academy of Natural Sciences of Drexel University, Philadelphia</b></font><br>
<i>callomon@ansp.org Tel 215-405-5096 - Fax 215-299-1170</i><br>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Nhcoll-l <nhcoll-l-bounces@mailman.yale.edu> on behalf of Bentley, Andrew Charles <abentley@ku.edu><br>
<b>Sent:</b> Tuesday, March 21, 2023 5:11 PM<br>
<b>To:</b> nhcoll-l@mailman.yale.edu <nhcoll-l@mailman.yale.edu><br>
<b>Subject:</b> [Nhcoll-l] Digital density meter vs refractometer</font>
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<p style="font:small-caps bold 100% sans-serif">External.</p>
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<p class="x_MsoNormal">After receiving an enquiry from someone about cheap alternatives to expensive digital density meters, I purchased a refractometer from Amazon for $22 (<a href="https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.amazon.com%2Fdp%2FB018LSMI34&data=05%7C01%7Cprc44%40drexel.edu%7Cb87a66f4bdba443f856808db2a50e0e6%7C3664e6fa47bd45a696708c4f080f8ca6%7C0%7C0%7C638150299084791886%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=CijD0jCBSRBmMJsPoEiSY%2Bw9XytR%2BXqlsYcrB%2BOR0CU%3D&reserved=0" originalsrc="https://www.amazon.com/dp/B018LSMI34" shash="I4AwFsHMtmU97ZNGA9VWzCNJrPiKbdIjCTiQQBVx9P4H1oD+VwCkBgisOBmhkf0W3MmQ7mub95KMmcI/PDMByJWt58DkLgo5fTY/GAnv3mwnYkI3anEf2GHy769k14sGMX6mdsUy8qokWiznSI5w8VEl6jYHa5m95QFZu6UUFk4=">https://www.amazon.com/dp/B018LSMI34</a><span class="x_MsoHyperlink">)</span>.
I did a number of tests against 70%, 50% and 30% and various concentrations in between measured with our $3,000 Anton Paar DMA 35 digital density meter. The refractometer is not super accurate but is probably within 2-3% once calibrated. I first calibrated
against distilled water using the method in the instructions but found that it was reading a little high and so then calibrated against a known 70% concentration and then it was reading a little more accurately. Take home I think is that if you are not too
concerned about super accurate readings and just want to get in the ballpark it is a viable, cheap (can’t beat $22) alternative to a digital density meter.</p>
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<p class="x_MsoNormal">Just an FYI for those working with wet collections who may be working with restrictive budgets.</p>
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<p class="x_MsoNormal">Andy</p>
<p class="x_MsoNormal" style=""><span lang="EN-AU"> A : A : A :<br>
}<(((_°>.,.,.,.}<(((_°>.,.,.,.}<)))_°><br>
V V V<br>
Andy Bentley<br>
Ichthyology Collection Manager<br>
University of Kansas<br>
Biodiversity Institute</span></p>
<p class="x_MsoNormal" style=""><span lang="EN-AU">Dyche Hall<br>
<a href=""><span style="color:#0563C1">1345 Jayhawk Boulevard</span></a><br>
<a href=""><span style="color:#0563C1">Lawrence, KS, 66045-7561</span></a><br>
<a href=""><span style="color:#0563C1">USA</span></a><br>
<br>
Tel: <a href="tel:%28785%29%20864-3863" target="_blank"><span style="color:#0563C1">(785) 864-3863</span></a><br>
Fax: <a href="tel:%28785%29%20864-5335" target="_blank"><span style="color:#0563C1">(785) 864-5335</span></a> <br>
Email: <a href="mailto:abentley@ku.edu" target="_blank"><span style="color:#0563C1">abentley@ku.edu</span></a> </span></p>
<p class="x_MsoNormal">ORCID: <span style="color:#494A4C; background:white"><a href="https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Forcid.org%2F0000-0002-3093-1258&data=05%7C01%7Cprc44%40drexel.edu%7Cb87a66f4bdba443f856808db2a50e0e6%7C3664e6fa47bd45a696708c4f080f8ca6%7C0%7C0%7C638150299084791886%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=fxy8AKRyYn5m576PG84ddCBzSRdBTK6CIXfz6CloWzg%3D&reserved=0" originalsrc="https://orcid.org/0000-0002-3093-1258" shash="HVn+iwZTehLTpar2QcXfeJ9Vr6BsJOdQHl6suzTDnHPedwTRfRFpNhX5bjiCTbB+7VVZYfJsf5VddRU6PhOUbE4wRQMHZcwegen5259VmGHxKD0ulNR+/xpl+0OH2Tmz6qpoDRcmKQy6R+miyaMyFj8mMf8YgmHOx0nel4Ygt1k="><span style="color:#0563C1">https://orcid.org/0000-0002-3093-1258</span></a></span></p>
<p class="x_MsoNormal" style=""><span lang="EN-AU"><a href="https://nam10.safelinks.protection.outlook.com/?url=http%3A%2F%2Fichthyology.biodiversity.ku.edu%2F&data=05%7C01%7Cprc44%40drexel.edu%7Cb87a66f4bdba443f856808db2a50e0e6%7C3664e6fa47bd45a696708c4f080f8ca6%7C0%7C0%7C638150299084791886%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=UpXiVUCnUV0oZMCGuD21ZUQLDuQqpBqGvNtLJZLjsyc%3D&reserved=0" originalsrc="http://ichthyology.biodiversity.ku.edu/" shash="nyR3KZlw6T6f+5LDq96E+zzYaDApyK42/6KdUD4BVNHKHVLO0cpck8RGIzVxK7SWNDhNxUAxvbcDDsgHj+AQeAFU/uL5SHWrbi4gMAEJj67ZJqHrGIENKLpoSS9wH8PqYAx/vvl0pjc1rqRtYd28khQD5zyftB2QdF6eTSNNsmE=" target="_blank"><span style="color:#0563C1">http://ichthyology.biodiversity.ku.edu</span></a></span></p>
<p class="x_MsoNormal" style=""> A : A : A :<br>
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