<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto">Last year, we experienced severe and consistent specimen contamination a few months after we switched to an ethane cylinder which was purchased 4 years before we started using it. The issue disappeared after we switched again to a newly purchased cylinder. <div><br id="lineBreakAtBeginningOfSignature"><div dir="ltr"><blockquote type="cite">On Sep 9, 2025, at 11:56 AM, Thomas, Leonard M. via 3dem <3dem@ncmir.ucsd.edu> wrote:<br><br></blockquote></div><blockquote type="cite"><div dir="ltr">
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Hello All,</div>
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Sort of oddish question but how long is a research grade Ethane cylinder good for? We have one that is probably at least 6 years old and I was wondering when I should worry about the quality of the ethane for plunge freezing. It really was not used much when
it was first purchased but has been since we got a hold of it.</div>
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Thank in advance for any thoughts,</div>
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Len</div>
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<p style="margin: 0in; font-family: Aptos, sans-serif; font-size: 12pt;"><span style="font-family: Calibri, sans-serif; font-size: 11pt;">Leonard M. Thomas, Ph.D.</span></p>
<p style="margin: 0in; font-family: Aptos, sans-serif; font-size: 12pt;"><span style="font-family: Calibri, sans-serif; font-size: 11pt;">Biomolecular Structure Core Director</span></p>
<p style="margin: 0in; font-family: Aptos, sans-serif; font-size: 12pt;"><span style="font-family: Calibri, sans-serif; font-size: 11pt;">Oklahoma COBRE in Structure Biology</span></p>
<p style="margin: 0in; font-family: Aptos, sans-serif; font-size: 12pt;"><span style="font-family: Calibri, sans-serif; font-size: 11pt;">Department of Chemistry and Biochemistry</span></p>
<p style="margin: 0in; font-family: Aptos, sans-serif; font-size: 12pt;"><span style="font-family: Calibri, sans-serif; font-size: 11pt;">Stephenson Life Science Research Center</span></p>
<p style="margin: 0in; font-family: Aptos, sans-serif; font-size: 12pt;"><span style="font-family: Calibri, sans-serif; font-size: 11pt;">101 Stephenson Parkway</span></p>
<p style="margin: 0in; font-family: Aptos, sans-serif; font-size: 12pt;"><span style="font-family: Calibri, sans-serif; font-size: 11pt;">Norman, OK 73019</span></p>
<p style="margin: 0in; font-family: Aptos, sans-serif; font-size: 12pt;"><span style="font-family: Calibri, sans-serif; font-size: 11pt;">(405)325-1126</span></p>
<p style="margin: 0in; font-family: Aptos, sans-serif; font-size: 12pt;"><span style="font-family: Calibri, sans-serif; font-size: 11pt; color: rgb(5, 99, 193);"><u><a href="https://urldefense.com/v3/__https://www.ou.edu/structuralbiology/cobre-core-facilities/mcl__;!!Mih3wA!DO0wJMyTsaMFQOwuJ7rLyohXQv3uYiN8RO0vsX_tMhhE9EWUMoK9DC5af0LS758PNfUK3-1O0-zOMb3vY78$" data-outlook-id="092a501d-c945-40a4-ac63-244a5deac28b" style="color: rgb(5, 99, 193); margin-top: 0px; margin-bottom: 0px;">https://www.ou.edu/structuralbiology/cobre-core-facilities/mcl</a></u></span></p>
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