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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='color:black'>Dear RASMB,<o:p></o:p></span></p><p class=MsoNormal><span style='color:black'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:black'>This question is in regards to an SPR application. We are currently investigating the use “calibration free concentration analysis” (CFCA) to monitor the stability of macromolecular preps over time in terms of their activity. Input parameters for this analysis are ff0, viscosity, MW and D and we are using AUC to better determine both. Current applications seem to assume ff0=1.5, which may not be correct for monoclonal preps based on my reading of the literature.<o:p></o:p></span></p><p class=MsoNormal><span style='color:black'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:black'>My query.<o:p></o:p></span></p><p class=MsoListParagraph style='text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='color:black'><span style='mso-list:Ignore'>1.<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span style='color:black'>Is it currently the common practice to measure these quantities and if so what is the preferred method to do so?<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Courier New"'><o:p> </o:p></span></p><div><p class=MsoNormal><span style='font-size:12.0pt'>Thank you all and Happy New Year,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt'>John Sumida, Ph.D.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt'><a href="http://depts.washington.edu/cidb4bio/index.shtml"><span style='color:windowtext'>Analytical Biopharmacy Core Facility</span></a><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt'>University of Washington<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt'><a href="http://www.moles.washington.edu/"><span style='color:windowtext'>Molecular Engineering & Sciences Institute, G22</span></a><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt'>3946 West Stevens Way NE<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt'>Seattle WA 98195-1653<o:p></o:p></span></p></div><p class=MsoNormal style='text-autospace:none'><span style='color:black'><o:p> </o:p></span></p></div></body></html>