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<TITLE>Re: [RASMB] densitometer</TITLE>
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<BLOCKQUOTE><FONT COLOR="#800000">Hi Eray<BR>
<BR>
I can warmly endorse Jo's comments concerning the excellence of the Anton Paar instrument, which we have in our Lab in the NCMH.<BR>
<BR>
As regards the partial specific volume of PPA, the density of the acid form is given as 1.09 g/cm^3 and of the sodium salt as 1.15 g/cm^3 at 20 deg (www.kelien.com/products/POLYACRYLIC_9003-01-4.htm). That would make the partial specific volume to be 0.917 cm^3/g and 0.870 cm^3/g respectively, if one neglects any solute-solvent interaction. Especially for the sodium salt that may very well not be valid, so the densimeter would be invaluable.<BR>
<BR>
Kind regards<BR>
<BR>
Arthur<BR>
<BR>
<BR>
</FONT></BLOCKQUOTE>--<BR>
*******************************************************<BR>
Arthur J Rowe<BR>
Professor of Biomolecular Technology<BR>
NCMH Business Centre<BR>
University of Nottingham<BR>
School of Biosciences<BR>
Sutton Bonington<BR>
Leicestershire LE12 5RD UK<BR>
<BR>
Tel: +44 (0)115 951 6156<BR>
+44 (0)116 271 4502<BR>
Fax: +44 (0)115 951 6157<BR>
email: arthur.rowe@nottingham.ac.uk<BR>
Web: www.nottingham.ac.uk/ncmh/business<BR>
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</FONT><BLOCKQUOTE><FONT COLOR="#800000"><BR>
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<BLOCKQUOTE><TT>Dear Eray,<BR>
<BR>
I can certainly help with an answer to the question about density <BR>
meters. One very good one, measuring to precision of 10**-6 g/ml, is <BR>
the density meter DMA60, with a DMA602 cell, (from Anton Paar, Graz, <BR>
Austria). The sample volume is slightly less than 1ml. There may be <BR>
other ones with similar precision, but I do not know of them.<BR>
One other thing which you do absolutely need with this is a <BR>
thermostatting system, capable of giving a liquid flow through the <BR>
jacket of the cell and accurate (particularly stable) to 0.01°C, in <BR>
order to prevent fluctuations in density due to the temperature <BR>
dependence of the solvent (usually water).<BR>
<BR>
Yours,<BR>
<BR>
Jo<BR>
<BR>
Eray Dalgakiran wrote:<BR>
> Hi!<BR>
> <BR>
> We have recently purchased a ProteomeLab XL-I analytical <BR>
> ultracentrifuge. We are dealing with synthetic polymers, proteins, <BR>
> biopolymers, and complexes of protein-polymer molecules.<BR>
> <BR>
> So far, I understand that we have to know partial specific volume of <BR>
> solute material to make calculations. We now want to buy a <BR>
> densitometer in order to measure partial specific volumes. Can <BR>
> anyone recommend me a good densitometer (company, model etc.)?<BR>
> <BR>
> And is there anyone knows the v-bar value of PAA (Polyacrylic acid)?<BR>
><BR>
> Many thanks...<BR>
> <BR>
> <BR>
> <BR>
> Eray Dalgakiran<BR>
> <BR>
> Department of Bioengineering<BR>
> Yildiz Technical University<BR>
><BR>
> www.bioeng.yildiz.edu.tr <http://www.bioeng.yildiz.edu.tr><BR>
> ------------------------------------------------------------------------<BR>
><BR>
> _______________________________________________<BR>
> RASMB mailing list<BR>
> RASMB@rasmb.bbri.org<BR>
> http://rasmb.bbri.org/mailman/listinfo/rasmb<BR>
> <BR>
<BR>
-- <BR>
Dr P.J.G. Butler,<BR>
MRC Laboratory of Molecular Biology,<BR>
Hills Road, Cambridge, CB2 2QH, UK.<BR>
Tel. +44 (0)1223 402296<BR>
<BR>
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