[RASMB] densitometer

[Arthur Rowe]

Hi Eray

I can warmly endorse Jo's comments concerning the excellence of the Anton
Paar instrument, which we have in our Lab in the NCMH.

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.

Kind regards

Arthur


--
*******************************************************
Arthur J Rowe
Professor of Biomolecular Technology
NCMH Business Centre
University of Nottingham
School of Biosciences
Sutton Bonington
Leicestershire LE12 5RD   UK

Tel:        +44 (0)115 951 6156
           +44 (0)116 271 4502
Fax:        +44 (0)115 951 6157
email:      arthur.rowe at nottingham.ac.uk
Web:        www.nottingham.ac.uk/ncmh/business
*******************************************************




Dear Eray,

I can certainly help with an answer to the question about density
meters.  One very good one, measuring to precision of 10**-6 g/ml, is
the density meter DMA60, with a DMA602 cell, (from Anton Paar, Graz,
Austria).  The sample volume is slightly less than 1ml.  There may be
other ones with similar precision, but I do not know of them.
One other thing which you do absolutely need with this is a
thermostatting system, capable of giving a liquid flow through the
jacket of the cell and accurate (particularly stable) to 0.01°C, in
order to prevent fluctuations in density due to the temperature
dependence of the solvent (usually water).

Yours,

Jo

Eray Dalgakiran wrote:
> Hi!
>  
> We have recently purchased a ProteomeLab XL-I analytical
> ultracentrifuge. We are dealing with synthetic polymers, proteins,
> biopolymers, and complexes of protein-polymer molecules.
>  
> So far, I understand that we have to know partial specific volume of
> solute material to make calculations. We now want to buy a
> densitometer in order to measure partial specific volumes. Can
> anyone recommend me a good densitometer (company, model etc.)?
>  
> And is there anyone knows the v-bar value of PAA (Polyacrylic acid)?
>
> Many thanks...
>  
>  
>  
> Eray Dalgakiran
>  
> Department of Bioengineering
> Yildiz Technical University
>
> www.bioeng.yildiz.edu.tr <http://www.bioeng.yildiz.edu.tr>
> ------------------------------------------------------------------------
>
> _______________________________________________
> RASMB mailing list
> RASMB at rasmb.bbri.org
> http://rasmb.bbri.org/mailman/listinfo/rasmb
>   

-- 
Dr P.J.G. Butler,
MRC Laboratory of Molecular Biology,
Hills Road, Cambridge, CB2 2QH, UK.
Tel. +44 (0)1223 402296

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