[RASMB] 20 mm path cells [was: peptide in DMSO]

[Tom Laue]

Hi-
If there is sufficient interest, Spin Analytical will make epon 
(charcoal or aluminum) versions of the 20 mm centerpieces. We currently 
make 1.2, 3 and 12 mm centerpieces.
Best wishes,
Tom

Kristian Schilling wrote:
> John,
>
> I have been planning for years to post some information on our 
> centerpieces on the website. Perhaps I should eventually get back to 
> that...
>
> The initial point about our centerpieces was Dr. Mueller's (Bayer) 
> efforts years ago to persuade Beckman to offer titanium centerpieces, 
> inert to acids, bases, and organic solvents. After this did get 
> nowhere for years, it was him and Helmut Coelfen who eventually found 
> workshops here in Germany capable of manufacturing standard 12 mm 
> centerpieces with sufficient surface smoothness.
>
> When I opened up this business in 2000 I was in need of these 
> centerpieces as well (I encountered them in Helmut's lab during my PhD 
> work) which made three of us. We then agreed that for the future I 
> coordinate the making of centerpieces and gradually I have been 
> providing them to other users as well.
>
> In the course of the recent years, I have been extending the scope to 
> 20mm, 3mm and 1.5mm centerpieces; we have also made six channel but I 
> was not really happy with those - they tended to leak from one sector 
> to the other. While we were at it, I have also been making housings, 
> window holders, screw rings, and plug screws. One motivation was to 
> switch to metric plug screws that do not wear off as quickly as the 
> brass inch screws made by Beckman. Another was to have suitable 
> housings for longer and shorter centerpieces. A third was to save money.
>
> It is correct that there is a balance issue. It is already with 
> 12-mm-centerpieces that the Beckman weight set cannot balance the 
> additional weight. It has been attempted to make screws from heavy 
> metals but those are still too long and may stand proud of the thread. 
> So we make titanium counterbalances as well, and they can be balanced 
> with the Beckman weight set. They have the slit masks for radial 
> calibration.
>
> Beckman once stated (in the course of Dr. Mueller's correspondence) 
> that they see no security issue concerning the rotor - the additional 
> weight is no problem. However, their policy is that their warranty 
> does not cover rotors and instruments if any non Beckman cell material 
> is used. I tell this all users that have purchased cell components 
> from us. I might add that we give no warranty either, but we have been 
> using these cells at full rated speed for years.
>
> One point you asked about the 20-mm-cells (where our housings are 
> required, of course): No, they do not protude from the rotor hole. But 
> there is not much left. For sure, we would have come to yet longer 
> cells, as low concentrated samples are frequent. 20 mm is the best one 
> can do.
>
> And yes, the standard centerpieces fit into the Beckman cell housings, 
> and they require the same gaskets as do the aluminum centerpieces. 
> Needless to say that we have found a workshop for the gaskets as well.
>
> Best wishes,
> Kristian
>
>
> At 08:30 29.04.2008 -0700, John Philo wrote:
>> Steve (or Kristian)
>>
>> I for one had not heard about these 20 mm pathlength cells, and I 
>> could find
>> nothing about them on the Nanolytics web site. Could you elaborate a bit
>> about the configuration? Do the housings actually project out of the 
>> rotor?
>> Other than a special housing and centerpiece, are other parts 
>> (centerpiece
>> gaskets, screw rings, windows, window holders, etc.) the same? Is a
>> different counterbalance required to achieve balance?
>>
>> John
>
>
>
> =================================
> Nanolytics
> Gesellschaft fuer Kolloidanalytik mbH
> Dr. Kristian Schilling
>
> Am Muehlenberg 11
> 14476 Potsdam
> Tel.:    +49 331 5818360
> Fax:    +49 331 5818361
>
> e-mail:    schilling at nanolytics.de
> Internet:    www.nanolytics.de
>  
>
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-- 
Department of Biochemistry and Molecular Biology
University of New Hampshire
Durham, NH 03824-3544
Phone: 603-862-2459
FAX:   603-862-0031
E-mail: Tom.Laue at unh.edu
www.bitc.unh.edu
www.camis.unh.edu