[RASMB] Beckman Analysis Software

John Philo jphilo at mailway.com
Tue Oct 23 08:39:36 PDT 2001


This conversion factor is the number of fringes per mg/ml of concentration,
(as stated on page 8-67 of the Training Guide for those of you who have
taken the course in Palo Alto). For absorbance data this is the absorbance
per mg/ml.

Also please note that the association constants in the simulator are entered
in quite a different way from the values returned by the Beckman fitter (or
NONLIN); they are entered as the log (base 10) of the association constant
in molar units.

That concentration conversion factor is, as you say, related to the
refractive increment, wavelength, and pathlength through

factor = (dn/dc)* pathlength / lambda

and is usually about 3.3 (except for those of you with the very newest
XL-Is, which have a different laser wavelength).

John Philo
Alliance Protein Laboratories

-----Original Message-----
From: rasmb-admin at server1.bbri.org
[mailto:rasmb-admin at server1.bbri.org]On Behalf Of Kristian Schilling
Sent: Tuesday, October 23, 2001 8:17 AM
To: rasmb at server1.bbri.org
Subject: [RASMB] Beckman Analysis Software

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Hello out there,

in the Beckman analysis software package, there is a simulator for
equilibrium data. To get the correct fringe displacement for a given
concentration, you need to enter a conversion factor.

Common sense says that this factor should contain the refractive index
increment, the optical pathlength and the laser wavelength. However, my
efforts to make a connection between the conversion factor and these
variables have been fruitless.

Does anybody know how the conversion factor is defined?

Thanks for any suggestions,


Gesellschaft fuer Kolloidanalytik mbH
Dr.  Kristian Schilling

Hauptstr. 20
D-14624 Dallgow

Tel.:		+49/3322/24200-5
Fax:		+49/3322/24200-6
e-mail:	schilling at nanolytics.de
Internet:	www.nanolytics.de

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