Circular Dichroism

Jelena Zaitseva zaitseva at biochem.purdue.edu
Wed Mar 26 11:14:39 EST 1997


     Hi!
     Gunter Maubach <gmau at mti-n.uni-jena.de> wrote:
>Dear netters,
>
>If there anybody with experience in CD-measurement. I have the problem
>to choice the buffer with the lowest background at wavelengths from 260
>to 180 (or 184)nm. In the buffer I must include any solubilizer (we use
>Acetonitril 10%). Another question is, if NaCl has any effect on the
>spectra.If there any suggestions, please mail me.
>
>Gunter
     In preparing solutions avoid use of chlorides which absorb strongly 
below 210 nm. Thus do not use NaCl and buffers adjusted with HCl. 
     For best resolution you have to adjust all parameters:
     - cell thickness (we work with 1 mm and 0.2 mm path length)
     - sample concentration (about 0.1 mg/ml with absorbance preferably 
       in the range 0.1 - 0.5 absorbance units); PMT voltage is no more 
       negative than -800 volts at any point in the scan
     - time constant should be no greater than 40 (2 sec. in our case)
     - run more scans for one sample (say, 5)
and other (we use 2 nm band width, 20 nm/min scan speed).
     We used up to 0.1% detergent in KPi or Hepes buffers without 
problem.
     Lena.





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