Hello,
I dissolved my peptide of interest in DMSO as it was not dissoluble in water. Now I want to determine the peptide concentration with help of the absorbance at 280 nm (my peptide includes Trp). I read that DMSO has absorbance itself in this area. I thought I could use DMSO as blank and hopefully the background will be substracted.
Can you tell me if this is possible or do I need to find another way to determine the peptide concentration?
Best, Sandra
DMSO does absorb in the UV, but the attached file shows only slight absorption at 280 nm, so what you propose should work.
The attached PDF is a prep HPLC run with a photodiode array detector, so I am able to display the UV of the various peaks. The first eluting peak is the DMSO used to dissolve the sample, and the UV of this peak (center of the peak) is shown in the PDF.
I usually make a dilution of the peptide 1/10 in H2O or some other aqueous solvent, than use a solution of DMSO also diluted the same way (1/10 in water or aqueous solvent) to blank the nanodrop. Then I use the UV mode in the nanodrop. It works, just make sure your peptide is concentrated enough initially so that you can dilute 1/10 and get a reading considerably higher than background in the nanodrop. Good luck!
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