Hydrogen Bonding and UV Absorbance

[mrz198]

Hi

Does hydrogen bonding of acrylamide with another molecule affect its absolute contribution in UV absorbance?

in detail if X concentration of acrylamide has AX absorbance at 200 nm, by adding another molecule which not absorb at this wavelength and interact with acrylamide only by hydrogen bonding, does the absorbance value (AX) affected? Why ? if yes, increases or decreases? why?

(the UV absorbance measured around 200 nm because of C=O bonds)

Thanks in advance for your prompt response

[DeborahFoxWalsh]

Hi Mahdi,

  If you don't see the expected response at the predetermined wavelength for UV absorbance measurement, think about where you may be losing your molecule of interest during the experimental process.  Is it soluble?  Did you attempt to isolate the molecule? Was the recovery poor, was it lost during the extraction process?  Consider the HPLC system, is it performing properly? Are you using the correct column, or could it be your mobile phase or gradient? Is your molecule bonding irreversibly to the column or vials?

Although I don't have any specific experience with acrylamide, these are some of the things I'd consider.....

[mrz198]

Hi Deborah

thank you for your response

actually I measured the UV absorbance of a certain Concentration of acrylamide (which i dissolved in water), and in parallel I measured the UV absorbance of a certain Concentration of a protein which i dissolved in water at the same wavelength.

and subsequently when I mixed the solutions, the absorbance of the mixture was significantly less than sum of two absorbance values.

all I know about the mixture is that there are only hydrogen bonds between acrylamide and the protein.

[An-PhongLe]

This may seem like a silly question, but are you taking into account any dilution which is taking place?  From what you described above, the concentrations of both the protein and the acrylamide will decrease if you are mixing the two solutions together.