Chemical Forums

Specialty Chemistry Forums => Biochemistry and Chemical Biology Forum => Topic started by: Jassim on January 16, 2020, 02:45:14 AM

Title: The absorbance of a solution
Post by: Jassim on January 16, 2020, 02:45:14 AM
Hello everyone,,

The absorbance A of a solution is defined as:

A=log10(I0/I)

In which I0 is the incident light intensity, and I is the transmitted light intensity. The absorbace is related to the molar absorption coefficient(extinction coefficient) ε (in M-1 cm-1), concentration c (in M) and path length l (in cm) by

A= εlc

The absorption coefficient of myoglobin at 580nm is 15,000 M-1 cm-1. What is the absorbance of a 1mg/ml solution across a 1cm light path? What percentage of the incident light is transmitted by this solution?

The first step that comes to mind is to convert mg/ml to moles/ml (since the absorption coefficient is in units of M-1 cm-1), but I'm not sure how to do that! Does anyone have any ideas on how to solve this problem?
Title: Re: The absorbance of a solution
Post by: Borek on January 16, 2020, 03:39:24 AM
I would try to google for myoglobin molar mass.
Title: Re: The absorbance of a solution
Post by: Babcock_Hall on January 16, 2020, 11:57:25 AM
Myoglobin is a very well known protein.  Your textbook probably has the molar mass, among other sources.  Your second question is, "What percentage of the incident light is transmitted by this solution?" Do you know the relationship between absorbance and transmittance?