Is it possible to calculate chromacity coordinates using absorbance values? I have absorbance values for blood plasma. Absorbance was measured in range of 380 – 600 nm every 5 nm ending up with absorbance values for 45 wave lengths.
I was browsing through literature, and  I came  across chromacity coordinates (XYZ) and this seems to be a very convenient way of summarizing data about color in just two data points. 
I have been reading some literature about different colorimetric systems, but since my background is in genetics, it didn’t make much sense for me. 
Therefore, I would like to ask you if it is possible to calculate these chromacity coordinates using my absorbance values and if so does anyone now some kind of software for this or exact formulas on how to do it?
This is a partial answer to your question.  I have used chromaticity coordinates for various scientific endeavours (air quality mainly).  I found that it is a very powerful means of determining colour differences.

A bit of searching and there is somewhat of a precedent for using chromaticity for blood plasma.  An example is the article Features of Color Characteristics of Blood Plasma of Patients with Liver Cirrhosis in the Colorimetric System XYZ as Compared with Healthy People (Dolomatov et al. 2012) - even though it may be a different context to your study, but does show that it can and has been done before.  Specifically, their method was


  by colorimetric method, based on absorption electromagnetic radiation in visible area.


There are several more examples of how it can be used.