Dear Sir, Thank you very much for an elaborated explanation on DR. 

Useful indeed

Thank you Sirs

Dear Prof. Trevor R. Griffiths

I take the chance to ask here my question, in case other people reading the discussion asked themselves the same.

I'm a PhD student now and working on solid coordination polymers. Among the common analysis to asses our materials, we use DR-UV-vis spectroscopy. I could read your paper about the topic in Analytical chemistry 1959 and also could find a copy of your PhD thesis, where I deepened a little further the topic. Then I could find more literature also from Kortüm and others. Now, we use BaSO4 as standard reference but I found in literature that it is limited in the

Thank you sir.