How do I find similar research problems in other fields? I have published a paper about the combinatorics of adding a mixture of chemicals to a compound and observing a number of spectral peaks for this, which allows the user to gain information about the compound involved, while keeping cross-chemical effects low. 

I am pretty sure the same approach not only occurs in my field of expertise, but also elsewhere in science, as this is a pretty abstract concept. Where can i find other problems like this, so that my algorithm can be solved by simply modifying the input/output of my software? A specific journal would of course only hold articles concerning my own field/their own field.
Here are some pointers that one can start with; on the multidisciplinary aspects of Combinatorics. 

See Annals of Combinatorics


  Annals of Combinatorics will publish outstanding contributions to
  combinatorial mathematics in all its aspects. Special regard will be
  given to new developments which have yet to be given proper
  recognition, but which in the opinion of the editors show promise of
  eventual mathematical breakthroughs.
  
  Papers published in Annals of Combinatorics will not be limited to the
  field of combinatorics in the strict sense. They will range over
  problems and theories that have arisen, or will arise, in applications
  to computer science, biology, statistics, probability, physics and
  chemistry, as well as over work of a combinatorial nature in
  representation theory, number theory, topology, algebraic geometry and
  the theory of special functions.


See also Journals in Combinatorics and Related Fields and Preprint Links in Combinatorics. The site also has a list of  Open Problems in Combinatorics.

From the list of journals, find those are closely related to your requirements and subscribe to their email alerts or RSS feeds using Google Reader or the likes; for latest articles.  

Hope these wiki articles (and the external links there) are already looked into; Combinatorics, Combinatorial chemistry, Outline of combinatorics, Combinatorics and physics