code: public void setMonoIsotope(IsotopeContainer isoContainer) {
          if (!isotopeCList.contains(isoContainer)) 
              isotopeCList.add(isoContainer);
          monoIsotopePosition = isotopeCList.indexOf(isoContainer);
      }
docs: Set the mono isotope object. Adds the isoContainer to the isotope
  pattern, if it is not already added.
  
  @param isoContainer   The IsotopeContainer object