In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: CONCLUSIONS : The methodology used allowed the detection of lymphocyte sensitization to sera containing ex vivo - prepared dilevalol antigens , suggesting the involvement of an immunologic mechanism in dilevalol - induced liver injury .
### Output Text:
CONCLUSIONS : The methodology used allowed the detection of lymphocyte sensitization to sera containing ex vivo - prepared <span class="chemical">dilevalol</span> antigens , suggesting the involvement of an immunologic mechanism in <span class="chemical">dilevalol</span> - induced liver injury . 