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: METHODS : Peripheral blood mononuclear cells collected from the patient were cultured in the presence of a solution of dilevalol and also with sera collected from a volunteer before and after dilevalol intake .
### Output Text:
METHODS : Peripheral blood mononuclear cells collected from the patient were cultured in the presence of a solution of <span class="chemical">dilevalol</span> and also with sera collected from a volunteer before and after <span class="chemical">dilevalol</span> intake . 