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: RESULTS : Our patient was admitted to the MICU after being found unresponsive with presumed toxicity from acetaminophen which was ingested over a 2 - day period .
### Output Text:
RESULTS : Our patient was admitted to the MICU after being found unresponsive with presumed toxicity from <span class="chemical">acetaminophen</span> which was ingested over a 2 - day period . 