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: METHOD : Case - based observations from a medical intensive care unit ( MICU ) in a tertiary care facility in a 27 - year - old female with FHF from acetaminophen and resultant cerebral edema .
### Output Text:
METHOD : Case - based observations from a medical intensive care unit ( MICU ) in a tertiary care facility in a 27 - year - old female with FHF from <span class="chemical">acetaminophen</span> and resultant cerebral edema . 