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: Delirium in an elderly woman possibly associated with administration of misoprostol .
### Output Text:
Delirium in an elderly woman possibly associated with administration of <span class="chemical">misoprostol</span> . 