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: Water intoxication associated with oxytocin administration during saline - induced abortion .
### Output Text:
Water intoxication associated with <span class="chemical">oxytocin</span> administration during saline - induced abortion . 