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: The otoprotectant L - NAME was administered topically to 12 / 27 animals .
### Output Text:
The otoprotectant <span class="chemical">L - NAME</span> was administered topically to 12 / 27 animals . 