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: CONCLUSION : When performing intracarotid injection of carboplatin , we must be aware of its potentially blinding ocular toxicity .
### Output Text:
CONCLUSION : When performing intracarotid injection of <span class="chemical">carboplatin</span> , we must be aware of its potentially blinding ocular toxicity . 