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: Carboplatin has been reported to cause acute renal failure when administered in high doses to adult patients .
### Output Text:
<span class="chemical">Carboplatin</span> has been reported to cause acute renal failure when administered in high doses to adult patients . 