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 hypothesis that fenoldopam could be used to induce hypotension and preserve blood flow to the kidney was tested .
### Output Text:
The hypothesis that <span class="chemical">fenoldopam</span> could be used to induce hypotension and preserve blood flow to the kidney was tested . 