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 purpose of the study was to determine the efficacy of furosemide in addition to intravenous fluids in the prevention of radiocontrast nephropathy .
### Output Text:
The purpose of the study was to determine the efficacy of <span class="chemical">furosemide</span> in addition to intravenous fluids in the prevention of radiocontrast nephropathy . 