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: Upon additional retrospective analysis , it was noted that bumetanide is a loop diuretic that may cause significant hypocalcemia .
### Output Text:
Upon additional retrospective analysis , it was noted that <span class="chemical">bumetanide</span> is a <span class="chemical">loop diuretic</span> that may cause significant hypocalcemia . 