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: Reversibility of captopril - induced renal insufficiency after prolonged use in an unusual case of renovascular hypertension .
### Output Text:
Reversibility of <span class="chemical">captopril</span> - induced renal insufficiency after prolonged use in an unusual case of renovascular hypertension . 