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: Comparison of effects of isotonic sodium chloride with diltiazem in prevention of contrast - induced nephropathy .
### Output Text:
Comparison of effects of isotonic <span class="chemical">sodium chloride</span> with <span class="chemical">diltiazem</span> in prevention of <span class="chemical">contrast</span> - induced nephropathy . 