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: Physicians who use sulfasalazine to treat patients with inflammatory bowel disease should be aware of the signs of sulfasalazine - induced lupus syndrome .
### Output Text:
Physicians who use <span class="chemical">sulfasalazine</span> to treat patients with inflammatory bowel disease should be aware of the signs of <span class="chemical">sulfasalazine</span> - induced lupus syndrome . 