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: Hepatotoxicity associated with sulfasalazine in inflammatory arthritis : A case series from a local surveillance of serious adverse events .
### Output Text:
Hepatotoxicity associated with <span class="chemical">sulfasalazine</span> in inflammatory arthritis : A case series from a local surveillance of serious adverse events . 