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: This case is the earliest ( second day of treatment ) NMS due to ziprasidone reported in the literature .
### Output Text:
This case is the earliest ( second day of treatment ) NMS due to <span class="chemical">ziprasidone</span> reported in the literature . 