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: Most had hyperacute presentation ; the median icterus encephalopathy interval was 4 . 5 ( 0 - 30 ) days .
### Output Text:
Most had hyperacute presentation ; the median icterus encephalopathy interval was 4 . 5 ( 0 - 30 ) days . 