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: Encephalopathy has been reported in 10 - 40 % of patients receiving high - dose IV ifosfamide .
### Output Text:
Encephalopathy has been reported in 10 - 40 % of patients receiving high - dose IV <span class="chemical">ifosfamide</span> . 