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: METHODS : Retrospective chart review including clinical data and EEG recordings was done on five patients , admitted to MD Anderson Cancer Center between years 2009 and 2012 , who developed ifosfamide related acute encephalopathy .
### Output Text:
METHODS : Retrospective chart review including clinical data and EEG recordings was done on five patients , admitted to MD Anderson Cancer Center between years 2009 and 2012 , who developed <span class="chemical">ifosfamide</span> related acute encephalopathy . 