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: We strongly suspect that this lethal anuria was mainly due to ifosfamide , occurring in a patient having received previous cisplatin chemotherapy and with poor kidney perfusion due to transient hypotension .
### Output Text:
We strongly suspect that this lethal anuria was mainly due to <span class="chemical">ifosfamide</span> , occurring in a patient having received previous <span class="chemical">cisplatin</span> chemotherapy and with poor kidney perfusion due to transient hypotension . 