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: Urinary excretion of Pirarubicin in the first 24 hours was less than or equal to 10 % .
### Output Text:
Urinary excretion of <span class="chemical">Pirarubicin</span> in the first 24 hours was less than or equal to 10 % . 