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: Polyuria above 3 litres / 24 hours was found in 10 % of patients .
### Output Text:
Polyuria above 3 litres / 24 hours was found in 10 % of patients . 