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: The incidence of venous discomfort was lower in Group L ( 76 . 6 % ; P < 0 . 05 ) than in Group C ( 100 % ) but not different from Group T ( 90 % ) .
### Output Text:
The incidence of venous discomfort was lower in Group L ( 76 . 6 % ; P < 0 . 05 ) than in Group C ( 100 % ) but not different from Group T ( 90 % ) . 