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: Patients in Group C received 2 ml normal saline , Group L , 2 ml , lidocaine 2 % ( 40 mg ) and Group T , 2 ml thiopentone 2 . 5 % ( 50 mg ) .
### Output Text:
Patients in Group C received 2 ml normal saline , Group L , 2 ml , <span class="chemical">lidocaine</span> 2 % ( 40 mg ) and Group T , 2 ml <span class="chemical">thiopentone</span> 2 . 5 % ( 50 mg ) . 