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: Finally , 15 patients were excluded from the study ( noncompliance 14 , death 1 ) ; thus , 60 patients ( 31 in group I and 29 in group II ) were eligible for analysis .
### Output Text:
Finally , 15 patients were excluded from the study ( noncompliance 14 , death 1 ) ; thus , 60 patients ( 31 in group I and 29 in group II ) were eligible for analysis . 