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: METHODS / MATERIALS : As part of the ongoing Quality Assurance process , data on all sedations are reviewed monthly and protocols modified as needed .
### Output Text:
METHODS / MATERIALS : As part of the ongoing Quality Assurance process , data on all sedations are reviewed monthly and protocols modified as needed . 