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: Thirty minutes from the start of the procedure , the donor noted tingling around the mouth , hands , and feet .
### Output Text:
Thirty minutes from the start of the procedure , the donor noted tingling around the mouth , hands , and feet . 