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 patient tolerated the procedure well without any signs of citrate toxicity and maintained adequate anticoagulation for patency of the dialysis circuit .
### Output Text:
The patient tolerated the procedure well without any signs of <span class="chemical">citrate</span> toxicity and maintained adequate anticoagulation for patency of the dialysis circuit . 