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: Citrate dialysate , a new dialysate with citric acid can be used for anticoagulation in patients who cannot tolerate heparin or regional citrate .
### Output Text:
<span class="chemical">Citrate</span> dialysate , a new dialysate with <span class="chemical">citric acid</span> can be used for anticoagulation in patients who cannot tolerate <span class="chemical">heparin</span> or regional <span class="chemical">citrate</span> . 