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 spinal cords of the animals that received bupivacaine , low pH normal saline ( pH 3 . 0 ) , or normal saline did not show abnormal findings .
### Output Text:
The spinal cords of the animals that received <span class="chemical">bupivacaine</span> , low pH normal saline ( pH 3 . 0 ) , or normal saline did not show abnormal findings . 