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 65 dogs in the study received injections in the subarachnoid space as follows : 6 to 8 ml of bupivacaine ( N = 15 ) , 2 - chloroprocaine - CE ( N = 20 ) , low pH normal saline ( pH 3 . 0 ) ( N = 20 ) , or normal saline ( N = 10 ) .
### Output Text:
The 65 dogs in the study received injections in the subarachnoid space as follows : 6 to 8 ml of <span class="chemical">bupivacaine</span> ( N = 15 ) , <span class="chemical">2 - chloroprocaine - CE</span> ( N = 20 ) , low pH normal saline ( pH 3 . 0 ) ( N = 20 ) , or normal saline ( N = 10 ) . 