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: Piglets were then randomly allocated to four groups : control ( saline ) , Intralipid ( ) alone , epinephrine alone , or a combination of Intralipd plus epinephrine .
### Output Text:
Piglets were then randomly allocated to four groups : control ( saline ) , Intralipid ( ) alone , <span class="chemical">epinephrine</span> alone , or a combination of Intralipd plus <span class="chemical">epinephrine</span> . 