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 subcellular and lobular production of hepatic neoantigens recognized by halothane - induced antibodies following enflurane and isoflurane , and the biochemical nature of these neoantigens was investigated in two animal models .
### Output Text:
The subcellular and lobular production of hepatic neoantigens recognized by <span class="chemical">halothane</span> - induced antibodies following <span class="chemical">enflurane</span> and <span class="chemical">isoflurane</span> , and the biochemical nature of these neoantigens was investigated in two animal models . 