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: It is considered unlikely that etomidate will prove to be the hypnotic of choice for a totally intravenous anesthetic technique in adults because of the high incidence of myoclonia after prolonged administration .
### Output Text:
It is considered unlikely that <span class="chemical">etomidate</span> will prove to be the hypnotic of choice for a totally intravenous anesthetic technique in adults because of the high incidence of myoclonia after prolonged administration . 