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: Age at presentation , time of ictus after intoxication , Hunt and Hess grade of subarachnoid hemorrhage , size of the aneurysm , location of the aneurysm , and the Glasgow Outcome Scale score were assessed and compared .
### Output Text:
Age at presentation , time of ictus after intoxication , Hunt and Hess grade of subarachnoid hemorrhage , size of the aneurysm , location of the aneurysm , and the Glasgow Outcome Scale score were assessed and compared . 