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 entire procedure was repeated during glyceryl trinitrate infusion ( Nitrolingual 1 microg / kg / min for 120 min ) .
### Output Text:
The entire procedure was repeated during <span class="chemical">glyceryl trinitrate</span> infusion ( <span class="chemical">Nitrolingual</span> 1 microg / kg / min for 120 min ) . 