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: Sodium nitrite in combination with quinacrine hydrochloride appeared to have no additional effect .
### Output Text:
<span class="chemical">Sodium nitrite</span> in combination with <span class="chemical">quinacrine hydrochloride</span> appeared to have no additional effect . 