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: Additional therapy with chloroquine ( CQ ) was started because of arthralgia .
### Output Text:
Additional therapy with <span class="chemical">chloroquine</span> ( <span class="chemical">CQ</span> ) was started because of arthralgia . 