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: In levels 5 and 6 the carboplatin dose was targeted at AUCs of 6 and 7 . 5 , respectively , combined with a fixed paclitaxel dose of 185 mg / m2 .
### Output Text:
In levels 5 and 6 the <span class="chemical">carboplatin</span> dose was targeted at AUCs of 6 and 7 . 5 , respectively , combined with a fixed <span class="chemical">paclitaxel</span> dose of 185 mg / m2 . 