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: EDDs had concentrations of cocaine and benzoylecgonine in autopsy blood that were similar to those for controls .
### Output Text:
EDDs had concentrations of <span class="chemical">cocaine</span> and <span class="chemical">benzoylecgonine</span> in autopsy blood that were similar to those for controls . 