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: With this model we investigated the effect of chronic doxorubicin administration on the ECG of freely moving BALB / c mice and the efficacy of ICRF - 187 as a protective agent .
### Output Text:
With this model we investigated the effect of chronic <span class="chemical">doxorubicin</span> administration on the ECG of freely moving BALB / c mice and the efficacy of <span class="chemical">ICRF - 187</span> as a protective agent . 