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: The purpose of the present study was to determine if elevated reactive oxygen ( ROS ) / nitrogen species ( RNS ) reported to be present in adriamycin ( ADR ) - induced cardiotoxicity actually resulted in cardiomyocyte oxidative / nitrative damage , and to quantitatively determine the time course and subcellular localization of these postulated damage products using an in vivo approach .
### Output Text:
The purpose of the present study was to determine if elevated reactive <span class="chemical">oxygen</span> ( ROS ) / <span class="chemical">nitrogen</span> species ( RNS ) reported to be present in <span class="chemical">adriamycin</span> ( <span class="chemical">ADR</span> ) - induced cardiotoxicity actually resulted in cardiomyocyte oxidative / nitrative damage , and to quantitatively determine the time course and subcellular localization of these postulated damage products using an in vivo approach . 