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: When CPA , diazepam or 2PAM was given immediately after DFP - atropine , these treatments prevented , delayed or shortened the occurrence of serious signs of poisoning .
### Output Text:
When <span class="chemical">CPA</span> , <span class="chemical">diazepam</span> or <span class="chemical">2PAM</span> was given immediately after <span class="chemical">DFP</span> - <span class="chemical">atropine</span> , these treatments prevented , delayed or shortened the occurrence of serious signs of poisoning . 