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: RAST for BPO - PLL and AX - PLL was done .
### Output Text:
RAST for <span class="chemical">BPO - PLL</span> and <span class="chemical">AX</span> - PLL was done . 