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: Four groups were used , i ) the PAN group ( 14 ) , ii ) PAN / temocapril ( 13 ) , iii ) temocapril ( 14 ) and iv ) untreated controls ( 15 ) .
### Output Text:
Four groups were used , i ) the <span class="chemical">PAN</span> group ( 14 ) , ii ) <span class="chemical">PAN</span> / <span class="chemical">temocapril</span> ( 13 ) , iii ) <span class="chemical">temocapril</span> ( 14 ) and iv ) untreated controls ( 15 ) . 