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: Levels were significantly greater in patients with acute liver failure due to paracetamol overdose ( median , 28 . 7 U / mL ; range , 12 . 8 - 52 . 7 U / mL , n = 17 ) than those due to non - A to E hepatitis ( median , 12 . 5 U / mL ; range , 6 . 9 - 46 . 0 U / mL , n = 7 , P < 0 . 01 ) .
### Output Text:
Levels were significantly greater in patients with acute liver failure due to <span class="chemical">paracetamol</span> overdose ( median , 28 . 7 U / mL ; range , 12 . 8 - 52 . 7 U / mL , n = 17 ) than those due to non - A to E hepatitis ( median , 12 . 5 U / mL ; range , 6 . 9 - 46 . 0 U / mL , n = 7 , P < 0 . 01 ) . 