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: METHOD : We retrospectively evaluated the medical records of 205 consecutive adult patients who underwent full - size liver transplantation between January 2006 and December 2010 due to end - stage or malignant liver disease .
### Output Text:
METHOD : We retrospectively evaluated the medical records of 205 consecutive adult patients who underwent full - size liver transplantation between January 2006 and December 2010 due to end - stage or malignant liver disease . 