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: Potential renal toxicity and elevated alanine transaminase ( ALT ) concentration were reported in 12 . 2 % and 48 . 8 % of dogs , respectively .
### Output Text:
Potential renal toxicity and elevated <span class="chemical">alanine</span> transaminase ( ALT ) concentration were reported in 12 . 2 % and 48 . 8 % of dogs , respectively . 