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: A 2 - wk administration of LiCl ( 4 mmol . kg ( - 1 ) . day ( - 1 ) ip ) in mPGES - 1 + / + mice led to a marked polyuria with hyposmotic urine .
### Output Text:
A 2 - wk administration of <span class="chemical">LiCl</span> ( 4 mmol . kg ( - 1 ) . day ( - 1 ) ip ) in mPGES - 1 + / + mice led to a marked polyuria with hyposmotic urine . 