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: In the first experiment , four groups of mice received physiological saline ( 0 . 9 % ) , L - arginine ( 300 mg / kg , i . p . ) , L - NAME ( 100 mg / kg , i . p . ) and diazepam ( 2 mg / kg ) , respectively .
### Output Text:
In the first experiment , four groups of mice received physiological saline ( 0 . 9 % ) , <span class="chemical">L - arginine</span> ( 300 mg / kg , i . p . ) , <span class="chemical">L - NAME</span> ( 100 mg / kg , i . p . ) and <span class="chemical">diazepam</span> ( 2 mg / kg ) , respectively . 