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: Scanning electron microscopy of the glomerular endothelia , urinary measurements of sodium , potassium , endogenous lysozyme , N - acetyl - beta - D - glucosaminidase ( NAG ) as well as clearance and accumulation experiments after i . v . administration of egg - white lysozyme and measurements of inulin clearance ( GFR ) were done in each treatment group .
### Output Text:
Scanning electron microscopy of the glomerular endothelia , urinary measurements of <span class="chemical">sodium</span> , <span class="chemical">potassium</span> , endogenous lysozyme , N - acetyl - beta - D - glucosaminidase ( NAG ) as well as clearance and accumulation experiments after i . v . administration of egg - white lysozyme and measurements of inulin clearance ( GFR ) were done in each treatment group . 