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: The nephrotoxic potential of amphotericin B ( 5 mg / kg per day intraperitoneally for 3 weeks ) has been investigated in salt - depleted , normal - salt , and salt - loaded rats .
### Output Text:
The nephrotoxic potential of <span class="chemical">amphotericin B</span> ( 5 mg / kg per day intraperitoneally for 3 weeks ) has been investigated in salt - depleted , normal - salt , and salt - loaded rats . 