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: However , at the end of 3 weeks , amphotericin B levels in the kidneys and liver were significantly higher in salt - depleted and normal - salt rats than those in salt - loaded rats , with plasma / kidney ratios of 21 , 14 , and 8 in salt - depleted , normal - salt , and salt - loaded rats , respectively .
### Output Text:
However , at the end of 3 weeks , <span class="chemical">amphotericin B</span> levels in the kidneys and liver were significantly higher in salt - depleted and normal - salt rats than those in salt - loaded rats , with plasma / kidney ratios of 21 , 14 , and 8 in salt - depleted , normal - salt , and salt - loaded rats , respectively . 