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: Although the explanation for the association between artery calcification and growth status cannot be determined from the present study , there was a relationship between higher serum phosphate and susceptibility to artery calcification , with 30 % higher levels of serum phosphate in young , ad libitum - fed rats compared with either of the groups that was resistant to Warfarin - induced artery calcification , ie , the 10 - month - old rats and the restricted - diet , growth - inhibited young rats .
### Output Text:
Although the explanation for the association between artery calcification and growth status cannot be determined from the present study , there was a relationship between higher serum <span class="chemical">phosphate</span> and susceptibility to artery calcification , with 30 % higher levels of serum <span class="chemical">phosphate</span> in young , ad libitum - fed rats compared with either of the groups that was resistant to <span class="chemical">Warfarin</span> - induced artery calcification , ie , the 10 - month - old rats and the restricted - diet , growth - inhibited young rats . 