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: Concentrations of coniine and nicotine sulfate were 0 . 015 % , 0 . 03 % , 0 . 075 % , 0 . 15 % , 0 . 75 % , 1 . 5 % , 3 % , and 6 % and 1 % , 5 % , and 10 % , respectively .
### Output Text:
Concentrations of <span class="chemical">coniine</span> and <span class="chemical">nicotine</span> sulfate were 0 . 015 % , 0 . 03 % , 0 . 075 % , 0 . 15 % , 0 . 75 % , 1 . 5 % , 3 % , and 6 % and 1 % , 5 % , and 10 % , respectively . 