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: Haemodilution in groups B and C was produced by withdrawing approximately 1000 mL of blood and replacing it with the same amount of dextran solution , and final haematocrit values were 21 or 22 % .
### Output Text:
Haemodilution in groups B and C was produced by withdrawing approximately 1000 mL of blood and replacing it with the same amount of <span class="chemical">dextran</span> solution , and final haematocrit values were 21 or 22 % . 