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: CONCLUSION : This study documents good compliance in New Hampshire ' s birthing hospitals with national guidelines for perinatal hepatitis B and rubella prevention and highlights potential areas for improvement .
### Output Text:
CONCLUSION : This study documents good compliance in New Hampshire ' s birthing hospitals with national guidelines for perinatal hepatitis B and rubella prevention and highlights potential areas for improvement . 