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: A 34 - year - old lady developed a constellation of dermatitis , fever , lymphadenopathy and hepatitis , beginning on the 17th day of a course of oral sulphasalazine for sero - negative rheumatoid arthritis .
### Output Text:
A 34 - year - old lady developed a constellation of dermatitis , fever , lymphadenopathy and hepatitis , beginning on the 17th day of a course of oral <span class="chemical">sulphasalazine</span> for sero - negative rheumatoid arthritis . 