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: INTRODUCTION : Diazinon Yis one of the most broadly used organophosphorus insecticides in agriculture .
### Output Text:
INTRODUCTION : <span class="chemical">Diazinon</span> Yis one of the most broadly used <span class="chemical">organophosphorus</span> insecticides in agriculture . 