This example demonstrates how to handle the events of an element. You can change it to be used on a DataCell rather than a DataRow. Note that the sender will be the element and can be cast as such.
http://doc.xceedsoft.com/products/XceedWpfDataGrid/Subscribing_to_the_events_of_an_element.html
If you have the DataRow, you can get the cell from its Cells collection. If you have the cell, you can access its content through its Content property.
Technical Writer - Xceed Software
In three words I can sum up everything I've learned about life: it goes on.