Zend certified PHP/Magento developer

Looking for a way to remove duplicate entries with variable information

looking to remove duplicates with variable information.
Column F = DEL time
Column Q = recipient code
Column R = recipient address

I need to remove the duplicates that match the row information. The defining variable is column F which can be variable by up to 15 minutes. the difficulty for me is that there are hundreds of line items that match Column Q & R. So i sort via column F and then i have to look line item by line item for column Q & R and its very time consuming. Any hep is greatly appreciated!