All the 22-inch widescreens use similar TN panels, but they are not identical.
The first one out the door was ChiMei, then Samsung. Samsung now has 2 distinct panels, the latest one being rated at 2ms. AU Optronics has 2 of them, including a newer one with wide color gamut (92%), but there is still no WCG 22-inch monitor available. LG-Philips have their own panel, to become available in their recently announced 22-inch monitor.
It is easy to assume that Samsung, LG and ChiMei use their own panel in their monitors. But I have not found a good source of info on what panels are in other brands, such as Viewsonic, Westinghouse, Dell.
Maybe a Dell E228 owner could have a look in the factory menu to look for the panel Mfgr/model.
This menu can be accessed as follows:
Powering off your screen
Holding down MENU and + buttons while powering it on
Release those buttons and enter the MENU
Select FACTORY RESET
Scroll down to FACTORY