Granted Patent
Utility
US 5,368,729 · App. 08/097,396
Solid phase extraction device
Inventors:
Joseph Stefkovich, Alfonso Liu
Patented Case
View Patent ↗
Granted: Nov 29, 1994
Filed: Jul 23, 1993
Inventors
Joseph Stefkovich
Alfonso Liu
Assignee (at issue)
Whatman GmbH
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.