Abstract: Analyte-insensitive materials comprising polymerizable monomers suitable for use in forming a hydrophilic, cross-linked gel comprising on the surface of a substrate for an electrode.

Abstract: A filter element includes a ring of filtration media circumscribing a central axis and defining a central cavity. An annular end cap of the filter element is sealingly bonded at an end of the media. The end cap includes a central opening into the central cavity, and a lateral opening spaced laterally outward from the central opening. The central opening includes a threaded connection portion to enable the element to be spun-on to a complimentarily-threaded connection portion of a filter head. The connection portion of the central opening includes at least one axially-extending slot opening radially away from the connection portion.