Restrictor heating in supercritical fluid chromatography

In a chromatographic analysis system, apparatus for raising the temperature of the mobile phase at a desired level, comprising in combination a restrictor, through which the mobile phase passes, said restrictor having a minimum taper length;

• and heated zone means for creating a temperature zone in an area immediately prior to the outlet end of said restrictor, said temperature zone having a length equal to the minimum length necessary to transfer sufficient heat to said mobile phase so that as said mobile phase passes through said zone, the temperature of said mobile phase is maintained at said desired level.

In a chromatographic analysis system, apparatus for maintaining the density of the mobile phase at a desired level prior to detection, comprising in combination a restrictor, through which the mobile phase passes, said restrictor having a minimum taper length;

• and heated zone means for creating a temperature zone in an area immediately prior to the outlet end of said restrictor, said temperature zone having a length equal to the minimum length necessary to transfer sufficient heat to said mobile phase so that as said mobile phase passes through said zone, the density of said mobile phase is maintained at said desired level.

Apparatus for causing the temperature of the mobile phase to be at a desired level in a chromatographic analysis system, said apparatus comprising a restrictor, through which the mobile phase passes, said restrictor having a minimum taper length, and temperature zone means for creating a temperature zone in an area immediately prior to the outlet end of said restrictor, said temperature zone having a length equal to the minimum length necessary to transfer sufficient heat in relation to said mobile phase so that as said mobile phase passes through said zone, the temperature of said mobile phase is at said desired level.

Apparatus for causing the temperature of the mobile phase to be at a desired level in a chromatographic analysis system, said apparatus comprising:

• a restrictor, through which the mobile phase passes, said restrictor having an inlet end and a minimum taper length;
• and
• temperature zone means for creating a temperature zone in an area immediately prior to the outlet end of said restrictor, said temperature zone having a length no longer than that length necessary to ensure that the density of said mobile phase at said inlet end does not drop more than fifty percent when said mobile phase passes out of said restrictor.

Apparatus for causing the temperature of the mobile phase to be at a desired level in a chromatographic analysis system, said apparatus comprising:

• a restrictor, through which the mobile phase passes, said restrictor having an inlet end and an outlet end;
• and
• temperature zone means for creating a temperature zone in an area immediately prior to the outlet end of said restrictor, said temperature zone having a length no longer than that length necessary to maintain the density of the mobile phase at a level which prevents solutes from dropping out of solution.

Apparatus for causing the temperature of the mobile phase to be at a desired level in a chromatographic analysis system, said apparatus comprising:

• a restrictor, through which the mobile phase passes, said restrictor having an inlet end and an outlet end;
• and
• temperature zone means for creating a temperature zone in an area immediately prior to the outlet end of said restrictor, said temperature zone having a length no greater than 20 mm.