Robert G Rhoads

US Patent:

48386880, Jun 13, 1989

Filed:

Oct 18, 1988

Appl. No.:

7/259488

Inventors:

Robert Rhoads - Chelmsford MA

International Classification:

G01N 2105
G01N 2164

US Classification:

356 72

Abstract:

A high sensitivity fluorescence and absorption detector comprising an elongated substantially cylindrical flow cell connected to and receiving the outflow of a fluid chromatography column; a mechanism for projecting a fluorescence generating beam of electromagnetic energy along on an axis substantially coincident with the axis of the flow cell; the flow cell including an elongated substantially cylindrical midsection housed by a tubular capillary transparent to the fluorescent radiation generated by the beam; a fluorescence integrating sphere completely surrounding the midsection of the capillary, the integrating sphere collecting at least about 3 pi steradian of the fluorescent radiation emanating through the capillary tube and into the sphere; the beam being projected to enter one end of the cylindrical flow cell, focus at about the center point of the axis of the cylindrical midsection, emanate through the other end of the flow cell and impinge upon a photodetector for detecting the portion of the beam which is not absorbed by the outflow flowing through the cell; the cross-sectional diameter and the axial length of the flow cell being selected such that the axially coincident beam which is projected into the cell and is not absorbed travels in its essential entirety along a direct or internally reflected path out of the other end of the cell; the integrating sphere having an aperture for allowing the fluorescent radiation which enters the sphere to emanate therethrough and impinge upon a fluorescence detector along a path offset from the axis of the cell.