Combining transmittance detection and chromatographic strip techniques for quantification of analyte in biological fluids
View Patent ↗Chromatographic strip is used in combination with a transmittance detecting system in a test to quantitate analytes in biological fluid. Chemical reagents or conjugate labels are simply absorbed on the passages' materials of the strip. The substrates, affinity reagents, or antibodies are immobilized on transparent beads in the detection cell of the strip. The biological fluid passes through the strip. The captured analytes are detected by transmittance detection for quantification. Uncaptured elements and interferences in the fluid are drained to the absorbent portion of the strip when the fluid passes the cell as a wash. This chromatographic strip with an analyte capture zone simplifies the procedures that a transmittance detecting system alone cannot overcome. Adjustable light path of the cells in the strip overcome the sensitivity limitation of reflectance detection.
1. A method for detection of analytes in a biological fluid comprising:
a) providing a dry test strip comprising:
a sample application well;
a reference cell and a detection cell;
a first passage connecting said sample application well to said reference cell;
a second passage connecting said sample application well to said detection cell;
an absorbent portion filled with absorbent material, said absorbent portion connected to said reference cell and said detection cell;
wherein each of said first and second passages are not in fluid communication with each other and each contains a material permeable to fluids and said permeable material in said first and second passages further includes a detection reagent;
wherein said reference cell contains transparent beads and said detection cell contains transparent beads that are linked with binding partners that are capable of binding with the analyte, wherein the binding partners are selected from ligands, antibodies or antigens;
b) placing a light source and detection unit on opposite sides of the test strip;
c) contacting the biological fluid with the sample application well;
d) allowing the biological fluid to flow through the first and second passageways to provide binding between the analytes and the binding partners in the detection region;
e) detecting noise produced by said transparent beads in said reference cell by transmittance to provide a first signal;
f) detecting binding produced by said analyte in said detection cell by transmittance to provide a second signal; and
g) subtracting said first signal from said second signal thereby determining the amount of analyte in the biological fluid sample.