Calibrating assays using reaction time
A method for performing an assay on a liquid sample for the detection of one or more analytes of interest in an assay device having a flow path which includes a sample zone and detection zone thereon includes: dispensing the sample onto the sample zone; combining the sample and a reagent, wherein the sample and reagent may be combined prior to addition of the sample to the sample zone or on the assay device, flowing the combined sample/reagent by capillary action into and through the detection zone having capture elements bound thereto, wherein a signal at least partially representative of the presence or concentration of analyte(s) is produced and detected; determining a reaction time or reaction volume; and determining the concentration of the analyte by using both the detected signal and the reaction time or reaction volume.
1. A method for performing an assay on a liquid sample for the detection of one or more analytes of interest in an assay device having a flow path which includes a sample zone, a reagent zone, a detection zone and a wicking zone disposed thereon, wherein the method comprises:
dispensing the liquid sample onto the sample zone of the assay device, wherein the liquid sample is caused to flow under capillary action along the flow path;
combining the sample and a reagent, wherein the sample and reagent may be combined prior to addition of the liquid sample to the sample zone or on the assay device in the reagent zone, the reagent being capable of reacting with the one or more analytes in the flowing liquid sample and creating a combined sample/reagent containing a detection element,
flowing the combined sample/reagent by capillary action into and through the detection zone having capture elements bound thereto for binding the one or more analytes such that the combined sample/reagent is retained and detected in the detection zone, wherein a signal at least partially representative of the presence or concentration of the one or more analyte(s) is produced through the detection element that is either associated with the reagent or with the combined sample/reagent generated through a reaction involving the reagent and detected by a detection instrument disposed in relation to the detection zone;
determining a reagent dissolution time based on a first time point when the signal is first detected at a point in the detection zone downstream of the reagent zone and a second time point in which the signal is no longer detected at said point;
determining a reaction volume which is the volume of sample flowing through the reagent zone during the determined reagent dissolution time;
obtaining a detection signal indicative of the concentration of the one or more analytes of interest by using the detection instrument to detect the signal at least partially representative of the presence or concentration of the one or more analyte(s); and
adjusting the detection signal by multiplying the obtained detection signal by the reaction volume.
2. The method as claimed in claim 1 , wherein the reaction volume is the product of reagent dissolution time and flow rate.