Calibration for multi-component assays

An automatic analyzer for analyzing a biological sample, comprising:

• an assay apparatus operable to measure an intensive property of an analyte in a biological sample and generate a signal descriptive of the intensive property of the analyte, wherein the intensive property is a concentration of the analyte and wherein the analyte is C-reactive protein (CRP), the assay apparatus comprising an assay reagent having a predetermined number of at least two components, each having distinct particle sizes and each having a distinct relation between the concentration of CRP and the generated signal, wherein each of the predetermined number of components is a distinct assay;
• a dispenser, for dispensing the assay reagent into the biological sample comprising the CRP;
• a photometric measurement instrument configured to measure the generated signal, wherein the signal is within at least a portion of a photometric transmission spectra;
• a computer comprising:
• a hardware interface in communication with the dispenser and the photometric measurement instrument;
• a memory encoded with a control module comprising computer-executable code for controlling the operation and function of the automatic analyzer when executed;
• and
• a processor in communication with at least the hardware interface, and the memory, the processor configured to execute the computer-executable code of the control module, wherein the execution of the computer-executable code causes the processor to:
• receive a set number of calibration samples with known values for the concentration of CRP using the analyzer and/or receive parameter information descriptive of a calibration, wherein the set number is two times the predetermined number of components plus one, two, three, four or five;
• measure a calibration signal for each of the calibration samples using the analyzer and the assay reagent;
• determine the calibration by fitting a calibration function to the calibration signal for each of the calibration samples and the known CRP concentration values;
• wherein the calibration function is equivalent to a constant plus an exponential decay for each of the predetermined components, wherein the calibration function includes a sum of two exponential decay terms, wherein each exponential decay term has two calibration parameters;
• add the assay reagent to the biological sample using the automatic analyzer;
• measure the generated signal of the biological sample using the automatic analyzer;
• and
• calculate the concentration of CRP in the biological sample based on the generated signal and the calibration.