Sample Dilution Factor Determination Using Internal Standards
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Solution Overview
Problem
Existing methods for determining the concentration of an analyte in a sample require known sample and calibrator volumes, which can be challenging when samples have unknown or variable volumes, especially for volatile, viscous, or solid samples.
Innovation Solution
A method that involves preparing a mixture by diluting defined volumes of calibrators with a dilution reagent containing an internal standard, performing sample preparation workflows, and using an in vitro diagnostic medical device to determine the dilution factor by comparing area ratios of the analyte and internal standard.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pipetting is used to transfer defined sample volumes, then the required sample volume can be accurately transferred, but the method becomes complex and error-prone, especially for volatile, viscous, or solid samples
Solution Approach 1:
The invention extracts the volume measurement function from the pipetting operation by using an internal standard whose signal intensity directly reflects the sample volume. This eliminates the need for manual pipetting while maintaining volume accuracy, as the internal standard signal serves as a direct measure of the actual sample volume present.
Solution Approach 2:
The internal standard acts as an intermediary between the sample and the measurement system. By spiking the sample with a known amount of internal standard before analysis, the system can determine the sample volume through the internal standard's signal, avoiding direct volume measurement and pipetting operations.
2Quantity of substance
If pipetting operations are performed, then defined sample volumes can be transferred, but additional error contributions are introduced and analysis time increases
Solution Approach 1:
The internal standard is spiked into the sample in advance, before the actual analysis. This preliminary action allows the volume determination to occur automatically during the analysis process itself, eliminating the need for separate pipetting and volume measurement steps that would consume additional time.
3Measurement precision
If known sample and calibrator volumes are used, then dilution factors can be calculated, but the method cannot handle samples with unknown or variable volumes
Solution Approach 1:
The system uses the internal standard signal as feedback to determine the actual sample volume present. This feedback mechanism allows the calculation of accurate dilution factors even when the initial sample volume is unknown or variable, as the internal standard signal provides real information about the actual volume used in each analysis.
Data Source
AI summary
A method for determining a dilution factor of a sample comprising an analyte (115) of interest is disclosed. The method comprises the following steps:a) (136) preparing a mixture (113) by diluting defined volumes of calibrators (114) comprising the analyte (115) of interest with a defined volume of a dilution reagent comprising at least one first internal standard ISTDa (118);b) (138) performing at least one sample preparation workflow (120) on a defined volume of the mixture (113) thereby generating a prepared mixture (122), wherein the sample preparation workflow (120) comprises adding at least one second internal standard ISTDb (124);c) (140) performing at least one sample measurement on the prepared mixture (122) comprising determining a peak area for each of the first internal standard ISTDa (118) and the second internal standard ISTDb (124) using an in vitro diagnostic medical device (110) and determining an area ratio ARsample of ISTDa (118) and ISTDb (124) by using at least one processing device (130);d) (142) performing at least one calibration measurement on a plurality of calibration samples (128), wherein the calibration samples (128) have a predefined concentration of ISTDa (118) and ISTDb (124), and determining an averaged area ratio ARcalibration,av of ISTDa (118) and ISTDb (124) of the calibration samples (128) by using the processing device (130);e) (144) determining the dilution factor by determining a deviation of the area ratio ARsample and the averaged area ratio ARcalibration,av by using the processing device (130).