Peptide dilution integrity evaluates whether samples above the validated analytical range can be diluted and still produce reliable quantitative results. It is particularly relevant when sample concentrations vary widely.
Why dilution needs verification
Diluting a sample seems simple, but the process can introduce volumetric error, adsorption, matrix changes or concentration-dependent instability.
Stay within the validated range
If a sample exceeds the upper calibration limit, a validated dilution approach can bring the final concentration into the supported analytical range.
Matrix effects
Dilution can change the proportion of matrix components relative to the analyte. In LC-MS methods, this may alter ionisation and create bias.
Surface adsorption
At lower concentrations, adsorption to containers or tubing may become more significant. This can reduce recovery after dilution.
Assessing dilution integrity
Researchers can prepare samples above the nominal calibration range, dilute them by predefined factors and compare the measured result with the expected concentration.
Document dilution factors
Calculation errors are a common source of quantitative mistakes. Dilution factors should be traceable in worksheets or electronic systems.
Relation to calibration curves
Dilution integrity does not extend the calibration curve itself. It demonstrates that a controlled dilution can bring a sample into the validated range. See Peptide Calibration Curves.
Frequently asked questions
Can any sample be diluted into range?
Not automatically. Dilution should be shown to preserve acceptable accuracy and precision.
Why can recovery fall after dilution?
Surface adsorption, matrix changes or preparation error may become more important.
Does dilution integrity replace calibration?
No. Calibration still defines the quantitative range.
Should multiple dilution factors be tested?
When routine samples may require different factors, evaluating representative dilutions can be useful.
Why verify calculations?
Because a correct instrument result can still become a wrong reported result if the dilution factor is applied incorrectly.
Final perspective
Dilution integrity protects quantitative peptide analysis from hidden preparation bias. A validated dilution approach lets laboratories handle high-concentration samples without unsupported extrapolation.
This VLS Peptide article is intended for laboratory and scientific education only.