I would like to ask which Blank type you use for measuring the LOD, LOQ peaks in relation to the blank peak?
are you using matrix-matched blank - if the sample contains analyte+ acetonitrile + Aerosol. Should we use the blank as (acetonitrile and Aerosol )
or you are using the Mobile phase as a blank?
Hi,
Example of FDA definitions could be helpful:
Blank: A blank is a sample of a biological matrix to which no analytes have been added that is used to assess the selectivity of the bioanalytical method.
Zero calibrator: A zero calibrator is a blank sample to which the internal standard is added.
Calibrators/Calibration standards: Calibrators, or calibration standards, refer to a biological matrix to which a known amount of analyte has been added. Calibration standards are used to construct calibration curves from which the concentrations of analytes in QC samples and in study samples are determined.
Stock Solution: A stock solution refers to an analyte in a solvent or mixture of solvents at a known concentration, which is used to prepare calibrators or QCs.
Your matrix should be a key component of a blank sample. So if your matrix is a blood plasma for example then a key component of the blank sample is pure blood plasma. Calibrators as LOD or LOQ samples are blank samples spiked by internal standard solution (if needed) and stock solution. The stock solution is made in a mixture of solvents or solvents and the composition of this mixture is a part of method optimization. The analyte concentration in the stock solution should be chosen so that the volume added to the calibrators is as low as possible. The mobile phase you can use for carry-over.
I highly recommend the FDA guideline as an example.
https://www.fda.gov/files/drugs/published/Bioanalytical-Method-Validation-Guidance-for-Industry.pdf
Best regards
Tomasz
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