Biomedical Engineering Reference
In-Depth Information
Experiment . Place a control blank after the second ULOQ sample in each accuracy
and precision run.
Acceptance . It is acceptable if carryover blank has analyte peaks that are
£20.0 % of the lowest peak area of the acceptable LLOQ and carryover blank
has internal standard peaks that are £5.00 % of the mean peak area of internal
standard in the run.
5.2.4
Method Selectivity (Matrix Effects)
Purpose . To demonstrate the ability of the method to measure what it is intended to
measure and not be affected by other sample components such as endogenous
matrix elements. A minimum of six different matrix lots from individual donors has
to be evaluated. It contains three individual experiments:
Experiment#1 . Selectivity Blank Test: Extract selectivity blanks from six different
lots.
Acceptance . Same as above for carryover assessment.
Experiment #2 . Selectivity LLOQ Test: Extract selectivity LLOQ at replicate of one
from six different lots.
Acceptance . The mean and the RSD of the selectivity LLOQ concentration must not
deviate £20.0 % from their target concentrations. At least five out of six individual
selectivity LLOQ must be acceptable.
Experiment #3 . Matrix Factor (MF) Test: Extract six blanks from six different lots.
Spike appropriate and same amount of analyte and IS into the postprocessed extract
and neat sample, respectively. MF is the ratio of the peak area of the analyte in
extract vs. neat sample. For stable labeled IS, the response can be normalized and
peak area ratio (instrument response) can be used for MF calculation. For analog
IS, the matrix factor must be calculated individually for analyte and IS. The recom-
mended concentration for MF test is at medium QC level.
Acceptance . The RSD of the matrix factor for all lots must not deviate £ 15.0 %.
If MF = 1, it indicates that there is no matrix effect. If MF >1, it indicates that
there is ionization enhancement. If MF <1, it indicates that there is ionization
suppression.
5.2.5
Interference
Purpose . To determine the ability of the method to measure what it is intended to
measure and not be affected by other compounds, i.e., concomitant compounds,
prodrugs, metabolites. It contains two separate experiments:
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