Biomedical Engineering Reference
In-Depth Information
6.2
Preparation of Calibration Standards and QCs
STDs in matrix may be prepared ahead of the time and stored as long as analytes
stability in matrix has been demonstrated. STD and QC pools are prepared accord-
ing to the specific validated analytical methods. Spiked solutions cannot be used
beyond the established stability. After qualification, the standard and QC pools
should be prealiquoted out and stored under designated condition and temperature.
6.3
Prestudy Assay Evaluation (PSAE)
Prior to sample analysis, a test batch is required if (1) STD and QC pools need to be
qualified, (2) there has been a significant lapse in time since any previous analysis,
(3) the scientist does not have documentation with the assay or a similar assay.
The test batch should contain minimally low, medium, and high QC at six repli-
cates. Dilution QC samples may be included if dilutions are expected during sample
analysis. The acceptance of PSAE is the same as described in intraassay precision
and accuracy.
6.4
Sample Batch
Each sample batch contains replicates of two sets of standard calibrators which are
placed at the beginning and end of the batch to bracket study samples and QC
samples. The total numbers of QC samples from all levels should be >5 % of the
number of unknown samples in the run and at a minimum of
N
= 2 at each level or
N
= 3 for Dilution QC. Minimum three system suitability test samples (SST) should
be included in the beginning of the batch: (1) SST-LLOQ sample to evaluate the
signal to noise ratio of the instrument on the day of the analysis. (2) SST-QC0
sample (a blank sample is fortified with IS) to evaluate any potential contamination
of IS solution. (3) SST-Control blank (a double blank sample) to evaluate any inter-
ference or contamination of the blank matrix lot.
6.5
Sample Extraction and Analysis
Extraction scientist who is responsible for sample preparation should be certified prior
to extracting real study samples. The validated extraction method has to be followed
exactly. The raw data entries have to be documented promptly such as lot numbers of
STD and QC, IS, extraction reagents, matrix, the IDs of automation tool and pipette,
the time for study sample removal and return to storage and the completion of extrac-
tion. Instrument operator who is responsible for analysis has to perform SST test and
assess sensitivity and carryover prior to initialing batch. Instrument operator has to
