250 | Chapter 5: Qualification
Washer Qualification Liquid Tests
Dispense Precision and Accuracy Test
Dispense precision is a measure of the variability of volumes dispensed from tube
to tube across the manifold. The optical density of the solution in a well is
proportional to the total volume of the solution in the well. If the % Coefficient of
Variation (%CV) is calculated, the result is a measure of the uniformity of the
distribution of dispensed volumes across the manifold. It is the ratio, expressed in
percent, of the standard deviation of the distribution of fluid volumes in the wells
to the mean value of volume per well. The uniformity of distribution across the
manifold improves as the %CV is lowered.
Dispense accuracy is a measure of the average volume dispensed per well. It is
independent of precision. The volume per well may vary greatly over a plate, yet
the accuracy may be exact because it is an average of the volumes.
n
Important
: For
IQ/OQ/PQ
testing purposes 1.0% tolerance has been added
to some of the
for Precision %CV to accommodate
variations in test solutions, off-peak wavelengths, reader errors, and pipette
errors. % Accuracy Error is calculated for the dispense volume specified in the
respective test procedure in adherence to the published specifications.
Evacuation Efficiency Test
The Evacuation Efficiency test measures the
residual volume
(mean residual
weight) per well after aspiration is performed. The lower the residual per well, the
better the evacuation efficiency of the washer. A known solution is dispensed into
all wells of a previously weighed microplate. Aspiration is performed and the plate
is re-weighed. The total residual fluid is calculated based on the weight difference,
and this value is divided by number of wells in the plate, to obtain the
mean
residual weight
.
In addition, a diagnostic tool is provided for use, if necessary, to identify problem
wells: a known dye concentration is dispensed to and evacuated from the wells,
and the plate is weighed. Buffer is then dispensed to all wells to bring the volume
of fluid to a more optically measurable volume. The optical density (OD) of each
well is measured and the background is subtracted to account for scratches on the
plate or particulates in a well. Each well’s residual volume is calculated using its
OD and a calibration factor derived from the mean residual weight and the mean
MultiFlo™ FX Multi-Mode Dispenser
Содержание MultiFlo FX
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Страница 67: ...Set Up the Peri pump Dispenser 45 MultiFlo FX with closed Peri pump cover panel BioTek Instruments Inc ...
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