BioSciences - Polysciences, Inc.

Additional Particles
Microspheres & Particles
Instrument Quality Control
For confidence in test or assay results, a facility must employ a comprehensive quality assurance program that encompasses employee
training and routine instrument maintenance and quality control. Facilities should also ensure that studies, particularly those involving
quantitative fluorescence measurements, are conducted with appropriate standardization.
Microsphere standards aid in defining the instrument’s capabilities and limitations in terms of sensitivity, precision and accuracy and
provide a means for ensuring that the instrument is stable and suitable for use. They are also helpful in understanding the effects of
extraneous factors, such as temperature, humidity and electronic noise. The comparison of daily and historical QC data aids in the
identification of random errors (due to electronic noise, air bubbles, etc.) and systematic errors (due to bias, shifts and trends caused by
temperature variation, laser deterioration, misalignment, etc.) so that suitable corrective action may be taken.
Daily Controls
Flow cytometers are highly configurable and results can vary dramatically with different instrument settings. Establishing a common “Win-
dow of Analysis” for each detector, with the upper and lower fluorescence limits defined, allows reference populations to be positioned in
approximately the same place on the same scale. This type of standardized instrument set-up ensures consistency of results from specific
instruments and enables meaningful comparison between instruments. Therefore, the general status and stability of the cytometer must
be checked daily. In addition, by plotting values over time, random and systemic errors may be identified and corrected. Manually aligned
instruments must be aligned daily. If the data from multiple instruments and/or sites are to be compared, all instruments must be standardized
daily, using the same standard bead. If multi-color analysis and/or quantitation is being performed, then the appropriate standards
must be run on that same day.
Weekly Controls
If only qualitative analyses are being run, weekly checks of the detection threshold, resolution and linearity are sufficient to establish sensitivity.
Some cytometers are fixed alignment instruments. For these, alignment may be verified weekly rather than established daily.
In addition to a regular QA/QC program, specific analyses may require other controls, such as count standards, size standards or
reference standards. Experiments and analyses must be critically evaluated for inclusion of the appropriate controls prior to
instrumental analysis.
For more information please call (800) 523-2575 or visit: polysciences.com 307