Daily Monitoring to Assess Instrument Performance
For a daily quality check, Quantum QC can be used to measure fluorescence at optimal PMT settings to ensure that the flow cytometer is performing its best. These PMT settings should be held consistent to gauge instrument performance day-to-day, and plotted on appropriate control charts to help determine drops in instrument performance before it becomes a larger problem (e.g. Levey-Jennings Charts).
Daily Monitoring Protocol
- Dilute blank and dyed beads at 1 drop of each in 1.6 mL of lab-use diluent and mix via vortex or tapping.
- Set the PMT voltages for all fluorescence channels to the daily PMT voltages used for quality control. These PMT values should be pre-determined from experiments investigating the optimal PMT settings for the instrument.
- Place the tube on the cytometer and run the beads, recording the lab standard number of events (typically 10,000).
- Record median fluorescence intensity and %CV for each fluorescence channel for one, several, or all present peaks of Quantum QC. Which peaks are chosen to be measured is dependent on the user, but data from the chosen peaks will have to be consistently monitored.
- Control limits must be established. This choice is up to the user, but typical limit values are 2 standard deviations or 10% +/- of the averaged median channel values. Tracking of daily values should be done with Levey-Jennings charts or equivalent for each fluorescence channel.
- If a daily setup value is found to be outside of the determined control limits, another bead sample should be prepared and run to corroborate the deviant data.
These steps should be followed daily, and are generally included in instrument startup procedures following any warm up periods recommended by your instrument manufacturer. By monitoring the flow cytometer in such a manner, instrumental variations can be determined by a recorded value being outside the predetermined control limits. If this occurs, another bead sample should be prepared and recorded to corroborate the findings from the first run. If the deviant data is corroborated by a second run, this inconsistency should be reported to laboratory personnel in charge of instrument maintenance for investigation into the issue.