Instrument Operation Flashcards
7 cards from real SCYM practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Instrument Operation flashcards as text
What is the primary purpose of the sheath fluid in a flow cytometer?
Answer: To hydrodynamically focus cells into a single-file stream
Sheath fluid creates laminar flow that hydrodynamically focuses the sample stream so cells pass through the laser interrogation point one at a time.
Which parameter is used to distinguish doublets from single cells during flow cytometric analysis?
Answer: FSC height vs FSC area (or width)
Doublet discrimination is performed by comparing FSC-H (height) vs FSC-A (area); doublets produce disproportionately higher area relative to height.
When performing daily QC on a flow cytometer using fluorescent beads, a sudden rightward shift in bead peak CV is most likely caused by:
Answer: Laser power fluctuation
Laser power instability causes variable fluorescence excitation, broadening the bead peak and increasing CV.
In a spectral flow cytometer, unmixing algorithms require which reference material?
Answer: Single-color controls (single-stained references) for each fluorochrome
Spectral unmixing requires single-color reference spectra for each fluorochrome to mathematically separate overlapping emission signals across detectors.
The time delay setting in a cell sorter is used to:
Answer: Synchronize the deflection charge with the droplet containing the target cell
The time delay (sort delay) accounts for the transit time from the laser interrogation point to the droplet break-off point so the correct droplet is charged.
Which action should be taken first if the sample flow rate on a benchtop cytometer drops unexpectedly mid-run?
Answer: Check for a clog in the sample line and perform a backflush if needed
A sudden flow rate drop typically indicates a partial clog; checking and performing a backflush resolves most sample-line obstructions before escalating.
What does a low coefficient of variation (CV) for a fluorescent bead peak indicate during instrument QC?
Answer: The instrument is performing consistently with tight measurement precision
A low CV on bead peaks indicates that the instrument is producing highly reproducible fluorescence measurements, reflecting good optical and electronic performance.