ISAC Equipment Operation and Maintenance 5

Question 1

What is the purpose of running a 'fluidics startup' or 'prime' procedure at the beginning of each day?

Accepted Answer

To purge air bubbles and refresh sheath fluid in the flow lines before sample acquisition

Answer

The prime procedure fills all fluidic lines with fresh sheath fluid and removes air bubbles that could disrupt laminar flow and data quality.

Question 2

A flow cytometrist observes a population of doublets (two-cell aggregates) in the data. Which gating strategy BEST discriminates singlets from doublets?

Accepted Answer

Gating on FSC-H vs FSC-A (or SSC-H vs SSC-A) to exploit pulse geometry

Answer

Plotting pulse height (H) vs. pulse area (A) exploits the fact that doublets have proportionally wider pulses; singlets fall on a tight diagonal while doublets deviate.

Question 3

Which of the following is an appropriate frequency for replacing the sample injection tube (SIT) or sample probe on a high-use clinical flow cytometer?

Accepted Answer

According to manufacturer's scheduled maintenance interval, typically every few months or upon signs of degradation

Answer

Preventive replacement on a manufacturer-specified schedule reduces the risk of unexpected sample line failure or carryover contamination.

Question 4

In mass cytometry (CyTOF), what replaces fluorescent dyes as detection labels?

Accepted Answer

Heavy metal isotope-chelated polymers conjugated to antibodies

Answer

CyTOF uses antibodies conjugated to heavy metal isotopes (e.g., lanthanides) detected by time-of-flight mass spectrometry, eliminating spectral overlap.

Question 5

What is the consequence of running samples at an event rate that exceeds the instrument's maximum recommended acquisition rate?

Accepted Answer

Increased coincident events (doublets/multiplets) and reduced data accuracy

Answer

At high event rates, the probability of two cells occupying the interrogation zone simultaneously increases, producing coincident events that corrupt data.

(ISAC) International Society for the Advancement of Cytometry Practice Test

(ISAC) International Society for the Advancement of Cytometry Practice Test

ISAC Equipment Operation and Maintenance 5