ISAC Laboratory Safety and Procedures 2 — Questions and Answers
Question 1: When working with fixed cell samples in flow cytometry, which fixative poses the greatest inhalation risk requiring use in a chemical fume hood?
- Methanol
- Paraformaldehyde (Correct answer)
- Acetone
- Ethanol
Correct answer: Paraformaldehyde
Paraformaldehyde releases formaldehyde vapors, a known carcinogen, requiring mandatory fume hood use during fixation procedures.
Question 2: A cytometry lab receives a new fluorochrome-conjugated antibody with the GHS flammable liquid pictogram. What is the minimum storage precaution required?
- Store at -80°C only
- Store away from ignition sources in a flammable materials cabinet (Correct answer)
- Store in a standard refrigerator with the door locked
- Store at room temperature in a dark drawer
Correct answer: Store away from ignition sources in a flammable materials cabinet
Flammable liquids bearing GHS Category 1-3 labels must be stored in approved flammable materials cabinets away from ignition sources.
Question 3: Which biosafety level (BSL) is required to process unfixed specimens from HIV-positive patients on a flow cytometer?
- BSL-1
- BSL-2 (Correct answer)
- BSL-3
- BSL-4
Correct answer: BSL-2
HIV-positive patient specimens are classified as BSL-2 agents, requiring standard precautions, PPE, and BSC use for aerosol-generating procedures.
Question 4: During a flow cytometry run, the sheath fluid line develops a small leak. What is the FIRST action the operator should take?
- Continue the run and flag the data as suspect
- Pause the instrument and notify the supervisor
- Immediately shut down the instrument and don full PPE before investigating (Correct answer)
- Switch to a backup sheath fluid reservoir
Correct answer: Immediately shut down the instrument and don full PPE before investigating
Any instrument leak involving sheath fluid that has contacted biological samples requires immediate shutdown and PPE donning before investigation to prevent exposure.
Question 5: What is the correct order for removing PPE after handling BSL-2 flow cytometry samples?
- Gloves → gown → mask → eye protection → hand hygiene (Correct answer)
- Gown → gloves → eye protection → mask → hand hygiene
- Gloves → eye protection → gown → mask → hand hygiene
- Mask → gloves → gown → eye protection → hand hygiene
Correct answer: Gloves → gown → mask → eye protection → hand hygiene
CDC guidelines specify removing gloves first (most contaminated), then gown, then face/eye protection, with hand hygiene performed last.
Question 6: A researcher accidentally spills a 1 mL aliquot of unfixed peripheral blood on the cytometer sample injection port. Which decontamination agent is most appropriate?
- 70% isopropyl alcohol wipe only
- 10% bleach solution followed by 70% ethanol (Correct answer)
- Quaternary ammonium wipe only
- Soap and water rinse
Correct answer: 10% bleach solution followed by 70% ethanol
A 10% bleach solution (1:10 dilution of household bleach) is the recommended disinfectant for bloodborne pathogen spills, followed by ethanol to neutralize residual chlorine.
Question 7: Under OSHA's Bloodborne Pathogens Standard (29 CFR 1910.1030), how often must flow cytometry staff who work with human specimens receive bloodborne pathogen training?
- Once at initial hire only
- Every 5 years
- Annually (Correct answer)
- Every 2 years
Correct answer: Annually
OSHA requires annual retraining for all employees with occupational exposure to bloodborne pathogens, regardless of prior training history.
ISAC Laboratory Safety and Procedures 2
When working with fixed cell samples in flow cytometry, which fixative poses the greatest inhalation risk requiring use in a chemical fume hood?