CABT Laboratory Equipment 3 — Questions and Answers
Question 1: What does the term 'dead volume' refer to in the context of automated liquid handling systems?
- Volume remaining in a well that cannot be aspirated (Correct answer)
- Maximum volume the system can dispense
- Volume lost to evaporation during runs
- Volume of waste fluid produced per cycle
Correct answer: Volume remaining in a well that cannot be aspirated
Dead volume is the residual liquid that cannot be aspirated from a vessel due to the geometry of the tip and container, and must be accounted for in assay planning.
Question 2: Which electromagnetic spectrum region is used by a spectrophotometer in the 'UV range'?
- 700-1000 nm
- 400-700 nm
- 200-400 nm (Correct answer)
- 1000-2000 nm
Correct answer: 200-400 nm
The ultraviolet (UV) range spans approximately 200-400 nm, below the visible spectrum, and is commonly used to measure nucleic acids and aromatic amino acids.
Question 3: A biomedical technician is qualifying a new analytical balance. Which weight class is recommended for calibrating Class I analytical balances?
- Class F weights
- Class M weights
- Class E2 or E1 weights (Correct answer)
- Class III weights
Correct answer: Class E2 or E1 weights
Class E2 or E1 OIML reference weights provide the accuracy required to calibrate Class I analytical balances used in laboratory settings.
Question 4: Which safety feature prevents a centrifuge from operating when the lid is open?
- Thermal overload relay
- Interlock switch (Correct answer)
- Speed governor
- Ground fault circuit interrupter
Correct answer: Interlock switch
An interlock switch (lid interlock) is a safety mechanism that disables centrifuge operation whenever the lid is opened, preventing rotor exposure.
Question 5: In a clinical chemistry analyzer, what is the purpose of a cuvette wash station?
- To calibrate the photometer detector
- To remove residual reagents and samples between measurements to prevent carryover (Correct answer)
- To sterilize cuvettes between patient samples
- To maintain cuvette temperature
Correct answer: To remove residual reagents and samples between measurements to prevent carryover
The cuvette wash station removes residual reagents and sample between reactions to minimize carryover error that could affect subsequent test results.
Question 6: What maintenance schedule is typically recommended for replacing the HEPA filter in a biological safety cabinet (BSC)?
- Every 30 days
- Annually or when filter resistance exceeds specifications (Correct answer)
- Every 6 months regardless of usage
- Only when visible damage is observed
Correct answer: Annually or when filter resistance exceeds specifications
HEPA filters in BSCs are typically replaced annually or when airflow measurements indicate filter resistance has exceeded the manufacturer's specifications.
Question 7: A clinical thermometer used in a specimen incubator reads 2°C above the expected set point after calibration. The technician should:
- Adjust the incubator set point to compensate and document the offset (Correct answer)
- Replace the thermometer immediately
- Continue using the incubator without changes
- Apply a correction factor of -2°C to all readings
Correct answer: Adjust the incubator set point to compensate and document the offset
Adjusting the set point to compensate and documenting the calibration offset is the appropriate corrective action when a calibrated thermometer reveals a systematic error.
CABT Laboratory Equipment 3
What does the term 'dead volume' refer to in the context of automated liquid handling systems?