CLT Equipment Operation & Maintenance 2 — Questions and Answers
Question 1: When performing a daily function check on an automated hematology analyzer, which control material should be run first?
- High-level control
- Low-level control
- Normal-level control (Correct answer)
- Calibrator material
Correct answer: Normal-level control
Normal-level (mid-range) controls are typically run first to verify the analyzer is operating within the expected reference range before running abnormal controls.
Question 2: A centrifuge makes an unusual grinding noise during operation. What is the FIRST action the technologist should take?
- Increase the speed to see if the noise resolves
- Stop the centrifuge and remove it from service for inspection (Correct answer)
- Continue the run and document the noise in the maintenance log
- Add lubrication to the rotor shaft immediately
Correct answer: Stop the centrifuge and remove it from service for inspection
Unusual noises during centrifuge operation indicate a mechanical problem; the unit must be stopped and removed from service to prevent injury or damage.
Question 3: What is the purpose of a Westgard rule (1-3s) in laboratory quality control?
- It rejects a run when one control result exceeds ±3 SD (Correct answer)
- It warns when one control result exceeds ±2 SD
- It rejects a run when two consecutive controls exceed ±2 SD
- It warns when the range between duplicates exceeds 4 SD
Correct answer: It rejects a run when one control result exceeds ±3 SD
The 1-3s Westgard rule is a rejection rule triggered when any single control value falls beyond ±3 standard deviations from the mean.
Question 4: Which maintenance task is MOST important to perform before storing a pH meter electrode overnight?
- Calibrating the electrode with two buffer solutions
- Rinsing the electrode with distilled water and storing in storage solution (Correct answer)
- Drying the electrode completely with lint-free cloth
- Immersing the electrode in a high-pH buffer solution
Correct answer: Rinsing the electrode with distilled water and storing in storage solution
pH electrodes must be kept hydrated; rinsing with distilled water then storing in appropriate storage solution prevents the sensing glass from drying and cracking.
Question 5: A pipette calibration check shows volumes consistently delivered are 2% below the nominal volume. This represents:
- Random error due to improper technique
- Systematic error requiring pipette recalibration or replacement (Correct answer)
- Acceptable performance within the ±5% tolerance
- A matrix effect from the calibration fluid used
Correct answer: Systematic error requiring pipette recalibration or replacement
A consistent bias in one direction (always low) is a systematic error, indicating the pipette needs recalibration or servicing.
Question 6: During operation of an automated chemistry analyzer, a flag for 'clot detected' appears on the sample. What should the technologist do?
- Dilute the sample 1:2 and rerun
- Visually inspect and recentrifuge the sample, then rerun (Correct answer)
- Accept the result if it is within the reference range
- Add anticoagulant to the tube and mix
Correct answer: Visually inspect and recentrifuge the sample, then rerun
A clot can cause falsely low results; the sample should be inspected and recentrifuged (if possible) or a new specimen collected before rerunning.
Question 7: What is the correct frequency for replacing the light source (lamp) in a spectrophotometer used in a clinical laboratory?
- Every 24 hours of continuous use
- According to manufacturer guidelines and when wavelength accuracy fails verification (Correct answer)
- Once per calendar year regardless of use
- Whenever the absorbance reading drops below 0.1 AU
Correct answer: According to manufacturer guidelines and when wavelength accuracy fails verification
Lamp replacement intervals are specified by the manufacturer and should also be triggered when performance verification (wavelength accuracy or stray light checks) fails.
CLT Equipment Operation & Maintenance 2
When performing a daily function check on an automated hematology analyzer, which control material should be run first?