Laboratory Equipment Operation & Maintenance Flashcards
7 cards from real CLT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Laboratory Equipment Operation & Maintenance flashcards as text
When an automated urinalysis analyzer uses reflectance photometry for dipstick reading, a falsely elevated bilirubin result is MOST likely caused by:
Answer: Highly pigmented (dark orange) urine obscuring pad color change
Highly pigmented urine can cause false-positive bilirubin readings by reflectance because the natural color of the urine interferes with the colorimetric pad reaction being read optically.
The deionized water used in laboratory reagent preparation should have a resistivity of at least:
Answer: 18.2 MΩ·cm
Type 1 (ultrapure) deionized water used for critical reagent preparation should have a resistivity of 18.2 MΩ·cm at 25°C, indicating the near-complete removal of ionic contaminants.
A laboratory uses a two-level Westgard rule scheme. A 1₃s warning on level 1 QC followed by a 1₃s warning on level 2 QC on the same run triggers the:
Answer: R₄s rule indicating random error between levels
When level 1 exceeds +3s and level 2 exceeds -3s (or vice versa) in the same run, the R₄s rule is triggered, indicating random error (range between levels ≥4s), not systematic error.
After replacing a reagent lot on an automated chemistry analyzer, which validation step is required BEFORE releasing patient results?
Answer: Recalibration, QC verification, and comparison to previous lot if required by policy
A new reagent lot requires recalibration with appropriate calibrators, verification by running QC controls within acceptable ranges, and often parallel testing against the previous lot to confirm comparable patient results.
A microplate washer used in ELISA testing is not dispensing the correct wash volume. The FIRST maintenance step is to:
Answer: Check the wash manifold for clogged or kinked tubing
Incorrect dispense volume in a microplate washer is most commonly caused by kinked, clogged, or partially blocked manifold tubing; inspection and clearing of the tubing is the first corrective step.
Gas chromatography (GC) column efficiency is expressed as the number of theoretical plates (N). A higher N value indicates:
Answer: Greater separation resolution between closely eluting peaks
A higher number of theoretical plates means narrower, more distinct peaks, resulting in greater resolution and better separation of compounds with similar retention times.
The primary reason a laboratory must document centrifuge rotor speed verification with a tachometer during preventive maintenance is to:
Answer: Confirm that the manufacturer's rated RPM matches actual performance for specimen integrity
Verifying actual RPM against the set RPM ensures the centrifugal force (RCF) applied to specimens matches the required value for proper separation, directly affecting specimen quality and downstream test accuracy.