AACC AACC Laboratory Instrumentation & Technology 3

Question 1

What is the purpose of a Levy-Jennings chart in laboratory instrumentation monitoring?

Accepted Answer

To graphically track QC values and detect systematic or random error trends

Answer

Levy-Jennings charts plot sequential QC results against time, with control limits at ±2SD and ±3SD to visualize shifts, trends, and random errors.

Question 2

In clinical immunoassays, what does the 'hook effect' (prozone phenomenon) cause?

Accepted Answer

Falsely low results at very high analyte concentrations due to antigen excess

Answer

At very high analyte concentrations, excess antigen saturates both capture and detection antibodies independently, preventing sandwich formation and producing falsely low results.

Question 3

Which type of analyzer configuration processes one test at a time on a single patient sample?

Accepted Answer

Discrete analyzer

Answer

Discrete analyzers process individual reaction vessels for each test-patient combination, preventing carryover between tests on different patients.

Question 4

What is the main advantage of using tandem mass spectrometry (MS/MS) over single-stage MS in clinical newborn screening?

Accepted Answer

Ability to simultaneously quantify multiple analytes with high specificity in one run

Answer

MS/MS uses two mass analyzers in series, allowing simultaneous identification and quantification of dozens of metabolites from a single dried blood spot with high specificity.

Question 5

What type of interference is caused by lipemia in photometric assays?

Accepted Answer

Optical interference due to light scattering by lipid particles

Answer

Suspended lipid particles in lipemic samples scatter light, increasing apparent absorbance and causing falsely elevated results in photometric methods.

AACC - American Association for Clinical Chemistry Certification Practice Test

AACC - American Association for Clinical Chemistry Certification Practice Test

AACC AACC Laboratory Instrumentation & Technology 3