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AACC Instrumentation & Technology Flashcards

6 cards from real AACC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. In electrochemiluminescence immunoassay (ECLIA) technology, what generates the measurable signal?

    Answer: Light emitted when a ruthenium-labeled complex is electrochemically stimulated at an electrode surface

    ECLIA uses an electrical stimulus at an electrode to cause a ruthenium(II) tris-bipyridyl label to emit light, which is measured to quantify the analyte.

  2. Which specimen type is preferred for most routine clinical chemistry tests run on automated analyzers?

    Answer: Serum or lithium heparin plasma

    Serum and lithium heparin plasma are the most commonly used specimen types for automated chemistry analyzers because they are compatible with most assay chemistries.

  3. What is the analytical sensitivity of a laboratory test?

    Answer: The lowest concentration of analyte that can be reliably distinguished from zero (blank)

    Analytical sensitivity (limit of detection) is the smallest concentration measurably different from zero signal, reflecting the assay's ability to detect very low analyte levels.

  4. In clinical mass spectrometry, what does 'tandem MS' (MS/MS) improve compared to single-stage MS?

    Answer: Specificity by fragmenting precursor ions and measuring characteristic daughter ions

    MS/MS selects a precursor ion, fragments it, and measures specific product ions, dramatically improving specificity and reducing interference from co-eluting compounds.

  5. Which type of interference can cause falsely low results in spectrophotometric assays by absorbing the same wavelength used to measure the analyte?

    Answer: Icterus (bilirubin)

    Bilirubin (icteric samples) absorbs light in the 415–460 nm range, which overlaps with many spectrophotometric assay wavelengths, causing negative interference and falsely low results.

  6. What is the primary advantage of using ion-selective electrodes (ISEs) for electrolyte measurement compared to older flame photometry?

    Answer: ISEs measure ion activity directly in undiluted samples with faster results and no combustion hazard

    ISEs measure ion activity directly using ion-selective membranes, eliminating the need for combustion, providing rapid results, and allowing direct measurement that avoids pseudohyponatremia.