AACC AACC Laboratory Instrumentation & Technology 2

Question 1

Which principle underlies the operation of an ion-selective electrode (ISE) used to measure electrolytes such as sodium and potassium?

Accepted Answer

Selective membrane potential difference (Nernst equation)

Answer

ISEs generate a voltage across a selective membrane that is proportional to the logarithm of the ion activity, as described by the Nernst equation.

Question 2

What is the function of a monochromator in a spectrophotometer?

Accepted Answer

To isolate a narrow band of wavelengths from a broadband light source

Answer

A monochromator uses a prism or diffraction grating to disperse light and select a specific wavelength range for the measurement.

Question 3

In point-of-care testing (POCT) devices, what type of calibration is typically used to ensure accuracy without full laboratory procedures?

Accepted Answer

Single-point or factory-embedded calibration with electronic verification

Answer

Most POCT devices use factory-set calibration encoded on cartridges or test strips, with single-point electronic verification rather than full wet chemistry calibration.

Question 4

Which component of an atomic absorption spectrophotometer (AAS) provides element-specific radiation for analyte measurement?

Accepted Answer

Hollow cathode lamp (HCL)

Answer

The hollow cathode lamp emits the characteristic spectral lines of the element being measured, providing the specific wavelength needed for absorption.

Question 5

What is the Beer-Lambert law relationship used for in clinical spectrophotometry?

Accepted Answer

Relating analyte concentration to absorbance at a specific wavelength

Answer

Beer-Lambert law states that absorbance is directly proportional to analyte concentration and path length, forming the basis of quantitative spectrophotometric assays.

AACC - American Association for Clinical Chemistry Certification Practice Test

AACC - American Association for Clinical Chemistry Certification Practice Test

AACC AACC Laboratory Instrumentation & Technology 2