Clin. Chem Flashcards
Which formula correctly describes the relationship
between absorbance and %T ?
A. A = 2 – log %T
B. A = log 1/T
C. A = –log T
D. All of these options
D. All of these options
A solution that has a transmittance of 1.0 %T
would have an absorbance of:
A. 1.0
B. 2.0
C. 1%
D. 99%
B. 2.0
A = 2.0 – log %T
A = 2.0 – log 1.0
The log of 1.0 = 0
A = 2.0
In absorption spectrophotometry:
A. Absorbance is directly proportional to
transmittance
B. Percent transmittance is directly proportional to
concentration
C. Percent transmittance is directly proportional to
the light path length
D. Absorbance is directly proportional to
concentration
D. Absorbance is directly proportional to
concentration
Which wavelength would be absorbed strongly
by a red-colored solution?
A. 450 nm
B. 585 nm
C. 600 nm
D. 650 nm
red-colored solution - 450 nm
A green-colored solution would show highest
transmittance at:
A. 475 nm
B. 525 nm
C. 585 nm
D. 620 nm
green-colored solution - 525 nm
SITUATION: A technologist is performing an
enzyme assay at 340 nm using a visible-range
spectrophotometer. After setting the wavelength
and adjusting the readout to zero %T with the
light path blocked, a cuvette with deionized water
is inserted. With the light path fully open and the
100%T control at maximum, the instrument
readout will not rise above 90%T. What is the
most appropriate first course of action?
A. Replace the source lamp
B. Insert a wider cuvette into the light path
C. Measure the voltage across the lamp terminals
D. Replace the instrument fuse
Replace the source lamp
Which type of monochromator produces the
purest monochromatic light in the UV range?
A. A diffraction grating and a fixed exit slit
B. A sharp cutoff filter and a variable exit slit
C. Interference filters and a variable exit slit
D. A prism and a variable exit slit
A prism and a variable exit slit
Which monochromator specification is required
in order to measure the true absorbance of a
compound having a natural absorption
bandwidth of 30 nm?
A. 50-nm bandpass
B. 25-nm bandpass
C. 15-nm bandpass
D. 5-nm bandpass
5-nm bandpass
Which photodetector is most sensitive to low
levels of light?
A. Barrier layer cell
B. Photodiode
C. Diode array
D. Photomultiplier tube
Photomultiplier tube
Which condition is a common cause of stray light?
A. Unstable source lamp voltage
B. Improper wavelength calibration
C. Dispersion from second-order spectra
D. Misaligned source lamp
C. Dispersion from second-order spectra
Which type of filter is best for measuring stray
light?
A. Wratten
B. Didymium
C. Sharp cutoff
D. Neutral density
Sharp cutoff
Which of the following materials is best suited
for verifying the wavelength calibration of a
spectrophotometer?
A. Neutral density filters
B. Potassium dichromate solutions traceable to the
National Bureau of Standards reference
C. Wratten filters
D. Holmium oxide glass
D. Holmium oxide glass
Why do many optical systems in chemistry
analyzers utilize a reference light path?
A. To increase the sensitivity of the measurement
B. To minimize error caused by source lamp
fluctuation
C. To obviate the need for wavelength adjustment
D. To reduce stray light effects
To minimize error caused by source lamp
fluctuation
Which component is required in a
spectrophotometer in order to produce a
spectral absorbance curve?
A. Multiple monochromators
B. A reference optical beam
C. Photodiode array
D. Laser light source
Photodiode array
The half-band width of a monochromator is
defined by:
A. The range of wavelengths passed at
50% maximum transmittance
B. One-half the lowest wavelength of optical
purity
C. The wavelength of peak transmittance
D. One-half the wavelength of peak absorbanc
The range of wavelengths passed at
50% maximum transmittance
