Question 1

In spectrophotometric determinations,which of the following is the formula for calculating the absorbance of a solution?

Accepted Answer

A)   (Molar absorptivity * length of light path) /concentration in mol/L
B)   (Molar absorptivity * concentration in g/dL) /length of light path
C)   Molar absorptivity * length of light path * concentration in mol/L
D)   (Length of light path * concentration in g/dL) /molar absorptivityE) A) and D)
F) B) and D) C

Question 2

A monochromator's filter must be tested to determine whether it can isolate a specific part of the electromagnetic spectrum.Percent transmittance (%T) of light is plotted against a specific wavelength in nanometers.It is noted at which wavelengths 50%T (one half of the peak transmittance) occurred.This type of test assesses the filter's:

Accepted Answer

A)   linearity.
B)   spectral bandwidth.
C)   calibration.
D)   absorbance spectrum.E) A) and C)
F) B) and C)

Question 3

Which one of the following optical techniques is not considered an emission technique?

Accepted Answer

A)   Phosphorimetry
B)   Nephelometry
C)   Luminometry
D)   FluorometryE) B) and D)
F) A) and C)

Question 4

Which one of the following wavelengths is within the "near" ultraviolet region of the electromagnetic spectrum?

Accepted Answer

A)   320 nm
B)   450 nm
C)   540 nm
D)   690 nmE) A) and C)
F) B) and C)

Question 5

Which one of the following statements best describes Beer law?

Accepted Answer

A)   The concentration of a substance is inversely proportional to the logarithm of transmitted light.
B)   Absorbance is inversely proportional to the logarithm of the concentration.
C)   Transmitted light is directly proportional to the concentration of a substance in solution.
D)   Intensity of incident light divided by intensity of transmitted light equals concentration.E) A) and C)
F) A) and D)

Question 6

Which one of the following statements concerning nephelometry is correct?

Accepted Answer

A)   Nephelometry is the measure of the concentration of particles by measuring the amount of incident light blocked by the particles.
B)   In a nephelometric measurement,light blocked by solutes in the solution at 180° from the incident light is measured by a photodetector.
C)   The decrease in the intensity of scattered light is directly proportional to the number of particles in the solution,and the measurement of this decrease is called nephelometry.
D)   In a nephelometric procedure,the measurement of scattered light that is not in the direct path of the transmitted light is made at right angles to the incident light.E) A) and C)
F) None of the above

Question 7

Atomic absorption spectrophotometry is an emission technique that is used frequently in clinical laboratories to measure:

Accepted Answer

A)   complex antigen-antibody reactions.
B)   rotational relaxation of bound fluorophores.
C)   elements.
D)   high-molecular-weight compounds.E) All of the above
F) A) and B) C

Question 8

Laboratory analysis of free thyroxine (fT4) in your chemistry laboratory is performed with a conventional fluorometric analyzer,which uses a laser light as the excitation source.You have received a sample from an individual known to have a very elevated fT4 level.For the sample's value to be within linear range of the assay,you dilute the sample by a factor of 10 and proceed with the analysis.Upon reviewing the results,you note that the value of the diluted sample is reported as "none detected." What is the likely reason for this result?

Accepted Answer

A)   Hormones cannot be assayed using fluorometry because they will produce concentration quenching.
B)   The dilution of the sample has lowered produced photobleaching by the intense light source and photodecomposition of the analyte.
C)   Unwanted background fluorescence due to elevated protein hormone has produced a false-negative result.
D)   High intensity light emission can lead to pulse pileup in photomultiplier tubes,leading to an underestimation of the true light emission intensity.E) A) and B)
F) C) and D)

Question 9

A fluorometric measurement technique used to detect immunologic reactions that measures fluorescence produced by the rotation of small versus large fluorescent-labeled molecules and their relation to analyte concentration in an unknown sample is known as:

Accepted Answer

A)   phosphorimetry.
B)   reflectance photometry.
C)   nephelometry.
D)   fluorescence polarization.E) B) and D)
F) All of the above

Question 10

A light-beam chopper in a double-beam-in-time spectrophotometer is used to:

Accepted Answer

A)   isolate light of a desired wavelength.
B)   compensate for light source variation.
C)   atomize a sample on a carbon rod in an enclosed chamber.
D)   provide polarized light.E) A) and B)
F) None of the above

Question 11

In regard to absorption photometry,absorbance is calculated from transmittance by which one of the following formulae?

Accepted Answer

A)   A = log %T - 2
B)   A = log T
C)   A = -log T
D)   A = abcE) None of the above
F) A) and D)

Question 12

In regard to atomic absorption (AA) spectrophotometry,which one of the following statements is correct?

Accepted Answer

A)   The technique combines laser-induced fluorometry and particle light scattering analysis to differentiate molecules,cells,or particles by size and shape.
B)   The technique measures concentration through the detection of absorbance of electromagnetic radiation by atoms of elements instead of molecules.
C)   Oxidation of an organic compound such as luminol induces an excited state,and light is emitted when the electron returns to the ground state.
D)   The amount of light scattered at right angles to the incident light is directly proportional to the concentration of the analyte of interest.E) B) and D)
F) C) and D) B

Question 13

A blood specimen is obtained from an individual who is known to have elevated lipids and the serum appears milky.This individual's physician has ordered an estrogen immunoassay that your laboratory performs using a nephelometric technique.Which one of the following statements is correct concerning the possible outcome of this assay?

Accepted Answer

A)   Certain components of this individual's sample will likely produce excess fluorescence by the phenomenon called "solvent effect" in the nephelometric assay.
B)   The lipemic specimen will produce interfering background light intensity and excess light scatter in this type of assay.
C)   The sample flow rate will be affected through the analyzer's nebulizer because of the altered density of the sample.
D)   Elevated serum lipids will not interfere with this assay because nephelometry is not affected by any type of sample variability.E) B) and C)
F) A) and C)

Question 14

The light source in an atomic absorption spectrophotometer is typically a:

Accepted Answer

A)   prism.
B)   tungsten light.
C)   laser light.
D)   hollow cathode tube.E) B) and D)
F) B) and C)

Question 15

There are several interferences that can affect or limit fluorescence measurements.For example,the inner filter effect:

Accepted Answer

A)   occurs when the solution absorbs greater than 2% of the exciting light,producing a nonlinear response between concentration and fluorescence emission.
B)   involves fluorophores that have overlapping excitation and emission spectra and that are susceptible to loss of detection because of background light scatter.
C)   involves solvents such as ethanol that cause appreciable fluorescence due to the interaction of the fluorophore with the solvent.
D)   is caused by light scattering of proteins and other macromolecules in the sample matrix,which might cause unwanted background fluorescence.E) None of the above
F) B) and C)

Question 16

In a fluorometric measurement,the difference between the maximum wavelength of the excitation light and the maximum wavelength of the emitted fluorescence light is a constant referred to as:

Accepted Answer

A)   Beer law.
B)   chemiluminescence.
C)   polarization.
D)   the Stokes shift.E) All of the above
F) B) and D)

Question 17

Which two optical techniques are combined operationally in a flow cytometer?

Accepted Answer

A)   Laser-induced fluorometry and light scattering techniques
B)   Atomic absorption spectrophotometry and light scattering techniques
C)   Spectrophotometry and fluorescence polarization techniques
D)   Fluorescence polarization and laser-induced fluorometryE) A) and D)
F) None of the above

Question 18

The visible spectrum is composed of those wavelengths between 380 and 750 nm.

Accepted Answer

A) True 
 B)False

Question 19

When selecting a photometric technique that is more sensitive to a low concentration of analyte,a laboratory director compares absorbance measuring devices against those that measure fluorescence intensity.Which technique is considered more sensitive in its measurements and why?

Accepted Answer

A)   Absorbance measurements are more sensitive because of the ability of the monochromator to isolate very specific parts of the spectrum.
B)   Fluorescence intensity measurements are more sensitive because the fluorophores used are very specific to the analytes they bind to and will bind to small analytes easily.
C)   Fluorescence intensity measurements are more sensitive because of the use of intense light sources,signal filtering,and sensitive light emission photometers.
D)   Absorbance measurements are more sensitive because the flame can break down complex compounds into elements that are specifically measured.E) B) and C)
F) A) and D)

Question 20

A molecule is said to fluoresce when it absorbs light at one wavelength and emits light of:

Accepted Answer

A)   a lower energy.
B)   a shorter wavelength.
C)   a higher energy.
D)   the same wavelength.E) None of the above
F) A) and C)

Exam 9: Optical Techniques

In spectrophotometric determinations,which of the following is the formula for calculating the absorbance of a solution?

Correct Answer
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C

Correct Answer
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Which one of the following optical techniques is not considered an emission technique?

Correct Answer
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Which one of the following wavelengths is within the "near" ultraviolet region of the electromagnetic spectrum?

Correct Answer
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Which one of the following statements best describes Beer law?

Correct Answer
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Which one of the following statements concerning nephelometry is correct?

Correct Answer
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Atomic absorption spectrophotometry is an emission technique that is used frequently in clinical laboratories to measure:

Correct Answer
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C

Correct Answer
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A fluorometric measurement technique used to detect immunologic reactions that measures fluorescence produced by the rotation of small versus large fluorescent-labeled molecules and their relation to analyte concentration in an unknown sample is known as:

Correct Answer
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A light-beam chopper in a double-beam-in-time spectrophotometer is used to:

Correct Answer
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In regard to absorption photometry,absorbance is calculated from transmittance by which one of the following formulae?

Correct Answer
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In regard to atomic absorption (AA) spectrophotometry,which one of the following statements is correct?

Correct Answer
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B

Correct Answer
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The light source in an atomic absorption spectrophotometer is typically a:

Correct Answer
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There are several interferences that can affect or limit fluorescence measurements.For example,the inner filter effect:

Correct Answer
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In a fluorometric measurement,the difference between the maximum wavelength of the excitation light and the maximum wavelength of the emitted fluorescence light is a constant referred to as:

Correct Answer
verified

Which two optical techniques are combined operationally in a flow cytometer?

Correct Answer
verified

The visible spectrum is composed of those wavelengths between 380 and 750 nm.

Correct Answer
verified

When selecting a photometric technique that is more sensitive to a low concentration of analyte,a laboratory director compares absorbance measuring devices against those that measure fluorescence intensity.Which technique is considered more sensitive in its measurements and why?

Correct Answer
verified

A molecule is said to fluoresce when it absorbs light at one wavelength and emits light of:

Correct Answer
verified

Exam 9: Optical Techniques

In spectrophotometric determinations,which of the following is the formula for calculating the absorbance of a solution?

Correct AnswerverifiedC

Correct AnswerverifiedShow Answer

Which one of the following optical techniques is not considered an emission technique?

Correct AnswerverifiedShow Answer

Which one of the following wavelengths is within the "near" ultraviolet region of the electromagnetic spectrum?

Correct AnswerverifiedShow Answer

Which one of the following statements best describes Beer law?

Correct AnswerverifiedShow Answer

Which one of the following statements concerning nephelometry is correct?

Correct AnswerverifiedShow Answer

Atomic absorption spectrophotometry is an emission technique that is used frequently in clinical laboratories to measure:

Correct AnswerverifiedC

Correct AnswerverifiedShow Answer

A fluorometric measurement technique used to detect immunologic reactions that measures fluorescence produced by the rotation of small versus large fluorescent-labeled molecules and their relation to analyte concentration in an unknown sample is known as:

Correct AnswerverifiedShow Answer

A light-beam chopper in a double-beam-in-time spectrophotometer is used to:

Correct AnswerverifiedShow Answer

In regard to absorption photometry,absorbance is calculated from transmittance by which one of the following formulae?

Correct AnswerverifiedShow Answer

In regard to atomic absorption (AA) spectrophotometry,which one of the following statements is correct?

Correct AnswerverifiedB

Correct AnswerverifiedShow Answer

The light source in an atomic absorption spectrophotometer is typically a:

Correct AnswerverifiedShow Answer

There are several interferences that can affect or limit fluorescence measurements.For example,the inner filter effect:

Correct AnswerverifiedShow Answer

In a fluorometric measurement,the difference between the maximum wavelength of the excitation light and the maximum wavelength of the emitted fluorescence light is a constant referred to as:

Correct AnswerverifiedShow Answer

Which two optical techniques are combined operationally in a flow cytometer?

Correct AnswerverifiedShow Answer

The visible spectrum is composed of those wavelengths between 380 and 750 nm.

Correct AnswerverifiedShow Answer

When selecting a photometric technique that is more sensitive to a low concentration of analyte,a laboratory director compares absorbance measuring devices against those that measure fluorescence intensity.Which technique is considered more sensitive in its measurements and why?

Correct AnswerverifiedShow Answer

A molecule is said to fluoresce when it absorbs light at one wavelength and emits light of:

Correct AnswerverifiedShow Answer

Correct Answer
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C

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C

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B

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