QUIZ 1 extra Flashcards

A plasma sample is hemolyzed and turbid. What
is required to perform a sample blank in order
to correct the measurement for the intrinsic
absorbance of the sample when performing a
spectrophotometric assay?
A. Substitute deionized water for the sample
B. Dilute the sample 1:2 with a standard of
known concentration
C. Substitute saline for the reagent
D. Use a larger volume of the sample

Which instrument requires a highly regulated
DC power supply?
A. A spectrophotometer with a barrier layer cell
B. A colorimeter with multilayer interference
filters
C. A spectrophotometer with a photomultiplier
tube
D. A densitometer with a photodiode detector

Which statement regarding reflectometry is true?
A. The relation between reflectance density and
concentration is linear
B. Single-point calibration can be used to determine
concentration
C. 100% reflectance is set with an opaque film
called a white reference
D. The diode array is the photodetector of choice

Bichromatic measurement of absorbance can
correct for interfering substances if:
A. The contribution of the interferent to absorbance
is the same at both wavelengths
B. Both wavelengths pass through the sample
simultaneously
C. The side band is a harmonic of the primary
wavelength
D. The chromogen has the same absorbance at both
wavelengths

Which instrument requires a primary and
secondary monochromator?
A. Spectrophotometer
B. Atomic absorption spectrophotometer
C. Fluorometer
D. Nephelometer

Which of the following statements about
fluorometry is accurate?
A. Fluorometry is less sensitive than
spectrophotometry
B. Fluorometry is less specific than
spectrophotometry
C. Unsaturated cyclic molecules are often
fluorescent
D. Fluorescence is directly proportional to
temperature

Which of the following components is not needed
in a chemiluminescent immunoassay analyzer?
A. Source lamp
B. Monochromator
C. Photodetector
D. Wash station

Which substance is used to generate the light
signal in electrochemiluminescence?
A. Acridinium
B. Luminol
C. Dioxetane phosphate
D. Ruthenium

Light scattering when the wavelength is greater
than 10 times the particle diameter is described by:
A. Rayleigh’s law
B. The Beer–Lambert law
C. Mie’s law
D. The Rayleigh–Debye law

Which statement regarding nephelometry is true?
A. Nephelometry is less sensitive than absorption
spectrophotometry
B. Nephelometry follows Beer’s law
C. The optical design is identical to a turbidimeter
except that a HeNe laser light source is used
D. The detector response is directly proportional to
concentration

The purpose of the nebulizer in an atomic
absorption spectrophotometer that uses
a flame is to:
A. Convert ions to atoms
B. Cause ejection of an outer shell electron
C. Reduce evaporation of the sample
D. Burn off organic impurities

A flameless atomic absorption spectrophotometer
dehydrates and atomizes a sample using:
A. A graphite capillary furnace
B. An electron gun
C. A thermoelectric semiconductor
D. A thermospray platform

When measuring lead in whole blood using atomic
absorption spectrophotometry, what reagent is
required to obtain the needed sensitivity and
precision?
A. Lanthanum
B. Lithium
C. Triton X-100
D. Chloride

Interference in atomic absorption
spectrophotometry caused by differences
in viscosity is called:
A. Absorption interference
B. Matrix effect
C. Ionization interference
D. Quenching

All of the following are required when
measuring magnesium by atomic absorption
spectrophotometry except:
A. A hollow cathode lamp with a magnesium
cathode
B. A chopper to prevent optical interference from
magnesium emission
C. A monochromator to isolate the magnesium
emission line at 285 nm
D. A 285-nm reference beam to correct for
background absorption

When measuring calcium by atomic absorption
spectrophotometry, which is required?
A. An organic extraction reagent to deconjugate
calcium from protein
B. An internal standard
C. A magnesium chelator
D. Lanthanum oxide to chelate phosphates

Select the equation describing the potential that
develops at the surface of an ion-selective
electrode.
A. van Deemter equation
B. van Slyke equation
C. Nernst equation
D. Henderson–Hasselbalch equation

The reference potential of a silver–silver chloride
electrode is determined by the:
A. Concentration of the potassium chloride filling
solution
B. Surface area of the electrode
C. Activity of total anion in the paste covering the
electrode
D. The concentration of silver in the paste covering
the electrode

The term RT/nF in the Nernst equation
defines the:
A. Potential at the ion-selective membrane
B. Slope of the electrode
C. Decomposition potential
D. Isopotential point of the electrode

The ion-selective membrane used to measure
potassium is made of:
A. High-borosilicate glass membrane
B. Polyvinyl chloride dioctylphenyl phosphonate
ion exchanger
C. Valinomycin gel
D. Calomel

The response of a sodium electrode to a 10-fold
increase in sodium concentration should be:
A. A 10-fold drop in potential
B. An increase in potential of approximately 60 mV
C. An increase in potential of approximately 10 mV
D. A decrease in potential of approximately 10 mV

The response of a sodium electrode to a 10-fold
increase in sodium concentration should be:
A. A 10-fold drop in potential
B. An increase in potential of approximately 60 mV
C. An increase in potential of approximately 10 mV
D. A decrease in potential of approximately 10 mV

Which of the electrodes below is a current producing (amperometric) rather than a voltage-producing (potentiometric) electrode?
A. Clark electrode
B. Severinghaus electrode
C. pH electrode
D. Ionized calcium electrode

Which of the following would cause a “response”
error from an ion-selective electrode for sodium
when measuring serum but not the calibrator?
A. Interference from other electrolytes
B. Protein coating the ion-selective membrane
C. An overrange in sodium concentration
D. Protein binding to sodium ions

In polarography, the voltage needed to cause
depolarization of the cathode is called the:
A. Half-wave potential
B. Isopotential point
C. Decomposition potential
D. Polarization potential

Persistent noise from an ion-selective electrode is
most often caused by:
A. Contamination of sample
B. Blocked junction at the salt bridge
C. Overrange from high concentration
D. Improper calibration

Which element is reduced at the cathode of a
Clark polarographic electrode?
A. Silver
B. Oxygen
C. Chloride
D. Potassium

Which of the following statements accurately
characterizes the coulometric titration of chloride?
A. The indicator electrodes generate voltage
B. Constant current must be present across the
generator electrodes
C. Silver ions are formed at the generator cathode
D. Chloride concentration is inversely proportional
to titration time

In the coulometric chloride titration:
A. Acetic acid in the titrating solution furnishes
the counter ion for reduction
B. The endpoint is detected by amperometry
C. The titrating reagent contains a phosphate buffer
to keep pH constant
D. Nitric acid (HNO3

Which of the following compounds can interfere
with the coulometric chloride assay?
A. Bromide
B. Ascorbate
C. Acetoacetate
D. Nitrate

All of the following compounds contribute to the
osmolality of plasma except:
A. Lipids
B. Creatinine
C. Drug metabolites
D. Glucose

One mole per kilogram H2O of any solute will
cause all of the following except:
A. Lower the freezing point by 1.86°C
B. Raise vapor pressure by 0.3 mm Hg
C. Raise the boiling point by 0.52°C
D. Raise osmotic pressure by 22.4 atm

What component of a freezing point osmometer
measures the sample temperature?
A. Thermistor
B. Thermocouple
C. Capacitor
D. Electrode

What type of measuring circuit is used in a
freezing point osmometer?
A. Electrometer
B. Potentiometer
C. Wheatstone bridge
D. Thermal conductivity bridge

What type of detector is used in high-performance
liquid chromatography with electrochemical
detection (HPLC–ECD)?
A. Calomel electrode
B. Conductivity electrode
C. Glassy carbon electrode
D. Polarographic electrode

In gas chromatography, the elution order of
volatiles is usually based upon the:
A. Boiling point
B. Molecular size
C. Carbon content
D. Polarity

Select the chemical that is used in most HPLC
procedures to decrease solvent polarity.
A. Hexane
B. Nonane
C. Chloroform
D. Acetonitrile

In thin-layer chromatography (TLC), the distance
the solute migrates divided by the distance the
solvent migrates is the:
A. tR
B. Kd
C. Rf
D. pK

Which reagent is used in thin-layer
chromatography (TLC) to extract cocaine
metabolites from urine?
A. Acid and sodium chloride
B. Alkali and organic solvent
C. Chloroform and sodium acetate
D. Neutral solution of ethyl acetate

What is the purpose of an internal standard in
HPLC and GC methods?
A. To compensate for variation in extraction and
injection
B. To correct for background absorbance
C. To compensate for changes in flow rate
D. To correct for coelution of solutes

What is the confirmatory method for measuring
drugs of abuse?
A. HPLC
B. Enzyme-multiplied immunoassay technique
(EMIT)
C. Gas chromatography with mass spectroscopy
(GC-MS)
D. TLC

What component is used in a GC-MS but not used
in an LC-MS?
A. Electron source
B. Mass filter
C. Detector
D. Vacuum

In addition to velocity, what variable is also
needed to calculate the relative centrifugal force
(g force) of a centrifuge?
A. Head radius
B. Angular velocity coefficient
C. Diameter of the centrifuge tube
D. Ambient temperature in degrees Centigrade

In addition to velocity, what variable is also
needed to calculate the relative centrifugal force
(g force) of a centrifuge?
A. Head radius
B. Angular velocity coefficient
C. Diameter of the centrifuge tube
D. Ambient temperature in degrees Centigrade

When calibrating a semiautomatic pipet that has
a fixed delivery of 10.0 μL using a gravimetric
method, what should be the average weight of
deionized water transferred?
A. 10.0 μg
B. 100.0 μg
C. 1.0 mg
D. 10.0 mg

Which of the following contributes the most to
the serum total CO2?
A. PCO2
B. dCO2
C. HCO3
D. Carbonium ion

Chemiluminescence

Electrochemistry

Fluorescence

Gas chromatography

High-performance liquid chromatography

Ion-selective electrodes

Osmometry