1|Page
UF PHA6936 FINAL EXAM PREP;
COMPREHENSIVE QUESTIONS & VERIFIED
SOLUTIONS
Potential issue of cross-reactivity? -correct-answer-The concentration of the
individual drugs may not be enough to trigger a positive confirmatory test, where
the total concentration of the drugs gave a positive IA test.
Prior to applying an immunoassay technique in the lab -correct-answer-establish
and verify a limit of detection and linear range for the method.
Cut Off Levels -correct-answer-the concentration used to distinguish between
positive and negative results
Applications of IAs -correct-answer-postmortem investigations, workplace drug
testing, human performance investigation
Matrix of choice for IA -correct-answer-Urine, because it has fewer interfering
compounds and decomposition products
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Why not use blood for IA? -correct-answer-More complicated matrix due to
interfering compounds such as proteins.
UV-Vis Spectrophotometry -correct-answer-the principle that substances absorb
and emit electromagnetic radiation at different wavelengths and provide an
absorbance spectrum and determine the concentration of a substance in solution
Materials absorb energy causes... -correct-answer-molecules to oscillate, inducing
electric and magnetic fields which generate an electromagnetic wave or light
Electromagnetic Spectrum -correct-answer-Radiation Type Frequency Wavelength
Transition
UV 10^15 - 10^17Hz 200-400nm outer electron
Vis 4- 7.5 x 10^14Hz 400-800nm outer electron
NearIR 10^12 - 10^14 Hz 1 um - 3 um molecular vibrations
Chromophore -correct-answer-color-producing molecular groups responsible for
energy absorption
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Auxochrome -correct-answer-a saturated chemical group that has little to no
absorption but modifies the absorption spectrum when attached to a
chromophore
Beer's Law -correct-answer-considers sample concentration for a given path
length (b) the transmitted intensity (I) decreases exponentially with an increasing
sample concentration (c) of a homogeneously absorbing system.
Lambert's Law -correct-answer-considers instrument factors, states that for a
given concentration (C) the radiation transmitted through a homogeneously
absorbing system (I) decreases exponentially with increasing path length (b)
Beer-Lambert Law (commonly Beer's Law) -correct-answer-Absorbance (A) =
molar absorptivity (e)times concentration (c) times path length(b)
Does absorptivity in Beer's law have units? -correct-answer-No, the units cancel
out
Why would Beer's Law be non-linear? -correct-answer-1. electrostatic interactions
between molecules in close proximity
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2. scattering of light due to particles in the sample
3. fluorescence of the sample
4. changes in the refractive index at high concentration
5. non-monochromatic radiation
6. stray light
7. non-homogenous sample
8. reaction of the sample with the solvent
Solvent effects in UV-Vis -correct-answer-aromatic chromophores show fine
vibrational in non-polar solvents due to solute-solvent interactions. In aqueous
solutions, the pH affects ionizable chromophores due to conjugation changes in
the ionized and non-ionized chromophore
Bathochromic Shift -correct-answer-phenolic compounds the solution is more
alkaline leads to an absorption shift to a longer wavelength (red)
Hyperchromic effect -correct-answer-Loss of fine structure and an increase in
molar absorptivity
UF PHA6936 FINAL EXAM PREP;
COMPREHENSIVE QUESTIONS & VERIFIED
SOLUTIONS
Potential issue of cross-reactivity? -correct-answer-The concentration of the
individual drugs may not be enough to trigger a positive confirmatory test, where
the total concentration of the drugs gave a positive IA test.
Prior to applying an immunoassay technique in the lab -correct-answer-establish
and verify a limit of detection and linear range for the method.
Cut Off Levels -correct-answer-the concentration used to distinguish between
positive and negative results
Applications of IAs -correct-answer-postmortem investigations, workplace drug
testing, human performance investigation
Matrix of choice for IA -correct-answer-Urine, because it has fewer interfering
compounds and decomposition products
,2|Page
Why not use blood for IA? -correct-answer-More complicated matrix due to
interfering compounds such as proteins.
UV-Vis Spectrophotometry -correct-answer-the principle that substances absorb
and emit electromagnetic radiation at different wavelengths and provide an
absorbance spectrum and determine the concentration of a substance in solution
Materials absorb energy causes... -correct-answer-molecules to oscillate, inducing
electric and magnetic fields which generate an electromagnetic wave or light
Electromagnetic Spectrum -correct-answer-Radiation Type Frequency Wavelength
Transition
UV 10^15 - 10^17Hz 200-400nm outer electron
Vis 4- 7.5 x 10^14Hz 400-800nm outer electron
NearIR 10^12 - 10^14 Hz 1 um - 3 um molecular vibrations
Chromophore -correct-answer-color-producing molecular groups responsible for
energy absorption
,3|Page
Auxochrome -correct-answer-a saturated chemical group that has little to no
absorption but modifies the absorption spectrum when attached to a
chromophore
Beer's Law -correct-answer-considers sample concentration for a given path
length (b) the transmitted intensity (I) decreases exponentially with an increasing
sample concentration (c) of a homogeneously absorbing system.
Lambert's Law -correct-answer-considers instrument factors, states that for a
given concentration (C) the radiation transmitted through a homogeneously
absorbing system (I) decreases exponentially with increasing path length (b)
Beer-Lambert Law (commonly Beer's Law) -correct-answer-Absorbance (A) =
molar absorptivity (e)times concentration (c) times path length(b)
Does absorptivity in Beer's law have units? -correct-answer-No, the units cancel
out
Why would Beer's Law be non-linear? -correct-answer-1. electrostatic interactions
between molecules in close proximity
, 4|Page
2. scattering of light due to particles in the sample
3. fluorescence of the sample
4. changes in the refractive index at high concentration
5. non-monochromatic radiation
6. stray light
7. non-homogenous sample
8. reaction of the sample with the solvent
Solvent effects in UV-Vis -correct-answer-aromatic chromophores show fine
vibrational in non-polar solvents due to solute-solvent interactions. In aqueous
solutions, the pH affects ionizable chromophores due to conjugation changes in
the ionized and non-ionized chromophore
Bathochromic Shift -correct-answer-phenolic compounds the solution is more
alkaline leads to an absorption shift to a longer wavelength (red)
Hyperchromic effect -correct-answer-Loss of fine structure and an increase in
molar absorptivity
