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QC2 > MES > Flashcards

MES Flashcards

1
Q

FLUORESCENCE SPECTROPHOTOMETRY is also called

A

Fluorometry

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2
Q

Fluorescence Spectro Principle: Certain molecules, particularly those with a
____________ and a rigid structure (fluorophore),
can be excited by __________, and will then
emit the radiation absorbed at a _______ wavelength.

A

chromophore; UV/visible radiation; longer

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3
Q

longer wavelength = _______ (lower/higher) energy

A

lower

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4
Q

in UV-Vis spectroscopy, we only need
________________ for them to absorb UV-Vis
radiation

A

chromophores

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5
Q

in fluorescence, you need a ___________ structure

A

rigid

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6
Q

What theory: promotion of electron to an excited state

A

Absorption

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7
Q

What theory: excited electron returns to the ground
electronic state by emitting a photon

A

EMISSION

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8
Q

emission arising from an “allowed”
transition that typically has a short lifetime between 1
ns and 10 ns

A

Fluorescence

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9
Q

T/F: does Fluorescence have short life time?

A

T

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10
Q

In Fluoroscence: transition from the excited
state to the ground state _____________ (change/does not change) in
electron spin

A

does not change

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11
Q

emission arises from a
“forbidden” transition that typically has a long lifetime
between 1 ms and 1 s

A

Phosphorescence

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12
Q

In Phosphorescence, there is ________ (a/no) change in electron spin

A

there is a change in electron spin

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13
Q

In phosphorescence, the decrease in energy is not only due to the
release of energy, but also because of the
__________________

A

change of electron spin (intersystem crossing)

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14
Q

change in spin → intersystem crossing →

A

release radiation

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15
Q

a polyatomic fluorophore, once electronically
excited, experiences vibrational relaxation before
emitting a photon, causing a ______________ of the fluorescence spectrum relative to the
wavelength at which it was excited

A

red shift or Stokes
shift

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16
Q

change in energy or shift in
longer wavelength

A

red shift or Stokes
shift

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17
Q

excitation light sources

A

xenon lamps, lasers

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18
Q

most common excitation light source, high intensity and
broad wavelength range (UV to NIR)

A

Xenon lamps

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19
Q

highest-intensity source

A

Lasers

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20
Q

Lasers are used in applications where _____________ (short/long) collection times
and __________ (big/small) amounts of sample are required

A

short ; small

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21
Q

a filter or a monochromator with a known peak
transmission wavelength and bandwidth

A

EXCITATION WAVELENGTH SELECTOR

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22
Q

enables fluorescence excitation spectra to be
resolved

A

EXCITATION WAVELENGTH SELECTOR

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23
Q

Separates the wavelength

A

EXCITATION WAVELENGTH SELECTOR

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24
Q

includes all optics and other equipment needed to
deliver the excitation beam to the sample, collect
the emission from the sample, and hold the sample
in place

A

SAMPLING DEVICE

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25
Q

cuvettes, microwell plates, microarrays, microscope
slides, and flow systems

A

SAMPLING DEVICE

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26
Q

ensure that the emission wavelength region being
detected does not overlap with the excitation
wavelength profile

A

EMISSION WAVELENGTH SELECTOR

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27
Q

important for the rejection of stray light

A

EMISSION WAVELENGTH SELECTOR

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28
Q

filters, monochromators, and grating polychromators
often are used for

A

for emission wavelength selection

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29
Q

a photomultiplier tube (PMT) or a charge-coupled
device (CCD) array

A

DETECTOR

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30
Q

T/F: EXCITATION - EMISSION ORIENTATIONS depends on the nature of the sample

A

T

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31
Q

Angle used to measure dilute solutions and other
transparent samples

A

right-angle or 0°/90° geometry

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32
Q

excitation light is at ______° with emitted light

A

90°

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33
Q

used to measure optically dense samples

A

front-face geometry

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34
Q

In front-face geometry, fluorescence is collected at an angle ___________

A

≤90°; although <90° is more common to use

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35
Q

example of front face geometry

A

epifluorescence geometry

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36
Q

excitation
beam and collected fluorescence are both on the same side of the sample,

A

epifluorescence geometry

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37
Q

angle used in microscopy

A

0°/180° transmitting geometry

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38
Q

FACTORS THAT AFFECT QUANTITATION

A

intrument based, sample based

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39
Q

wavelengths, bandwidths, and detector
intensity of the excitation beam
linear intensity range of the detection system
diffraction efficiency of gratings

A

Instrument based factors

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40
Q

instrument based factor that can
introduce measurement uncertainty or bias that is
particularly significant when measured values are
compared between instruments

A

wavelengths, bandwidths, and detector

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41
Q

instrument based factor that can change
significantly with excitation wavelength or with time

A

intensity of the excitation beam

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42
Q

does not increase linearly
with concentration because of significant absorption
of the excitation beam and/or emission
(reabsorption) by the sample

A

optically dense samples

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43
Q

optically dense samples do not increase linearly
with concentration because of significant ________________
of the excitation beam and/or _____________ by the sample

A

absorption; emission

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44
Q

optically dense samples ____________ (increase / do not increase) linearly
with concentration because of significant absorption
of the excitation beam and/or emission
(reabsorption) by the sample

A

do not increase

45
Q

To fix opitcally dense samples we must ___________________

A

reduce the amount of fluorescence that reaches
the detector

46
Q

fluorescence intensity of a sample may ___________ (decrease/increase)
with time of exposure to light because of
photobleaching and photodegradation

A

decrease

47
Q

fluorescence intensity of a sample may decrease
with time of exposure to light because of
______________ and ____________

A

photobleaching and photodegradation

48
Q

intensity might _____________ with longer analysis
times

A

decrease

49
Q

fluorescence intensity of fluorophores is
temperature _____________ (dependent/independent)

A

dependent

50
Q

can introduce peaks into the
fluorescence spectrum - sample’s solvent or matrix

A

Raman signal

51
Q

Applications of fluorescence

A
  • analyzing fluorescent compounds (with
    fluorophores)
    -Determination of fluorescent drugs in low-dose
    formulations in the presence of non-fluorescent
    excipients.
    -carrying out limit tests
    -Useful for studying the binding of drugs
    -Widely used in bioanalysis
52
Q

T/F: proteins in general are also fluorescent, especially those that contains amino acids
tyrosine and tryptophan

A

T

53
Q

T/F: free drugs have higher fluorescence compared
to bound drugs

A

T

54
Q

Strenghts of fluorescence

A

-selective detection; quantify a strongly fluorescent compound in the
presence of a larger amount of non-fluorescent
material.
-used to monitor changes in complex
molecules

55
Q

Limitations of fluorescence

A

-only applies to a limited number of
molecules.
-subject to interference by
UV-absorbing species,

56
Q

According to Raman Spectroscopy, change in wavelength occurs because of the
molecules that ________ light and not because of
relaxation

A

deflect

57
Q

change in wavelength occurs because of the
molecules that deflect light and not because of
relaxation

A

RAMAN SPECTROSCOPY

58
Q

The Raman effect is analogous to fluorescence
except:

A

-not wavelength dependent
-not require the molecule to have a
chromophore
-Energy shift in cm-1 (wavenumber) is measured
instead of wavelength

59
Q

T/F: In Raman Spectroscopy, the shifts measured correspond to the
wavenumbers of the bands present in the middle-IR
spectrum of the molecule.

A

T

60
Q

lasers are used to provide high-intensity radiation in
the visible region, generally somewhere between
______________ and _________ (NIR lasers)

A

450 and 800 nm

61
Q

T/F: lasers do not excite fluorescence

A

T

62
Q

bands that absorbed weakly in middle -IR region
will absorb strongly in the ________

A

Raman region

63
Q

Raman application

A

-for identifying complex samples,
-peptide pharmaceuticals can be
analyzed for changes in their three-dimensional
structure
-Provides additional fingerprint identity information
complementary to middle-IR spectroscopy

64
Q

Raman strength

A

-requires very little sample preparation
-Increasingly a readily available option

65
Q

Raman limitations

A

-Not yet fully established
-solvent may interfere

66
Q

Instrument used in Raman

A

Laser

67
Q

Two types of MES

A

Fluorescence, Raman

68
Q

More modern type of MES

A

Raman

69
Q

compound present in a material that is responsible for the color of the compound

A

Chromophore

70
Q

T/F: compound with intense color have chromophore

A

T

71
Q

Compounds with chromophores (do not need/ need) a light source to emit a color

A

do not need

72
Q

rigid structure that gives glow characteristics to a material.

A

Fluorophore

73
Q

Principle involved in Glow in the dark material.

A

Fluorophore

74
Q

need a light source to be absorbed and the energy will be emitted as the “glow

A

Fluorophore

75
Q

UV VIS, once absorbed, it will emit it immediately
during the __________ state through a photon

A

excitation

76
Q

have more wv that it can absorb; longer wv

A

MES

77
Q

only one setting

A

UV:

78
Q

T/F: MES can absorb energy
at different wv so you can see the photon emission
at a longer time through the form of fluorescence or
glowing

A

T

79
Q

Fluorescence absorb ________ wv therefore it cannot go back to ground state immediately but it will come back since this is where it will emit the photon

A

longer

80
Q

T/F: Fluorescence will not come back since this is where it will emit the photon

A

False - it will come back

81
Q

T/F: Fluorescence = can see nanoseconds

A

F

82
Q

difference between the two peaks of
intensity between excitation and emission

A

Stokes shift:

83
Q

emit immediately after excitation

A

UV

84
Q

MES has __________ resulting to its glow in the dark property

A

overlap

85
Q

the energy at which is
absorbed by the compound

A

Wv

86
Q

In ________ vibration relaxation is not heard since compounds tested under UV does not contain a chromophore

A

UV

87
Q

Is vibration relaxation heard in Chromophore

A

yes

88
Q

has excitation and emission monochromator to resolve the Strokes shift

A

MES

89
Q

Resolve where the excitation ended and emission started

A

MES

90
Q

Signal is _________ in MES

A

accurate

91
Q

light source used if compound is really hard to excite

A

Lasers

92
Q

purpose: to separate the peaks of individual excitation
to know how it can be quantified.

A

Excitation Wavelength Selector

93
Q

to resolve, correct, or give clarity of the correct wv at
which the compound was excited

A

Excitation Wavelength Selector

94
Q

Light beams that reaches the detector without passing the sample

A

stray light

95
Q

stray light appear as _______

A

false negative

96
Q

resolve the emission wv so the overlap will be resolved

A

Emission Wavelength Selector (filters, monochromators, and grating
polychromators)

97
Q

right-angle excitation

A

0º

98
Q

right-angle emission

A

90º

99
Q

when the light source is placed at a different angle, it will (glow/not glow)

A

not glow

100
Q

T/F: When (light source) titled to a particular geometry, it will then be able to excite,
seen, emit photons

A

T

101
Q

T/F: when fluorescence is collected form above, you cannot get anything from the
light source

A

T

102
Q

Detector will not show a signal so must tilt the test instrumentation
at a particular orientation based on ________

A

the characteristic of the sample being
tested

103
Q

only one angle

A

microscope

104
Q

T/F: In microscopy, you cannot see anything if viewed from another side.

A

T

105
Q

T/F: Interferences can come from the instrument or the sample

A

T

106
Q

if detector is placed in an incorrect geometry, there will be an ________

A

interference or the noise

107
Q

Wrong wv: __________.

A

nothing will be absorbed

108
Q
A

QC2 (6 decks)

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