3. ANALYTICAL TECHNIQUES Flashcards

1
Q

Most often used to determine concentration of analytes
in Clinical Chemistry laboratory

A

Spectophotometry and Electrochemistry

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2
Q

o Is described as photons of energy traveling in waves
o Can take several forms, the most recognizable being
light and radiant energy

A

Electromagnetic radiation

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3
Q

o Is the linear distance between any two equivalent
points on a successive wave
o Unit used in the visible spectrum is nm

A

Wavelength

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4
Q

The relationship between wavelength (λ) and energy (E) is
described by

A

Planck’s formula (E = hv)

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5
Q

Planck’s constant

A

6.62 X 10 -27 erg sec

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6
Q

o The number of oscillations of the waveform in a
second

A

 Frequency

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7
Q

Changes that may occur over period of time such as movement
 Movement of waveform in a second

A

Oscillation

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8
Q

The relationship of energy and wavelength is that the frequency is _________________ to wavelength

A

inversely proportional

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9
Q

Visible region wavelength

A

400 - 700 nm

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10
Q

Ultraviolet region wavelength

A

< 400 nm

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11
Q

Infrared region wavelength

A

: > 700 nm

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12
Q

states that the concentration of a substance is directly proportional to the amount of light absorbed or inversely proportional to the logarithm of the transmitted light.

A

Beer’s law

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13
Q

Is used to measure the light transmitted by a solution to determine the concentration of the light-absorbing substance in the solution.

A

Spectrophotometer

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14
Q

Components of a spectrophotometer

A

Light Source
Monochromator
Sample Cell or Cuvet
Photodetector
Meter or read-out device

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15
Q

Provides polychromatic light

A

Light Source

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16
Q

light source provides light
at several wavelength

A

Polychromatic light

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17
Q

light source that provides visible and near-infrared regions continuum type

A

Incandescent tungsten or tungsten-iodide lamp –

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18
Q

light source that provides UV
region continuum type

A

Deuterium lamp and mercury arc lamp

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19
Q

2 types of Light Source

A

Continuum
Line

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20
Q

o Wide applications in the laboratory
o Emits limited number of discrete lines or
bands of radiation
o Examples: Tungsten (visible region) ,
deuterium (UV region), xenon (visible and
UV regions)

A

Continuum

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21
Q

o Emits a few discrete lines or bands of
radiation
o Examples:
 Mercury and sodium vapor lamps – UV
and visible regions
 Hollow cathode lamp - atomic absorption
spectroscopy / spectrophotometry

A

Line

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22
Q

Light source that provides visible and
UV regions continuum type

A

xenon

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23
Q

Light source that provides UV and visible regions line type

A

Mercury and sodium vapor lamps

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24
Q

Line type light source for atomic absorption spectroscopy / spectrophotometry

A

Hollow cathode lamp

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25
Q

 Isolates individual wavelengths of light

A

Monochromator

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26
Q

Characteristics of monochromators

A

Nominal wavelength
Spectral bandwidth (or FWHM)
Bandpass

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27
Q

Represents nanometers in peak
transmittance

A

Nominal wavelength

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28
Q

Range of wavelengths about ½ peak
transmittance

A

Spectral bandwidth (or FWHM)

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29
Q

Total range of wavelengths, as seen in the chart

A

Bandpass

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30
Q

Types of monochromators

A

Filters
Prism
Diffraction gratings

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31
Q

Simple, inexpensive, and useful monochromator that requires you to determine the analyte of interest and set the wavelength at a specific point

A

Filters

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32
Q

example of filters

A

Interference and absorption filters

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33
Q

Monochromator that can be rotated, allowing only the desired
wavelength to pass through an exit slit

A

Prism

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34
Q

Most commonly used monochromator ; contain parallel grooves

A

Diffraction gratings

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35
Q

 may be round or square and must be made of material that is transparent to radiation
 used to hold samples; path length is 1 cm (general)

A

Sample Cell or Cuvet

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36
Q

Types of cuvet

A

Plastic cuvet
Fused silica or quarts
Alumina-silicate glass

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37
Q

cuvet for UV region

A

Fused silica or quarts

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38
Q

cuvet for 350-2000 nm

A

Alumina-silicate glass

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39
Q

cuvet for visible region

A

Plastic cuvet

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40
Q

Converts the transmitted radiant energy into an equivalent amount of electrical energy

A

Photodetector

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41
Q

Types of photodetector

A

Barrier-layer cell or photocell
Phototube
Photomultiplier tube (PMT)
Photodiode

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42
Q

Photodetector

o Least expensive; temperature sensitive
o Composed of selenium on a plate of iron
o Used mainly in filter photometers

A

Barrier-layer cell or photocell

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43
Q

Photodetector

o Contains cathode and anode enclosed in a glass tube
o Has photosensitive material that gives off electrons when light energy strikes it

A

Phototube

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44
Q

Photodetector
o Most common type
o 200 times more sensitive than the phototube
o Highly sensitive to UV and visible radiation

A

Photomultiplier tube (PMT)

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45
Q

Photodetector

o Not as sensitive as PM tube but with
excellent linearity and speed
 Excellent linearity: beam of light that
strikes the photodetector reflects the
amount of analyte or concentration of
analyte present in the sample
 Speed: concentration is immediately
read out on the read out device or the
meter because it can immediately
transmit the radiant energy into electrical energy

A

Photodiode

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46
Q

 Displays output of the detection system

A

Meter or read-out device

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47
Q

Examples of Meter or read-out device

A

Digital meters, d’Arsonval meters, recorders, light-emitting diodes (LEDs), cathode-ray tubes (CRTs), and liquid crystal displays (LCDs).

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48
Q

uses 2 photodetectors 2 sample cuvets and 2 photodetectors

A

Double beam in space

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49
Q

– uses 1 photodetector; chopper is used to pass the monochromatic
radiation through the sample cuvet and then to the reference cuvet

A

Double-beam in time

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50
Q

a device that rotates or breaks up
radiation beams

A

Chopper

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51
Q

Wavelength or photometric accuracy
 Implies that a photometer is measuring at the wavelength that it is set to
 Can be checked by Special glass-type optical filters like

A

– didymium glass (600 nm); holmium oxide (360 nm)

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52
Q

Closeness of a measured value to its true or target value

A

Accuracy

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53
Q

Using glass filters or solutions that have known absorbance values for a specific wavelength

A

Absorbance check

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54
Q

The ability of a photometric system to yield a linear relationship between the radiant power incident upon its detector and the concentration

A

Linearity

55
Q

 Any light that impinges upon the detector that does not originate from a polychromatic light source

A

Stray light

56
Q

Measures concentration by detecting the absorption of electromagnetic radiation by atoms rather than by
molecule

A

Atomic Absorption Spectrophotometer

57
Q

Atomic Absorption Spectrophotometer light source

A

hollow-cathode lamp; electrodeless
discharge lamp

58
Q

In AAS the use of chopper comes in the form of?

A

Flame

59
Q

AAS Photodetector

A

PM tube

60
Q

Application of AAS

A

to measure concentrations of trace metals [lead, mercury, cadmium]

61
Q

o Uses an electric furnace to break chemical bonds (electrothermal atomization)

o It does not require burner to produce flame but requires electric current

o Sample is atomized still but does not require burner

A

Flameless AAS

62
Q

o Measures light emitted by excited atoms
o No longer routinely used

A

FLAME PHOTOMETRY

63
Q

Light source of flame photometer

A

Flame

64
Q

Internal standard of flame photometer

A

Lithium
Cesium

65
Q

Where is flame photometer used

A

To measure concentrations of sodium, potassium, and lithium

66
Q

measure the concentrations of
solutions that contain fluorescing molecules

A

Filter fluorometers

67
Q

Light source of filter fluorometers

A

mercury (filter fluorometers)

68
Q

Light source of spectrofluorometers

A

xenon arc

69
Q

Disadvantages of fluorometry

A

Sensitive to environmental changes

70
Q

 Is different from fluorescence in that no excitation radiation is required and no monochromators are needed

A

CHEMILUMINESCENCE

71
Q

Chemiluminescence reactions are oxidation reactions of
___________________ characterized
by a rapid increase in intensity of emitted light followed by a gradual breakdown/decay

A

luminol, acridinium esters, and dioxetanes

72
Q

Advantages of chemiluminescence

A

Subpicomolar detection limits, speed, ease of use, and simple instrumentation

73
Q

Disadvantage of chemiluminescence

A

Impurities can degrade sensitivity and specificity

74
Q

is the production of electromagnetic
radiation when a chemical reaction yields an excited products/excited immediate product, in short, it is the
emission of light as a result of chemical reaction

A

Chemiluminiscence

75
Q

TURBIDITY AND NEPHELOMETRY Applications:

A

measurement of antigen–antibody reactions,
prealbumin, and other serum proteins

76
Q

is the measurement of the light scattered by a particulate solution

A

Nephelometry

77
Q

o 3 types of light scatters:

A

 Rayleigh theory
 Mie theory
 Rayleigh-Debye theory

78
Q

If the wavelength (λ) of light > the
diameter (d) of the particle (d < 0.1λ), the light scatter is symmetrical around the particle. Minimum light scatter occurs at 90 degrees to the incident beam.

A

Rayleigh theory

79
Q
  • If the wavelength of light < the particle
    diameter (d > 0.1λ), then the light scatters forward.
A

Mie theory

80
Q

If the wavelength of light is approximately the same as the particle size, more light scatters in the forward direction than in other directions.

A

Rayleigh–Debye theory

81
Q

Nephelometer Components

A

Light Source
Collimator / lens
Monochromator
Sample cuvet
Photodetector

82
Q

Measurements are made with a spectrophotometer to determine the concentration of particulate matter in a
sample
o Determines the amount of light blocked by a suspension of particles

A

Turbidimetry

83
Q

Applications of turbidimetry

A

microbiology analyzers,

coagulation analyzers

quantify protein concentration
in biologic fluids such as urine and CSF.

84
Q

Involves measurement of the current or voltage generated by the activity of specific ions

A

ELECTROCHEMISTRY

85
Q

 Measurement of potential (voltage) between two electrodes in a solution

A

POTENTIOMETRY

86
Q

Tow electrodes in POTENTIOMETRY

A

Reference electrode
Indicator electrode

87
Q

– electrode with a constant voltage
o Calomel and Silver/silver chloride

A

Reference electrode

88
Q

– measuring electrode

A

Indicator electrode –

89
Q

o Is very sensitive and selective for the ion it measures
o Consists of a membrane separating a reference solution and a reference electrode from the solution to be analyzed

A

Ion-Selective Electrode (ISE)

90
Q

ISE Membrane for sodium

A

Glass aluminum silicate

91
Q

ISE Membrane for potassium

A

Valinomycin gel

92
Q

ISE Membrane for calcium and
lithium

A

Organic liquid ion exchangers

93
Q

ISE Membrane for carbon dioxide and ammonia

A

Gas electrodes

94
Q

ISE Membrane for urease and glucose oxidase

A

Enzyme electrodes

95
Q

2 types of ISE

A

 Direct: it does not require sample dilution
 Indirect: the sample requires dilution before the analysis phase

96
Q

o Used to measure hydrogen ion activity
o Buffer: has known hydrogen ion concentration

A

pH electrode

97
Q

Internal reference electrode of pH electrodes

A

silver/silver chloride

98
Q

External reference electrode of pH electrodes

A

Calomel electrode

99
Q

o A pH electrode within a plastic jacket (has sodium bicarbonate buffer and gas-permeable membrane)
o When whole blood contains CO2 contact with gas permeable membrane, it mixes with the buffer

A

pCO2

100
Q

 Measures the quantity of electricity (in coulombs) needed to convert an analyte to a different oxidation state

A

COULOMETRY

101
Q

COULOMETRY follows what equation

A

Faraday’s equation

102
Q

COULOMETRY Application:

A

to measure chloride ion in serum, plasma, CSF, and sweat samples

103
Q

 Is the measurement of the current flow produced by an oxidation–reduction reaction

A

AMPELOMETRY

104
Q

AMPELOMETRY application

A

to measure chloride ion in serum, plasma, CSF, and sweat samples; pO2 electrode in blood gas analyzers

105
Q

Is a method in which a potential is applied to an electrochemical cell and the resulting current is measured

A

VOLTAMMETRY

106
Q

used to measure heavy metals such as lead

A

Anodic stripping voltammetry

107
Q

is the measurement of the osmolality of an aqueous solution such as serum, plasma, or urine

A

OSMOMETRY

108
Q

Osmotically active particles

A

glucose, urea nitrogen,
sodium

109
Q

is the separation of charged
compounds based on their electrical charge

A

Electrophoresis

110
Q

2 TYPES OF ELECTROPHORESIS

A

Iontophoresis
Zone Electrophoresis

111
Q

Migration of small ions
 Very much associated with Cystic fibrosis
 Sweat test

A

Iontophoresis

112
Q

o Migration of charged macromolecules in a porous support medium
o DNA proteins
o Lipoproteins

A

Zone Electrophoresis

113
Q

o A substance that can have a negative, zero or a positive charge depending on conditions
o If the pH is basic, the sample could have a positive or negative charge
o There are also case that if the pH is acidic, the sample can be transformed from being ampholyte (can either
be a positive, negative or zero charge)

A

Amphotheric

114
Q

Negatively charge ion

A

Anion

115
Q

Postively charged ion

A

Cation

116
Q

Both positively and negatively charge at a same time

A

Zwitterion

117
Q

FACTORS AFFECTING MOBILITY OF PARTICLES

A

 Net charge of the particle
 Size and shape of the particle
 Strength of the electric field
 Chemical and physical properties of the medium
 Electrophoretic temperature
COMPONENT

118
Q

COMPONENTS of ELECTROPHORESIS

A

POWER SUPPLY
BUFFER
SUPPORT MEDIUM
SAMPLE
DETECTING SYSTEM

119
Q

 Supplies constant current or voltage in the system.
 This drives the molecules through the support medium
 Driving force

A

POWER SUPPLY

120
Q

 Used to provide ions that carry a current and to maintain the pH at a relatively constant value

A

BUFFER

121
Q

 A network of interacting fibres or a polymer that is solid but traps large amount of solvent in pores or channel inside

A

SUPPORT MEDIUM

122
Q

SUPPORT MEDIUM types

A

Cellulose Acetate
Agarose Gel
Polyacrilamide Gel

123
Q

Separates serum proteins into 5 bands
 Isoelectric focusing
 Very much famous and very much useful in performing electrophoresis for protein and is usually support medium of choice would be

A

cellulose acetate

124
Q

Used as a purified fraction of agar
 From red algae
 It is neutral and, thus, does not produce
electroendosmosis
 Separates proteins into 10 – 15 bands

A

Agarose Gel

125
Q

Must not interact with the analyte: what you want is for the analyte to just patch through the support media and you do not want your support media to be affecting your analyte which is called

A

electroendosmosis

126
Q

 Separation of protein base on charge and molecular
size
 Separates serum proteins into 20 or more fractions
 Isoenzyme determination

A

Polyacrilamide Gel

127
Q

Is a physical technique that separates mixtures into individual components
 Used to separate complex mixtures on the basis of different physical interactions between the individual compounds and the stationary phase of the system

A

CHROMATOGRAPHY

128
Q

2 CATEGORIES

A

Planar Chromatography
Column Chromatography

129
Q

 Fractionation of sugar and amino acid

A

Paper chromatography

130
Q

Paper chromatography Sorbent

A

Whatman paper

131
Q

Uses pressure for fast separation of
thermolabile substances

A

 HPLC – High – Performance Liquid
Chromatography

132
Q

Fragmentation and ionization of molecules using a suitable
source of energy

A

MASS SPECTROPHOTOMETER

133
Q

MASS SPECTROPHOTOMETER Has two distinct portion

A

fragmentation and ionization of
molecules

134
Q

Is an analytical technique in which chemical compounds are
ionized into charged molecules and ratio of their mass to
charged is measured (m/z)

A

o Quadropole Mass Analyszers
o Ion Trap Analyzers
o Time of Flight Analyzers