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Advanced Laboratory Operations and Automation > Detection systems > Flashcards

Detection systems Flashcards

1
Q

uses what as labels

Detection systems RadioImmunoassay

A

Uses radioactive isotopes as labels

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2
Q

RADIOIMMUNOASSAY: RIA

Are what

Adapted to many procedures

A
  • Very sensitive ~ 5 pg/ml
  • Adapted to many procedures
    ‣ Has been adapted to solid phase immunoassay for easy
    separation of bound and free components
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3
Q

RADIOIMMUNOASSAY: RIA

Requires special what

A
  • Requires licensure for handling radioactive substances
    & special disposal
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4
Q

B emission liquid scintillation

A

-Highly colored compounds (blood)
may need dilution due to interference
(quenching)
* γ counter – similar, but use a crystal
instead of fluidβ

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5
Q

β Emission – Liquid Scintillation

Parts

A

Scintillation fluid, Photocathode
Optical window
Scintillator
Light
Radition

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6
Q

β Emission – Liquid Scintillation

Two PMTs what

A

Decreases
noise due to thermionic
emission

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7
Q

Amount of radioactive material A compared to the original amount A0 or any quantity which is proportional to A

A

Radioactive decay

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8
Q

Spectroscopy

Beer lambert law

A

A= EbC

Were A= Absorbance
E= molar extinction
b= path length (1cm)
C= concentration

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9
Q

A=

A

2-log(%T)

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10
Q

Spectroscopy parts

A

Light source–> Entrance slit–> Monochromomator–> Exit slit–> cuvette–> Detector–> Readout device

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11
Q

Flame Emission

Prinicple

A

1.If energy (thermal, electrical, electromagnetic) is supplied to
anatom, its e-s can move to an orbit of higher energy
2.Excited atom releases a photon (of light) when its e-s fall back into their original orbits (ground state)

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12
Q

Flame emmission

The wavelength of emission gives the what

A

The WAVELENGTH of emission gives the IDENTITY of the element
while the INTENSITY of the emitted light is PROPORTIONAL TO THE
# OF ATOMS IN THE ELEMENT.

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13
Q

Instrumentation of flame photometer

A
  1. Radiation source (the excited atoms)
    Each element or ion emits a גּ or color characteristic for
    that element (SQB1)
    Na+ = yellow K+ = red-violet Li+ = red Mg2+ = blue
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14
Q

Instrumentation of flame photometer

sample cell or cuvette

A
  1. Sample cell or cuvette (the flame!)
    The greater the thermal energy of a flame, the greater the number of atoms
    that will be excited. BUT increased background noise is often an unwanted
    by product
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15
Q

Atomizer- Burner

Advantages

and disadvantages

A

✦Mixes liquid sample into the flame
✦Sample introduced at a rapid, stable rate
Advantages: delivery of a completely representative aliquot of
sample into the flame
Disadvantages: wide variation of droplet size, aspiration
variance due to sample viscosity, turbulence (results in much
background noise)

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16
Q

Monochrometer

A

‣ Isolates the characteristic wavelength of emitted light
‣ Accomplished via: prisms / diffraction gratings or filters

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17
Q

Detector

A

(photomultiplier tube or photocell)
‣ converts light emitted by excited atoms into electrical
energyInstrumentation of flame photometer

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18
Q

Internal standards

are used to

Simultaneous analysis for what

A
  • Internal standards are used to eliminate instrument variance
    due to temperature, atomization, oxygen / fuel flow, and
    voltage fluctuations
  • Simultaneous analysis for both (the internal reference
    standard & the element of interest)
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19
Q

Internal standards

Because both what

If running what then

A
  • because both internal standard & element of interest are
    affected in an identical manner
  • Internal standard - if running sodium, use lithium or cesium
    as internal standard
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20
Q

Atomic absorption spectrophotometry

Differences from flame emission photometry

A
  1. Specimen is atomized in flame, not excited
  2. Spectrally pure light source is also directed at flame
  3. Atoms in flame that match wavelength of light
    (spectral alignment) will absorb that light (atomic
    absorption)
21
Q

Atomic Absorption Spectrophotometry

Benefits

A

‣ 100 times more sensitive than FEP
‣ Highly specific for element being measured
‣ Used for Al, Ca, Cu, Pb, Li, Mg, and Zn

22
Q

Atomic Abs spectrophotometry parts

A

Light source–> atomizer–> emmision–> Detector

Sample–> atomic cell–> atomizer

23
Q

Atomic absorption spectrophotometry

step one

A

Hollow cathode (exciter) lamp produces a beam of high spectral
purity (monochromatic)

24
Q

Atomic Absorption Spectrophotometry

step two

A

Chopper transforms the specific incident light into a pulsing beam
(AC, alternating current

25
Q

Atomic Absorption Spectrophotometry

step three

A

Sample introduced to flame, vaporized (& reduced) to their ground
state

26
Q

Atomic Absorption Spectrophotometry

step four

A

Reduced sample atoms absorb the light when bombarded by AC
from chopper

27
Q

Atomic Absorption Spectrophotometry

step five

A

Reduced samples emit light that is not in a pulsing beam (DC

28
Q

Atomic Absorption Spectrophotometry

step 6

A

DC2 deflected by the Monochromator (grating) to the Detector
(photomultiplier tube

29
Q

Atomic Absorption Spectrophotometry

step 7

A

Modulated Meter is synchronized to the chopper so that it
recognizes AC as well as DC2

30
Q

Atomic Absorption Spectrophotometry

Chemical interferences

A

(contaminating chemicals might ionize &
interfere or merely interfere with reading)

31
Q

Atomic Absorption Spectrophotometry
Ionization interferences

A

(elements other than elements of interest
might ionize similarly)

32
Q

Atomic Absorption Spectrophotometry

Matrix interferences

A

(other components of the sample matrix such as
buffer salts or other additives like detergent or solvents may ionize
& interfere or merely interfere with reading)

33
Q

Atomic Absorption Spectrophotometry

Emission interferences

A

(other elements might absorb & emit at same
wavelength)

34
Q

Turbidimetry

A

Measurement of loss in intensity (dynamic change) of a
light beam through a solution that contains suspended particulate matter

35
Q

Nephelometry

A

The measurement of the intensity of reflected light

36
Q

Light scatter

Nephelometry & turbidimetry are related
techniques

A

that are dependent on measurement of
light scatter

37
Q

Quantitative relationships exist between what

Light scatter

A

size &
number of suspended particles degree of scatter.

38
Q

Oscillating dipole

A

When a light beam strikes a particle, its electric
field moves the particle’s electrons in one
direction and the nucleus in the opposite direction
(Oscillating dipole)

39
Q

Light scatter

the maximum amount of what is

A

The maximum amount of movement is
proportional to the electric field strength of the
light beam.

40
Q

Turbidimetry

A

➡ Turbidimetry can be performed on any standard
spectrophotometer
✦ Wavelength selection criteria.
* Turbidimetric measurement is based on the size of
the particle.
* Particles not more than 40 nm in diameter can be
measured with light of a 400 nm wavelength,
* larger particles (300 nm) as might occur with latex
agglutination are probably going to be measured
with a light of a wavelength in the 500-600 nm
range.

41
Q

Turbidimetry

Wavelength selection criteria

A
  • Turbidimetric measurement is based on the size of
    the particle.
  • Particles not more than 40 nm in diameter can be
    measured with light of a 400 nm wavelength,
  • larger particles (300 nm) as might occur with latex
    agglutination are probably going to be measured
    with a light of a wavelength in the 500-600 nm
    range.
42
Q

Nephelometry

A

Nephelometry is one of the most commonly used
measurement principle for the immunochemical
determination of protein in serum, urine and other body
fluids

43
Q

Nephelometry

Measurement of

Scattering

Instrumentation

A
  • Measurement of light scatter
  • Scattering
    – Size of particles
    – Number of particles
  • Instrumentation
    – Similar to spectrophotometers, fluorometer
44
Q

Types of light scatter

Small particles

A

Light scattered symmetrically but minimally at 90 degrees ( Rayleigh)

d< 0.1 lamda

45
Q

Large particles

A

Light scattered preferentially forward ( Rayleigh- Debye)

d< lamda

46
Q

Very large particles

A
  • Light mostly scattered forward ( Mie) d> lamda
47
Q

D= particle size
lamda= wavelength of light

A
48
Q

Immunonephelometry

A
  • Antigen
  • Antibody
  • Antigen-Antibody complexes
49
Q

Nephelometer

angle of detection

light sources

Uses

A
  • Angle of detection
    – 5°-90° (depends on light source)
  • Light source
    – Monochromatic (filtered, laser, diffraction gradient)
    – Polarized (collminating lens)
  • Use
    – Serum and CSF proteins, antibodies, drugs

Advanced Laboratory Operations and Automation (17 decks)

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