Turbid and Nephelometry Flashcards
Physical phenomenon in which a beam of light
changes its direction of propagation (known as
defection) as a result of interaction with sufficiently
small matter particles
LIGHT SCATTERING
Change of angle from propagation (incident light)
to its scattering angle
LIGHT SCATTERING
Caused by the particles present in the solution
LIGHT SCATTERING
Change in direction is known as
deflection
2 types light scattering
-elastic
-inelastic
In which the wavelength of the scattered light and
incident light is the same
ELASTIC SCATTERING
This is what we are concerned in Turbidity and
Nephelometry.
ELASTIC SCATTERING
In which the wavelength of the scattered light and
incident light is different or inequal with one
another
INELASTIC SCATTERING
The intensity of the transmitted light is measured
and the attenuation of the intensity of incident
light as a result of scattering is measured at the
direction of incident light (i.e., 0°) and compared to
the intensity of incident light (blank measurement)
TURBIDIMETRY
In turbidimetry, The intensity of incident light is
attenuated
In turbidimetry, Intensity of incident light ______
lowers
turbidimetry measures
intensity of transmitted light
attenuation of the intensity of incident light
Turbidimetry is the indirect measurement of the scattering effect of
the suspended particles and is referred to as
_____________
turbidance
In turbidimetry, it is important to ensure that the material (analyte)
being measured _____________ (does not absorb/absorb) light at the
measurement wavelength
does not absorb
In turbidimetry, The attenuation (lowering) of intensity is
due to the ______________, and not due to
the absorption.
scattering of light
If our suspension is highly turbid, we may
measure it with __________
turbidity.
measures low turbid solutions.
Nephelometry,
A measure of the decrease
of transmitted incident light beam intensity as a
result of the light-scattering effect of suspended
particles.
Turbidance
Measures the decrease in the intensity of
the incident light.
Turbidance
In turbidimetric
measurements, turbidity is the measure of the
_____________ in_________ length of a
given suspension.
decrease in incident beam intensity/unit
Measures the decrease in the transparency
of the liquid.
Turbidity
Turbidance and Turbidity are both caused by
suspended particles.
Turbidimetry measures the
the transmitted light
Nephelometry, measures the
scattered light detected at 90°
Measures the intensity of the scattered light at a
90° angle from the propagation direction of the
incident light is measured
NEPHELOMETRY
Nephelometry is the (direct/indirect) measurement of the scattering effect of
suspended matter
direct
More reliable in low turbidity ranges
Nephelometry
When the turbidity is measured using a
nephelometer, the units of turbidity are called
nephelometric turbidity units (NTUs)
nephelometric turbidity units (NTUs) are based on the turbidity generated by primary
___________ standard
formazin
a suspension made by
mixing solutions of hydrazine sulfate and
hexamethylenetetramine in water
formazin standard
Other recognized units of nephelometry are
-formazin turbidity (FTU)
-the formazin nephelometric unit (FNU)
FACTORS AFFECTING LIGHT SCATTERING
● Concentration of scattering particles suspended in
the medium
● Size distribution of scattering particles
● Shape, orientation, and surface condition of the
scattering particles
● Refractive index of the scattering particles
● Refractive index of the suspension medium
● Wavelength of the light source employed
APPLICATIONS
-Concentration determination of solutions and/or
suspensions
-Measurement of the degree of turbidity
-Determination of weight-average molecular weight
and dimensions of polydisperse systems
-Measurement of immunoassay’s reaction kinetics
or kinetics of immunoprecipitations (application of
rate nephelometry)
-Monitoring of cell and bacteria growth
-Particle size distribution determination
how fast is the reaction kinetics; formation of turbidity against time
Rate nephelometry
associate to
antigen-antibody complexes, or their
agglutination reaction
Immunoprecipitations
Widely used for vaccine components assays
and/or quantitation of components in blood serum
RATE NEPHELOMETRY
Used for host cell protein qualification in
recombinant biopharmaceuticals
RATE NEPHELOMETRY
Used to calculate the amount of antigen (Ag) or
antibody (Ab) responsible for the immunological
Ab-Ag precipitation reaction or agglutination reaction
RATE NEPHELOMETRY
Used in “particle-enhanced immunoassay” where
antigens under consideration are linked covalently or
absorbed to polymeric microspheres to increase the
scattering efficiency.
RATE NEPHELOMETRY
When antigens would cause very small
intensity (due to the low intensity of the
scattering of light), you can combine it with
polymeric microspheres
RATE NEPHELOMETRY Can determine concentration of antigen or
antibody component based on the formation of
precipitate.
Combines the technology of 90° nephelometry
and turbidimetry
Ratio turbidimeter
Also measures light transmitted directly
through the sample
Ratio turbidimeter
The benefit of using a ratio turbidimetric
system is
the measurement of stray
light becomes negligible
Used in determination of turbidity of colored
suspensions
Ratio turbidimeter
light source of ratio turbidimeter
tungsten lamp or infrared light emitting diode for eliminating the color effect
Ratio turbidimeter light source for for colored
suspensions
Tungsten lamp
Ratio turbidimeter light source used to
eliminate the effect of the colors
Infrared light-emitting diode
The of detectors are
silicon diodes and
photomultipliers
Nephelometry instrument wherein there is significant improvement in
signal-to-noise ratio at very low detection
levels
Laser Nephelometry
Higher intensity of light →
improve
signal-to-noise ratio,
The high power density of the laser beam
gives rise to the _________ scattered intensity
from smaller particles
higher
