U3 LAB: INSTRUMENTATION Flashcards
Four Major Disciplines of Analytic Techniques
- Spectrometry
- Luminescence
- Electroanalytic methods
- Chromatography
under Spectrophotometry
- Spectrophotometry
- Flame Emission Spectrophotometry
- Atomic Absorption
Measures intensity of light or light transmitted
Spectrophotometry
Spectrophotometry
directly proportional to concentration
Absorbance
Spectrophotometry
inversely proportional to concentration
Transmittance
Measures intensity of light after an ion is burned (light of a single atom)
Flame Emission Spectrophotometry
Principle of Flame Emission Spectrophotometry
excitation of electrons from lower to higher energy
Measure of light absorbed after ions are dissociated by heat
Atomic Absorption
Atomic Absorption is used to measure?
trace elements (Ca, Mg)
Measures the light produced when ions are excited to unexcited
Fluorometer
Luminescence
Material absorbs at high energy but short wavelength, emits light at lower energy (visible light)
Fluorescence
Luminescence
Measures analyte produced in the reaction vessels
Chemiluminescence
Chemiluminescence produces?
electromagnetic radiation of UV, visible, infrared
Luminescence
Chemical yields electronically excited intermediate/product responsible for the emission
Chemiluminescence
Luminescence
for proteinous analytes
Nephelometry
Luminescence
measures the light scattered by a particulate matter suspended in a solution
Nephelometry
Luminescence
Most common example of Nephelometry
measurement of antigen-antibody complexes (turbidimetry)
Separation of molecules by their molecular weight
Electrophoresis
This refers to separation techniques for soluble components in a solution by specific differences in physical or chemical characteristics.
Chromatography
Separation of compounds that are naturally volatile or chemically converted to a volatile form
Gas Chromatography
Beer Lambert’s Law
concentration of analyte is directly proportional to absorbance
The darker the sample?
the higher concentration, intensity, absorbance
<400nm
Ultraviolet (UV)
400-700nm
Visible Light
> 700nm
infrared
750-1600nm
mid IR / fingerprint region
longer wavelength, _____ energy and frequency
lower
shorter wavelength, _________ energy and frequency
higher
Planck’s Formula
E = hv
Planck’s Formula
E
energy of photon in Joules
Planck’s Formula
h (constant)
6.626 x 10-34
Planck’s Formula
v
frequency of electromagnetic radiation
Beer Lambert’s Law
What is inversely proportional?
Transmittance and absorbance
T/F: A solution transmits light corresponding in wavelength to its color, and usually absorbs light of wavelengths complementary to its color.
True
This minimizes unwanted stray light.
Entrance slit
This eliminates unwanted wavelengths.
Monochromater
Holds the solution
Cuvette
Two types of Light Source
- Continuum Source
- Line Source
Continuum Source
- Tungsten
- Deuterium
- Xenon
Continuum Source
Most common for visible infrared light sources
Tunsgten
Continuum Source
Routinely used for UV based light sources
Deuterium
Continuum Source
Used in most spectrofluorometers
Xenon
under Line source
Mercury-vapor lamps
Light under infrared region
Silicon Carbide
Stray light is considered as?
- any wavelength outside band
- causes absorbance error
- limits the maximum absorbance
- most common cause of lost linearity
Stray light can come from?
deteriorating light source
Kinds of Monochromator
- Prisms
- Diffraction Gratings
- Filters
- Holographic Gratings
Kinds of Monochromator
made up of glass
Prisms
Kinds of Monochromator
has grooves
Diffraction Gratings
This controls the width of the light beam.
Exit slit
Described as the total range of wavelengths transmitted
bandpass
Cuvette is also known as?
Analytical / Absorption / Sample Cell
Kinds of Cuvette
- Alumina Silica Glass
- Quartz Plastic
- Borosilicate glass
- Soft glass
Kinds of Cuvette
most common, wide range absorbance
Alumina Silica Glass
Kinds of Cuvette
Alumina Silica Glass has an absorbance range of?
350 - 2000nm
Kinds of Cuvette
measurement of solution requiring a UV and visible spectra
Quartz Plastic
Notes to remember for cuvette
1.) discard cuvettes with scratches (cause interferences)
2.) silica cuvettes transmit light effectively at wavelengths above 220nm
3.) prolonged alkaline solution may cause cuvette to corrode or dissolve
This detects and converts transmitted light into photoelectric energy.
Photodetector
Kinds of Photodetector
- Photocell
- Phototube
- Photomultiplier tube
- Photodiode
Kinds of Photodetector
most simple
Photocell
Kinds of Photodetector
most sensitive as it amplifies light first before converting to electricity
Photomultiplier tube
This splits monochromatic light into 2
Beam splitters
Double beam in space
2 photodetectors
Double beam in time
1 photodetector
FEP
Principle
excitation of electron from low energy to high energy
FEP
Photodetector
photocell
FEP
Light source
flame (also serves as cuvette)
FEP
Sodium
yellow-orange
FEP
Potassium
pink
FEP
Calcium
orange
FEP
Magnesium
bright white
FEP
Copper I
blue
FEP
Copper II
green
FEP
Lithium
red
FEP
Cesium
purple
FEP
known as internal standards and collects variation in flames
Lithium and Cesium
Most specific and most sensitive spectrophotometry
Atomic Absorption
AAS
Principle
element is not excited but merely dissociates from its chemical bond and placed in an unionized gram stain
AAS
Photodetector
Photomultiplier tube (measures trace elements)
AAS
Light source
Hollow cathode lamp
Volumetric (Titrimetric)
Principle
unknown sample is made to react with a known solution in the presence of an indicator
Volumetric (Titrimetric)
Examples
- Schales and Schales
- EDTA Titration method
Volumetric (Titrimetric)
Schales and Schales
for chloride
Volumetric (Titrimetric)
EDTA Titration
for calcium
Nephelometry
Principle
determines amount of scattered light by a particulate matter suspended in a turbid solution
Nephelometry
Light scattering depends on:
- particle size
- wavelength
Nephelometry
Angle
15 to 90 degrees
Nature of antigen
provokes immune response
Detection methods of the antibody molecule
- Direct neutralization
- Opsonization
- Complement activation
- Somatization
- Control of inflammatory response
Phenomenon of forward scatter
Mie scatter
Mie scatter occurs because most complexes have a diameter of around?
250-1500nm
Wavelengths in Mie scatter
320 to 650nm
Light source of nephelometry
- laser (most common)
- light amplification (stimulated emission of radiation)
- Tungsten Iodide lamp
Turbidimetry
Principle
measures reduction in light transmission by one particle formation
measure of blocked light or light reduced in large particles by a particulate matter in a solution
Turbidimetry
Clinical applications of Turbidimetry
- CSF
- urine
Phenomenon in Turbidimetry
Raleigh scatter
This refers to scattered light in any directions, particles are smaller than wavelengths of light.
Raleigh scatter
T/F: Raleigh scatter will scatted light in many directions, but not equally forward and backward.
False
equal lang
separate DNA and RNA based on size and electrical charge
Electrophoresis
separating charged constitutents of a sample by means of an electrical current
Electrophoresis
Migration of charged macromolecules in presence of electrical power through porous support
Zone electrophoresis
Porous support for electrophoresis
- Paper
- Cellulose acetate (densitometry)
- Agarose gel (DNA, RNA, proteins)
has a net charge that can be either positive or negative depending on pH conditions
Amphoteric
movement of buffer ions and solvent relatives to the fixed support
Electroendosmosis / Endosmosis
migration of small charged ions
Iontrophoresis
Five components of Electrophoresis
- driving force (electrical power)
- support medium (gel, cellulose paper)
- buffer
- sample
- detecting system
Detecting system for DNA
UV Transilluminator
Detecting system for Proteins
Densitometry
Support media for Electrophoresis
- Cellulose acetate
- Agarose gel
- Polyacrylamide gel
This separates serum into 5 bands.
Cellulose acetate
Support media for DNA, separates 10-15 bands, predominant component of agar
Agarose gel
For protein, separates based on charge and molecular size, 30 fractions, neurotoxic, used to study isoenzymes
Polyacrylamide gel
This is lighter than the molecule of interest.
Tracking dye
T/F: The brighter the band, the higher the protein is in electrophoresis
True
Procedure for Electrophoresis
- Loading of sample
- Electrophoretic migration
- Wash and fix
- Staining
- Visualization
- Quantification
5 Bands of Separated Proteins
- Albumin
- Alpha 1
- Alpha 2
- Beta
- Gamma
Stains for Proteins
- Amido Black
- Ponceau S
- Oil Red O
Stains for Lipids
- Sudan Black
- Fat Red 7B
Other stains
- Coomassie Blue
- Gold/Silver Stain
Stain that is very sensitive to nanograms of proteins
Gold/Silver Stain
Reagent to measure protein in CSF
Coomassie brilliant blue
Elution of volatile compounds based on boiling point, used to separate steroids, lipids, alcohols
Gas Chromatography
Fragmentation and ionization of molecules
Mass Spectroscopy
GC-MS is gold standard for?
drug testing
MS/MS is gold standard for?
newborn screening
used to determine structure of organic compound (e.g. MRI)
Nuclear Magnetic Resonance Spectroscopy
Migration based on electrical charge
Electrophoresis
Migration based on physical/chemical properties
Chromatography
Migration is through a pH gradient
Isoelectric focusing
Migration is through electro-osmosis flow
Capillary Electrophoresis
Measures light from excited to unexcited
Fluorometry
Fluorometry
Primary filter
UV light
Fluorometry
Secondary filter
Visible light
Detection systems in PCR is based on?
fluorescence
Chemiluminescence
Principle
measurement of luminescence produced by chemical reaction producing light emission