PRELIMS WEEK 4 Flashcards
– depicts light as an energy that tends to travel in waves
SINE WAVE MODEL
The shortest wavelength comes from the:
Gamma Rays and X-Rays (diagnostic imaging)
Photons or packets of energy that travel in waves
ELECTRO-MAGNETIC RADIATION
The distance between the top and the bottom peak
AMPLITUDE
- Number of oscillations of waveforms for given time period
- Usually per second.
FREQUENCY
- Distance between two successive peaks, in a series of waves
- The measurement is horizontal
WAVELENGTH
Wavelength is ___________proportional to Energy and Frequency
inversely
EMR energy is _________ to frequency and ____________
to wavelength
. Directly proportional; inversely proportional
The longest wavelength in the visible spectrum is colored?
RED
Measurement of light intensity
PHOTOMETRY
The measurement of light intensity at selected wavelengths; uses monochromatic light
SPECTROPHOTOMETRY
- Talks about absorbances
- Way to measure end color intensities and the reactions that
can help us come up with our quantitative results
what type of photometry
ABSORPTION SPECTROPHOTOMETER
“The concentration of a substance is ____________ to the absorbance and inversely proportional to transmittance”
directly proportional
As light reaches the solution or sample the light coming from
a light source and the one that reaches the sample is known
as ??
INCIDENT LIGHT
– the solution lets go of or allows to pass through
TRANSMITTED LIGHT
a solution of exact known concentration
standaaard
This represents light that passes through a solution
transmittance
The function of the light source:
provide radiant energy
- “Wavelength selector”
- The one that isolates the specific wavelength of light that you
need for the test.
monochromator
Wedged pieces of glass that would rely on the principle of
light bending or refraction
prism
- Also called “diffraction gratings”
- Has grooves that would diffract light
gratings
The _________ would simply be in charge of preventing stay light from entering the monochromator.
entrance slit
The purpose is to focus the light coming from the light source.
collimating lens
the ____ cuvet has been used when working on the visible region,
glass
Detects transmitted light and convert it into electrical signals
to be able to generate quantities for the results
photodetector
- Also known as a photocell or photovoltaic cell
- Simplest, doesn’t require a power source
barrier layer cell
Composed of positive and negative component, a cathode,
and an anode.
phototube
Highly sensitive due to electron multiplication through the use
of modified anodes (dynodes)
photomultiplier tube
- Measurements can only be done one at a time, you measure
first the standard, then the sample. - There is only one sample compartment, one cuvet
compartment
single beam
- Uses dichroic mirror – used to reflect some light to the other
compartment
double beam in SPACE
There are intervals created, at one point light is directed to
the sample, at another point it is directed to the reference
compartment through the rotating chopper
DOUBLE BEAM IN TIME
refers to the wavelength at more than ½ of the peak of transmittance.
SPECTRAL BANDPASS OR BANDWIDTH
_____________ Accuracy
Use potassium dichromate solutions for assessment
photometric accuracy
made possible when a sample you are measuring in the reaction happens on a solid surface.
reflectometry
the start of the use of dry slides for chemistry analysis.
Kodak Ektachem Analyzer
Basic Working Principle: Electron excitation – flame will be
used to excitable atoms which emit their own radiant energy.
Uses internal standards: Lithium or Cesium
emission flame photometer
- We are after the light absorbed by the atoms upon being
dissociated from their chemical bonds.
atomic absorption spectrophotometer
- More sensitive than flame photometry and
spectrophotometer techniques. - It cannot be used for larger molecules (glucose, cholesterol),
they would only involve atoms.
also uses flame
atomic absorption spectrophotometer
______________ is used that would accomplish the chemical
bond dissociation by the use of electricity instead of heat.
Graphite furnace
- The classic light source – has to be composed of the atom
you are measuring - Has to be composed by the atom you are going to measure
hallow cathode lamp
__________ law - Whatever the wavelength of light emitted
or produced by a particular ion is also the wavelength of light
it absorbs.
Kirchhoff’s
- We are after light emission by certain substances.
- Involves light emission but not that sensitive & specific.
- This type of light production is not native to all substances.
luminescence
- It involves chemical/redox reaction, involving some enzymes
they end up with light production (what we measure). - Tends to be more sensitive than ordinary spectrophometery
techniques.
chemiluminescence
- Light emission in a triplet excited state.
- Involves unpaired electrons.
- Much longer decay time →
phosphorescence
- Must have a light source to provide energy (excitation signal)
to wake up the fluorophores. When the fluorophore wakes
up, it will emit its own light.
fluorometry / molecular emission spectrophotometry
_______ Signal: The light coming from the light source.
It has a shorter wavelength, thus more energy.
Excitation
Difference between the excitation and emission signals in flouremetry
stoke’s shift
Fluorescence signals decrease because of
these environmental changes.
quenching
- Selects the light coming from the light source and produces
what is needed for the fluorophore (selective).
primary monochromator
- Positioned at a right angle from the Cuvet.
- wants to avoids light
photodetector
- Called as light scattering techniques
- The positive result is not an end color or light emission but
rather formation of particles by certain reactions.
particle formatioln
- Measurement of light scattering at various angles by particles
in solution with respect to the light source.
nephelometry
- Amount of light blocked by a suspension of particles in
solution. - Only uses one 180-degree angle
turbidimetry
Which technique may be used to measure precipitation
reactions?
A. Atomic Absorption
B. Chemiluminescence
C. Fluorescence
D. Nephelometry
d nephelometry
Uses more than one wavelength selector:
A. Atomic Absorption
B. Chemiluminescence
C. Fluorescence
D. Nephelometry
c fluorescence
involves measurement of voltage differences between two kinds of electrodes: Reference & Measurement electrodes.
potentiometry
Measurement of potential or voltage differences at a constant
current it is governed by the
nernst equation
- Most commonly used reference electrode.
- It is composed of mercury and potassium chloride solution.
what type of reference electrode
calomel electrode
- Involve Faraday’s Law and electrical current measurements.
- Well-known as a method for chloride measurement.
coulometry and amperometry
It is the coulometric and
amperometric technique.
cotlove chloridometer
Use for the measurement of PO2
(partial pressure oxygen from BGA) is amperometric.
clark electrode
Migrate to the positive (+) electrode which is the
Anode (Anion goes to Anode).
anions
You put a particular substance at a particular pH:
- If it is HIGHER than its isoelectric point, then it tends
to become
anionic
- Provide a certain pH
- Common routine pH: 8.6
buffer
Driving force of electrophoresis
electricity
Used to measure intensity of staining of
solid support medium.
densitometers
- It is referred to as a procedure that would be based on
physical properties.
chromatography
- Widely used and applicable for volatile substances.
- Good and reliable use for drug detection.
gas chromatography
Gold standard for drug detection.
Gas Chromatography-Mass Spectrophotometry Technique
Was introduced by Technicon in 1957; a contínuous flow,
single channel analyzer
autoanalyzer
Introduced by DuPont in 1970; the first discrete analzer
automatic clinical analyzer
Runs multiple tests one sample at a time or multiple samples
one test at a time; most popular and versatile type.
discrete analysis
LIQUID-LIQUID CHROMATOGRAPHY
PARTITION
WHICH PART OF A PHOTOMETER SENSES TRANSMITTED LIGHT??
WHAT KIND OF EMR WILL BE PRODUCED BY A SILICONE CARBIDE ROD
INFRARED LIGHT