ANALYTICAL METHODS AND INSTRUMENTATION Flashcards
Red: ______ energy; _______ wavelength
lowest
highest
relationship of wavelength to energy:___________ proportional
INVERSELY
Violet : ______ energy; _______ wavelength
Highest
Lower
Visible light
400-700nm
UV light
<400
Short wavelength with high energy
UV light
Long wavelength with low energy
IR light
IR light
> 700
- most common analytical method
- most common type of assays in clinical chemistry
SPECTROPHOTOMETRY
measures the light transmitted by a solution in order to determine the concentration of the light-absorbing analyte
SPECTROPHOTOMETRY
different types of colored solutions should be analyzed in different wavelength
SPECTROPHOTOMETRY
provides continuous spectrum of polychromatic light
Light source
Tungsten-halogen, Tungsten-iodide lamp
Visible to infrared
Mercury-arc, Xenon lamp, Deuterium-discharge lamp
UV region
allows the entry of a narrow beam of radiant energy or light energy
Entrance slit
minimizes stray light or unwanted light
Entrance slit
light that enters and exits the entrance slit
Polychromatic light
- polychromatic light reaches it but monochromatic light comes from the monochromator
Monochromator/Wavelength selector
disperses polychromatic light into its separate wavelengths
Monochromator/Wavelength selector
- isolates a specific wavelength of interest
Monochromator/Wavelength selector
controls the width of light beam or bandpass
. Exit slit
- holds the solution containing the analyte to be measured
Sample cuvette/ holder
round-end cuvette
Sample holder/cuvette
Which is more preferred, round or square cuvette?
Square-end
measures and converts the transmitted light into an equivalent amount of electrical energy
Detector
Is the most sensitive Detector.
Photomultiplier tube
measure the magnitude of the current that is generated by the detector
Read-out Device/ Meter
- measures current of electrical energy
Read-out Device/ Meter
Governed by BEER’S LAW:
Read-out Device/ Meter
- the concentration of a substance is ____________ proportional to the light absorbed
DIRECTLY
- the amount of energy absorbed or transmitted by a solution is ____________ to the solution’s molar absorptivity and the concentration of solute
proportionalq
o Absorbed light is DIRECTLY proportional
o Transmitted light is __________ proportional
INVERSELY
Measures transmitted light directly
Read-out Device/ Meter
Absorbance is a ______ value form the transmitted light; absorbance is indirectly measured
DERIVED
makes one measurement at a time at one specific wavelength; simplest type of spectrophotometer
Single beam
contains two cuvettes or sample holders where one is for the specimen and the other is for reference solution of standard
Double beam
splits the monochromatic light into two components which pass through two cuvettes or sample holders
Double beam
all in internal component is duplicated except the light source
- instrument with 2 photodetectors
. Double beam in space
- only the sample holder or cuvettes are duplicated
Double beam in time
- one at a time detection by a single photodetector
Double beam in time
alternately passes the monochromatic light through the sample cuvette and then the reference cuvette
Double beam in time
- a technique that utilizes the phenomenon of molecular fluorescence
- involves measurement of emitted fluorescent light
FLUOROMETRY
absorb light and emit light in a longer wavelength; the emission of electromagnetic radiation that occurs when a molecule absorbs light at one wavelength and reemits light at a longer wavelength, when it returns to ground state with the excitation
event caused by photo illumination
- Fluorescence
emitted light has the same wavelength to the absorbed light
Phosphorescence
molecule that fluoresces (in all direction
- has an absorption spectra @WL 300-700 nm
Fluorophore
released from light source which has high energy with shorter wavelength that will pass through
entrance slit aka attenuator will control the amount of light that will reach the excitation monochromator which is responsible for
isolating a particular wavelength of excitation light that is best absorbed by the analyte of interest.
Excitation light or Excited light:
the specific wavelength of excitation light will pass through the _______ and through the _____ which contains the analyte of interest
exit slit
sample
Molecules in the sample will _______ excitation light and they will become excited. When the molecular energy of molecules is higher than the heat of the environment, it will release excess energy in the form of __________ in all directions.
absorb
fluorescence
- detects even the lowest energy level of light and amplifies more light compared to the PMT
- more ideal in molecular studies
- charge couple detector
- presence of molecules that absorbs or steals the fluorescence of the analyte leading to decrease fluorescence
Quenching
increase temperature resulting to more collisions in solutions thus, energy molecules will be converted to heat energy instead of
fluorescence hence, decrease fluorescence
Temperature
- relationship of temperature to fluorescence —-> ________ proportional
inversely