Analytical Techniques Flashcards
Wavelength for Visible light
400-700 nm
It takes advantage of the property of colored
solutions to absorb light of specific wavelengths.
Spectrophotometry
Provide incident light for the system
Light source
- For visible and near infrared
region spectrum - Commonly used in the
laboratory
Incandescent tungsten or tungsten iodide lamp
Minimizes the unwanted or stray light and
prevents the entry of scattered light in the
monochromator system
Entrance Slit
Isolates a specific wavelength from the light
source
Monochromator
- Controls the width of the light beam
- Could only allow a narrow fraction of spectrum to
pass through and reach the sample cuvette
Exit slit
- Also known as cuvette or analytical cell
- Holds the solution of which the absorption is to be
measured
Sample cell/Cuvette
Converts transmitted radiant energy into an
equivalent amount of electrical energy
Photodetector
Most common type of
photodetector used in
spectrophotometer because it
could measure visible and UV
region
Photomultiplier tube
- Has a beam splitter that splits the
monochromatic light into two
components
○ First component goes to the
patient sample cell.
○ Second component goes to the
standard material or reference
cell.
Double-beam spectrophotometer
Measures light emitted by excited atoms
- Used to measure sodium, potassium and
lithium because the are easy to excite
Flame Emission Spectrophotometry (FES)
Principle of FES
Flame using propane is used to excite
the atoms (higher energy state)
It is used to correct the variation in flame and atomizer characteristics
Internal Standard
Internal standard for Lithium
Cesium
