What Is Spectrophotometry? Flashcards
Examples in Biomedical Science..
Measurement of glucose in diabetics, disease diagnosis
What is Spectroscopy?
Study of molecular structure through the absorption, emission and scattering of light
Explain wavelengths of Electro Magnetic Radiation…
Long wavelength= low frequency (power)
high wavelength= high frequency (power)
EMR transmits…
Energy
Radiant Energy transmitted to matter as…
PHOTONS
Emitted and absorbed by matter (charged particles) at different wavelengths
Spectroscopy …
Measures how molecules absorb or emit radiation
Absorption = the amount of energy absorbed
How does EMR affect molecules?
EMR causes atoms to move from ‘ground’ to ‘excited’ state (energy/light in)
Absorption- electrons in high energy state
Emission- electrons back to original state (energy/light out)
What does a spectrophotometer do?
Measures molecular absorbance of EMR
Laws of light absorption?
Transmittance= lt/l0- proportion of light passing through substance. Lt= light leaving sample l0= light entering sample
Beer-Lambert Law
- Absorption of light is related to concentration of molecules.
- Absorption of light is related to length of light path.
Also known as…
A=e l c A= absorbance e= absorption coefficient (constant) I= length path (cm) (constant) C= concentration
If concentration increases, absorbance will…
INCREASE
Reasons for Beer-Lambert failing
Sample may aggregate so wavelength not correct
Cloudy solution
Sample to concentrated for detector to measure efficiently
What is fluorescence spectroscopy?
Fluorescence occurs when a molecule absorbs light photons from the uv spectrum.
Then emits fluorescent light photons as it returns to ground state
Why is it good?
Quick
Non evasive
High sensitivity (low concentrations needed).
Diagnosis of cancers
