Scripps Laboratories

Summary of Spectroscopic Techniques

Electron Spin Resonance Spectrophotometry

Principle
Detection of magnetic moment associated with unpaired electrons.
Main Uses
Research on metalloproteins, particularly enzymes and changes in the environment of free radicals introduced into biological assemblies, e.g. membranes.

Flame (Emission and Absorption) Spectrophotometry

Principle
Energy transitions of outer electrons of atoms after volatilization in a flame.
Main Uses
Qualitative and quantitative analysis of metals, particularly in clinical biochemistry. Emission techniques are for routine determination of alkali metals. The absorption technique extends the range of metals that may be determined and the sensitivity.

Infra-red and Raman Spectrophotometry

Principle
Atomic vibrations involving a change in dipole moment and a change in polarizability, respectivley.
Main Uses
Qualitative analysis and fingerprinting of purified molecules of intermediate size. Mainly used in research.

Mass Spectrophotometry

Principle
Determination of the abundance of positively ionized molecules and fragments.
Main Uses
Qualitative analysis of small quantities of material (10-6 to 10-9 g), particularly in conjunction with gas liquid chromatography. Mailnly used in research, but has high potential for the rapid determination of the primary structure of peptides.

Nuclear Magnetic Resonance Spectrophotometry

Principle
Detection of magnetic moment associated with an odd number of protons in an atomic nucleus.
Main Uses
Research into the structure of organic molecules of molecular weight less than 20,000 daltons.

Spectrofluorimetry

Principle
Absorbed radiation emitted at longer wavelengths.
Main Uses
Routine qualitative and quantitative analysis, enzyme analysis and kinetics, and detection of changes in protein conformation. More sensitive at lower concentrations than visible and u.v. absorption spectrophotometry.

Ultra-violet and Visible Light Spectrophotometry

Principle
Energy transitions of bonding and non-bonding outer electrons and molecules, usually delocalized electrons.
Main Uses
Routine qualitative and quantitative biochemical analysis including a vast number of colorimetric assays. Enzyme analysis and kinetics. Difference spectra, turbidometry, and nephelometry.

Technical Info

Spectroscopic Data