Absorption
Definition
The purification technique in which a crude antiserum is mixed with antigen preparations from cross-reacting species. Cross-reactive antibodies bind those antigens and are removed by centrifugation, leaving behind antibodies specific to the target species.
- In spectroscopy
- Photon energy is taken up by a molecule, which moves to an excited electronic state.
- In serology
- Antigen is added to antiserum to bind and remove specific antibodies from the mixture.
Common questions
What does absorption mean in forensic spectroscopy?+
In spectroscopy, absorption is when a photon's energy is taken up by a molecule, which gets promoted to an excited state. This is the molecular basis of color and all spectroscopic analysis, allowing forensic analysts to identify substances by the wavelengths they absorb.
How is absorption used in blood typing?+
In ABO serology, absorption is the process of adding antigen to antiserum. Specific antibodies in the serum bind to the antigen and get removed from the mixture. This technique is used both to remove unwanted antibodies from reagents and to concentrate antibodies onto a bloodstain.
Why does absorption matter in forensic analysis?+
Absorption is fundamental to how substances interact with light and reagents. Understanding absorption lets forensic scientists identify biological evidence (like blood type), chemical compounds, and trace materials through spectroscopic and serological methods.
Related terms
- Titre
- The concentration of antibody in a solution, expressed as the reciprocal of the highest dilution at which agglutination is still visible. A...
- Adjuvant
- A substance co-administered with an antigen to amplify the immune response. Freund's Complete Adjuvant (FCA), containing killed mycobacteria in mineral oil, is...
- Antiserum
- Serum collected from an immunised animal containing antibodies directed against a specific antigen or group of antigens. In species identification, antiserum raised...
- Beer-Lambert Law
- A = εbc. Absorbance equals molar absorptivity times path length times concentration. The linear relation between absorbance and concentration that makes UV-Vis...
- Chromophore
- The molecular subunit responsible for a dye's colour, typically a conjugated double-bond system; chemical erasure destroys the chromophore while leaving the decolourised...
- Elution
- The release of antibody from antigen, typically by heating to 56-70 degrees Celsius. In the absorption-elution method, this step liberates the antibody...
- Fluorescence Lifetime
- The average time a fluorophore spends in the S1 excited state before emitting a fluorescence photon; typically 1-10 ns for organic fluorophores,...
- Fluorescence Quantum Yield (Phi)
- The fraction of absorbed photons that result in fluorescence emission (0 to 1); determines the brightness of a fluorescent signal and is...
- Indicator Cells
- Commercially prepared or freshly washed red cells of known ABO group used to detect antibody activity in an eluate or residual antiserum....
- Inhibition Index
- A quantitative measure of PCR inhibitor burden in a DNA extract, derived from the Ct shift of an internal positive control (IPC)...
- Jablonski Diagram
- An energy-level diagram showing the ground state, singlet excited states, and triplet state of a molecule, with arrows indicating absorption, internal conversion,...
- Kubelka-Munk Model
- A diffuse-reflectance theory relating the measured reflectance of a scattering-plus-absorbing layer to its absorption and scattering coefficients; used in forensic paint and...
Explained in these topics
- ABO Typing on Stains: Absorption-Elution and InhibitionIn serology, the process of adding antigen to an antiserum so that specific antibodies bind to the antigen and are removed from the mixture. Used both to deple...
- Antisera Production, Standardisation, and Cross-ReactivityThe purification technique in which a crude antiserum is mixed with antigen preparations from cross-reacting species. Cross-reactive antibodies bind those anti...
- Light-Matter Interaction: Absorption, Reflection, FluorescenceThe process by which a photon's energy is taken up by a molecule, promoting it to an excited electronic state; the molecular basis of all colour and spectrosco...