Internal Standard
Internal Standard — A known compound added to a sample at a fixed concentration before analysis, used to correct for variability in peptide quantification methods.
What Is an Internal Standard?
An internal standard (IS) is a known compound added to every sample at a fixed concentration to correct for analytical variability in sample preparation, injection, and detection. For peptide LC-MS/MS quantification, stable isotope-labeled (SIL) analogs of the target peptide are ideal internal standards because they co-elute and ionize identically.
Requirements
- SIL-IS: ¹³C/¹⁵N-labeled peptide. +6-10 Da mass shift. Co-elutes with native peptide
- Correction: Target area / IS area ratio corrects for matrix effects and injection variability
- Addition: Add IS at earliest possible step in sample preparation
Frequently Asked Questions
What is Internal Standard?
A known compound added to a sample at a fixed concentration before analysis, used to correct for variability in peptide quantification methods.
Why is Internal Standard important in peptide research?
Internal Standard is a fundamental concept in analytical as it relates to peptide science. It directly influences experimental design, compound characterization, and the reliability of research outcomes across biochemistry and molecular biology disciplines.
Authority Sources
- Internal Standard on Wikipedia
- Search Internal Standard on PubChem (NIH)
- Research articles on ScienceDirect