Selection Parameter
Specific ion pairs used in triple quadrupole mass spectrometry allow for the highly sensitive detection of target peptides. These MRM transitions consist of a precursor ion that represents the whole peptide and a product ion that represents a fragment. By monitoring only these specific pairs, the instrument ignores background noise from other chemicals.
This is the standard method for quantifying animal fibers in complex textile blends.
Fragmentation Logic
Breaking a molecule at a specific bond creates a predictable pattern of smaller pieces. In the mass spectrometer, the first quadrupole selects the precursor ion and the second quadrupole breaks it apart. The third quadrupole then filters for the MRM transitions that match the target fiber.
This two step process ensures that the signal comes only from the desired protein.
Measurement Fidelity
Using multiple pairs for each peptide increases the confidence in the final result. Setting the correct MRM transitions is essential for distinguishing between fibers that have very similar protein structures. A well defined method will monitor several transitions to confirm the identity of the marker.
This prevents false positive results in the lab report.
Analyte Confirmation
High speed switching between different ion pairs allows the machine to detect many different fibers in a single run. The intensity of the signal from the MRM transitions is proportional to the amount of the peptide in the sample. This data is used to calculate the percentage of cashmere or wool in a sweater.
It is a vital tool for modern textile forensic science.
