Selected Molecules
Gas-phase parent molecules are selected in the first stage of a tandem mass spectrometer before being fragmented into diagnostic product ions. These precursor ions represent intact peptide chains extracted from the wool or cashmere fibers. Their specific mass-to-charge ratios are used to target particular animal species during analysis.
Diagnostic Separation
The instrument filters out all other masses to focus solely on the chosen precursor ions of interest. This selective filtering reduces background noise and improves the sensitivity of the analysis. Once isolated, the precursor ions are accelerated into a collision cell where they are broken down to yield unique product ions.
This step is necessary to confirm the identity of the target peptide, ensuring that the detected signal belongs to the authentic animal fiber rather than an environmental contaminant.
Fiber Discrimination
In textile testing, isolating these precursor ions allows the lab to distinguish between very similar hair fibers like cashmere and camel hair. Each animal species produces unique protein sequences that correspond to specific mass signatures. By targeting these mass signatures, the testing laboratory can confidently identify the composition of a yarn blend.
Technical Settings
Technicians must calibrate the mass filters to ensure they capture the correct parent masses during each run. Incorrect settings can miss the precursor ions completely, resulting in false negatives. This careful setup is essential for maintaining the accuracy and reliability of luxury fiber verification.
