Molecular Offsetting
Chemical modification alters the mass of distinct peptide molecules by an identical value without changing their charge or retention time in simple chromatography. This phenomenon, known as isobaric mass shift, occurs when two different protein modifications result in the same total molecular weight increase. In animal hair analysis, this can complicate the identification of cashmere and mohair.
Fiber Distinction
Distinguishing these high-value fibers from cheap sheep wool requires separating these identical masses. If the isobaric mass shift is not resolved, the tester might confuse a treated sheep wool peptide with a premium camelid marker. This could cause the system to misclassify the fabric composition of a finished coat.
Analytical Challenge
Advanced tandem mass spectrometry is deployed to break the isobaric peptides into distinct daughter ions. By analyzing the fragments, the laboratory can identify where the mass change is situated on the peptide chain. This process reveals whether the shift comes from natural sequence differences or from artificial chemical processing of the fibers.
Production Audit
Fabric importers utilize these detailed analyses to verify that the wool has not been chemically treated to mimic cashmere. If the supplier has used chemical treatments to alter the mass of the wool, this molecular testing will expose the deception. It ensures that the premium prices paid by the buyer match the authentic physical properties of the delivered goods, protecting the brand’s reputation for quality in the retail marketplace.
