Mass Spectrometry SRM Calibration Protocols for Cashmere Wool Blends
Selected reaction monitoring mass spectrometry quantifies cashmere wool blends down to one percent using species-specific tryptic keratin peptides.
Stable Isotope Aqua Standards
Isotopic Calibration
Synthetic peptides labeled with stable heavy isotopes are used as internal references to achieve absolute quantification of proteins in complex biological samples. In fiber testing laboratories, stable isotope aqua standards help measure the precise concentration of cashmere and wool markers. This reference is crucial for identifying the fiber ratio of high-grade blends.
Digestion Integrity
Spiking the sample with these heavy standards accounts for any peptide loss during the extraction and trypsin digestion steps. Because stable isotope aqua standards behave identically to the natural wool and cashmere peptides, they undergo the same chemical changes. This allows the software to normalize the final peak areas.
Precision Analysis
Chromatography systems separate the target peptides from the bulk of the sample matrix before the mass spectrometry scan. The mass shift provided by stable isotope aqua standards ensures that the reference signal is separated from the natural analyte signal. This allows for the precise measurement of the native peptide concentrations.
Market Regulation
Implementing this advanced reference standard technique provides the highest level of confidence in fiber composition reports. With stable isotope aqua standards, laboratories can deliver highly accurate results that withstand regulatory scrutiny. This testing helps apparel brands protect themselves from costly labeling lawsuits and ensures that consumers receive high-quality wool products.
The systematic use of these standards has transformed the verification of luxury yarn shipments.