Mass Coordinate
Molecular mass divided by charge represents the fundamental coordinate used to identify and isolate specific peptide ions within a mass spectrometer. This precursor m/z ratio acts as a unique address for each protein fragment extracted from cashmere and wool fabrics. It allows the instrument’s mass filter to select only the target peptides for detailed fragmentation.
Species Identification
Every animal fiber has a unique genetic code that translates into specific proteins with distinct precursor m/z ratio values. By targeting these specific ratios, the system can distinguish sheep wool from alpaca or cashmere in a blended yarn sample. This measurement is highly precise and is unaffected by the fiber’s color or physical processing.
It provides a solid foundation for quantitative testing, allowing the lab to calculate the exact percentage of each fiber type in a finished piece of clothing.
Analytical Precision
If the measured precursor m/z ratio deviates from the expected theoretical value, the instrument may fail to target the peptide or select the wrong molecule. High-resolution mass analyzers are calibrated daily to keep these mass errors below a few parts per million. This calibration ensures that the testing system remains accurate and reliable over long-term use.
Mill Compliance
Fabric buyers rely on these mass signatures to audit the fiber declarations made by spinning mills. Identifying the correct precursor m/z ratio ensures that the testing laboratory can detect even small amounts of cheap sheep wool in a luxury cashmere batch. This prevents suppliers from using low-cost fibers to inflate their profit margins.
