Meaning
Intensity distortion of mass peaks that occurs when the concentration of a chemical changes during a single detector scan. If a compound is eluting rapidly from a gas chromatograph, the amount of material entering the ion source rises or falls while the mass analyzer is moving through the spectrum. This spectral skew makes the resulting data look different from a reference library entry.
It happens frequently in high-speed screening of polymer volatiles where peaks are very narrow.
Measurement Distortion
High concentrations of a resin outgassing product can saturate the detector and worsen the effect. When the front of a peak is scanned, the intensities of the lower masses are underrepresented compared to the higher masses. This leads to a lopsided spectrum that is hard to interpret.
Scan Speed
Modern instruments use time-of-flight technology to collect all masses at once and avoid this problem. Older scanning systems move from low to high mass over a fraction of a second. Increasing the scan speed reduces the magnitude of the shift.
Identification Error
Failure to account for the concentration change leads to the wrong chemical name being assigned to a peak. Software identifies the wrong molecule. This causes false alarms in quality control reports for automotive interior air quality.
