Meaning
Chromatographic measurement errors arise from variations in how different chemical compounds respond to a detector compared to a reference standard. Accounting for relative response factor uncertainty is essential when analyzing polymer extracts for unknown non-intentionally added substances. This variable represents the risk that the calculated concentration of a contaminant is lower than its true value due to detector bias.
Measurement Variance
The detector’s response varies depending on the chemical structure, volatility and ionization of the compound. When using a single standard to quantify multiple additives, the assumption of equal response can introduce significant errors. This uncertainty is particularly high in gas chromatography coupled with mass spectrometry, where ionization efficiencies differ widely.
Failing to account for these differences can result in reported concentrations that are off by a factor of three or more, undermining the reliability of the chemical safety certificate.
Quantification Impact
Underestimating the level of an unknown migrant due to this uncertainty can lead to regulatory non-compliance. It can also cause disputes between the polymer supplier and the testing laboratory.
Uncertainty Mitigation
Chemists apply safety factors to the calculated concentrations to compensate for the potential underestimation of contaminants. Another approach is to use multiple standards that represent different chemical families found in the polymer matrix. These measures ensure that migration limits are never exceeded in food contact plastics.
