Meaning
Analytical discrepancies in the quantification of polymer additives or contaminants arise when the testing instrument has varying sensitivities for different chemical compounds. Correcting for response factor error prevents the miscalculation of substance concentrations in food-contact migration tests. This correction is made by comparing the detector response of a target compound to that of an internal standard.
Testing Pitfalls
Using a single generic response factor for multiple migrating substances can lead to the underestimation of hazardous chemicals. The response factor error can be large in gas chromatography when comparing compounds with different functional groups or volatility. If this systematic error is not resolved, the analytical report may falsely show that migration levels are within safe limits when they actually exceed the threshold.
Industrial Impact
Plastics manufacturers depend on precise analytical reports to declare the safety of their food packaging products. When response factor error causes a false low reading, it exposes the manufacturer to regulatory non-compliance during subsequent checks by authorities. Conversely, a false high reading can lead to unnecessary reformulation of the polymer, increasing compounding costs and wasting valuable additives.
Calibration Method
Establishing compound-specific calibration curves for every potential migrant is the most reliable way to eliminate these measurement discrepancies. While this calibration requires more laboratory time and resources, it reduces the response factor error to negligible levels. For complex mixtures with many unknown compounds, laboratories use semi-quantitative methods with conservative correction factors to ensure that all estimations remain on the side of safety.
This thorough calibration process is necessary when submitting safety files to food-contact authorities, where high accuracy is demanded to secure product approvals.
