Meaning
Analytical evaluation limits define the concentration level below which chemical extractables from a polymer do not require identification or toxicological risk assessment. Establishing a screening threshold allows laboratory analysts to focus their resources on the chemical migrants that pose a genuine risk to consumer safety. This threshold is calculated based on the exposure scenario of the final part, such as a medical device or a food container, and the daily intake limits of the patient or consumer.
It acts as a filter to streamline the testing of complex plastic formulations that may contain dozens of trace additives.
Evaluation Limit
Numerical values of the limit derive from the threshold of toxicological concern for the given application. For high risk medical devices, this value is extremely low to ensure that even trace mutagens are detected. In contrast, food contact plastics may have a higher limit based on standard dietary exposure models.
Extractable Identification
Chemical peaks that rise above the determined limit must be identified and quantified using mass spectrometry. Any peak that remains below this screening threshold is recorded but does not require further chemical characterization or toxicity evaluation. This selective approach prevents the analytical process from becoming bogged down by insignificant trace impurities.
Risk Assessment
Using a standardized threshold ensures that the safety evaluation of moulded parts is both thorough and efficient. It provides a clear, defensible boundary for when a chemical migrant must be reported to regulatory authorities.
