Analytical Techniques for Non Intentionally Added Substances in Recycled Plastics
Non-target HRMS screening combined with toxicological threshold evaluation provides the empirical basis for verifying recycled plastic safety before market entry.
Post Consumer Resin Traceability
Meaning
Documented chain of custody procedures allow processors to verify the origin and chemical history of recycled feedstock. Post consumer resin traceability assigns a unique identifier to material batches as they move from collection points through sorting facilities to extrusion lines. This framework defines the physical and digital trail necessary to confirm recycled content claims against regulatory requirements.
Accurate data regarding the provenance of plastic waste prevents the commingling of non-recyclable materials with high-grade reclaim.
Processing Verification
Injection moulding machines require precise rheological stability to maintain cycle consistency during production. When post consumer resin traceability remains weak, fluctuations in molecular weight or impurity levels force operators to adjust injection pressure and holding times unpredictably. A standard material specification describes the range of physical properties, whereas a part specification demands adherence to specific mechanical tolerances under load.
Virgin economics rely on predictable supply chains, while regrind economics suffer when the ratio of unknown contaminants forces a reduction in throughput speed. Drift in melt flow rate occurs if an unidentified stream of polymers enters the hopper, which produces dimensional instability in the final moulded part.
Audit Accuracy
Independent certification bodies assess the integrity of records linking incoming bales to outgoing pellets. Mass balance accounting provides the statistical proof that the volume of output resin does not exceed the documented input of validated waste. Each link in the supply chain maintains logs showing transit times, supplier certifications and contamination percentages per pallet.
Discrepancies within these logs indicate a failure in the documentation protocol rather than a physical flaw in the resin itself.
Chemical Integrity
Analytical labs perform selective testing to detect non-polymer markers that distinguish food-grade recyclate from industrial waste sources. High-resolution gas chromatography measures the residual volatile organic compounds found within the polymer matrix. These readings establish the boundary between acceptable purity levels and feedstocks that risk mechanical failure under environmental stress.
Polymer degradation during the remelting phase alters these markers, so repeated thermal cycles require rigorous recalibration of the baseline values.