Meaning
Chromatographic signals represent the individual chemical components that have been removed from a polymer matrix during an analytical test. Interpreting extraction peaks allows lab technicians to identify and quantify additives, residues, and non-intentionally added substances present in a plastic part. Each signal appears at a specific retention time, which is characteristic of the molecular structure of the substance being measured.
Signal Identification
Analysis begins with the separation of the extracted liquid into its constituent parts using a column. The extraction peaks are then compared against a library of known standards to confirm the identity of each additive, such as irganox 1010 or various slip agents. The height or area of a peak is proportional to the concentration of that chemical in the original sample.
Baseline Resolution
Accuracy in quantification depends on the clear separation of one signal from another. When extraction peaks overlap, it indicates that the chromatographic conditions need adjustment or that the sample contains complex mixtures of similar molecules. High-resolution mass spectrometry is often used to resolve these overlaps and provide a more precise chemical fingerprint of the resin.
This resolution is especially important when identifying contaminants in recycled feedstocks that might interfere with the performance of the final moulded part.
Quantification Result
Integrating the area under the curve provides the mass of the migrant per unit of polymer.
