One Material, Thirteen Laboratories
Untargeted screening for non-intentionally added substances (NIAS) is an important tool for characterising the chemical profile of PET materials intended for food-contact applications. However, comparing results from different laboratories can be challenging when different analytical methods are used.
A recent interlaboratory study involving 13 laboratories provides a clear illustration. Each laboratory analysed the same material using its own commercial methods, including GC-MS, GC-MS/FID and LC-(HR)MS. The results varied depending on the analytical techniques used, as well as on standards, spectral libraries and reporting approaches. Greater consistency was achieved when more closely aligned methodologies were applied.
These findings demonstrate a key limitation: results from different NIAS screening programmes cannot be compared directly without taking differences in analytical methods and reporting practices into account.
“With NIAS, an analytical result always needs to be considered together with information about how it was obtained. Differences between laboratories do not necessarily mean that one is right and the other is wrong. They can result from the analytical method, the scope of the analysis or the way substances are identified. As the volume of data increases, so does the importance of data quality and comparability,” says Bernd Schwarz, Chief Chemical Officer at KÖR.
Importantly, differences in screening results do not, in themselves, demonstrate differences in material safety. Analytical findings need to be interpreted in context, with a clear distinction between what a method detects and what the available evidence supports in terms of safety assessment.
Material History Matters
The volume of analytical data available to the industry continues to grow. The challenge is to turn that information into meaningful, comparable and actionable knowledge.
A separate study of PET materials containing between 0% and 100% recycled PET (rPET), processed using different extrusion technologies, investigated both intentionally added substances and NIAS. The researchers found differences in the migration profiles of cyclic oligomers depending on the proportion of rPET and the processing technology used. Multivariate analysis also identified potential markers that could help distinguish between materials.
These findings underline why analytical results should not be viewed in isolation. Understanding what is present in a sample is important, but so is understanding the material’s composition and processing history.
“As the use of rPET grows, understanding the history of the material becomes increasingly important. If we want to develop a truly circular system, we need to understand not only what is present in a given sample, but also where the material comes from and how it has been processed. Combining this information with analytical results is essential for interpreting observed differences correctly,” says Raphaël Jaumotte, Technical Manager at PETCORE EUROPE.
