Measuring bad smells in recycled plastics

The analysis of plastic has gained increased attention in recent years, due to the global push to move to a circular economy – meaning the increased use of recycled materials to reduce waste. Manufacturers are being urged to produce or use more use post-consumer recycled (PCR) plastics. PCR plastics require more rigorous quality control (QC) measures to ensure that they will not produce volatile emissions that could be considered harmful or have a negative impact on the packaged product (e.g., malodours). However, there are several limitations with the existing methods used for the detection of odours from plastics – such as, human sensory panels, eNose detection and GC-MS. For example, in 1D GC-MS the odour profiles are dominated by aliphatics from the polymer itself, which easily mask the trace-level odorants (e.g., oxygenated species). Additionally, common sample introduction techniques such as headspace injection and solid phase microextraction (SPME) may lack the necessary sensitivity to capture the trace odorants. Therefore, with these approaches it is often not possible to identify the precise compounds responsible for malodours in recycled plastics, meaning that the recycling process cannot be improved, and QC failures continue to occur. Thermal desorption (TD) coupled with comprehensive two-dimensional gas chromatography and time-of-flight mass spectrometry (TD–GC×GC–TOF MS) can address these challenges, by providing high sensitivity and improved separation of the odour profiles, prior to confident identification of the individual analytes. Here, we demonstrate how TD–GC×GC–TOF MS can provide confident characterisation of complex odour profiles from recycled plastics, for fast and simple identification of the compounds causing QC failures. Once the key odorants are known, methods can be easily translated to TD–GC×GC–FID for routine screening in QC labs at production sites. More information here: https://www.sepsolve.com/solutions/ba...