The doctoral dissertation in the field of Chemistry will be examined at the Faculty of Science, Forestry and Technology, Joensuu campus.
What is the topic of your doctoral research? Why is it important to study the topic?
My doctoral research focuses on identifying brominated flame retardants (BFRs) in plastic waste using a direct insertion probe mass spectrometry (DIP-MS) technique. BFRs are commonly used in electronics and automotive parts to improve fire retardancy, but they hinder plastic recycling and pose risks to human health and the environment. Due to their harmful effects, many BFRs are restricted or completely banned in the EU. Current analysis methods for BFRs are either slow or unable to detect individual compounds, making safe reuse of recycled plastics challenging.
The developed method enables rapid, compound-specific identification of BFRs directly from solid plastic samples with minimal sample preparation. The method supports circular economy goals by helping ensure that recycled plastics comply with legal requirements and are safe for reuse.
What are the key findings or observations of your doctoral research?
This doctoral research introduces the DIP-MS method for rapid, direct identification of BFRs and other additives in plastics without sample pretreatment, such as dissolution or extraction. The method also provides information about the composition of plastics in a single run. DIP-MS demonstrated effectiveness in the quantitative analysis of two commonly used BFRs, namely decabromodiphenyl ether (decaBDE) and tetrabromobisphenol A (TBBPA), and the results were consistent with the more traditional X-ray fluorescence (XRF) method across a wide concentration range.
Although the quantitative determination of hexabromocyclododecane (HBCD), was challenging due to its high reactivity, the detection limits for all studied BFR compounds were clearly below the current regulatory threshold of 500 ppm. Thus, the method offers the recycling industry an efficient tool for monitoring harmful substances, promoting circular economy goals, and enhancing safety in the reuse of plastics.
How can the results of your doctoral research be utilised in practice?
The results of the study offer a faster and more accurate method for identifying and quantifying harmful compounds, such as brominated flame retardants, in recycled plastic fractions. The DIP-MS method can be utilized in quality control of recycled materials to ensure the materials meet the requirements of EU chemical legislation and are safe for reuse.
Additionally, the developed DIP-MS method is also suitable for research purposes in analyzing the composition of various materials.
What are the key research methods and materials used in your doctoral research?
This doctoral research was part of the three-year EU-funded PRIMUS project. The model plastic samples used in the study were prepared by VTT Technical Research Centre of Finland. The samples were produced by compounding either high impact polystyrene (HIPS) or acrylonitrile butadiene styrene (ABS) with a BFR (decaBDE, TBBPA or HBCD) and antimony trioxide, which acts as a synergist.
The samples were analyzed using a temperature-programmed DIP-MS method, which enables the separation of compounds based on either their boiling point or decomposition temperature. The results were compared with XRF analysis, a commonly used method in the recycling industry. Unlike XRF, DIP-MS enabled compound-specific identification of the sample and proved to be a promising method for detecting regulated flame retardants in recycled plastics.
The doctoral dissertation of Krista Grönlund, MSc, entitled Improving plastic recycling: Direct mass spectrometric analysis of brominated flame retardants in synthetic polymer samples will be examined at the Faculty of Science, Forestry and Technology, Joensuu campus. The opponent will be Professor Chrys Wesdemiotis, University of Akron, USA, and the custos will be Professor Janne Jänis, University of Eastern Finland. Language of the public defence is English.
