TD-PTR-MS for nanoplastics research – high sensitivity and big challenges

Thermal Desorption – Proton Transfer Reaction – Mass Spectrometry (TD-PTR-MS) is a sensitive method capable of measuring nanoplastics in environmental samples. The method works on the principle that different types of plastic have different melting points (also different from many organics in the matrix), and they release rich (semi)volatile organic compounds signal (smells) when heated up. A gradual increase of the sample temperature combined with real-time, quantitative mass spectrometry (PTR-MS) allowed us to selectively measure the type and concentration of the nanoplastics. Data processing involves multiple ions associated with thermal degradation products of plastics, which ensures selectivity in identifying different plastic types.However, the method is procedural and challenging. The sampling practice, sample treatment, instrument's operational settings, and data processing can result in large uncertainties, which need to be addressed in each experiment. Here we discuss these analytical challenges in the context of complex environmental nanoplastic measurement and provide recommendations for good experimental practice and robust quality control.