Using Pyrolysis-GCMS Analysis to Measure Microplastics in Compost
University of the Pacific PhD candidate Tommy Nguyen uses Py-GCMS to estimate quantities of microplastic polymers in various solids.
The sample preparation method includes removing 5 grams of solids and placing them in a boat for oven drying. A small amount of sample should then be frozen in liquid Nitrogen bath and placed in a cryo-crusher to achieve a homogeneous paste-like mixture. This mixture can be metered out into Ecocups for the pyrolyzer.
It is recommended that 2 replicates be prepared for each sample. Lab blanks, or empty cups, can be placed in the autosampler before, between, and after analysis.
Each cup will enter the pyrolyzer once the oven reaches a temperature of 600o C to allow for the complete combustion of the sample. Pyrolyzates go directly into the gas chromatograph and are read by the mass spectrometer according to their ion abundance and retention time. The analysis take about 30 minutes.
The method relies on F-Search MPs software for peak matching of 12 common plastic polymers. Each is reported out as mass per sample.