Quantitative methodology for poly (butylene adipate-co-terephthalate) (PBAT) microplastic detection in soil and compost

With the increasing use of biodegradable plastics in agriculture and food packaging, it has become increasingly important to assess the effects of their fragmentation and mineralization in the environment (i.e., soil, compost). PBAT is a biodegradable polyester widely used in biodegradable mulch films that are intended to fragment and mineralize in soil. To study these effects, novel methodologies are needed to quantify PBAT microplastics in these diverse environments. This work seeks to answer whether gas chromatography mass spectrometry (GCMS) can be used as a tool to assess PBAT microplastics in soil. A method was developed that allows PBAT soil extraction by ultrasonication and GCMS quantification after a fatty acid methyl ester derivatization. To validate the method, an industrial compost degradation experiment was carried out to evidence the weight loss of PBAT film and quantify the micro- and nano-plastic generated from them. The presented method improved the existing resolution by, at least, one order of magnitude compared to reported methods. In conclusion, a novel, simple, affordable, and reproducible methodology for PBAT microplastic detection was developed improving the limits of detection and quantification. The method was tested on an industrial compost experiment, demonstrating the ability to trace the totality of the plastic over time, evidencing that PBAT is consumed in the industrial compost environment.