Toward the Systematic Identification of Microplastics in the Environment: Evaluation of a New Independent Software Tool (siMPle) for Spectroscopic Analysis

Microplastics (MP) are of major concerns for the society and currently in the focus of legislators and administrations. A small number of measures to reduce or remove primary sources of MP to the environment are currently coming into effect. At the moment, they have not yet tackled important topics such as food safety. However, recent developments such as the 2018 bill in California are requesting the analysis of MP in drinking water by standardized operational protocols (SOP). Administrations and analytical labs are facing an emerging field of methods for sampling, extraction and analysis of MP, which complicate the establishment of SOPs. In this review the state of the currently applied identification and quantification tools for MP are evaluated providing a harmonized guideline for future SOPs to cover these types of bills. The main focus is on the naked eye detection, general optical microscopy, the application of dye staining, flow cytometry, Fourier-Transform Infrared (FTIR) spectroscopy and microscopy, Raman spectroscopy and microscopy and thermal degradation by pyrolysis gas-chromatography/mass spectrometry (Py-GC/MS) as well as thermo-extraction and desorption gas-chromatography/mass spectrometry (TED-GC/MS). Additional techniques are highlighted as well as the combined application of the analytical techniques suggested. An outlook is given on the emerging aspect of nanoplastic analysis. In all cases, the methods were screened for limitations, field work abilities and, if possible, estimated costs and summarized into a recommendation for a work-flow covering the demands of society, legislation and administration in cost efficient but still detailed manner.