Determination of additives as markers of microplastic contamination in the environment

Microplastics are mostly inert particles and, therefore, may exhibit low toxicity, but adverse health effects may result from chemical additives commonly added to plastics. Plastic additives serve to make the material workable and thermodynamically stable as well as acting as softeners, fillers and colorants. They may include hazardous chemicals, such as organic phosphates, phthalates, terephthalates, adipates, benzoates, citrates, sebacates, trimellitates, etc. The use of chromatography coupled to Mass Spectrometry for the analysis of plastic additives can constitute a valid support for the determination of microplastics in the environment. In this paper, results of investigation by chromatographic techniques coupled with mass spectrometry for analysis of phosphates, phthalates, terephthalates, adipates, benzoates, citrates, sebacates, trimellitates in settled dust of a workplace are reported. Both gas and liquid chromatography were used to separate the analytes with different chemical-physical properties. An excellent extraction and evaporation method preceded by an efficient clean-up process were fundamental steps for the subsequent proper detection of the analytes. LOD and LOQ values sufficiently low to detect the analytes in the environmental samples and good instrumental repeatability were obtained as a result of thorough cleaning cycles of sorbents and extraction cells, prior to the treatment of real samples. Such a step was crucial due to the ubiquity of many of the analytes investigated. Their presence in blank samples was minimized, obtaining statistically acceptable values to be subtracted from real samples. Our optimized method enabled the detection in samples of settled dust of most of the analytes investigated, some known as substances of very high concern and/or persistent, bioaccumulative, and possible reprotoxic endocrine disruptors. Safe, non-toxic, and biodegradable plasticizers were also found. This search for plastic additives in dust samples to which workers may be exposed has the dual purpose of identifying the presence of toxic chemicals and detecting the presence of microplastics.