Optimising sample preparation for FTIR-based microplastic analysis in wastewater and sludge samples: multiple digestions

Serena Cunsolo*, John Williams, Michelle Hale, Daniel Read, Fay Couceiro

*Corresponding author for this work

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The lack of standardised methodologies in microplastic research has been addressed in recent years as it hampers the comparison of results across studies. The quantification of microplastics in the environment is key to the assessment of the potential ecotoxicological impacts that this new category of emerging pollutants could have on terrestrial and aquatic species. Therefore, the need for protocols that are robust, simple and reliable together with their standardisation are of crucial importance. This study has focused on removal of organic matter with Fenton reagent from wastewater and sludge samples. This step of analysis was optimised by implementing a multi-digestion treatment on these samples that have high concentration of complex mixtures of organic matter, which interfere with microplastic enumeration. Moreover, this study targeted the detection of microplastics in the sub-hundred-micron size range due to the potential higher risks associated with smaller-sized particles and the limited data available from previous wastewater research. To show the validity of the method, triplicate samples of raw sewage, final effluent and sludge were independently spiked with two different sizes and types of microplastic polymers. Due to the various analytical stages required for the isolation of microplastics, time is a limiting factor in sample processing. The sequential digestion with Fenton reagent represents an inexpensive and time-efficient procedure for wastewater research providing effective degradation of organic material. These advantages over other currently available methods mean the method is suitable for analysis of large numbers of samples allowing robust monitoring data sets to be generated.
Original languageEnglish
Pages (from-to)3789-3799
Number of pages11
JournalAnalytical and Bioanalytical Chemistry
Early online date23 Apr 2021
Publication statusPublished - 1 Jun 2021


  • wet peroxide oxidation
  • organic matter
  • microplastics
  • wastewater
  • recovery
  • extraction


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