It matters how we measure - Quantification of microplastics in drinking water by μFTIR and μRaman

Majority of potable water microplastics are smaller than the 20 µm EU methodology limit for consumable water quality

“…These relatively high concentrations are likely attributed to the local water treatment process as tap water from this region is primarily sourced by treating surface water from the Garonne river (Toulouse Metropole, 2024). MP concentrations were estimated at 413 MPs (n/L) [0.096 µg/L] which in terms of mass is 35 times higher than concentrations reported in groundwater-sourced potable water in Denmark [0.0028 µg/L] (Maurizi et al, 2023), where ultrafiltration is not applied. This evidence supports the notion that ultrafiltration of potable water may lead to MP contamination in potable water.…”

“…The directive accepts a limit of detection of 20 µm despite MPs <10 µm being considered most relevant to human health (WHO, 2022). In addition, MPs <10 µm are significantly more abundant in potable water (Maurizi et al, 2023) and therefore it is crucial to encompass the entire size spectrum of MPs (1-5000 µm) for a comprehensive assessment of MP contamination in any product intended for human consumption.…”

Microplastic in Drinking Water: A Pilot Study

“…This difference could be due to the different analytical tools used: as illustrated at the beginning of this paragraph thanks to Maurizi et al's paper [43], the MPs amount detected had varied depending on the protocol and instrumental analysis, in fact, results obtained could differ due to the different instrumental performance of µ-FTIR and µ-Raman in relation to their detection limit. In fact, the limit of quantification in dimensional terms that for µ-FTIR was 50 µm while µ-Raman is able to investigate particles of nanometre dimensions.…”

“…The analytical protocol and method used play an important role in the MPs determination in the samples examined representing a criticality for this type of analysis. The study conducted by Maurizi et al [43] has observed how the amount of microplastics detected had varied depending on the protocol and instrumental analysis: from the analysis of the same set of water samples, taken at the inlet and outlet of the drinking water treatment plant, through µ-FTIR and µ-Raman, a different number of MPs can be observed. In particular, µ-FTIR obtained values of MPs lower (~150 times) than µ-Raman, which, instead, gave high values (input: 2500 ± 2000 N/m 3 , output: 1400 ± 1300 N/m 3 ) [44]; this could be caused by the limit of quantification in dimensional terms that for µ-FTIR was 50 µm, making, below this value, the µ-Raman the method of choice for MPs analysis in drinking water.…”

“…In addition, the final performance of the methods could also be affected by the protocol adopted for the samples prior to analysis and data processing step. This shows that this type of analysis is influenced not only by the nature of the contaminant, the type of matrix investigated, but also by the sampling, pre-treatment, analysis and data processing protocol optimised since it is necessary to reach a compromise between accuracy, time of analysis and requests from the state of the art [43].…”