Measures to prevent cross-contamination in the analysis of microplastics: A short literature review

Marine environments are the most studied habitats when addressing microplastic pollution. However, there are no standardized methodologies for this analysis, so methodologies are often adapted by researchers. This situation has raised doubts concerning the reliability and reproducibility of results that are related to the null or little use of measures to avoid cross-contamination. The objective of this work was to carry out a short review and analyze the different measures that have been reported in research articles for different marine habitats, published in the ScienceDirect database in 2020, to avoid cross-contamination during fieldwork and laboratory work. From the 115 analyzed articles, eight did not report measures at any stage, 61 took measures during sampling, and 98 did it in the processing stage. Even though most studies take steps to prevent cross-contamination, they do not specify the percentage of contamination avoided. However, from the concentrations of microplastics in the blanks and the total microplastic concentrations in the samples, we estimate that between 4.8 and 69 % of contamination is avoided in sampling and between 0.1 and 48.8 % in the laboratory. This shows the need to establish standards for sampling and sample processing, which must include measures regarding the marine environment studied and the stage addressed, as well as the minimum percentages that should be met for the data to be considered valid and reliable.