Homogenization of samples and the use of triplicates produce more consistent results in the analysis of sediments with microplastics

The standardization of methods for studying microplastics (MPs) is a fundamental factor in improving reproducibility and comparability between studies. Some simple procedures can prevent the generation of potentially biased or inaccurate results. One of these procedures is the homogenization of sediment samples. To verify the effect of this step, we analyzed marine sediment samples collected from the same point in the Ubatuba region (SP, Brazil) and subjected them to two experiments: (i) without homogenization, and (ii) with homogenization. In the experiment without homogenization, three fractions of the sample were taken directly from the collection bottle, exactly as they were stored in the field, forming a triplicate set. In the experiment with homogenization, the sample was transferred from the collection bottle to a container and thoroughly mixed with a spatula. Then, three fractions were taken, forming a triplicate set. The samples were processed according to general quality control recommendations. The triplicates without homogenization resulted in an average of 126 ± 95 parts/g sed dw, with a minimum of 46 and a maximum of 232 parts/g sed dw. The homogenized triplicates resulted in 177 ± 44 parts/g sed dw, with a minimum of 130 and a maximum of 218 parts/g sed dw. Although the variances are not significantly different (F=4.677;p=0.352), the coefficient of variation for the non-homogenized experiment was 75.4 Also see: https://micro2024.sciencesconf.org/559530/document