Are we contaminating our samples? A preliminary study to investigate procedural contamination during field sampling and processing for microplastic and anthropogenic microparticles

Methods for sampling, analysis and interpretation of fresh and saltwater microplastics and anthropogenic microfibers have improved since 2004, but techniques for reducing and monitoring procedural contamination are still limited. Quantifying the amount of procedural contamination introduced to samples improves the robustness of counts of microplastics and anthropogenic microfibers in the environment. This pilot study investigates procedural contamination introduced into water samples when rigorous QA/QC anti-contamination protocols are used and removed. Procedural contamination accounted for 33.8% of the total microfibers and microplastics found in samples when protocols were used (n = 81), but 70.7% when they were not (n = 8). With the use of extensive control sampling and full characterization of samples (morphological, optical and chemical) it was possible to identify the predominant sources of contamination (crew clothing) and make recommendations for anti-contamination and procedural contamination identification/reduction protocols for shoreline and small/medium sized vessel sampling for microplastics and anthropogenic microfibers. [Display omitted] •Contamination prevention protocols for field sampling of microplastics were tested.•Team-wide anti-contamination protocols can reduce sample contamination by 36.9%.•Procedural contamination will occur even with the strictest protocols in place.•Comprehensive control sampling from crew clothing and textile items is recommended.•Starting analysis with a polarizing light microscope saves time and improves accuracy.