Cross-contamination pathways in the analysis of plastics and related chemical compounds: Good laboratory practices and tips

The analysis of plastics and related chemical compounds, such as plasticizers, flame retardants, and micro- or nanoplastics, often requires working at trace levels, where even minimal contamination can significantly affect results. However, many of these target analytes are also present in common laboratory materials and environments, increasing the risk of cross-contamination. We identified six major cross-contamination pathways frequently found in analytical workflows: (I) laboratory materials, (II) environmental contamination, (III) human handling and manipulation, (IV) solvents and reagents, (V) cleaning and sample preparation, and (VI) instrumental and system-related contamination. For each of these, preventive measures and good laboratory practices are suggested based on both experimental experience and examples in the literature. As a general recommendation, procedural blanks should be included throughout the analytical process, and contamination risks should be anticipated as early as the experimental design stage. This work provides a structured reference to support more reliable and reproducible data generation in the analysis of plastic-related contaminants. Researchers are further encouraged to evaluate contamination risks throughout the workflow and to report them transparently in their publications. • Six main pathways of cross-contamination in plastics analysis are identified • Practical tips are offered to prevent contamination in plastic trace-level workflows • Procedural blanks are key to detect and control background contamination • Tips and solutions are shared to improve data quality in plastic compound analysis