Reuse of consumable pipette tips for large-scale trace analysis of contaminants of emerging concern in wastewater

Abstract

Scientific laboratories generate substantial plastic waste, particularly from single-use pipette tips, especially in high-throughput analysis. This study explores the feasibility of reusing pipette tips through green solvent washing within a large-scale environmental monitoring program analysing >100 contaminants of emerging concern (CECs) in water, including complex matrices like wastewater. Eleven cleaning solvents were screened for their ability to reduce chemical carryover, with four selected for further evaluation based on analytical performance and environmental impact using AGREEprep scores (i.e., acetonitrile (MeCN), acetone, ethanol:water (EtOH : H₂O, 50 : 50 v/v) and 1% nitric acid (NA) aq)). Solvent effectiveness varied with analyte hydrophobicity and tip material. A four-wash protocol (W4) was required to achieve >98% reduction in carryover. Tests using wastewater and up to 40 reuse cycles (i.e., W160) confirmed additional challenges due to matrix complexity but showed consistent solvent performance trends. Tip integrity was assessed through scanning electron microscopy (SEM) and gravimetric analysis; some solvent-tip combinations (e.g., 1% NA (aq) with capillary piston tips) showed some degradation. Life cycle assessment (LCA) indicated that although MeCN provided high cleaning efficacy, its high global warming potential (GWP) limited its sustainability in repeated use. EtOH : H₂O (50 : 50 v/v) offered the best overall balance of cleaning performance, low GWP, and minimal tip damage. A compound-specific removal profile and a practical selection tool were developed to guide solvent choice and reuse strategies. This is the first comprehensive study demonstrating solvent-based pipette tip reuse as a viable, environmentally sustainable approach for trace-level chemical analysis in complex environmental monitoring workflows.