Chain-length-dependent tissue biodistribution of polyethylene glycol oligomers with 9-20 subunits revealed by green UPC2-MS/MS.

Polyethylene glycol 600 (PEG600) is a widely used polydisperse polymer employed as a food additive. However, its safety profile remains incompletely understood, primarily because conventional analytical methods cannot resolve its tissue distribution at the level of individual oligomers. To address this gap, we developed a green analytical method based on ultra-performance convergence chromatography-tandem mass spectrometry (UPC2-MS/MS) for the specific quantification of twelve PEG600 oligomers (n = 9-20) across ten rat tissues. Optimization of ammonium adduct detection combined with post-column makeup flow significantly improved sensitivity and mitigated ionization suppression associated with supercritical CO₂ mobile phases. The validated method achieved complete baseline separation within 3.7 min. Tissue distribution analysis revealed chain-length-dependent accumulation patterns. High scores on the Greenness Evaluation Metric for Analytical Methods (GEMAM: 6.376) and the Blue Applicability Grade Index (BAGI: 80.0) confirmed the environmental sustainability and practical utility of the method.