A Green and Fast Ultra‐High Performance Supercritical Fluid Chromatography‐Tandem Mass Spectrometry Assay for Sensitive Quantification of Monomethoxy‐pentaethylene Glycol Amine in Rat Plasma: Application to Pharmacokinetic Study

ABSTRACT Here we present a novel, green analytical platform for the sensitive quantification of the short‑chain excipient monomethoxy polyethylene glycol amine, based on ultra‐high‐performance supercritical fluid chromatography‐tandem mass spectrometry. The core innovation is the effective coupling of supercritical carbon dioxide chromatography with the selective monitoring of protonated molecular ions ([M+H] + ), which collectively enhance sensitivity and minimize matrix interference. This method enables exceptionally rapid analysis, achieving baseline separation within 3.4 min, and demonstrates high sensitivity with a lower limit of quantification of 5 ng/mL in rat plasma. Comprehensive validation confirmed its robustness, precision, and accuracy across the analytical range. Its environmental sustainability and practical utility were quantitatively endorsed by excellent Analytical GREEnness (0.66) and Blue Applicability Grade Index (72.5) scores. As a demonstrative application, the validated strategy was successfully employed in a rat pharmacokinetic study, establishing a fast, green, and reliable analytical framework for the safety evaluation of PEGylated compounds.