USP’s characterization of commercial poly(lactic-co-glycolic acid) utilizing SEC-Multi-Angle Light Scattering and Refractive Index techniques via Absolute Method approach

This research focuses on evaluating the data quality and reliability of Size Exclusion Chromatography with Multi-Angle Light Scattering and Refractive Index (SEC-MALS/RI) chromatography in determining molecular weight-related parameters in poly(lactic-co-glycolic) acid (PLGA) polymers. The study utilizes key metrics, particularly percent relative standard deviation (%RSD), to evaluate the precision across different data processing conditions. Exploring baseline selection of the chromatograms reveals that selection of the baseline based on the intrinsic shape of the chromatogram, rather than relying on elution peaks, improves consistency. The study emphasizes the critical role of result fitting in addressing systematic errors and sample heterogeneity, recommending the minima of the elution peak selection range for realistic molecular weight distribution representation. Analysis of light-scattering (LS) detector chromatograms highlights varying effects on different PLGA polymers, emphasizing the need for careful assessment and potential exclusion for precision improvement, especially in the presence of experimental artifacts. Across diverse PLGA polymers, the utilization of different column types, along with considerations such as baseline determination and peak selection, shows minimal variations in Mn, Mw, and polydispersity index (PDI), affirming the consistency of the methodology. The %RSD analysis further supports the methodology's precision, with values well within acceptable limits. In summary, this comprehensive evaluation of methodological conditions, including baseline selection, result fitting, LS detector data management, and column types, establishes a reliable SEC-MALS/RI chromatographic approach by Absolute Method for determining molecular weight parameters in PLGA polymers.