Abstract
Polymer blends are used to achieve tailored properties, but the quantification of their components remains difficult. We developed an ultraviolet–visible spectrophotometric method with a two-step pretreatment that involves the conversion of polylactic acid (PLA) into methyl lactate via alcoholysis and then into sodium lactate through alkaline hydrolysis, followed by detection with ferric chloride at wavelengths from 400 to 410 nm. The method demonstrated linearity, with a correlation coefficient above 0.99. For PLA and polypropylene blends with proportions that ranged from 10 to 100 wt%, the bias was less than ± 4%, and the relative standard deviation was less than 7%. Conversion and identity were confirmed via Fourier transform infrared and proton nuclear magnetic resonance spectroscopies. Selectivity was validated in blends with polybutylene adipate–coterephthalate, polyhydroxybutyrate, and cellulose acetate, with absorbance deviations within ± 0.03. This cost-effective method enables reliable quantification for biodegradable plastic certification.
Data availability
The data that support the findings of this study are available from the corresponding author upon request.
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Acknowledgements
This work is financially supported by the Korea Ministry of Environment (MOE) Graduate School, which specializes in integrated Pollution Prevention and Control Projects.
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T.G.L. managed the whole project, designed all the experiments, and jointly wrote the manuscript. S.M.J. conducted the experiments, analyzed the data, and wrote the manuscript.
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Ji, S.M., Lee, T.G. A fast and accurate UV–vis method for the quantification of polylactic acid in biodegradable plastics. Sci Rep (2026). https://doi.org/10.1038/s41598-026-42821-4
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DOI: https://doi.org/10.1038/s41598-026-42821-4
