Quantification of Synthetic Polyesters from Biodegradable Mulch Films in Soils

Soil biodegradable mulch films composed of the polyester polybutylene adipate-co-terephthalate (PBAT) are being increasingly used in agriculture. Analytical methods to quantify PBAT in field soils are needed to assess its soil occurrence and fate. Here, we report an analytical method for PBAT in soi...

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Bibliographic Details
Published in:Environmental science & technology 2020-01, Vol.54 (1), p.266-275
Main Authors: Nelson, Taylor F, Remke, Stephanie C, Kohler, Hans-Peter E, McNeill, Kristopher, Sander, Michael
Format: Article
Language:English
Subjects:
Agricultural land
Analytical methods
Biodegradability
Biodegradation
Chloroform
Deuteration
Environmental monitoring
Mathematical analysis
NMR
Nuclear magnetic resonance
Physicochemical properties
Polyester resins
Polyesters
Polylactic acid
Protons
Quantitation
Recovery
Soils
Solvent extraction
Solvents
Sorbents
Spectroscopy
Terephthalate
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Summary:Soil biodegradable mulch films composed of the polyester polybutylene adipate-co-terephthalate (PBAT) are being increasingly used in agriculture. Analytical methods to quantify PBAT in field soils are needed to assess its soil occurrence and fate. Here, we report an analytical method for PBAT in soils that couples Soxhlet extraction or accelerated solvent extraction (ASE) with quantitative protonnuclear magnetic resonance (q-1H NMR) spectroscopy detection. The 1H NMR peak areas of aromatic PBAT protons increased linearly with PBAT concentrations dissolved in deuterated chloroform (CDCl3), demonstrating accurate quantitation of PBAT by q-1H NMR. Spike-recovery experiments involving PBAT addition to model sorbents and soils showed increased PBAT extraction efficiencies into chloroform (CHCl3) with methanol (MeOH) as cosolvent, consistent with MeOH competitively displacing PBAT from H-bond donating sites on mineral surfaces. Systematic variations in solvent composition and temperatures in ASE revealed quantitative PBAT extraction from soil with 90/10 volume % CHCl3/MeOH at 110–120 °C. Both Soxhlet extraction and ASE resulted in the complete recovery of PBAT added to a total of seven agricultural soils covering a range of physicochemical properties, independent of whether PBAT was added to soils dissolved in CHCl3, as film, or as particles. Recovery was also complete for PBAT added to soil in the form of a commercial soil biodegradable mulch film with coextractable polylactic acid (PLA). The presented analytical method enables accurate quantification and biodegradation monitoring of PBAT in agricultural field soils.
ISSN:0013-936X
1520-5851
DOI:10.1021/acs.est.9b05863