Isolation, Characterization and Structural Elucidation of Polybutylene Terephthalate Cyclic Oligomers and Purity Assessment Using a ¹H qNMR Method

Round 1

Reviewer 1 Report

I think that this is a good paper and merits publication. I recommend the authors to include in the reference list additional references where other oligomers were syntetized and purified for quantitative purposes in food packaging materials studies, such as

Determination of oligomers in virgin and recycled polyethylene
terephthalate (PET) samples by UPLC-MS-QTOF

Analytical & Bioanalytical Chemistry, 2018; 410 (9): 2377-2384, DOI:10.1007/s00216-018-0902-4

Author Response

Dear reviewer, thank you very much for your time and effort to revise our work. Your suggestion and comment to include certain references, referring to other purified or synthetized oligomers, has been already implemented to the manuscript.

Reviewer 2 Report

This manuscript describes four PBT cyclic oligomers have been isolated and purified from a PBT raw material with an automated preparative HPLC-DAD system. Also, the authors examined that comprehensive characterization of the  compounds  was  performed  using  UHPLC  with  high  resolution  time-of-flight  mass spectrometry,  Fourier-Transform  Infrared  spectroscopy,  Differential  Scanning  Calorimetry  and Nuclear Magnetic Resonance spectroscopy. The purity of each oligomer was assessed using a 1H qNMR method and ranged from 96.1 % to 97.0 % for PBT tetramer and trimer respectively. In consequence, the purities were ranged from 96.1 % to 97.0 % for PBT tetramer and trimer respectively.

The systematic fundamental study of development of new analytical method and purification is valuable, and worth publishing in this journal, I think.

Author Response

Dear reviewer, thank you very much for your time and effort to revise our work.