Living with Breakthrough: Two-Dimensional Liquid-Chromatography Separations of a Water-Soluble Synthetically Grafted Bio-Polymer

Round 1

Reviewer 1 Report

In the manuscript by van de Ven et al., authors evaluated the use of various two-dimensional liquid chromatographic methods to characterize a water-soluble, synthetically grafted bio-polymer. The work is of interest and has enough novelty to allow its publication in the journal. In general terms it is also well developed, presented and discussed. I only have some minor comments that may help to improve the quality of the paper.

Specific comments

More keywords could be included.

The introduction section is too short. It should be lengthen. Authors should also try to provide a better and wider description of the problem and to highlight the novelty of the work. Authors should pay particular attention to this part of the work since it should be highly improved.

More data concerning IR identification should be provided (i.e. blank, number of scans, wavenumber range, etc.).

Line 156. Reagents or samples?

Authors should carefully revise the use of abbreviations, acronyms, etc. all over the text, specially in the headings of each section.

Figure captions. Authors should indicate the detection system (in some captions such data is missing). Please, also clarify the elution gradient when applicable (as they are they can be confusing).

Line 185. “This was thought to be…”. How can authors think so? I suppose they might support on other analysis…

I believe authors could add the chemical structures of PAA and MD and also that of the polymer HY (at least a tentative one).

Section 4 is the conclusions section not a “discussion” section.

The information provided by MS experiments is not sufficiently described in the text.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

In this work, van de Ven and co-workers have characterized a water-soluble biopolymer consisting of long poly(acrylic acid) chains which were synthetically grafted with maltodextrin molecules. To this, several liquid chromatographic techniques, including RPLC, HILIC and SEC, were used for initial reagents and final products characterization, complementing the analyses with an off-line characterization with Fourier Transform infrared spectroscopy and mass spectrometry. Besides, SEC-RPLC and HILIC-RPLC combinations were found to be interesting in order to provide more information on the grafting process. The results presented in this work show that the use of LCxLC techniques can provide very useful information about synthetic processes in combination with other characterization techniques typically used for polymers. In general, the work is interesting, and it could be considered for its publication in this journal, although some minor aspects should be considered before:

• In the Introduction section, some information about the interest of this kind of polymers, and especially the one characterised in this work, should be given. In general, this section could be highly improved.
• On several occasions, the possibility of using a PGC stationary phase in the first dimension with a RPLC in the second is mentioned in the manuscript. In fact, the authors tested it and include some information in the Supplementary Material. It could be very interesting to include this information in the manuscript and discuss more about the results obtained.
• Did the authors explore the use of other characterization techniques? Other techniques, such as differential scanning calorimetry, are commonly used for the characterization of polymeric materials.
• In relation to IR measurements, more data about instrumental conditions should be provided.
• More should be discussed in the manuscript about the IR and MS spectra obtained.
• Elution gradients are confusing in many cases. Try to describe them in more detail.
• Section 4 should be Conclusions section instead Discussion section.
• Line 370: and “a” is between “130” and “min”. It should be a space.
• Abbreviations and acronyms should be revised throughout the manuscript.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

This paper describes attempts to establish whether grafting maltodextrin salts onto poly(acrylic acid) chains are successful. The authors go into great detail in discussing the results they obtained throughout their experiments, and are to be commended for their perseverance in trying to discern whether their grafts were successful. Additionally, the quality of the english and scientific writing is exemplary throughout. 

However, there are a number of significant flaws in the mansucript as it is presented, including:

1. The authors state in their abstract that "conclusive information demonstrating the success of the grafting reaction could be obtained". In the main body of the paper however, the authors could only conclude that their results suggested reactions were successful, based on relative intensities of peaks and IR absorption bands of starting materials, which is not a conclusive demonstrable success. 
2. Throughout the text, the authors provide confusing and often contradictory commentary on their results, e.g. in line 187 in the same sentence the authors acknowledge that there was no separation between PAA and HY, but also state that the extent of the separation is encouraging and should be the basis of the next part of the research. 
3. The authors present and discuss every aspect of each of their experiments to the same exhaustive extent. The manuscript would be significantly strengthened if they considered which aspects where relevant to the main narrative, and edited their discussion to focus on the most salient outcomes of failed experiments.
4. The paper sections seem to be incorrectly titled. Section 3 is I think Results and Discussion, and Section 4 is Conclusions.

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The authors have addressed al the reviewers' comments. Therefore, I believe that the article is now acceptable for its publication in the journal.

Reviewer 2 Report

The authors have followed the indications given by the reviewers and have made the corresponding corrections. In general terms, the manuscript meets the requirements to be published now.

Reviewer 3 Report

The authors have made significant efforts to address the comments from my original review and I am happy that it now appropriate for publication.