Hyphenation of Thermodesorption into GC × GC-TOFMS for Odorous Molecule Detection in Car Materials: Column Sets and Adaptation of Second Column Dimensions to TD Pressure Constraints

Round 1

Reviewer 1 Report (New Reviewer)

Comments and Suggestions for Authors

 

The authors attempt to present the advantages of using GCxGC-TOFMS for the detection of odorous molecules in car materials. In the experiments, authors set up various column combinations in the system, which provided the best separation and detection of odorous molecules. As stated in the introduction, the detection of odorous molecules is one of the challenges, especially with conventional GC methods, and it is proposed that using TD-GCxGC-TOFMS offers the best separation performance. It is an interesting article, yet there are several things that need to be clarified and revised."

 

1.     I suggest that authors present all detected (75-147 odorous compounds) instead of only 20 abundant compounds in order to demonstrate the sensitivity of these 2D GC/GC TOFMS.

 

2.   Please incorporate all chromatograms obtained from ABS, Dashboard, and Decor into the manuscript.

 

3.     In line 369, why did the authors not try to inject standard compounds into the system? I believe the injection of standard compounds can help evaluate the performance of the GCxGC system, including the efficiency of modulation, peak shape, and detector response.

 

4.     In line 370, on what basis did the authors make a statement regarding the estimation of compounds detected ranging from 10-1000 ng?

 

5.     Please rearrange the table of the compounds detected from different parts of the car into one table to make it easier to read. I suggest that authors add the class of compounds detected in the table

 

6.     Please revise the format of references to ensure compliance with the guidelines stated in the instructions for authors: https://www.mdpi.com/journal/separations/instructions.

 

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report (Previous Reviewer 3)

Comments and Suggestions for Authors

Dear authors,
Thank you for your excellent works on finishing revision point(s) that I gave in prior reviewing stages.
Herewith, I stated that this manuscript can be accepted as published article in Separations journal.

Sincerely,

Comments on the Quality of English Language

Minor editing of English language required

Author Response

Dear reviewer,

Thank you for your comments and your contribution to this manuscript

Sincerely

Reviewer 3 Report (Previous Reviewer 4)

Comments and Suggestions for Authors

The suspected results are now removed from the improved version. However, related to my comment in the first version "3) Identified compound profile (possible compound names with their retention times and peak areas) in each sample should be reported.", the retention time data in first and second dimensional separations are still missing from Table 2. These are important parameters in GCxGC. The running letters a), b), c) and d) in the caption of this table should also be removed or clearly defined. 

Comments on the Quality of English Language

Minor editing of English language/consistency check required

Author Response

Dear reviewer,

Thank you very much for your precious comments that highly improved the quality of this manuscript. Your last comments have been included to the revised version.

Sincerely

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript describes optimization and determination of odor volatile compounds generated from car materials using TD-GC×GC/TOFMS. First of all, I have no big question about potential usefulness of the study. However, TD- GC×GC/TOFMS determination of VOCs have been well reported. I agree that optimizations for analytical study is important of sensitive and accurate determination, although novel information for readers are quite limited in this manuscript with regards to separation science and analytical chemistry.

I think that the real value of the manuscript could be found in other journal.

 

Specific

1. Figure 4, axis labels must be described. (i.e., First dimension retention time (min))

2. A space must be inserted between numerical value and SI unit through the manuscript.

Author Response

Please see the attachement.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The topic of the identification of odor active compounds in car interior part is of importance and worth to be published in the submitted journal.

Unfortunately, in my opinion the content of the manuscript does not justify the title. It deals mainly with the optimization process of column selection testing various column combination for improved separation efficiency and for general issues of coupling a thermo desorption unit to a GCxGC instrument.

There is no information given about the relevance of specific compounds and/or substance classes. Further no information is given about the sensitivity of the method.

As the authors describe in their manuscript …it has been noted that minor changes in the composition of a material may have a strong impact on the perceived odour of the emissions….

the concentration, or even more important the OAV of individual compounds should be added to the manuscript.

As a proof of concept, a selection of two identical materials with different odor properties would be interesting to see the differences in the volatile composition. The authors mentioned the use of four different PP samples but no further details are given.

 

Also, some chromatograms should at least in the supplement displayed on the relevant contour plot area to demonstrate the complexity of these samples and also here in a “good-bad smell” comparison.  

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

This study displays essential information on the potential development of thermodesorption to GCxGC-TOFMS for the purpose of polar and odorous molecules detection. Although outlined in a fresh idea and logical framework, this study needs amendment to improve the quality of manuscript in order to meet the requirements by the separations journal. Especially, please carefully refer to the “INSTRUCTION FOR AUTHOR” on how to prepare the manuscript; the formatting, the writing style and etc.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

Based on the reviewing procedure that have been conducted by the reviewer, it is highly suggested that authors can firstly submit the manuscript to professional English editing company.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

Please see the attached file and carefully addressed all my concerns. 

Comments for author File: Comments.pdf

Comments on the Quality of English Language

Moderate editing of English language required

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The revised manuscript is well revised.

Reviewer 3 Report

Comments and Suggestions for Authors

Dear author,

I enclosed several revision points that supposed to be revised by author(s) in order to improve the quality of the manuscript. However, reviewer does not see any satisfying or significant improvement made by the author(s).
Therefore, unfortunately, reviewer would like to recommend a rejection and suggestion to make significant changes prior re-submission to this journal.
Thank you.

Comments on the Quality of English Language

Minor editing of English language required.

Reviewer 4 Report

Comments and Suggestions for Authors

Based on the provided answers, the authors have not got the information that I tried to transfer and still have not realized the scientifically incorrectness of the data especially in Figure 2. Regardless of the complexity of the configurated tubing, the part of "50cm*0.1mm" (OR "50+60cm*0.1mm" that the authors mentioned) should have the higher flow resistance and should be observed with the higher pressures in Figure 2 than the tubing part of "100 cm, 0.18 ID" (OR "100+60cm*0.18mm" that the authors mentioned). However, the Figure 2 showed lower pressures for the "50cm*0.1mm" which should be incorrect? If this is not corrected, the work is not acceptable to a reliable scientific journal. Please consult a person with significant GC or related experience to confirm this.

Comments on the Quality of English Language

Moderate editing of English language required